Proceedings Volume 1230

International Conference on Optoelectronic Science and Engineering '90

DaHeng Wang
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Proceedings Volume 1230

International Conference on Optoelectronic Science and Engineering '90

DaHeng Wang
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Volume Details

Date Published: 1 July 1990
Contents: 1 Sessions, 277 Papers, 0 Presentations
Conference: The Marketplace for Industrial Lasers 1990 1990
Volume Number: 1230

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Front Matter: Volume 1230
This PDF file contains the front matter associated with SPIE Proceedings Volume 1230, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.
Some recent progresses on opto-electronics in China
Da-Heng Wang
A brief account on some of recent developments on opto-electronics and relevant subjects in China is given. Topics include opto-electronic systems, opto-electronic materials and devices, opto -electronic integrating technology, image converters and streak camera tubes, optical information processing, special laser systems and ultra-short laser pulses, optical chaos, fiber optics etc.
Coherence control by acousto-optic multifrequency Bragg diffraction
Jari Turunen
We propose a novel method for reducing the spatial coherence of a laser beam by sound-light interactions. Use is made of a combination of Bragg diffraction and Raman-Nath diffraction in an acousto-optic deflector. Applications in beam splitting, beam profile shaping, and generation of highly directional, partially coherent wavefields are dis- cussed and demonstrated.
Fabrication of acousto-optic modulators on GaAs substrates
Acousto-optic modulators were fabricated on the GaAs substrates. Low loss hetero- structure GaAs/AlGaAs waveguides of 0.8 dB/cm at 1.3 pm wavelength have been fabricated by the use of the MBE method. ZnO film was then deposited on the waveguides by r.f. sput- tering. A pair of interdigital transducers (IDTs) was made on the ZnO/GaAs waveguides using conventional photolithography and lift-off technique. The total insertion loss measured at a central frequency of 25.37 MHz was 20 dB. Fresnel lens was used to focus and collimate the laser beams. The Ge photodiodes were used attached to the A-O devices as the detectors. Finally the integrated A-0 modulators were made and studied.
Development of weatherproof LED
Shouji Usuda
Light emitting diodes (LEDs) incorporating a newly developed passivation LED chip and sealed with an organic ADC monomer have excellent characteristics in weather resistance, heat resistance, and chemical resistance. Various weatherproof tests have proved that the weatherproof LEDs are applicable to outdoor use where conven- tional epoxy LEDs cannot be used.
Optical properties of a liquid crystal microlens
The liquid crystal microlens can be obtained by molecular orientation effects in a non-uniform electric field which is produced by the asymmetric electrode structure with a hole-patterned electrode and an ITO coated counter electrode. In this cell, an axially symmetric distribution of the liquid crystal molecules; that is, a radial distribution of refractive indices is achieved. Relations between the optical properties and the geometric factors, such as the diameter of the hole-pattern and the thickness of the cell are investigated. An optical fiber coupler with a variable coupling efficiency is prepared and its switching properties are discussed.
Growth of Bi12GeO20 (BGO): influence of stoichiometry and doping elements on photorefractive parameters
Jean Claude Launay
Photorefractive materials have been great potential in applications such as phase conjugation, optical data processing, image amplification and laser beam steering. The purpose of this communication is to show that crystals of different batchs-nominally pure and doped-may have different characteristics thus leading to significant variations in the photorefractive properties. The influence of the crystal growth conditions was recognized in early experiments of phase conjugaison based on degenerates four wave mixing in BGO.
A bird's eye view on semiconductor lasers in China
The history of semiconductor lasers has two key milestones, Lincoln Laboratories, IBM and GE gave the initial simultaneous demonstration of lasing action of homojunction GaAs diode at 1962, continuous operation (CW) of a semiconductor laser at room temperature did not occur until 1970, which were contributed by the loffe Institute of USSR and Bell Laboratories. It is worth pointing out that since then several important events on this field have occured, such as GaAlAs DFB LD(1971), quantum well lasers(1978), 1. 3um LD(1977), InGaAsP DFB & DBR (1979), 1. 55um LD and optical bistability LD(1981). Soon after development of important semiconductor lasers in the advanced countries, Chinese scientists developed their own novel devices. The comparison of the development of semiconductor lasers device between the world and China is shown in figure 1. It seems that some important devices with bright future of application in China are not far behind the world level. We will show the new achievements in three different devices as following.
Wideband optical waveguide phase modulation
Jihu Peng
Wideband optical waveguide phase modulator is a basic device in high speed or coherent optical fiber communication system. Because of the limit from electrode capacitance, conventional modulators based upon standing wave voltage E / 0 modulation hardly get the bandwidth as wide as several GHz. This paper presents an optical waveguide phase modulator, which takes the advantage of travelling-wave modulator. Its 3dB bandwidth of phase modulation index (5 (peak to peak value) has reached 6 GHz, while the total insertion loss is moderately 5dB in all over the band.
Electra-optic branching waveguide mode converter with low drive voltage
Y. F. Yuan
Electro-optic branching device is one of very promising and basic structure in integrated optical circuit. Such dielectric waveguides have been the subject of extensive theoretical and experimental investigations [ 1,2] , It may be used as power dividers, switches / modulators and TE-TM mode splitters in integrated optical circuits. _
Effect of 1-MeV electron irradiation on the AlGa/GaAs lieterof ace solar cell
Zhengyun Wu
The change of performance of AlGaAs/GaAs heteroface solar cell before and after irradiation has been studied by experiments and numerical fitting. The major reasons for the degradation of cell performance are discussed, and a method for improving the irradiation resistance of the cell is proposed.
Analysis of in-situ monitoring technique for fabrication of high quality diffraction gratings used in integrated optical circuits
Jianping Xie
In developing process of photoresist, high quality diffraction grating can be fabricated on GaAs substrate by in-situ monitoring the diffraction intensity from the photoresist. The diffraction intensity variation with development is analyzed, and the optimum end point of developing is indicated in this paper. The analyses are good coincident with the experiment results.
Infrared acousto-optic tunable filter
Yan Cui
The Acousto-Optic Tunable Filter (AOTF) is an electronically tuned optic filter that operates on the principle of acousto-optic diffraction in an optically anisotropic medium. It was first reported by Harris and Wallace (1) based on the collinear acousto-optic diffraction in an anisotropic medium. Later, I. C. Chang introduced a noncollinear AOTF concept (2) with a quasi -normal Bragg diffraction caused by an acousto shear wave traveling along the (110) axis in Te02 where the collinear acousto-optic interaction is not caused. Many papers reported collinear (3. 4) and noncollinear (5. 6) AOTFs and discussed the advantages and applications of them. The advantage of these devices over conventional methods of spectroscopy, prism or grating, is that its characteristics are determined by electronic signals, so that the spectrum scan rate is not limited by mechanical motions, the complete spectra can be run with a fast scan rate. Another advantage of electronic operation is that AOTF can interface very naturally with microcomputers for scan control, data collection and analysis. In addition, AOTF has large angular aperture while maintaining high spectral and imaging resolution, wide tuning range without secondary passbands. All these advantages make the AOTF potentially attractive for a variety of application. A brife theory of AOTF is presented in the first of following sections. Next, we discuss the design considerations. Then, some measured results of the performance of infrared AOTF are provied.
Study of the measurement system for high extinction ratio
Guohua Li
A measurement system for high extinction ratio is reported. As improvements on common methods, several new steps are adopted in the system. This makes the system have a high sensitivity and precision.
Dark-current of field-assisted GaAs semiconductor photocathodes
Jinmin Li
The dark-current of GaAs field-assisted photocathodes with red and near infrared response is larger than that of common GaAs photocathodes. The major source of dark- current of the photocathodes is impact ionization of hot holes in high field deple- tion region. In this paper, a model and creating mechanism of impact ionization in the photocathodes is described in detail, and a specific expression of the dark-curren of the photocathodes at different operation conditions can be predicted once the appro- priate parameters have been determined. It may be helpful to design a field-assisted photocathode and choose an optimum operation condition.
The hard x-ray quantum detection efficiency of CsI-coated MCP
Shi-Ming Xiang
An analysis model is presented for dealing with the hard X-ray quantum detection efficiency (XQDE) of a CsI-Coated MCP. It has been proved that the model is in good agreement with the experimental results of XQDE's relation to CsI layer thickness for a series of input X-ray photon energy. Its practical significance and applications have been discussed for our designing hard X- ray wafer image intensifiers using CsI-coated as a refiction mode photocathode.
High speed photography by two-dimensional acousto-optic lattice deflection
Anzhi He
This paper presents a new method of high speed photography which is by using technique of acousto-optic deflec- tion to take high speed photography, that is the 10 x 10 lattic picture can be recorded on a fixed film by time-serial.With this technique, various transient process may be recorded with high speed interferiometry. The expoure time is from 10-sto 3 x 10-6sec by using C.M laser as soure and is about 10-9sec by using serial pulse laser. The framig frequency is about 105frame / sec.
The regularization analyse method of the distribution function of the heterodyne quantum efficiency of the HgO 8CdO2Te photo-electrical diode
Yongjiang Dai
A regularization analyse method of the distribution function of the heterodyne quantum efficiency function for the Hg..Cdo 2Te Photo-electrical Diode on photosurface has been introduce. And the distribution function of the heterodyne quantum efficiency n (x,y) has been measured by the coherent laser detection system. The experimental and calculative results for the regularization analyse method has been discussion. (Financed by the NNSEC)
Phase conjugation in doped bismuith germanate crystals
The doped bismuth germanate (BGO) crystals have excellent phase conjugate effect. This effect can be observed in pure BGO crystal under an applied electric field. But in doped BGO, electric field doesn't necessary. The crystals were grown by czochralski method.
A study of new methods for designing electrostatic and magnetic imaging system with variable magnification
Guoqiang Ni
Electrostatic and magnetic imaging systems have long been widely used in photoelectronic imaging device, such as image converters and image intensifiers, camera tubes and electronic photographic image tubes. But for a long period of time, the design of electrostatic and magnetic imaging systems still remains at the level of direct (normal) method of design, in which the field distributions are calculated by the given electrodes and magnetic coils, the electron trajectories are then computed from the known field distributions, and finally the image position and magnification as well as the aberrations can be determined. The result that we expect is obtained through the method of step by step approximation. This method , of course, is tedious, especially for the design of electrostatic and magnetic imaging systems with variable magnification, the problem becomes much more complicated. In present paper, some inverse designs of realizing different focusing fields for electrostatic and magnetic imaging without image rotation but with variable magnification are investigated, some methods of optimization have been developed, an universal package of programme by using FORTRAN language has been drawn up, an experimental prototype of electrostatic and magnetic imaging intensifier with unsaturated iron medium has been designed, which can produce an image without image rotation but with variable magnification from 0. 3 to 3. 6.
Liquid crystal infrared optics and applications
Yongji Shi
In this paper infrared properties and electro-optical effects of liquid crystal are described. The main specifications and applications of the liquid crystal paper in our laboratory are reported.
Joint transform optical correlator using LCTV
Tianji Wang
A novel optical correlator that is able to cognize two identical diffuse objects is described. The experiment arrangement is achieved to reverse incoherence to coherence of the diffuse object image by LCTV spatial light modulator. A diffuse object image is input to a joint transform optical correlator with BSO crystal.
A new application of an acousto-optic tunable filter fast measuring chromaticity value
Guanhong Gao
A fast spectrocolorimeter which spectroscope is an acousto - optic tunable filter is described. The in- strument is controlled by a microcomputer to detect spectra of a object and complete real - time calculation of chromaticity values.
Two ion-exchanged microlens arrays
1. There have been many methods to fabricate microlens arrays, such as, the ion-exchanging, molding. plasma CVD, interfacial-gel copolymerising, photolytic, and monolithic techniques. Among them, the ion- exchange process has achieved the better improvements and results in theory and practice. The authors obtained analytic solutions of the diffusion equations for window and disc mask processes in fabricating ion-exchanged planar microlens array, derived the optimum index distribution for disc-mask microlens (DM lens), gave the image matrix of microlens, fabricated the divergent disc- mask planar microlens array and show the parameters and the picture taken with the array.
Optical properties and annealing behaviors of amorphous silicon phosphorus alloy films
Jianping Zhou
Based on the structural analysis of a-SiP:H alloy films prepared by the GD method, we have investigated their optical gap and refractive index as a function of compositions,and report here a preliminary study of their change rules of reflectivity and absorption in the processes of optical characteristic change and phase change, respectively.
Theoretical analysis of two element HBR waveguide array
Jian-Guo Xin
As known, eigen modes in a waveguide with cross section 2ax2b can be described by the following equations,
A novel polarization-independent optical waveguide modulator on z-propagating Ti:LiNbO3
Kuiru Wang
Integrated optical devices in which the modulation characteristic are the same for both the TE and TM modes are of considerable interest for the use in systems incorporating ordinary single mode fiber. A number of polarizaMon-independent devices have been demonstrated, including modulators and couplers formed on a LiNbO3 substrate. However, they suffer from disadvantages of optical damage, Li2O out diffusion and small tolerance of fabricational errors. Earlier work shows that when a laser beam propagates in a Ti:LiNb0301 waveguide along the crystal's Z-axis, the light beam suffers no observable degradation . In this paper we report a novel polarization-independent modulator with optical-damage-immune performance on X-cut Z-propagating LiNbO,.
A study of the semiconductor colour-sensing detector
Biao Chen
The semiconductor colour-sensing detector is composed of two parts: a colour-sensing device and a processing circuit. The design of the colour-sensing device is based on the principle of the colour mixture of the three base colours, light of different colours having different transmission depthes in silicon(red is the deepest, blue the shallowest, and green the medium). For the three depthes in silicon correspond to three base colours, plancediffusion technique or ion implantation technique is used to form three PNJs with different depthes and the PNJs filter colours automatically. When shone by white light, each of the three PNJs generates a photocurren simultaneously. When the three PNJs are shone by a light of one of the three base colours, only one photocurrent is generated by the corresponing PNJ.
An enlightening viewpoint and new result on improving frequency limit of high frequency electro-optic modulation
Tingwan Wu
In this paper we probe into the principle of traveling-wave modulation with which the frequency limit in high-frequency modulation can be overcome, as it is known to all. Developing a new viewpoint and method, we have corrected the fore theoretical result.
Investigation on evaporating CSL x-ray photocathode into MCP
The principles and the experiment methodes on evaporating CsI X-ray photocathode into MCP , and the improvement of the properties of a wafer X-ray intensifier has discussed.
Designing for acousto-optic deflectors of the z-polarized shear wave in TeO2
Ning Li
It has been suggested for the first time that the Z--polarized shear mode in Te02 is a kind of the mode which is appropriate to operate in a high frequency region and possesses a large time bandwidth product. By solving the Christoffet equation, the characteristic mode of the Z--polarized shear wave has been obtained. Some practidal examples show that the mode is of a wide bandwidth, and a proper center frequency makes the relative bandwidth approach 1.
Infrared planar optical waveguide coupling system for magneto-optical waveguide characteristic research
Kangying Wu
A planar magneto-optical waveguide coupling system has been set up. Some design consideration of the sys- tem are discussed. By means of the system, the refractive index and thickness of magnetooptical waveguide were measured, and guided light beam deflection induced by magnetostatic forward volume wave (MSFVW) in YIG waveguide was observed by either varying the frequency of the MSFVW at a fixed DC magnetic field or varying the DC magnetic field at a fixed frequency of the MSFVW. Finally, the measurement error of system is analysed.
Research and developments in the area of Optoelectronics in Optical Engineering Department at Zhejiang University
Jinfa Tang
This comprehensive review presents the research work carried out in Optical Engineering Department at Zhejiang University on lasers and non-linear optics; fiber optic sensors; scanning photothermal deflection spectroscopy; multilayered magneto-optical recording media; liquid crystal tight valves using amorphous silicon photoconductor ; and nonliear interference filters.
Study of the fine dividing technique for unity interference fringe by using OCV
Mingshan Ren
Both of counting the interference fringes and fine dividing unity interference fringe are important essential technique in the field of the accurate measurement. The counting technique has been ripe, but the fine dividing technique (FDT) is just developing. There are several FDT such as: electronics method, optical frequency doubling method, CCD method and computer programing method, etc. A new FDT with opti- cally controlled varactor (OCV) is reported in this paper. A real-time data acquisition system consisted the OCV as photoelectric detector and a special interface circuit connected with microprocessor for coun- ting the interference fringes and fine dividing unity interference fringe has been developed which can print and process data. Advantages of this system are following: real-time operation, intellectuality, and it is simple, reliable and economical. The photoelectric device OCV is a kind of new type detector and is very sensitive to weak light and the spectrum response peak condition, the capacitance of the OCV has a direct relationship to light in- tensity. It is small size and fast response. This system for fine dividing of unity interference fringe with OCV device not only can be of great use for the interference fringe but also for the Moire fringe. The test results indicate: The fine dividing for unity interference fringe can be accurate to l%( /100).
A new type of optically controlled varactor
Changchun Zhu
A new type of three-terminal optically-controlled varactor (OCV) in Metal-P/N semiconductor- Isolator-Metal (MPNIM) structure has been reported in this paper. The dependence of the capacitance on the voltage at the control base, and on the intensity and wavelength of light and on the temperature have been studied.
Optical 2D associative memory with hybrid thresholding and feedback
A 2-D hybrid holographic associative memory using single memory hologram, com- puter-controlled electronic circuit and LCTV is presented. And an orthogonal ized model is designed for this system that makes the holographic recording spatially separated. Hence there would be no losses in diffraction efficiency.
A new, monolithic encoding digital photodetecter array
Xuan Huang
At present, each element of the photodetecter array (PDA) is an individual source providing electronic signal, it must be connected with a seperate signal amplifying circuits. The more the array elements are, the more complex the circuits are. Another problem is that this kind of PDA has a high false-code-rate. We have designed and manufactured a new monolithic encoding digital PDA adopting the Gray encoding mode which has low false-code- rate. It is made of 32 photodiodes on one silicon chip. All 32 photodiodes is divided into six groups according a certain pattern, then connected to six output points followed by six groups of hybrid integrated amplifieres where the electronic signal is amplified and out put a 6-bit binary digit according Gray code. They are all mounted in a single sealed package. If the design is changed, similar encoding digital photodetecter array can also out put other bits binary code. Some measurement results is presented.
The application of CCD frame-transfer sensor to the performance test of angle tracking system of radar
Gangqiang Huang
As a photoelectric sensor, the CCD camera which is composed of solid state elements, is small in size and light in weight. It not only has advantages of a low operating voltage, good reliability and long service life, but also facilitates picture dot addressing. Therefore the CCD camera has been used more and more widely in the sphere metering instrument test, production process monitoring and quality control in industry. This detecting system is made up of a CCD camera and a monolithic microcomputer. The following is the operating principle of the detecting system in detection of the match of light axis and electric axis and the transient performance of antenna tracking system of radar.
A new type of shearing SH wavefront sensor
Peiqian Zhao
In adaptive / active aptics and computer aided manufacturing of large optical mirrors, Shack- Hartmann (S-H) [ 1] method which is derived from the well-known conventional Hartmann technique is well used to test wavefront in real time because it has many advantages. a) It collects and samples virtually 100% of the light entering the optical system; b) It measures the even wavefront slope over each zone even when the phase of the light from one side of the subaperture to the other side exceeds 2ir , which is well suitable for adaptive / active optical systems as well as reflectors; c) It requires only one detector array compared to four for a shearing interferometer with same optical efficiency; d) It can also detect wavefront tilt of white light because it is independent of wavelength; e) It is mechanically less complex than the shearing interferometers, replacing optical and mechanical hardware with electronic processing. Fig. 1 shows the principle of S-H wavefront sensor. The detected wavefront and plane reference wavefront are both divided into a number of zones, usually contiguous and equal size, by S-H plate which is a small lens array and imaged into separate foci by sampling lens. The distance between couple of foci corresponding to detected wavefront and reference wavefront reveals the mean wavefront slope over each zone. From the principle, we know that S-H sensor only can measure the average wavefront slope over each zone, unable to test the slope over the area smaller than the zone. Another disadvantage of S-H sensor seems to be its sensitivity to the shape of the source to be corrected in the case of low signal conditions.
Some means to raise properties of four terminals optical compensation network
Qianbin Wen
Four-terminal optical compensation network is a novel compensative network. The instantaneous compensative relationship of the transmissivity of detective field for all kinds of error factors is described first. And several means to raise the properties of an optical compensation network sensor system are presented. The accuracy of transmissivity of this system gets to be superior to 0.4 %.
Optoelectronic detection and analysis of ultraweak biophoton emission carrying new bio-information
Humio Inaba
The phenomenon of ultraweak light emission which is closely related to the process of life and biological activities has recently been recognized. Called as biophoton, this phenomenon has been detected in various plant tissues such as the subroots of onions, the stem of wheat, beans arid seeds, and animals organs like liver, heart, kidneys, lungs and brain, and vital tissues such as muscles and neurons as well as whole blood, blood plasma, membranes, bacteria, yeast, polymorphonuclear leukocytes, monocytes and macrophages, malignant tumor tissues and cells, and other cells. Thanks to recent advancement made in optical electronics, a development base has been established for the quantitative measurement of ultraweak light undetectable by the human eye and for information analysis of its various features. _
Compact disc inspection through measurement of low birefringence
Recent increase in use of compact discs attracted more attention to the problem of the quality control. Since those discs are made form polycarbonate they may exhibit birefringence introduced during manufacturing process. Such birefringence changes the index of refraction of the polycarbonate, which in turn causes deviation of the reading laser ray from rectilinear path. Currently available devices utilize laser based systems for reading of residual birefringence during disc rotation. As a result, this process is time consuming and provides averaged through the circular track information.
Image profile alignment applied to optical gauging in a bar mill
Eric Pickett
In a steel bar rolling mill, billets are run through a series of rolling stands to produce steel bars with various cross-sectional shapes. An optical gauge is used to provide on-line measurements for the purpose of statistical process control of the mill operation. The orientation of the bar in the gauge must be determined in order to accurately infer critical dimensions. An algorithm is developed for aligning the optical image to remove any bar twist. Determination of bar dimension from the aligned measurement sequence with an exact interpolation technique is also described.
Contribution of lateral waves and surface plasmons to the shift of a reflected beam
G. Carbonara
Reflected field intensity distributions are reported for surface plasmon wave excitation in an attenuated total internal reflection configuration for different metal film thicknesses. The behaviour of the measured lateral shift is compared with theoretical predictions.
Thermal nonlinearities of an aqueous polystyrene microspheres suspension
We report an experimental, measurement, based on an interferometric technique,for the determination of the temperature coefficient of the refractive index (andaT) of liquid suspensions of dielectric spheres in the thermal range 20 °C - 50 °C. Measured values of ani jaT of order of magnitude 10-4 °C- 1 were obtained at various dilution ratios of the spheres.
Measurements of crystallization velocity and activation energy in the optical recording films with In-Sb-Te system
Crystallization velocities and activation energies in the initial crystalli- zation process, obtained from measurements transmissivity(reflectivity), are de- scribed for amorphous In-Sb-Te films 400-600 A thick, which are set up in a chamber with a window guiding of the light through a long-distance focused lens. The crystallization velocity was obtained to about 100 Ajs for Inx(Sb0.4Teo.6)1-. x=0.2--0.3) films. The activation energy was determined by Kissinger's plot to be 1.5--2.0 eV. The frequency factor was calculated by the Johnson-Mehl-Avrami equation; logi 0 v 0=20-30 (Hz). Static repetition cycles of about 3 X 104 were recognized in the film composition of x = 0.2 for the sample structure without upper protection layer.
Analysis of signal-to-noise ratio in readout system of the magneto-optic memory
V. S. Sobolev
It is represented the analysis of signal-to-noise ratio according to the characteristics of the optical readout system elements. For any given value of the Kerr rotation we found the optimum angles between the plane of polarization of the lazer beam and the axes of analyzer and the partially polarizing beam splitter(PPBS);the correlation of the coefficients of the PPBS transmission for P- and S-polarizations , for which signal-to-noise ratio reaches it's maximum value.
Optoelectronics for automatic inspection
G. Longobardi
High performance optoelectronic devices are rapidly developing, because of their vital industrial importance and related practical advantages. In this framework, both the optronic systems and the metrological and control methodologies are presented, by making references to some branches of industry. Some particular encountered cases are discussed.
A laser based high performance universal product code reader
Charles C. K. Cheng
At present, more than 99% of the packages in the grocery stores have been marked by the manufacturer with laser scannable UPC symbols and the installation of laser based optical readers is expected to expand into all stores. This paper describes a laser based reader that was designed and engineered for reliable,high speed and safety uses in an ordinary store environment.Areas to be discussed are:laser/optics scan pattern generation,signal processor,characteristics and encodation of the UPC and the laser safety program.
The third-generation satellite laser ranging system at Shanghai Observatory
Fumin Yang
The paper describes the performance of the third-generation satellite laser ranging system at the Shanghai Observatory, Academia Sinica, and the observation summary of Lageos, Ajisai and Starlette satellites in recent two years . It has been shown that the ranging accuracy of this laser ranging system is about 5cm(r. m. s. ), by means of satellite orbital fitting and the ground target ranging experiments.
VHRSR's optical system
Qinbo Zheng
VHRSR's optical system is one of key parts of the remote sensors on FY-1 Meteosat. Its main purposed are: a. to receive and focus the radiation from the Earth; b. to form multichannel detection and define its spectral band with splitters / filters; c. to determine IFOV of the instrument and register fields of view of the channels; d. to assure the high imaging quality so as to have more than 0. 3 MTF each channel; e. to perform radiation calibration and determine dynamic range; f. to provide mechanical tolerances to meet optical imaging requirement; g. not to change imaging quality after launch and during operation at space. Radiation from the Earth enters telescope that consists of primary mirror and secondary mirror, of which the axis is tilted 45 degrees with scanning mirror. Exit radiation from telescope is parallel to entrance radiation. IR / visible dichroic beamsplitter divides rays into two parts. IR radiation reflected is focused by a Germanium lens on Mercury Cadmium Tellurium (MCT) detector, which works at 105 Kelvin. Lens and MCT are in a radiant cooler. Visible / near IR radiation transmitted is split into other two rays by a visible / N-IR beamsplitter. Transmitted radiation is focused on the field stop of channel 2 then projected on Si-detector. And reflected radiation is focused on Three-element linear array Si-detector by bi-separate lenses. Three channel micro- filters are near the linear array detector. Before launch, VHRSR designed and installed elaborately underwent many tests and accurate radiation calibration. FY-1 Meteosat was launched successfully on the 7th of Sept. ,1988 in China. High quality pictures of 5 channels were acquired by local stations or central station. It is proved that the quality of VHRSR's optics is excellent and satisfied with the harsh requirements of space engineering.
A research on ultrafast scanner
Ruilin Ma
A research on ultrafast scanner in ps range is reported in this paper. It is based upon the self-induced deflection by passing the laser pulses through a semiconductor wedge. Its principle and computer simulation are presented. Using 'Inclined Surface Fourier Transform 'to consider deflection, diffraction and attenuation synthetically, computation results indicate that the attenuation worsens seriously the performances of this type of scanner. Effectual correction can be obtained by adding two special attenuators on both sides of the wedge.
The effect of the camera resolution on fringe patterns in electronic shear speckle pattern interferometry
Fugen Zhang
An electronic speckle pattern interferometry system is an Optic,-electronic hybrid system, in which laser speckle field is used to carry the information of a object under test to the photoelectric target of television camera in the system, which transforms the speckle signal into video signal, then the video signal is transmitted to a television monitor after being processed by the following elec- tronic processor, at last a speckle fringe pattern is displayed on the screen of the monitor, which shows the displacement or the deformation of the object. In the ES PI system, the camera is a key device because it connects optical method with electronic method. Unfortunately, the camera usu- ally can not resolve the fine detail of the speckle field, for example, if the numerical aperture (NA) of lens is 16, and the wavelength of the laser 0.63 pm, then the maximum spatial frequency of the speckle field on the image plane of the system is 99 mm-1 (1) , while the size of pixel of the target of a industrial camera is about 20pm, which is approximately equivalent to 50 mm-1 in sampling fre- quency. Therefore, it is significant to study such a problem: how does the resolution of the camera effect on the ES PI fringe patterns?
The electrographic camera for astronomy
Delian Fu
The electrographic camera is one of the most powerful modern detectors having high sensitivity, extend spectral response, high spatial resolution, low background, no threshold, good linearity and large dynamic image. That is precisely because of this, the electrographic cameras with various designs have been developed in the past decades and many exellent astronomical results were obtained by use of them (Chicarini et al. ,1974). In general, the effect of their utilization in astronomical observations not only is to extend the detection limit of a large telescope, but will be to transform every existing telescope of <1. 5-m aperture into one of 5-m.
Compression of YAG mode-locked optical pulses and its application in microwave measurements
Z. H. Zhu
The optical pulses from a cw mode-locked Nd:YAG laser are compressed from 100ps down to 3ps by using a single -mode optical fiber and a grating dispersion delay line. The compressed pulses are successfully used to detect the standing-wave in GaAs CPW (coplanar waveguide) in utilizing the electro-optical probing technique.
Microcomputer-based speckle pattern imaging system
Yaohuan Gong
An automatic speckle pattern imaging system for measuring minute displacement without contact is presented in this paper. The system uses double-exposure method to produce the speckle pattern which is transformed into digital signal by CCD camera and A / D converter and then processed by a microcomputer -based imaging system for noise filtering, feature extraction and result display. The basic relation of the measurements, the system setup, the basic idea of the noise filtering and feature extraction are described, and the experimental results are given.
Direct subdivision of Moire fringe with CCD
Pin Long
This paper describes a new Moire fringe subdivided technique--direct subdivision technique, in which a linear CCD is used to subdivide Moire fringe directly. The CCD signals, after amplified and digitized, were sent into microcomputer. The microcomputer processed these signals and showed the direction and magnitude of displacememt.
A scanning system for inputting the optical pattern
Min Pei
This paper presents a high resolution •photoelectric scanner system which has been developed in order to input image information into a computer. A paper with the format of 297mm x 420mm can be scanned in 90 seconds, and the scanning resolution is 300 dots per inch. A pattern recognizing software system has also been developed to transform the scanned matrix patterns to the vector patterns so that the image signals may be edited, modified and plotted.
New development in measuring large gradient temperature field with optical interference
In this paper, we report a new development in the study of large gradient natural convection temperature field around a horizontally positioned cylinder by means of optical interference. The errors in measuring the temperature field caused by the light deflection and the method to reduce the errors are discussed. A series of interference patterns corresponding to the cylinder diameter of 33-86 millimeters and the wall temperature of 200-1180 C are presented. All these interference patterns are analyzed by the image processing. Results show that it is possible to obtain a high precision profile of the large gradient temperature field around the cylinder by means of optical interference. The boundary layer is as thick as several tens millimeters above the cylinder and 3-6 millimeters under and beside the cylinder. The results also show that the maximum value of the refractive index gradient does not occur at the surface of the cylinder.
The index and testing of extinction ratio for pulsed laser rangefinder
Jixian Hu
Maximum range is a main tactical and technical index for designing manufacturing and accepting a pulsed laser rangefinder. For direct determination of the maximum range, the climate condition and target characteristics such as visibility grade or meteorological visual distance, size and reflectivity of the simulative target and its setting distance should all be known concretely in advance. If the weather is not permitted, for instance the meteorological visual distance is less than the required maximum range, or the simulative target is fairly large and distant, that may be limited by the surrounding topogrophic condition, the direct determination of the maximum range becomes very difficult or even impossible. At present, for determining the maximum range of a laser rangefinder, extinction test is the most effective and optimum method.
A high sensitivity picosecond optoelectronic sampling system
Xinan Guan
In this paper we describe an optoelectronic sampling system with time resolution of several ps and sensitivity of 10y v. It is an useful tool to measure the time characteristics of high speed photoelectronic or electronic devices.
Research on real-time measurement of size and distributilon of atomized particles in high speed centrifugal spray field
Particle Measurement Research Group
To discuss optimum parameters of substances participating chemical reaction in industry reaction tower, and some mechanism of reaction process, it is necessary to understand information of particle crowd in reactionary process. For example, we can obtain size parameter,distribution parameter and SM1) from size and distribution information of crowd particles. In order to know optimel reaction effect in high speed centrifugal spray field, it is very important to measure particle size and distribution in atomized field. That requirs an instrument, whose measurement principle should be right and can work well under severe atomized field circumstance. This paper describes the principle of such an instrument ,analyses work-site environment and takes some relative measures to ensure measurement, give the measure results at work- size, and finally proposes atomizing quality problem.
Clipped speckle technique used in digital speckle photography
Qiang Fang
Clipped speckle technique is used to speed the abstracting of point information in digital speckle photography. Theoretical analysis and experimental results are given.
High-accuracy photoelectric measurement of length
Yongchai Yang
Photoelectric automatic measurement of lenghth on a belt conveyer has a lot of advantages, such as cheap cost, long lifespan, simple construction and convenient operation, etc. , which make it develop fast and apply widely. However, it is easily disturbed by many factors so that its precision is not ideal. How to improve the precision is one of the problems which need to resolve imperatively at present. This paper will discuss the reasons why the precision is not ideal and put forward a series of measures to correct the errors. At last, a schematic diagram to realize high-accuracy measurement of length are given.
The phase conjugation adaptive optics: return-wave algorithms and acquisition performance for multiple glints
Jiaxiong Ye
The optical phase conjugation technique is the implementing technology of wavefront or phase interchanges,which used some special optical effects and techniques imple- menting such imterchanges,This process in mathematically equal to the complex conju- gation transform of complex amplitude of lught wave.The phase conjugation adaptive optical technique can be used to compensate the phase distortions experienced by optical beam propagating in a turbulent and absorbing atmosphere,which principle of operation is the wavefront or phase interchange.By means of return wave algorithms, we provided a theoretical results of inve stigating the properties of the phase con- jugation adaptive optical system.The compensation performance fpr atmospheric aberra- tions and the ecquisition performance for multiple glints have been discussed.
Coarse grating precision displacement measuring system with opto-scanner
Xianghui Yuan
A coarse grating precision displacement measuring system is described in the paper. The system consists of an opto-scanner used as a displacement sensor, a simple optical system, a large pitch reflecting coarse grating (X=0.635mm) and signal processing circuits etc. After describing the opto-scanner briefly, the paper expounds the principle of the system, the schematic circuits and the theory of dynamic phase discriminating and subdivision. Experiment results is satisfactory.
A computerized photoelectric refractometer
Baoyong Mi
This paper describes design idea of a computerized photoelectric refractometer and its construction and discusses the sources of error. The refracti',ve indices _of optical glasses are measured with this instrument. The measuring uncertainties of 3x10 and 3x10 in the wavelength ranges of 300 to 2800 nm and 2800 to 12000 nm are obtained, respectively.
Temperature mapping by double grating diffraction system with microcomputer image process
Jinhong Tu
An improved method of temperature mapping by means of double grating diffraction System with microcomputer image processing technique is presented. The result of this method is satisfying.
Optimization techniques for combination-matching of systematic accuracy of opto-electronic instrument
Erqi Wang
Allocation of accuracy index is an engineering problem of general significance in the layout design of the opto-electronic instrument. This paper, with achieving the lowest production cost as its aim, discusses the optimal combination-matching of the allocation of accuracy index. An automatic search algorithm and its application example are also provided. This paper as a whole unfolds the possibility of realizing automatic allocation of accuracy index.
Survey of the velocity constant in the chemical reaction in liquor by means of the speckle focus-out of laser
Chen-Yuan Sun
The chemical reaction in liquor results in the nonlinear index of refraction which modulates the nonlinear expansion of He-Ne laser transmission light field in space. The speckling deviation angle of equation can be obtained theoretically and the tangent of the characteristic curve of the light field can be obtained with the help of optoelectronic detector and optoelectronic Automatic Data Processing (ADP). Then we can survey the velocity constant in chemical reaction by computing temperature gradient in the index.
A new method of radiation calibration in visible and near infrared wavebands for VHRSR
Zhimin Zhang
There are five channels in the Very High Resolution Scanning Radiometer (VHRSR) installed on FY-1 Meteorological satellite, the channel 1 to 4 are visible and near infrared wavebands. The channel 1, 0. 58-0. 68,2 m, is used for detecting cloud cover, vegetation and content of the mud and the sand in the sea, the channel 2, 0. 725-1. 1 g m, for identifying boundary of water and land, the channels 3 and 4, 0. 48-0. 53 m and 0. 53-0. 58 p. m respectively, for detecting the content of chlorophyll in the sea. In order to obtain the target features of the earth from the output signal of VHRSR, radiation calibration of each channel of VHRSR should be finished before launching the satellite. The main task of radiation calibration is to determine the gain and dynamic range of amplifier of each channel to assure that the useful signal of the target is neither saturated nor too small. By means of radiation calibration of visible and near infrared wavebands, the relative curve between output signal from VHRSR and radiation brightness or albedo of the earth target is also determined so that when satellite operates, radiation brightness or albedo of the earth target can be obtained by means of output signal of VHRSR.
Design and study of pre-amplifier of APD photoelectrical signal
Huiluo Liu
This paper presents the application of APD photoelectrical transformation components to the technology of photomagnetical memory system. An expression for the signal-to-noise ratio has been derived by the mathematical method. This theoretical expression points out the path to improve the signal-to-noise ratio and also provides the technical requirements for selecting the components. This paper analyzes the important parameters of the APD pre-amplifier of photoelectrical signal and the measurement of equivalent input noise Eni, at the last gives the test results of the pre-amplifier.
Measuring system of digital-optical power spectrum
Hegao Li
Measuring System of Digital-Optical Power Spectrum (MSDOPS) is a digit-optical hybrid processing system. The method of designing the system is given in this paper. It includes: Selecting the suitable detector, designing optical system and the electronic circuit. The schematic diagram of the MSDOPS is shown in Fig.l. The optical system consists of He-Ne Laser, spacial filter, collimating lens, Fourier Transform lens (FTL), and magnifying lens. Its function is to give the Fourier spectrum for the input. 64-element photo-electric detector, electric shutter, electronic circuit, and A/D converter make up the optic-electric converter. Optical signals are converted into electric signals. Digital signal processing is carried out by a microcomputer. The input image, recorded on films, can be transmitted by auto-transfering mechanism into the liquid-gate at the entrance of MSDOPS.
An automatic photoelectric detection system with high accuracy for laser alignment
Yanling Dong
An automatic photoelectric detection system with high accuracy for laser alignment is discussed in this paper. The system consists of laser alignment, a photocell, a high precision displacement transducer, a motor -driven guide body, control circuit, and computer. Alignment laser, which is regarded as measuring datum, illuminates the photocell of detection system. The photocell is regarded as aimer. While the aimer is under aiming, a aiming signal controls a computer to acquire output data of the displacement transducer at that moment. The aimer is driven by motor-driver and passes aiming point in the two opposite directions in the process of measurement. The average value is used for measuring data. The measuring process is automatically accomplished by computer control. The distinguished feature of the photoelectric detection system is that the linearity error of photocell is elinimated, the range of measurement is enlarged, the sensitivity and accuracy is improved, and the measurement is completed automatically.
Shearing interferometry of double frequency grating to measure temperature field
Here the shearing interferometry of double frequency grating to measure flame temperature field is proposed. It is a real-time schlieren interferometry with a quantitative measurement capability and the experimental results are given.
Computerized measurement of synthetic characteristics of microchannel plates
Yinghui Li
A computerized measurement has been developed to assess the characteristics of microchannel plate (MCP). This paper discusses the microcomputer hardware and software techniques used in the system in circuit control, signal acquization and software package, etc.. Some measuring results have been presented.
Photodiode linear array used for spectral recognition
Wang
The color spectrum recognition method using statistical methods to extract the features of the spectra is fast, insensitive to noise and especially suitable for industrial environment. Because the color spectra are directly discriminated, there is no metamerism. And so the color spectral recognition may be widely used for on-line quality control and machine vision. We aim to study how many color differences can be discriminated by the spectrum recognition method in general condition. A color spectrum recognition system is introduced in this paper. In our experiments, two sheets of white paper with 1. 1 NBS unit of color difference between them were used as targets and the Averaged Learning Subspace Method (ALSM) was used to calculate subspace classificatory. Using this subspace classificatory, the system can recognize the two targets in real time.
Real-time automatic calibration method of PMT drift
Zhihong Liu
In order to calibrate the drift of PMT used measure, the intensity of the reflected or transmitted light, the incident beam was divided into two beams, measuring beam and reference beam. Passing through the same mechanical chopper, the reference beam was chopped into 3. 2KHZ light pulse beam while the measuring beam into 200HZ light pulse beam. By the same PMT, both the light pulse beams were transformed into electric pulse signals, which were then amplified by the same preamplifier and VCGN. The reference pulse signal and the measuring pulse signal separated from each other by the bandpass fillters were rectified to DC signals, and a constant was subtracted from the reference DC signal by subtracter. After the remainder signal sent out from the subtracter was further amplified, it was used as controlling voltage of VCGN. The drift except the filters, the subtracter and the DC amplifier could be automatically calibrated by VCGN in real-time. The output variation of the calibrated reference signal was less than 0. 01% when the reference signal that came out of PMT varied from 1mV to 980mV. The output instability of the measuring signal was less than 0. 1% in eight hours. A highly stable light source supplied the reference beam for calibration PMT drift used to measure the intensity of the emitting light.
System for spectrum parattet detection and continuous Tong record
Xiaosu Zhu
A system, which has been set up, can efficiently collect spectrum information in an intelligent mode. It comprises common spectrometer,a solid-state photodiode self-scanuing array detector, amplifier,a new data acquisition interface card and RAT microlomputer.System block diagram is shown in Fig.1. The spectrometer is Ebert-Fastie grating dispersion apparatus, in which slit is 2.5 mm tong and 25 micron wide. The detector contains a photodiode array sensor, a scanning moving out circuit and a preamplifier.The array sensor is located at the position of the first order of spectrum and its spectral range is 200-1100 nm.On the sensor there are 512 photodiode pixels aligned, every one has dimensions of 2.5 m m by 25 micron, total active area is 2.5 mm by 12.5 nun. Pixels' maximal spectral response is near by 580 nm wave length. Dynamic range of signal may reach 103-104, By cooling the detector it may he higher. As array sensor is possessed of some advantages , such as less size, convenience , good spectrum outline translation, it gets more and more application. On array, spectral signals are accepted in parallel multichannel and turned into electrical signals, then detector moves them out in series. Aa soon as signal of a pixel is carried away the pixel will begin next integrating of optical signal. Under control of microcomputer the signals out from sensor are amplified and then digitized by acquisition subsystem in real-time.
Photoelectric centering and measuring instrument with double-pass zero position method
Changxin Zhou
A new type of high precision photoelectric centering instrument for measuring centering error of lens has been successfuly developed. It is used for processing and assembling of many precision lenses with resolution near diffraction limitation. The accuracy of the instrument for measuring centering error may be up to 1 arc second. The accuracy for measuring spherical center deviation is lit m and its optimum centering sensitivity is 0. 1it m. Using the instrument has successfuly completed fabrication and assemble of many precision lenses, such as reconnaissahce satellite camera lenses, reproduction lenses for manufacturing LSIC, flat field apochromatic microscopy objective with high amplification ratio, aerial photography lenses as well as plate -making lenses etc. . According to the appraisal national authoritits, the main technical specifications of the instrument are authenticated to exceed the same kind of instrument made abroad and come up to world advanced level in 1980's. This achievement in scientific research has won the first class Sciences and Technologies Progress Prize awarded by Chinese Academy of Sciences in 1987, and has obtained Chinese invention patent (patent number:CN 85 1 01621A).
Measurement of the response time of ultrafast photoelectric detectors and dispersive broadening effect of connector with picosecond photoconductive sampling techniques
Shuzhong Yuan
For measured the response time of ultrafast detectors and some material, we have made one picosecond photoconductive sampling system, it consists of a mode-locked dye laser sysnchronously pumped by a mode -locked argon ion laser and a photoconductive switch using the SOS as substrate. This system has demonstrated a temporal reslution. of under 7 ps, offering a sensitivity of l0 uv
UV photo-method for measurement of MCP characteristic parameters
Jingquan Tian
In this paper, the measurement unit and the operating principle are introduced. The key problems are represented. The experimental results are given and peculiar advantages of this method are pointed out.
Approach for the on-line equipment for measuring variation in a turning size using laser
Haibao Lu
In the paper an experimental on-line measurement equipment using laser, which is used for measuring the variation in the turning size of a workpiece is reported.The equipment is the part and parcel of an on-line system for controlling the machining size of the workpiece. In the equipment the variation in the turning size of the workpiece is determined by using a laser triangulation method. A Lowpass filter is disposed in the equipment, so that the effect of vibration in cutting and the cutting trace of the workpiece surface on measuring may be effectivelly eliminated. In the paper the principle of measuring is presented, the overall constitution of the system is described, and some experimental results in the approach are given.
New method for improving MCP operating characteristics
Lichen Fu
A microchannel plate(MCP) consists of a parallel array of individual electron multiplier channels of microscopic glass in diameter(10-40um). It is a kind of ideal two-dimensional electron multiplier. However, if the ordinary MCP is used for a time or baked, its electron gain will be decreased dramatically and the reliable operating time will be shortened. Therefore, with the increase of the requirement for using MCP, it becomes a pratical problem to be urgently solved that MCP gain stabillity is improved and the service life is extended.
The characteristics of Moire signals in diffraction from super-imposed dual gratings
Bin Du
It is well known that the characteristics of Moire signals: Contrast(C), Sinusoidally(S), and the sensitivity of the light intensity to the variation of air gap between the two gratings(H) are the main factors affecting the accuracy of dual gratings measuring system. The paper presents a general formulation concerning the diffraction light intensity from dual gratings, and discusses the characteristics of diffraction pattern.
Research about an opto-electronic and intelligent measurement system of organism activity in medicament test of center nervous system
Guan-Lin Yang
In order to develop traditional chinese medical science cause rapidly, we must be getting pharmacology research of traditional chinese medicine and understanding the medicinal effect for organism. Researching test theoretics of traditional chinese medicine pharmacology and device of test system with modern science and technology is an important means for research of bioclimatoloy and biochemistry.
The single way detection system of lightwave polarization with high SNR
Naijian Guo
Fig. 1 shows a schematic configuration of the typical single way detection system of lightwave polarization. The detection system is composed of a current sensor including a polarizer, a Faraday rotator and an analyzer, and a photoelectric detector including a photodiode, a preamplifier, AC & DC amplifiers and a divider. The light beam of the laser is linearly polarized through the polarizer. The polarizer direction of light is rotated in the Faraday rotator. By using the optical analyzer, the polarization modulation due to the Faraday effect is converted into intensity modulation. When the angle between the optical axis of the analyzer and that of the polarizer is 45 ,the maximum sensitivity and linearity of measurement are obtained. The light intensity P at the detector is expressed by P =Po( l+sin2cp ) ( 1)
System with high resolution for measurement of ultrashort pulse
Zhenglie Gong
The duration of ultrashort light pulse gets from ps order of magnitude to fs due to the techniques of colliding mode-locking and pulse compressing. It challenges the routine method of intensity correlation curve( i. e. 3:1 curve). It is, of cause, interesting to find a new method for raising the precision of measurement of ultrashort pulse. Reference[ 1] measured the pulsewidth of 6 fs using the streak numbers of the interference correlation curve (i. e. 8:1 curve), and [ 2,3] presented a technique of equality-width.
Optical heterodyne detection via four wave mixing process in iodine and sodium molecules
As a high sensitivity and high resolution spectroscopy, opti.cal heterodyne detection via nearly- degenerate four-wave mixing has been investigated since 1980 . The technique has been used for stabilizing lasers and precision spectroscopy measurement. Using optical heterodyne technique, we performed experiments to detect four-wave mixing process in iodine and sodium molecules.
The basic operation principle of measurement system of a phase grating of non-Moire fringe, single-grating and modulation of multiphase light
Zengyao Zhang
This paper presents a new type of grating measuring system. Its light source is encoded multiphase pulse linear arry light source. It only has a scale grating with wide pitch, does not use Moire fringe, and only has a single-ended output. Its signal process system uses frequency tracking measurement circuit. this paper centred on analysis the basic operation principle of measurement system, also explained the function of filter and demodulation of the silicon photoelectric generator to output signal I(x,t) by use of transfer function and amplitude-frequency characteristic of the silicon photoelectric generator from automatic control theory.
Accurate measurement of ST and CCI of camera lens with double light paths
Yongchai Yang
The spectral transmittance (ST) and colour contribution index (CCI) are two important quality indexes of the colour camera lens. Automatic and accurate measurement of above indexes is imperative demand of factories which produce the colour camera lens. Because the instruments produced atpresent use single light path, they require long measuring time and are easily disturbed by voltage fluctuation and temperature variation so that the precision and stability are not idea. In order to improve the characteristics of the instrument, we have researched and produced the automaticmeasuring instrument with double light paths, whose precision and stability are higher than those of the same kind of instrument with single light path. This paper will discuss the following contents: the principle and adjusting technique for measuring ST and CCI with double light paths; the demodulating circuit and the automatic scanning circuit; the flowchart of program.
An intelligent video measuring system with illuminance self-adaption and pixel to pixel AGC function blocks
Rong Wang
In this paper the effects of variation of illuminance, spatial frequency and color on measuring accuracy are discussed. The illuminance self-adaption and pixel to pixel AGC function blocks are introduced. By means of the blocks, tolerance of illuminance variation is expanded greatly and several objects with different spatial frequencies or different colors can be measured simultaneously. When optical amplification is 1, the measuring accuracy of the system is 1 micro meter.
Infrared CCD application in the equipment of circuit systems fault diagnosis
Li Yi
With the development of the electronic technology and with the improvement of the theory of circuit system fault diagnosis, many kinds of fault diagosis equipment have been designed. But the former equipment have a mortally drawback. The interchangeable property of its enterface between the test system and tested system is bad. If we use a uncontact interface, the drawback can be overcome. As we know, the devices in circuit have thermalradition when power on. So the whole circuit system can form a thermal image. The normal thermal image of circuit system is different from the unormal thermal image. By this principle, we can use a infrared CCD to get the thermal image and make a processing system(digital image processing system) to process this image. Then by computer, we'll compare the image of the normal system with the image of tested system, check the different, find the faults.
Theoretical computation for measurement of gaussian beam divergency using grating
A method to measure the divergency of a singlemode TEMoo laser Gaussian beam using grating with a range of Q parameters is presented through computation with theoretical error about 1%, which is from error analysis using one-dimension regression equations.
Multi-function grating measurement instrument: a new production having development prospect for large machine and middle or small factory
Pin-Zhong Ma
The multi-function grating measurement instrument is a digital readout precision metroscope, which can cover a wide range of applications for scientific research and industrial measurement. This instrument with measuring range 0-100 mm, resolution 0. 001 mm may be used to determine the workpiece dimensions by methods of direct or comparative measurement.
The optimum output electrode structure of MCP
Jinxiang Wang
This article starts from the kinetic equations of the secondary electrons in the channel and near the output end of the channel, gives the optimum output electrode structure and its criterion of MCP for the first time, and discusses the effect of the output electrode structure on EDOE and spatial resolution as well as the gain.
Study of automatic surface inspection for cold rolled steel strip
Zelin Xu
The paper describes a feasibility study of on-line inspection of visible defects in the surface of cold rolled steel strip by a experimental inspection system. The system incorporates CCD linear image sensor and illumination placed in specular reflection direction . To cope with the wide variety of different defect mixed with lot of noise and continuous changing of environment, the paper propose a segmentation algorithm using a special two dimensional filter and adaptive threshold varying with environment to get a quite accurate defect binary image. Defect deleanation and classification algorithm analyses defects, removes noise and extracts features of defects, then classify them by statistics decision tree.
Intellectualization in crossed molecular beam experiment
Bing Xue
The intellectualized works in the crossed molecular beam and LIF (laser induced fluorescence) experiment are presented. By applying computer in the experimental apparatus, the signal to noise ratio is raised, the wavelength is calibrated automatically, the laser power and the fluorescence are recorded synchronously. The experimental data are processed by computer.
Measuring the angular drift of laser beam with a knife-edge method
Shan-Zhong Zhang
Good directivity produces laser a promising applying prospects. For the characteristic of laser itself and the environmental effects, there are drifts in laser beam with random quantity and direction. In the cases of some very high accuracy, especially in laser directivity and laser alignment, the error caused by drift is unneglected. So it is necessary to measure the drift of laser beam with high accuracy.
The explanation of the gain anomaly of the stimulated Raman scattering in non self-focusing media
Zi-hua Zhang
We deduced a more general formula to describe the growth of Stokes feild pumped by the focused beam, and proposed a new explanation about the gain anomaly of SRS in non-self focusing media. The phenomena of the gain anomaly of the Stimulated Raman Scattering (SRS) in non-self focusing media was observed and interpreted by the feedback in the Stokes amplification from Rayleith Scattering or diffuse reflection from walls or windows, or the parameters instabilities ''2, , All of these explanations are based only on the experimental value of the gain deduced from the exponential growth law deviated from that evaluated from the SRS theory. Here we shall analyse the influence of the covergence and the intensity distribution imhomogeneity on the gain measurement. At present, according to the planar wave theory, when the coherence ani4 other higher order Raman Scattering have been ignored, the coupled wave equation are known , when focused beam be employed, a correction term T must be added. In such case the beam size W and the field intensity E have such relationpip: E (z) =E2(o) • W (o) / W (z), therefore, if we consider that, the energy density w=E. I E I / 2, and4 the photon density n =w / hv, we can get the coupled rate equations of the photon density n as
Measuring red blood cell velocity in microvessels by images correlation technique
Shifa Xiang
By means of a microscopic TV system with computer image processing equipment and a application program, the flow velocity of red blood cells can be quantitatively measured by spatial correlation detection as well as the change of the flow regime of microcirculation can be clearly observed on the monitor. This system not only reserves all the advantages of microscopic TV systems which are widely used in clinical detection now, but also can get satisfied measuring results by applying digitized processing on the images of microvessels to eliminate the background fluctuation and other disturbance signals which often lead to wrong results in the measurement of red blood cell velocity.
A passive countermeasure for laser range finder
El-Sayed A. El Badawy
This paper investigates the detection of targets and determination of its location using laser beams. A passive method to decrease the visibility of targets by laser range finders or designators using simple coatings and paints is proposed.
Spectroscopic characteristics of praseodymium doped YaG crystals
Characteristics of Pr3+ doped Y3A15012 (YAG) crystals are discussed with reference to possible.laser applications. The fluorescence spectra and decays from the 3P1, 3P0 and 1D2 excited states are measured in crystal of 0.12 ? Pr3 4 concentration. Application of the Judd-Ofelt theory yielded values of radiative transition rates, branching ratios and oscillator strengths. The calculated peak emission cross sections are compared with those for Nd3+ in the same host and Pr3+ in another laser materials.
Computer holograms ss HOE's and optical interconnects
Eero Byckling
Recent research on computer-generated holography at Helsinki University of Technology (HUT) is reviewed. This work contains both fundamental and applied aspects and falls in two (somewhat artificial) main categories: holo- graphic optical elements (HOE's) and space-invariant optical interconnects. Special attention is paid on optimization and fabrication of holographic interferograms (e.g. those producing so-called general diffraction-free beams), and on Dammann grating and kinoform-type optical interconnects.
Optical gain in GaAs/GaAlAs graded-index separate confinement single quantum well heterostructures
Glen A. B. Feak
Results of investigations on the dependence of the gain spectra, their polarization properties, and their peak emission values, on both the quantum well width and injection current are presented for single mode GaAs/AlGaAs graded-index separate confinement heterostructure single quantum well (GRINSCH SQW) lasers. Further, the relationships between the laser parameters critical to lasing with the n = 1 subband transitions are analyzed in terms of the material optical gain of the quantum well.
Output characteristics of a stable resonator for a transverse: flow CW CO2 laser
G. Rabczuk
The Kirchhoff-Fresnel diffraction integrals for the stable resonator with nonlinear gain medium have been solved in order to specify conditions for fundamental mode ope- ration of a 1 kW transverse - flow CO2 laser. The basic output characteristics such as the beam intensity profile and the laser output power for the different resonator geometries are presented in the paper.
Holographic interferometry in predicting cathodic deposition of metals in aqueous solution
A mathematical model relating surface and bulk behaviors of metals in aqueous solution has been developed. The model was established based on principles of Holographic interferometry for measuring microsurface deposition, i.e., mass gain, and with those of electrochemistry for measuring the bulk electronic current, i.e., electroplating current. The model can be utilized to predict the electroplating behavior on metals subjected to cathodic reaction in aqueous solution. In other words, the cathodic current density of metals can be predicted as a function of microsurface deposition.
A laser radar for the measurement of liquid level heights
The construction and capabilities of a pulsed time-of-flight laser radar device constructed for the measurement of liquid levels is presented. The system consists of a measurement head, an electronic unit and a fibre optic connection between the two. The measurement head includes the laser transmitter, which is a collimator pen laser diode with a peak output power and repetition rate of 10 mW and 1 MHz, respectively, and single axis optics. The novel construction of the optics together with the highly non-divergent beam of the laser diode (< 0.3 mrad) and the mirror-like reflection of the liquid level enable measurement situation to be achieved in which the amplitude of the received pulse remains constant as a function of the measurement range. This simplifies the construction of the system and increases its accuracy, as the errors entailed in automatic gain control electronics can be avoided. On the other hand, the construction increases the accuracy needed in the set-up of the system, as the received beam has to fall on the receiver lens. Time interval measurement is based on the counting of the pulses of an accurate free-running 100 MHz oscillator within start/stop time intervals. By averaging 106 measurement results a resolution of about 1 mm is achieved. The averaging circuit is constructed in such a way that missing stop pulses, e.g. due to momentary fluctuations in liquid level, do no interrupt the measurement. The resolution and accuracy of the system were measured to be 1 mm (a-value) and 2 mm, respectively. If the liquid level fluctuates, the accuracy deteriorates due to dispersion effects in the receiver fibre, which may have a length of up to a hundred of metres. This error can be reduced, however, by use of a mode scrambler at the input to the receiver fibre.
Weak optical feedback and self-coupling effects in single-mode in-gap lasers
F. Brivio
In a microscopic approach to single-mode semiconductor laser dynamics, the nonlinear dependence of interband carrier lifetime on optical field intensity accounts for some nonlinearities in the characteristic curve appearing in the weak feedback regime. The exploitation of self-coupling effects to monitor laser dynamics and system properties in comparison with actual optical communication systems is discussed.
DYE/polymer systems for holographic recordings
Roger A. Lessard
Recent and future developments in holography require new recording materials. Photopolymers and photocrosslinking materials seem to be good candidates due to their high-spatial frequency responses. Those dye/polymer systems are studied to record both reflection and/or transmission holograms, to perform real-time holo- graphy as well as four-wave mixing techniques. Characterization studies were considering polarization holography in thin films made with azo dyes or thianine colored polyvinyl alcohol, dichromated polyvinyl alcohol and methylene blue sensitized gelatin.
Recent progress in France on aerothermodynamic limitations in high average power excimer laser
Patrick Canarelli
Acoustic waves damping in a high repetition rate X-ray preionized excimer laser (XeCI ) is studied by means a test bed which consists in a subsonic loop and a laser head. The residual shock waves induced by input energy inhomogeneities can strongly affect the excitation quality and so the output laser energy. First results of the influence of a damping of these waves between two successive pulses are presented.
Room temperature carbon dioxide lasers
K. H. Tsui
Abstract A carbon dioxide laser operating in the high nitrogen partial pressure regime is reported. This regime requires a higher gas temperature to maintain an optimum output therefore cooling systems are not desirable. The output of this regime is comparable to that of the low nitrogen partial pressure.
Interferometry with wavelength change
Change of wavelength in interferometry modifies interferograms without any mechanical movement. If a series of interferograms are taken by successive change of wavelength and analyzed by computer, it brings a new technique called wavelength scanning interferometry. Two examples of such a technique are presented.
Laser welding of SUS 316 stainless steel
Jian Wang
Laser welding of SUS 316 stainless steel was conducted in a 2 KW CO,laser and a good butt weld was formed. Weld appearance, microstructure, composition and corrosion resistance performances were investigated by a HITACHI X-650 scanning electron microscope, a PHILIPS EDAX PV9100 energy dispersive spectrum meter and a corrosion-electrochemistry microcomputer on line measuring system. It is found that columnar and equiaxed grains are well bound in the weld. Intergranular corrosion resistance property of the weld is improved with high contents of nickel, chromium and molybdeum in the boundaries. The weld presents the same excellent corrosion resistance property as the base metal in 10% NaOH solution, and provides better corrosion resistance performance in 1 N H2SO4solution.
38-femtosecond pulse generation from a simple linear-cavity synchronously pumped dye laser
Yupu Liu
Since the colliding pulse mode-locking CPM) technique and the intercavity group-velocity dispersion (GVD) compensation have been used in the generation of ultrashort pulses,the optical pulses generated from mode-locked dye lasers have been reduced to the femtosecond region.MA By using these techniques, pulses of about 30-fs can be obtained, but usually employing a ring cavity and with a four Brewster- angled-prism GVD compensator in it. The laser system is more complex and it is not easy to adjust it reaching optimum condition.
A new method to laser-CCD scanning system applied to seamtracking
Shiwen Xu
In this paper, it is described that a new method to laser-CCD scanning system is applied to seamtracking. Theoretically, the deviation of the seam position can be determinied by comparing their real-time position with their references. The experiments show that the method take the precision of 0. lmm horizontally, and 0. 5mm vertically.
Metal ceramic sealed mini-tea CO2 laser
Qianhua Qu
In this report, the selection of parameters for mini-TEA CO2 laser is theoretically analysed. A practical complete metalic-ceramic sealed off mini-TEA CO2 laser has been constructed.The technique of metal solder is adopted to seal the window of the laser component. The output of principle mode is greater than 20 mj with a operating life longer than 106 times, pulse width smaller than 50ns, and shelf life longer than 10 years.
Fabrication and characteristics of 1.3 Urn InGaAsp-InP large optical cavity lasers
Jingchang Zhong
Analysing in InGaAsP-InP semiconductor lasers the effects of carrier leakage, non-radiative Auger electron process, inter-valence-band absorption as well as lattice mismatch on lasing characteristics, we have successfully designed and perfectly grown by a modified LPE technique a large optical cavity (LOC) structure in order to obtain the 1. 3 u m InGaAsP-InP lasers with low threshold current density, high output power and high characteristic temperature (To). We have also optimized the LPE procedure and diode-making process which accrue benefits in improving performances of, the devices. The lasers exhibit fairly low threshold current density 5 KA / cm for broad area devices), high output power (up to 3 W in pulsed operation) with high external differential quantum efficiency and high characteristic temperature (T0=150K). It is evident that the quaternary system LOC structure provides a laser which is superior to a conventional DH device.
Picosecond optical pulses generation from actively mode-locked semiconductor lasers in an external cavity
Fengzhen Guo
We report the observation of 17 ps optical pulses from actively mode-locked BCS laser diode in an external resonator. Repetition frequency up to 458. 5MHz. The optimal active mode- locked conditions and the dependence of the pulse width on external cavity will be discussed.
The display fingerprints by exciting fluorescence with laser
Shurong Wu
This paper reports the method of the displaying fingerprints, by exciting fluorescence with laser. The experiments have demonstrated this way being more superior to the normal method. In the fingermarks, left on the surface of objects, there are very small amount of aminoacid containning in the sweat. when they are painted some materials consisting of fluorescent substance leave on the marks, it may form a compound with the aminoacid. Therefore visible fluorescent light will be excited by a laser with certain wave-length. A picture of the fingerprint-particularly for those cannot be shown by normal method is displayed. In our experiments, Samples of one kind are more over four hundred fingerprints with appropriate pressure less perspiration, and gathered on white paper. The results show that the sum of clear and perfect fingerprints inspected by this way, is 2. 3 times of that observed by normal method (see Table I and II). Samples of another kind are the fingermarks remained on the surface of less smooth, hard and black plastics. It is almost impossible to take photographs of theese samples by normal method. By using our method, the clear picture of fingerprint can not merely be seen but also may take nice photographs of them. This have been successfully applied to investigate facts. Thus, the method of displaying fingerprint with fluorescence excited by laser is superior to the normal method. In these experiments, we have used the source of Ar+ laser with wave-length 514. 5nm and 488. 0 nm. In observing the photographs, we use an adequate filter for decreasing the strong background laser and rejecting the interference of fluorescent light from the fingerprints carrier.
Laser medical in China
Guoxiang Xu
This paper reports the present status of laser medicine including clinical application, basic research, laser safety, and education in China.
High speed optoelectronic sampling system with laser diode sources
Yushu Zhan
A high speed optoelectronic sampling system with LD sources is presented. This system is very useful in industry. The sensitivity and resolution of the system are analysed in theory. Finally, the experimental results are given.
All home-made avalanche transistor driven single pulse selector for Nd:YaG mode locking lasers
Liu Huang
A noval all home-made avalanche transistor driver for single pulse selector with one side triggered, pulse width variable, and the pockels cell grounded, are described. A Marx Bank and an avalanche transistor chain absorber are combined to build a tiny high voltage nanosecond pulsewidth producer without any high voltage power supply. The output electric nanosecond pulse is about 4kv to meet the v of KDP. The risetime is less than 3ns, the avalanche absorber shortens the pulsewidth obviously. The triggered signal is taken from the intracavity polarizer ensuring the signal triggers the avalanche transistor or Marx Bank just in time to pick the peak pulse from the pulse train. We found several kinds of home made avalanche transistor, such as 3DG84I, 3DA151D, 3DA152E, that can be used as good as 2N5551 to build the single pulse slicer. The life time is over one million shots, the output stability is better than 5%, the mistrigger rate is less than 0. 1%, the single pulse selected probability is about 99. 9%, and the selected single pulse energy is larger than 500uj. The tasted parameters of the avalanche transistor, figues, dynamic measurement circuits and the selected picosecond laser pulse are given.
Deposition of superconducting thin films with excimer laser ablation of sintered oxide ceramics
Chengwu An
Superconducting Y-Ba-Cu oxide thin films with zero resistance temperature 85 K were prepared by laser ablation of sintered oxide ceramics. The laser fluence threshold and the deposition coverage were discussed.
The design of a repetition rate laser rangefinder
Chongjuen Den
In this paper, the design of a repetition rate laser rangefinder is discussed, the technical significations of a practical laser rangefinder are presented, and the ranging capacities are estimated. The program of ranging is an optimized one, and the block diagram and the time series diagram of the rangefinder are give. The experiments using a repetition rate laser rangefinder by wind cooling method have been conducted. And this kind of laser rangefinder has already put into practical use.
The line broadening and red shift satellite line phenomena in 1000 GW Nd3+:Phosphate-glass laser system
Dounan Zhuang
Using a grating spectrograph with a 0. 006nm resolution to monitor the laser spectrum of ai 1000 GM Nd phosphate-glass laser system. When the laser power intensity is up to 1 GW / cm (100 ps pulse), the laser linewidth has a 1. 04nm broadening, and there is a red-shift(3. 77nm away from the main laser line)satellite line appears. The red shift line consists of several peaks, and spectral intensity is nearly 3 / 5 of the main laser line intensity. When laser power intensity is reduced to 0. 37 J/ cm (3 ns pulses), the red shift phenomena disppears, and line width broadening is less too. The red shift phenomena probably comes from the Raman scattering of the phosphate glass and has been amplified in the gain medium.
Sensing of minerals and rocks from a distance using a laser fluorosensor
Xiouhong Sun
laser induced luminescence emission spectral data of 31 kinds, 4 group of the geologic species asso- ciated with hydrothermal, metamorphose, sedimentary, and volcanic regions respectively have been acquired by using a laboratory operated laser fluorosensor. It is shown that the backscatter luminescence signals of the observed minerals and surrounding rocks are varying enough to be distinguished, and many of such signals are sufficiently intense for aerial remote sensing.
Study of a tunable mode 2KW CW CO2 laser
Zuhai Cheng
The beam mode and the output characteristics of a 2kw CW CO laser with tunable mode resonator (TMR), in which the beam mode can be tuned continously from TEM°, mode higher-order mode has been described. At the premise of no exchanging the structure of the resonator, in order to fit the beam quality for different targets of laser processing, it is the expectant goal to the people for long time to make the Laser can continuously select any output beam mode which it can be changed from TEMoi mode to higher-order mode. We ingeniously use the change of the relative location between the ray axis and the symmetrical centre of the active medium in this paper, it makes one set of resonator output several beam modes become in truth.
The experimental research on the statistical distribution of the short term spread of the laser beam propagating in the random medium
Guan-long Tan
A method was proposed for measuring the statistical distribution curves of the short term spread of laser beam. The technique were found on the beam width-Time-Amplitude conversion, The precision of the system was of 4. 7eu m. It was determined that the relative fluctuation of the beam width was of 1% in the static air, of 1. 3% in the turbulent air. And when the laser beam passes through the rigion of flame of the alcohol lamp, the relative fluctuation was of 2. 7%.
Discussion about the stress distribution in a high average power laser
The main difficulty for these lasers is the thermal effects which induced by thermal stress. The stress distribution takes a very important part in a high average power laser. The optical distortions which include thermal focusing, stress induced biaxial focusing, stress induced birefringence can be known easily if the stress distribution is already known clearly. In order to know the stress distribution, the temperature distribution is discussed at first because the nonuniform temperature distribution is the main reason which induces the thermal stress. Our discussion mainly aimed at the the stress distribution in the high average power lasers, especially in annular geometry lasers.
A phased array laser made of GaAs/GaAlAs graded barrier single quantum well structure
Longde Zhu
A phased array laser made of MOCVD-grown GaAs / GaAlAs graded barrier separate confinement heterostructure single quantum well (GBSC SQW) wafer was investigated. The threshold current of the array composed of ten ridge waveguide lasers was 67mA, linear output power was more than 500mW, and the external differential quantum efficiency was 60%. The configuration of the array is consisted of strongly coupling central region and weakly coupling mirror regions, and the effect of the geometrical configuration of the strongly coupling region on the coupled array supermode was examined.
The measurement of absorption uniformity on thin film by scanning laser photothermal deflection spectroscopy
With the development of high energy laser, optical thin films used in this laser system are required with higher qualities which include the weak absorption and its uniformity. When the films are irradiated by a sufficiently energetic laser pulse, any local point on films which has more strong absorption may be damaged. In addition, the absorption uniformity of bistable thin films is also required because the different bistable properties occur at the different absorption points. Therefore it is very important for detecting correctly the absorption distribution on optical thin film and providing trustly the information for the coating of optical thin films. There are various techniques [ 1] for measuring weak absorption on thin films, but most of them are local measurements and difficult to detect the absorption distribution on the whole surface of films. Since the early 1980, scanning photothermal microscopy (SPIM) which based on the photothermal effect has been developed [ 2] . It can not only detect the absorptivity in the localized region of a sample in fast and high sensitivity by using a simple experiment setup, but also easily measure the absorptivity distribution on the whole surface by scanning the sample. Therefore, it is a novel technique for measuring the absorptivity distribution on optical thin films with the prospect of development and application.
An automatic recording laser interferometer for verifying standard scales to 3 meters
Hongyan Diao
A description is given of an automatic recording Laser interferometer for verifying inval leveling rod up to 3 meter. The interferometer adopts a novel optical system for Abbe's error compensation instead of the contraditional Eppenstein's system. The interferometer mainly consists of two parts: the dynamic photoelectric microscope and the parallel length measurement system. When the instrument operates, electric pulses which correspond to the central positions of lines are produced by the zero crossing method. By means of an interface unit, the electric pulses can control the interferometer to record the measuring length values correspondent to the control positions of the lines. And then the measuring length values are inputted the computer for processing and printing automatically. The experiments show that(1) the interval positioning accuracy of the microscope is better than ± 2p. m. (2) overall accuracy of the instrument is better than ± 7µ m.
Multi-pulse modulated short pulse Nd:YaG laser
Liu
A new technique, multi-pulse modulation technique for generating short laser pulse is developed. Applying this technique to a electro-optics Q-switched Nd:YAG laser, completely modulated laser pulse trains can be obtained. The width of a single pulse in the trains is less than 1 ns, with peak power higher than 15 MW, and the amplitude stability of the pulse train is better than 5%.
Multifrequency CO2 laser heterodyne detection
Dong-song Sun
A heterodyne detection using a genaral CO, laser is proposed. Two detection systems are given that can theoretically measure the velocity of a target.
High power sum frequency generation of 230.8-223.2 nm in BBO crystal
Shi-Ping Lu
Continuously tunable second harmonic generation of 294. 8-280. 5 nm was obtained by Q -switched Nd:YAG laser pumped Rh. 6G dye laser in a 45t cutting fl -BaB2O4(BBO) crystal. The output energy of the second harmonic wave is about 8mJ around 285 nm. The continuously tunable output over the range of 230. 8-223. 2 nm was also obtained by the sum frequency mixing between the residual pump fundamental wave (1064 nm) and the second harmonic wave of Rh. 6G dye laser in other 45 cutting BBO crystal. The sum frequency output energy is about 120 µ J around 227nm, the corresponding peak power is 12 kW. The key techniques of sum frequency generation were indicated.
Laser devices made of magnesium doped lithium niobate
Chong-quan Xu
High quality magnesium doped lithium niobate (Mg: LiNbO3, Mg:LN) crystal with magmesium content being 6. 5mol% has been grown in our lab. The crystal's homogenity and antiphotorefractivity were investigated by polarization microscopy and beam-distortion method respectively. Experimentall results showed that this kind of doped crystal has not only high optical homogenity (10 -10 crp i ) but strong resistance to photo-induced index damage (photo -refraction)(up to 100mW / cm ), which means that the two obstacles of LN crystal to be used in laser technique were removed by doping MgO into LN host. So it is necessary to make laser devices of Mg:LN crystal which can be grown from melt easily. In our lab several laser devices, such as frequency doubler, Q-switch, parameter oscillator, were made of the crystal. The main results of laser doublers and Q-switches are reported in this paper.
Tunable UV generation in BBO short to 200nm
Chenhua You
The BBO crystal developed in recent years possesses good UV properties. The radiation of 204.8nm was obtained by K. Kato` with frequency doubling. We get the tunable radiation from 200nm to 218nm by mixing the second harmonics of 492nm to 550nm with 1064nm using BBO crystal. The fifth harmonic of 1064nm at 213nm is gotten in the same time, and the conversion efficiency from the fourth harmonic, 266nm, to the fifth is up to 48x.
Phase conjugation using Nd:Yag laser
Jun Chen
Two widely used methods of phase conjugation: four-wave mixing and stimulated Brillouin scattering (SBS) have been investigated. With 15ns pulsed Nd:YAG laser a reflectivity of 125% by degenerated four-wave mixing in silicon single crystal and a reflectivity of more than 80% by SBS in acetone or CS2 have been obtained. With the phase conjugate SBS-mirror a laser has been built, which compensates for phase aberration inside the laser resonator. Nonlinear optical phase conjugation is a newly developed technology in the region of nonlinear optic during the past seventeen years ' . With this technique we can get the wave front reversal of a given light wave, which is equivalent to performing the operation of complex conjugation on its complex spatial amplitude. 'Time-reversed" light waves can be used to improve laser-beam quality, compensate for atmospheric turbulence in optical systems or for the phase aberration caused by thermal effects at the high repetition frequency or by crystal defects in active laser media in solid state laser systems. Therefore a great interest has been shown and a good deal of investigations are being made in phase conjugation. In this paper we report the investigation on phase conjugation by four-wave mixing in silicon and SBS in fluids using l5ns pulsed Nd:YAG laser. Furthermore we have built a laser resonator with a SBS-cell inserted in a laser resonator, which has emitted laser pulses with 5ns pulse duration and 130mJ pulse energy. Elimination for phase aberration has been proved by insertion of an etched glass plate into the cavity.
A new development in frequency stabilization of a longitudinal Zeeman laser
Xue Shao
A new development has been increased in frequency stabilization of a 0. 6334u m He-Ne longitudinalA Zeemanip laser. With a simple electronics, the frequency of a dual isotope gases He -Ne ( Ne 20. Ne ) laser has been stabilized with beat frequency extreme method, the stability is better than 2 x 10 , the frequency reproducibility is better than +3 x 10 s , and the beat frequency is more than 1. 5MHz.
Displacement measurement using optical heterodyne detection
Bo Wang
A new technique of heterodyne interferometer for measuring a displacement is proposed. In this method, a frequency-modulated He-Ne laser is used as the light source of two-wavelength interferometer. The variation of the phase difference which is proportional to the measured displacement is detected. The displacement can be obtained from measurement of the phase variation. Some fundamental experiments have been done.
Laser-induced direct deposition of thin films: film transfer
Binglin Zhang
The process of the laser-induced direct deposition is that the original film on the back side of an optically transparent substrate is directly transferred to a target substrate locatted behind the film by focused pulsed laser radiation[ 1] . Only a small region of the original film, which is exposed by focused laser rediatiom, can be transferred to the target substrate using this technique. Obviously, the advantage of the new technique is to fabricate micro spots of thin films. In principle, micrometer spot of thin film can be fabricated by this technique, because laser beam can be focused in micrometer spot. Probably it is a potentially powerful technique for the fabrication of micro and opto-electronics devices.
The photochemical effect and application on free electron laser
Han Han
Under photochemical reaction the critical wavelength A o absorbed is different for different kind of molecule. And it varies with molecular excited state and environmental temperature T, and so on. Owing to the radiation wavelength A of free electron laser is tunable, therefore its applied range and quantum yield satisfied us.
Optical-parametric oscittators of BBO and KTP
Qikang Fan
Both KTP( KTi0PO4)"' and BBO( -BaB204)"' have striking features used for OPO: large nonlinear coefficients, high optical damage threshold, good chemical and physical properties and easily to be polished. In our experiment the output of BBO optical parametric oscillator (OPO) was obtained over the range of 0.33-1.73 µ m. The maximum energy conversion efficiency of BBO OPO is 11% and maximum output energy is 10mj/putse. The tuning range of KTP OPO covers from 0.76 to 1.78µm. The maximum conversion efficiency of KTP OPO is 20% and the maximum output energy is 20mj/pulse.
Reshaping and compression of picosecond optical pulses from a semiconductor diode laser by the method of spectral windowing
Nai Zhang
Compression of picosecond optical pulse from diode lasers has been realized by using dispersive devices such as grating pair(1), optical fiber(2) and Gires--Tournois interferometer(3). But these methods are only available for single-mOde or mode-locked chirped optical pulses. There has been no effective way to reshape and compress multi-longitudinal mode chirped optical pulses. This paper proposes the method of spectral windowing to reshape and compress multi-longitudinal mode chirped optical pulses and demonstrates it for the short optical pulses from a gain switched diode laser. It is known that strong RE modulation invoking fast gain switching is the simplest and most reliable way to generate high repetition picosecond optical pulses in diode lasers(4). But in this method multi-longitudinal mode oscillation and frequency chirping will easily occur. Especially, in the case of multi-longitudinal mode oscillation, chirping appears in each longitudinal mode, and for each longitudinal mode the band-time product is always far greater than the allowable value of transform-limited ones. This phenomenon suggests the method of spectral windowing. It can be used to filter out one of the strongest oscillating longitudinal modes, and by narrowing it, compression of optical pulses can be realized, if there exist fewer oscillating longitudinal modes.
Study of temperature field in the pulsed Nd-glass laser beam welding
Xiufeng Chen
In this paper, the historical developments of laser beam welding (LBW) are briefly reviewed. After extensive analysis, it is shown that LBW is very suitable for vacuum technology. A model of heat conduction is suggested. In this model, the surface reflectivity is assumed to vary continuously during the melting process. A fictitious temperature method is developed. This method has the merits of clear physical conception, high precision, simplicity and effectiveness. It is especially suitable for computing the unsteady temperature field with two-point forward difference scheme. A three-dimension finite element program is designed for the latent heat processing. The program is quite versatile, applicable for different laser energies, pulse width, material and thickness. The computation results show good agreement with the analytical results appeared in the literatures. The results also show that the temperature field of material surface is approximately of Gaussian distribution, the depth of penetration and the radius of fusion decrease almost linearly with the increase of pulse width, or with the decrease of pulse energy. The temperature in the centre of material surface is directly proportional to the pulse energy and inversely proportional to the pulse width. The variation of material thickness has great influence on the depth of penetration, but has less influence on the radius of fusion. The parameters of LBW are closely related with the thermal characteristics of material. Experiment results obtained with the laser welder type DW-1 is consistent with the computation results.
GaAs/GaAlAs travelling-wave type laser amplifier with tilted facets
Feng-lan Xu
GaAs/ GaAlAs travelling-wave type laser amplifiers with different tilted angle facets are defined by proton-bombardment. Some characters are measured. Maximum single-pass gain of 27. 8 dB are attained with optical fiber coupling system.
The surface temperature on the back surface of substrate in the pyrolytic LCVD
Jie Zhang
The surface temperature is an important parameter in LCVD which affects the characteristics of film deposition and determines its rate. The surface temperature in pyrolytic LCVD has been studied theoretically (1), some people used the other methods to measure the surface temperature such as pyrometry (2) and Ni-Au thin film thermocouple (3). But thermocouple may disturb the absorption of the incident light, and the process of the film deposition, by the reflection change, the temperature is changable during the deposition, and this phenomenon is called self-limit effect. In this paper, a new method for measuring the increase of surface temperature and the steady -temperature distribution with micro-thermocouple by CW CO2 Laser is proposed without the self -limit effect. In order to avoid the reflection of micro-thermocouple, the CW CO2 Laser was irradiated on the back of surface which was kept in the deposition used for pyrolysis of organic compound on it.
A new type high precision laser thickness gauge
Wei-Min Chen
The laser thickness gauge discribed in this paper can be used to measure thickness of plate, band, or film made of steel, iron, rubber, paper, plastics and any non-transparent meterial at real time, on-line and non-contract. It is able to operate in most adverse industry circumstance, such as hot or cold steel rolling production line, and possesses high long-time stability, reliability. It also can be used to measure place, distance or surface shape of any body in like manner. The equipment consists of several parts, such as, laser projectors, optical receivers, electronic signal handling units, computer system, state control system, mechanical gearing and protective system for industry circumstance. We will discribe its main technical distingushing features in this short paper.
Output of squeezed state light from lasers via phase-conjugation effects in resonators
Shangqing Liu
Recently much interest has been paid to squeezed states of light. Such states have important potential applications. Obviously, it is convenient for application if squeezed state light can be radiated from lasers directly. This letter proposes a regime for this kind of lasers.
Stereo-reconstruction of contour map using holography and computer
Hui Wang
It has been reported that stereograms (i. e. left eye picture and right eye picture) were extracted by a computer from a contour map and drawn on a piece of white paper in red and blue separately. Looking at the stereograms with the help of a stereoscope, one saw a stereo -image of the topography. But the above mentioned method is rather complicated and inconvenient for the observer. Using the liquid crystal light valve (LCLV) as a link between computer's CRT and holographic system, the authors have been able to conduct the stereo- reconstruction of a contour map. The stereograms are first extracted by a computer from a contour map and displayed on the CRT. The stereograms displayed are transformed into coherent light images with the aid of a LCLV. The hologram of the two images of the stereograms is then recorded. In this experiment the authors invented a new method to record the hologram. This new method is called double-half-slits rainbow holography. By this method, the holographic images of the stereograms may be reconstructed with white-light, and the waves of the images for the left eye and the right eye will propagate respectively to the watcher's left eye and right eye because the images of double-half-slits act here as directional carrier wave. So the watcher will see a stereo-image of the topography without the help of anything.
Thermal coupling of pulsed 0.53-pm laser radiation to aluminums in air
Meihua Li
Experiment and theoretical analysis have been performed to investigate the ther- mal coupling of focused pulsed 0.53-pm laser radiation to aluminum targets irradiat- ed in air. A normal pulsed energy of 0.1J and pulsed duration of lOns (FWHM) are used. The thickness of the experimental aluminum slabs is - 0.5mm. Thermal coupling coefficients are measured for commercial aluminums (as-received, polished, frosted surface). We find low intensity (.S108w/cm2) thermal coupling coefficients of 0.2 for as-received, 0.15 for polished and 0.25 for frosted-surface aluminums. Thermal coupling coefficients of larger than 0.4 were observed with the onset of a surface plasma. After the surface plasma formation, the thermal coupling coefficients fall down with the increasing intensity. Measurements are also presented for the plasma formation threshold above aluminum target irradiated at 0.53-pm. An intensity threshold of 2 X108w/cm2 is indicated for a 10 us laser pulse (FWHM).
Laser non-contacting displacement measurement
Huiming Tan
This paper discusses the principle of optical triangulation for non-contacting displacement measuring system which consists of a laser and a CCD. In the light of specific measuring installation, a kind of data acquisition and processing system based on single-chip microcomputer is projected and has been applied in the measurement. Hardware circuit, software design and the result in real application are given. In contacting displacement measurement, because of object deformation under stress at measuring point and the relative movement of gauge head with the surface of object, the improvement of measurement accuracy and speed are limited in real-time and on-line measurement. According to the optical triangulation, these drawbacks can be avoided by the non-contacting displacement measurement system which consists of a laser and a linear array CCD. If the data acquisition and processing system based on a single-chip microcomputer is adopted in the measurement, it will be simple for circuits, lower for cost and more suitable for real-time, on-line and high-speed measurement:
Development of a lasers sphere-surface interferometer
Yan Guo
The laser sphere-surface interferometer is mainly composed of spherical interference system, the interference system for length measuring and electronic counting display.
Some analyses for slow velocity measurement of the diffuser by using dynamic laser speckle
Y. Liu
The velocity of a diffuser which moves very slowly has been measured on the basis of photon temporal autocorrelation. The experimental results show that the correlation time is proportional to the reverse of the velocity, which is quite in agreement on the theoretical prediction. In order to gain insight into the abilities and limitation of the measurement system, the nonideal effects in photon counting correlation are analysed in theory. KeyWords: PhotonCorrelation, DynamicSpeckle, Slow Velocity
A new method of laser twice diffraction and interference for precisely measuring straightness of large-size objects
Yu Li
Straightness is an index which limits the deviation of an actul line from an ideal line. Properly mearuring straightness is a basic means to evaluate the precision condition of the shape and position of a machine part. Measurement of straightness is of great importance in a mechanical system. The problem of how to precisely measure straightness of a small-size object has been solved, but that of how to dynamically and automatically, and with high resolution, measure straightness of large- size objects is still being studied and tried. Now we present a new method of laser twice diffraction and inteference for measuring straightness, with a measuring range of dozens of meters, a resolution of ,u m order. This new method is of low cost and easy to get popularized.
Laser-ICP spectrum source
Yuxiu Fu
Through the analysis of the formula related to the intensity of spectrum line, the article points out that the key to raise the sensitivity of spectrum analysis is to increase the number of the atoms in the plasma area of source. Therefore, the laser-ICP Spectrum source is designed so that it can considerably raise the sensitivity of the spectrum analysis.
Study of atomization process due to absorption of laser radiation
Mengheng Jiang
The evolution of solid material surface radiated by Q-switched pulse laser has been analyzed. A phenomenological model is presented which divided the action of laser on material into four stages. These stages are independently, relatively and coherently. First, the surface temperature rises initially and then the super-heated solid phase is formed. Second, the micro photo-induced plasma emerges and expends originally. Third, the plasma expends freely while the surface of the material changes from super-heated solid phase into melting phase. Finally, the melting phase of surface volatilizes equilibriumly. This ends up until the surface is solidified. By this way, we have treated the phase changing processes with the theory of thermodynamics and plasma dynamics, and established a set of complete equations which can be calculated numerically. The result points out the optimal conditions and parameters for producing neutral sample atom streams which are necessary for spectrum analysis, and has been compared with the experimental.
Mode locking by coupled cavity injection
A new type of laser generating nanosecond and picosecond pulses is presented. Pulses of 20ps and about 10mJ can be generated. The advantages of the proposed mode locking method are the enhancement of reproducibility ( about 100% ) and reduction of time jitter to nanoseconds, also large mode volume and high beam quality can be obtained by proper coupling of the two cavities.
The characteristic of stabilized frequency of single-tube double-frequency CO2 laser
Jingda Nan
A single-tube CO, double-frequency laser was discribed. When the length of discharge tube shift, the double-frequencies will shift at the same time r and the frequency almost keeps constant. The stability of frequency difference will be kept 10 order. The laser will be applied on CO, coherent laser image radar. The system has high stability of frequency difference, simple collimating light path and small construction.
Monitoring the thickness of ZnO films on iso-axis magnetron sputtering using laser
Kecheng Xie
The film thickness monitoring technology is one of the factors in film manufacture. In isoaxis magnetron sputtering, to detect the film thickness in real time is very important. This paper presented a method which can monitor the thickness of ZnO films in a simple, quick and accurate way as well as in real time. The method is to trace the substrates on a TCT-300 type isoaxis magnetron sputtering machine using laser directly. The sputtering machine is made in our institute.
A practical power supply for fast axial flow CO2 laser
Yongpei Zang
Industrial CO2 laser in range of sub-kilowatt and kilowatt has progressed from large, heavy slow axial flow laser excited by DC longitudinal discharge to compactness, efficient fast axial flow (FAF) laser excited by DC longitudinal or transverse RF discharge. However, it is very difficult to get stable discharge because of flow disturbance causing by high gas pressure and flow velocity. Based on experiment, we have designed a FAF CO2 laser excited by DC longitudinal discharge with 4 segments of plasma tubes in series to get current-stabilized and 'non- pinch" discharge in plasma bore, CW 600W of power output can be obtained along 0. 94m of total gain length with power stability of less than ± 1. 5%.
The study of optogalvanic effect of CO2-waveguide laser with compound cavity
Yuqing Chen
This paper is the first to report on the Optogalvanic Effect (OGE) of CO, waveguide laser with Compound Cavity. The study shows that as compared with common CO, laser, the OGE of CO, Waveguide laser is markedly more than that of common CO, laser. The OGE in a CO, Waveguide laser is caused by Changes in gas temperature (and hence resistivity) arising from variations in the collisional energy exchange rate between the two energy levels of the lasing transition and background gas. Therefore, the OGE is closely related with the Operated Conditions of laser, such as gas pressure, discharge current, gas mixture, modulated frequence of cut light, etc.
An experimental observation and study of the abnormal effect on photoelectric characteristics of a PMT photon counting system
Jianping Yin
In this paper, the abnormal phenomenon on photoelectric characteristics of a PMT photon counting system is reported. The experimental apparatus and method for observation and study of the abnormal effect are described. The experimental results are presented. The influences of the PMT anode voltage, the wavelength and the polarization of the incident light on the abnormal effect are studied experimentally.
Optimization of the imaging properties of image tubes
Vladimír Jareš
The electron lens sections of image converters and image intensifiers are genera- lly designed using a computer model. The model developed at TESLA-Vacuum Engineering El,Ictron Optics Laboratories has proved very accurate in predicting the major lens cha- racteristics, for example position and shape of the image surface, magnification, dis- tortion and resolution. An analytical approach to the numerical calculation of the effect of curvature of the photocathode on imaging parameters of the triode electrode system is outlined. A semi-analytic relations is derived to analyse the imaging pro- perties and their dependence on certain geometric and voltage tube parameters.
An experimental study on photon noise limited wavefront sensor
An experimental study on the Hartmann type wavefront tilt sensor is carried out at photon noise limitation. The experimental results and analyses show that A/10 sensitivity of wavefront tilt detection for space objects with about 8th astro- nomical magnitude within 1 ms of time has been achieved. An algorithm and computer program related to the luminous flux and corresponding photo-electron rate for wavefront sensor based on photon counting technique has been established and verified by experiments.
A direct calculation method of IR remote sensing systems' detectability for forest fire
Xiaolin Zhang
IR Remote Sensing is an effective measure of monitoring the forest fire, especially, for those areas which can not be reached by the forest guards themselves or their sightline. We have carried out some analysis about the target resolution of IR line scanner[ 1] . Here, we further offer a direct calculation method of detectable lower limit of fire areas which are smaller than the instantaneous field of view (IFOV) using the systems' practically measured parameter NETD. Starting from the general condition, the sensitive equation is [ 2]
Testing MRTD And MUTD for complete thermal imaging systems
Dean Wang
The paper describes designing principle, basic relations, main specifications of the RXFT-1 equipment for testing MRTD and MDTD, and testing ambient and method. The RXFT-1 equipment is composed of temperature difference control unit, target generator, collimating optical system and temperature difference indicator. The target generator consists of the standard periodic test pattern and parallel to its a flat radiant source. The temperature control accuracy and uniformity is better than 0. 01 C. There are the kind of two types in the RXFT-1. One of them is two way liquid circulation of matter. It is respectively controled the target and background temperature of the generator. The second, temperature matter is semiconductor of peltier effect. Its temperatures are controled precise temperature difference controller.
Infrared-transmitting fluoroaluminate glasses
Fengying Lin
In this paper the glass-forming ability in the system of RF2-AlF3-YF3 was studied. The relationships between some physical properties, including refractive index, density, characteristic temperatures and viscosity, and chemical composition were reported. The crystallization kinetics of glass in the melt-cooling and glass-reheating process were investigated. The experimental results show that this fluoroaluminate glass is characterized by a widely transparent region from 0.2 to 7 um, a low refractive index, a high Abbe's vaille and other good physical and chemical properties. Especially this glass has much better chemical durability against water and higher mechanical strength comparing to the fluorozirconate glasses.
The timing properties of microchannel plate photomultiplier tubes
W. D. Pang
It is well known that the photomulitiplier tubes have widely being used in many fields. In the different field, there are different demands for the properties of the tubes. Particularly, the properties on time response of the tubes are very important in ultrafast phenomenon diagnosising. The timing properties of the MCP-PMTs are mainly limited by the following factors: 1. The electron transit time dispersion in all parts of the MCP-PMT, 2. The electron transit time between MCP output and collector (anode), 3. The capacitance between MCP output and collector.
A focus on lightwave local area networks
Hsi-Chiu Liu
This paper focuses on lightwave technology used in local area networks (LANs). Lightwave technology is one method to appease the greater demands placed on LANs, both now and in the future. We consider some of the main effects this has in both existing and future LANs, also noting any problems and limitations along the way. There is a look at the LAN topologies that can be used for lightwave networks, and concurrency technique that can be used to tap into the vast array of bandwidth lightwave medium has to offer. We also examine the performance effects lightwave technology is giving us currently, and what to expect in the future.
Polymer optical fibres, preparation of the step: index and gradient, index polymer preforms and fibres
Polymethyl methacrylate (PMMA) rods have been prepared under various polyme- rization conditions. All the obtained rod-preforms were subjected to a drawing process to examine their thermoplastic properties. The mechanical and optical properties of the drawn PMMA fibres were determined with respect •to the preparation and drawing conditions of the rods. Polystyrene - core polymer optical fibres (POF) manufacturing as well, as gra- dient - index (GRIN) polymer rod preparation were also briefly reviewed.
Calculation and measurement of birefringent properties of special optical fibres
Václav Sochor
Basic terms used to describe fibre birefringence are explained and a survey of fibre birefringence is presented .Methods of fibre birefrin- gence calculations are briefly reviewed with emphasis on the boundary elements method /BEM/used by the author for birefringence calculations of fibres with elliptical core and cylindrical/or elliptical inclusion. Selected experimental methods of fibre birefringence measurement are briefly described and obtained experimental results are presented.
Optical fibre optoelectronics oscillator
V. N. Konstantinov
Simple optoelectronics oscillator using optical fibre as a delayed feedback is described. Basic rate equations are formulated, conditions of steady state regime and relation between feedback delay and oscil- lation frequency are derived.Experimentaly obtained characteristics of realized circuit are displayed and its use as a displacement sen- sor is pointed out.
Fiberoptic vibration sensor for high-power electric plants
M. Brenci
An optical fiber sensor for vibration monitoring in high power electric plants is presented. The sensor uses an elastic cantilever as transducer, the motion of which is detected by a fiber-based optical head. Vibration measurements up to 250 p.m of peak amplitude, at the 100 Hz fixed frequency are performed, with an accuracy of 0.1 pm and a linearity error within 3%.
Photoluminescence in fluoride glass optical fibres
Gorachand Ghosh
Photoluminescence effect was found in Zr-based fluoride glass preforms and fibres doped with Nd, Eu and Er under excitation with Kr-ion laser. Generation of visible to middle infrared including 2.7 pm were observed. Er-doped fluoro-zirconate fibre is capable to lase many desired wavelengths.
Dispersion of thermo-optic coefficients of some optical fibre materials
Gorachand Ghosh
Refractive index, its dispersion and their variations with temperature are analysed in a physically meaningful model to verify the presently available experimental data on the temperature dependence of zero dispersion wavelength and cut-off wavelength for silica and fluoride glass optical fibre materials.
An analysis of pin-fet receiver sensitivity for Oeic design considerations
Moon-Soo Park
An exact prediction of the sensitivity of a fiber-optic receiver is important for optical link analysis as well as for OEIC receiver design. For this purpose we have paid a special attention to ilze effect of flicker noise in PIN-MESFET optical receivers and have been able to improve the exactness of noise calculation significantly. This is the first intensive treatment of flicker noise ever publislzed in calculating the sensitivity of MESFET-based optical receiver. We first calculated the total input equivalent noise current which was then used for the calculation of peak power penalty caused by flicker noise. We have found that the flicker noise affects the sensitivity over a wide range of bit rates up to 1Gbitls. The calculated peak penalties were between 1 and 8dB in the case of high-impedance type receivers. In the case of transimpedance type receivers, the penalties were less than 2.2dB for noisy devices. The results of sensitivity calculation show excellent agreement with the performance data of commercially available PIN-FET receivers. The analysis also shows that there exist, for each given bit rate, an optimum feedback resistance, an open loop gain of front-end amplifier, a total input capacitance depending on photodiode capacitance, all of which are important circuit parameters in designing an OEIC receiver.
The development of the deep He-Ne laser acupuncture stimulator and the clinical practice
Fangzheng Li
A He-Ne laser beam is modulated and split into three beams, which are coupled into three monofil optical fibres. After that they enter into the laser acupuncture pins which are sticked between optical fibre and stainless steel pipe through the optical fibre joiners. It raises curative effect of traditional acupuncture, because the laser beam and the pin give simultaneously the stimulation in the depth of the acupoint, and the modulated laser beam can simulate the customary acupuncture way such as twirling etc, The laser acupuncture pin can be used only once, for the price of the optical fibre joiner is low. It has been proved by the clinical use that the laser acupuncture stimulator has the notable efficiency for the palsy and post-palsy, sciatiac neualgia, migraine etc. The production cost of a stimulator is about Y 1000(RMB)
Parallel transmission and restoration of images through single optical fibers
Yuhong Chen
Abstract- A scheme is presented for recovering the transmitted image through a single optical fiber by using digital image processing technique. The basic- relations,characteristics and limits of this scheme is discussed.
Linearity analysis of fiber-optic gyroscope
Changhong Shang
Fundamental principles of closed-loop fiber-optic gyroscopes are described. Based on the closed-loop condition, simulated by computer, the linearity of scale factor is analyzed. The result shows, for a given gated time, it is possible to find the best amplitude ratio between the first and the second harmonics of feedback signal so that the optimum linearity of scale factor for fiber-optic gyroscope can be achieved. The scale factor of practical fiber-optic gyroscope should have good linearity in a wide dynamic range. Two techniques are used for this purpose, electrical signal processing and phase nulling. Limited dynamic range of fiber-optic gyroscopes is caused by the nonlinear relation between output signal amplitude and phase difference in the interferometer. The fundamental principle of electrical signal processing is to recover the original phase information in sensing loop. Pseudoheterdyne detection technique is to transfer Sagnac phase shift caused by gyroscope rotation into a phase of low frequency signal, so the dynamic range is extended. Phase nulling is to induce artificially a compensating phase whose amplitude is equal to Sagnac phase shift, but in opposite direction. As such, the gyroscope is operated at zero phase shift and gyroscope dynamic range is limited only by the feedback control component. Gated phase modulation approach can realize closed-loop operation of the gyroscope. The key component to this technique is a phase modulator giving two functions of biasing and nulling. For normal cylindrical piezoelectric phase modulator, it is difficult to have flat frequency response. To improve linearity of scale factor, one must control relative amplitudes and phases of different harmonics of nulling signal. The necessary nulling signal in closed-loop operation of fiber-optic gyroscope can be simulated by a microcomputer. Simulated result shows that the scale factor of fiber- optic gyroscope depends on the ratio of the fundamental and the second harmonics and the duty cycle of gating signal. For a given gating time a reasonable amplitude ratio for optimum linearity of scale factor of gyroscope can be found. The schematic diagram of fiber-optic gyroscope is shown in fig 1, where fb is the bias modulation frequency. Output signal of a pulse generator is applied to a low-pass filter and relative phase of different harmonics is adjusted to get a composite signal shown in fig 2, including the fundamental and the second harmonics. This signal used to give a compensating phase is added to the modulator to realize closed-loop operation. The output signal of the fiber-optic gyroscope is applied to PSD via a preamplifier and a bandpass filter. The error signal from PSD, whose output includes the information of rotation rate and direction is used to control the amplitude and the polarity of nulling signal. PSD output signal is represented as:
Effects of light feedback on CO2 laser instabilities
Li-gen Zhang
Up till now, the effects of transverse distribution of light field and atomic polarization on laser instabilities and chaos have not been considered in most of experimental studies, and the plane-wave model has been widely adopted in theoretical analysis. However, plane-wave model fails to predict some observed results. It is come to be shown that the plane-wave Maxwell-Block theory is only an approximate description on dynamic behavior of laser system, and some important factors have been neglected. More recently, Lippi et al. 1 took the transverse distribution of cavity mode into consideration and made a research on the effects of Gaussion distribution. Gao Jinyue et al. 2 made a theoretical calculation on a simplified model in which the light field is axix-symmetric and changes only along radial direction. In this paper we report the first observation of the pulsation frequency shift and the chaos operation caused by light feedback, which changes the transverse distribution of light field, in a single-longitudinal, multitransverse mode CO2 laser. The result shows that the transverse distribution of light field and population inversion is an important factor to affect laser stability.
Analysis of heat radiation characteristics of the probe of a dichromatic high-temperature optical fiber sensor
Zeying Chi
It was analyzed that the heat radiation characteristics of the probe of a dichromatic high-temperature opti- cal fiber sensor. The probe was made of sputtering Iridium(Ir) thin film on the end of a sapphire fiber forming a blackbody cavity. According to heat radiation characterisitics of a cylindrical cavity and characteristics of radia- tion, absorption and heat-transfer of a single crystal sapphire, the heat exchanges between the cylindrical Ir cavi- ty and sapphire fiber was neglected rationally. A theoretical model of the heat radiation of the probe, which con- sidered respectively radiation of cylindrical Ir cavity and radiation of sapphre fiber, was established. Then the analytical formula of measured object's temperature T was derived by two wavelengths/(21, 20 power ratio Q which was measured with dicromatic optical fiber pyrometer.
The study of dispersion characteristics of single mode optical fibers
Xian-hung Wu
In this paper, the 4th order Runge-Kutta method (1) has been used to study the dispersion characteristics of single mode optical fiber, especially the effect of axial index dip on the dispersion characteristics. And hence a new type of index profile, Laguerre-Lorentz profile, with low dispersion in wide spetrum range has been found. These results are useful to the design and manufacture of single mode optical fibers.
Wideband tunable UV laser sources by BBO crystal
Yiqian Yuan
We have performed the output of tunable UV laser wavelength 367.5-378.2nm, 281.8- 292.3nm, 223.2-230.8nm by P-BaB204(BBO). The sum-frequency generation between R6G dye laser and fundamental wave (W) of Nd-YAG laser by a BBO crystal cut at 38°, The output of continuously tunable over rage 376.5-378.2nm has been obtained. The pulse energy is over 1.3mJ, the conversion efficiency is 10%. The R6G dye laser, which pumped by frequency doubled YAG laser, has been frequency doubled in a BBO crystal cut at 45°, the tunable range of 281.8-292.3nm and about 8mJ pulse energy have been gained, efficiency is 30%, and the sum frequency of the pump laser's FW and the dye laser's SHG enter another BBO crystal cut at 45°, the tunable range 223.2-230.8nm, the pulse energy is over 100PJ, q=10%.
A novel inline tunable Fabry-Perot filter for WDM fiber systems
Zhongxian Zhang
A novel Optical Fabry-Perot Interferometer (FPI) which consists of a couple of GRIN lenses is presented. The GRIN lenses are used not only as a collimating lens and a focus lens respectively, but also as a Fabry-Perot resonator which is piezoelectrically tuned. Compared with other types of FPI for optical filter this device has a much simple structure, lower insertion loss. It is compatible with fibers and useful for different WDM's wavelength spans.
Line code nBCH for optical fiber digital transmission
Tingyao Wang
In the optical fiber digital transmission system for long haul trunk, line code is very important for quality of transmitted information. Our country has a vast territory. Not only long haul trunk with good quality is needed, but enough channels are also needed for local section communication along the line. For this purpose, Wuhan Research Institute of Posts and Telecommunications, China, has put forward line code 8B1H adoptable in the local section along the long haul trunk to insert and drop channels. But because code H and C are inserted alternatively, the synchronization of codewords, in service error rate monitoring, and the number of consecutive identical code are affected. A new kind of line code nBCH is presented here on the basis of studying to code 8B1H.
Continuum band jointly generated by SFPM and SRS in a multimode fiber
Shupo Shen
Stimulated four photon mixing (SFPM) and stimulated Raman scattering (SRS) are two third-order nonlinear effects with different mechanisms, occurring in intense light transmission process in fibers. Their common feature is that they are able to convert coherent pump light at a certain frequency into new coherent light at different frequencies. Since threshold power for SFPM and SRS in fibers is much lower than in bulk material, it is recognized that SFPM and SRS in fibers are effective approaches to the frequency tuning of laser radiation. Incomparison with SRS, the advantage of SFPM is that it is able to achieve frequency up- conversion as well as down-conversion, but the problem is that SFPM process requires a harsher phase matching condition. Therefore, it is rather difficult to generate a Stokes-anti -Stokes (S-AS) pair experimentally, and even more difficult to generate multiple pairs. So far as we know, only one or two, at most three S-AS line-pairs were reported to be observed simultaneously[ 1] . Recently, through many experiments, we have simultaneously recorded six S-AS line-pairs of SFPM for the first time. It is specially worth notice that the six Stokes lines of SFPM act as new "pump radiation" and initiate the multi-order Stokes lines of SRS. All these lines, overlapping the cascade Stokes lines of SRS directly generated by the initial pump radiation, form a continuum band in the spectral range of 540-640nm.
A new construction of optical fiber probe
Shuxin Dong
A new construction of optical fiber probe is introduced. It has the advantages of insensitive to outer disturbances.
The analysis of an all multimode fiber electric current sensor with fiber Fabry-Perot interferometer
Yuan-Ling Zhan
In this paper, an all multimode fiber electric current sensor with fiber Fabry-perot interferometer is presented. As shown in Fig. 1, our system mainly consists of a laser diode, a multimode gradient input fiber, a multimode gradient Fabry-Perot interferometer, a multimode output fiber and a detector as well as a processing unit. The interferometer is wrapped and fastened on a magnetostrictive amorph metal ring, the cable of electric current to be measured goes through the ring. The magnetic field of electric current changes the radius of the ring therefore the cavity length of the fiber Fabry-Perot interferometer. The output of the interferometer that is the number of interference fringes in one period of AC current depends on the strength of the magnetic field produced by the electric current to be measured. So, by counting the number of fringes, the electric current can be determined. The fiber Fabry-Perot interferometer is mostly made of single mode fiber in order to keep the coherence of light. R. Kist et al. [ 1] made the Fabry-Perot interferometer with multimode gradient fiber and used the single mode fiber as the input fiber, and got good results. But we also get good results with all of the fibers used in our system which are multimode gradient. There are two reasons to enable the system to work well: one is, in Fabry-Perot interferometer, the multimode fiber is bent, because of larger bend loss of high mode, the high modes are filtered, there are only several low modes; the other is because of energy distribution in modes, the output of interferometer is mainly determined by the interference of several modes. Additionally, the coherence of light source and the coupling efficiency have effect on the output of the interferometer.
Applications of FT-IR emission spectroscopy for superconductor YBa2Cu3 Ox and rare earth sesquioxides
Jun Yang
YBa,Cup superconductor orthorhombic-to-tetragonal structure phase transformation are measured. The infrared emission spectra with temperature increase show that the phase transformation occurs at 800K. The superconductivity of the sample disappear at 1000K. Rare earth sesquioxides infrared emission properties are measured. At 521 cm , , a new peak, appears in the infrared emission spectra and is split into two peaks at 528 cm and 517 cm at 1100K. The A-C-B structure phase transformation in relation to the infrared spectrum change is discussed.
Optic-fibre polarimeter for process control
Hong-guang Wan
So far, all polarimeters are used by sampling. But this optic-fiber polarimeter for process control designed here is able to work in manufacturing pipes or tanks with its sensor connected with optic-fibers is directly set into the liquid in these pipes or tanks. And its measuring range can reach -359. 99°- + 359. 99. It can successfully measure, keep watch and control automatic process. The system configuration of the instrument is displayed in Fig 1. The light from sodium lamp is sent to the sensor through one of the optic-fiber roads and polarized by the first polariscope. Then the light goes through the measured liquid to the second polariscope (its plane of the polarization is identical with the first one). Then, the light including rotatory power information of the liquid is sent to the photo-detector through optic-fibers and transformed into voltage by the photo-detector. With the voltage amplified the corresponding luminance I is obtained. The other road is a reference. Instead of polariscopes, this reference road has an attenuator which makes the light loss equal to the loss in that road with polariscopes when the rotation of the measured liquid is 0°. So the luminance measured by the latter road is always I . The rotation can be obtained from formula „ T2
An optical fiber system for the multiparameter observation of underground water precursors
Linlin Ge
The observation and study of groundwater behavior is believed as one of the most promising approaches of earthquake prediction. Primary results of the multimeasurand optical fibre system for monitoring underground water trends (OFSMUWT) are presented in this paper. The measurements include groundwater temperature, turbidity, PH, acoustic emission of rocks, and concentrations of bubble, hydrogen and methane, and their gradients.
An optical fibre magnetic field sensor system for measuring low frequency fields
Yanbing Liu
This paper describes an optical fibre magnetic field sensor system, developed by us based on previous work, for measuring D. C. or low frequency fields. In the measurement of low frequency magnetic fields based on the principle of magneto striction, such as the magnetic field of the earth, one of the main problems is the noise induces by the temperature fluctuations and low frequency vibrations. These low frequency noises can be reduced by letting the signal field to be carried by a high frequency carrier, provided by an oscillator. This was done in the work of P. Zhanzucchi[ 1] . In this system, two magneto strictive rods were used as sensor head in order to maintain some balance of the two arms. Based on this and other work [ 1] ,[ 2] ,[ 3] , we develop a sensor system which uses only one magneto strictive rod, instead of two, as sensor head. Our system has the main advantages of the system of Zhanzucchi, but is much simple in its structure.
Optical fibre remote monitoring system for boiler levels
Aizhong Li
The water quantity of a boiler drum is regarded as an primary factor for ensuring the safety of boiler. Once a drum is short of water, the consequence of a boiler explosion caused thereby is dreadful to contemplate; especially for a steam boiler of high or medium pressure, because it will affect the bolumetric watersteam ratio, furthermore affecting the working pressure. Therefore it is an important task for a boiler operator to keep close watch over boiler level. But a boiler drum is normally located 10m to 150m away from its control room and 20m to 60m above the ground, it is not easy to check directly the bicolour levelmeter on a drum. The electric sensor for observation of water level we are using nowadays is proved not reliable due to long-term service in high temperature environment. Up to now, no such a device which can ensure a direct observation of boiler drum water level from control room is availabe. In this case, the author has, through one year's research, developed by using optical fibre technology an optical fibre remote monitoring system for boiler water level (its working principle as per Fig,1).
Fiber-optic microphone
A fiber-optic microphone based on intensity modulation has been fabricated and tested. The device possesses sufficient sensitivity to detect acoustic waves in the frequency range from 300 to 3400 Hz. The signal to noise ration is 43 dB relative to 0. 1 pa 1 KHz. Since the device has been fabricated with standard GI (50 / 125) fibers it can be built quite simple and inexpensively with higher stability and reliability. The sensor is compatible with present fiber communication systems including sources, detectors and components.
Frequency-division multiplexing optical fiber transmission system applied in power system
Jinbo Kuang
In power system, there are various detected analog signals which need transmission from detecting site to remote control room. These signals are usually transmitted by cable. An optical fiber transmission system has been developed in this paper. It is used to transmit multiple analog signals detected. It can ensure safety for control room and prevent the electric -magnetic interferences. The transmission way of multiplex needs only one optical fiber system (light emit component, optical fiber and opto-electronic receiving component) to transmit multiple signals. It can decrease the cost and it is quite convenient for operation and maintenance. Frequency-division multiplex is applied in this transmission system to transmit multiple signals. That is, the different transmitted signals are carried by electronic carrier waves of different frequency. LED is chosen as the light emit component of the optical fiber system for its nice linearity of P-I (emitted power with driving current) characteristic and long duration of work. The opto-electric receiving component of optical fiber system is an integrated device called PIN- FET, it receives and amplifies the light signal. The transmission system can transmit distortionlessly four analog signals whose cut-off frequency is 200KHz. It has been used for on-line detecting system of partial discharge.
Experimental research on chaos operation in a CO2 laser caused by the transverse effect of the light fields
Nanpeng Chen
The instabilities of cw-0O2 laser have been the object of extensive investigation in the field of laser instabilities and chaos. It is well known that a chaos operation of a system requires at least three dynamical variables in phase-space. Therefore, the CO2 lasers used in chaos investigation are all supplied with either modulation or feedback to enlarge the phase-space dimensionality. Recently, it is come to be known that some instabilities maybe result from the transverse distribution of laser fiedl. When the transverse freedom degree is considered, theoatical analysis shows that the Maxwell-Bloch equations change obviously. Different simplified models have been discussed priliminarily, but to data no clear experimental demonstration has been given. Here we report our experimental studies on instabilities caused by the transverse effects. Chaos operation are first observed in a single-lingitudinal, multi-transverse mode cw-0O2 laser in the abscence of any kinds of modulation or feedback. The laser output evolves from stability to chaos along different routes when the laser parameter are changed. Our experiment shows that the transverse distribution of light field and population inversion is an important factor in causing laser instabilities.
Smart fiber optics flowmeter
Dong-xu Wen
Many of the problems of flow, electical noise and nonlinearity experienced when using vortex flowmeters at low rate are overcome by using a fiber optic displacement sensor. Due to vibration in the sensory beam, the lift signal is modulated by varying the amount of coupling between two facing fiber ends. Modulation is proportional to the change in overlapping surface area of the two fibers. Use of large core fiber with low numerical aperture enhances sensitivity; A simple LED / PIN photodiode serves as the light emitter and detector which reduces the cost. Vortex shedding flowmeters can benefit from both smart electronic and optic technologies. The technologies are interconnected. Fiber optics has been able to improve range sensitivity operating temperature up to 500 degree remote mounting capabilities and protection against EMI / RFI effects. Smart electonics provide higher accuracy and flow totalization etc.
On-line concentration measurement system with optical fibers
Jianshu Li
A novel on-line measuring method with four-terminal optical compensation network has been presented in this paper. It can eliminate influences of the fluctuation of light source, the transmission loss of light in optical fibers, the variation of amplifiers' gains and the characteristic value drift of photo-detector, so the signal-noise ratio of sensor is increased clearly. The concentration measurement system using this detective method can make the detective value of the concentration reliable and accurate when it is used in the on-line measurement.
On the efficient coupling of optical fiber and channel waveguides
Pingkai Qian
The coupling of optical fibers and channel waveguides has been important and difficult problem in integrated optics. It is, too, the only way for integrated optics from experiment approaching to its application. Here we report two parts of our works, namely, on the end fire coupling between single-mode optical fibers and Ti-diffused LiNbO3 channel waveguides.
Investigation of the main crystals in a MeF2-YF3-AlF3 (Me=Mg+Ca+Sr+Ba) glass
Ruihua Li
By means of Leitz optical microscope, scanning electron microscope and energy dispersive spectrometer, we have investigated the main crystals which form upon cooling in MeF,-YF -AlF3 (Me=Mg+Ca+Sr+Ba)glass.One of the crystal in the glass is enriched in Mg, Al and Ca. The crystallization mechanism of the glass and relative merits of the analysis techniques used are discussed.
Grazing incidence grating spectrometer in the low energy x-ray region
Xianxin Zhong
A new soft X-ray grating spectrometer for studying laser produced plasmas has been developed. The 1 m grating incidence vaccum spectrometer is equipped with a 1200 grooves / mm or 600 grooves / mm grating and a 1000 A thick aluminum filter. The spectrometer is arranged at a vaccum target chamber when it is used to measure the ionic distribution. It is aligned accurately in target plane using 4 D. adjustment unit and a system with optical fiber bundle, electronic camera and TV monitor. The design of optical system, novel construction of spectrometer, and experiment arrangement and results are discussed.
Properties and structure of the IR transmitting glasses in the CdC12 based systems
Haochuan Jiang
The glass forming region in the ternary system of CdC12-PbC12-KC1 was identified for the first time in this work, and the formation of some multicomponent glasses based on CdC12 and PbC12 was also reported. These glasses are transparent from visible to 25 um, and appear to be prime potential low loss waveguide for CO2 laser. According to Ramann spectra, the structure of CdC12 based glass can be described by polyhedra random packing model. The coordination number of Cd2+ is 6. The chemical durability of CdC12 based glass can be improved by the introduction of PbC12.
Linear output principle of fiber optic temperature sensor
It is known that the photoluminescence (PL) spectrum of the optical fiber temperature sensor, which uses the GaAs / GaAlAs double-heterostructure semiconductor as a transducer, is determined uniquely by the temperature of the transducer, and the changed range of the PL peak wavelengths is approximately from 0. 860 14 m to 0. 910 /2, m for the temperature range of 0-150 C, and the output signals of the sensor are nonlinear[ 1] .
Some optical fiber probes design and its application
Shuguang Dai
In the field of the measuring technology, the request of noncontacting measurement is raised for some purposes. The advantages of performing noncontacting measurement by utilizing optical-fiber sensors are their simple structure, small size, anti-electromagnetical field interference, and wide frequency capability. Fig. 1 shows the general principle of the optical fiber noncontacting sensor. The transmission fibers illuminate the test object, and the receiving fibers convey the reflected light to a detector, the output Y is related to the structure parameters of fiber probe S, the reflectivity p and roughness coefficient R. of test object, the distance X, and the illumination power P., i. e.
Study on photovoltaic effect of P-N junction
Zhonghou Liu
Based on the equivalent electric current source theorem, the reason for photovoltaic theory's error is analysed in the present paper, and the basis of correction the classical photovoltaic theory and the new idea are established here. The voltage in open circuit is given by the classical photovoltaic theory as follow:
Simulation of a LiNbo3 signal processor
In this paper, simulation of both range and azimuth compression of a guided-wave LiNbO3 synthetic aperture radar (SAR) processor is presented. An alternative choice of reference data type which improves the processor performances is proposed for the first time.
N.M.R. Radon Haar transforms
Joseph Ben Uri
In continuation of previous papers by the author [4 and 6] it seems to be suitable to discuss more in detail the NMR in connection with the Radon transform and obtain enhanced pictures by using the Haar transform also i.e. the Radon-Haar transform. There exist many methods of the inverse Radon transform but the two, the filtered back projec- tion - FBP [2, 3, and others] and the circular harmonic decomposition Radon transform, as suggested by Cormack and described e.g. by Chapman & Cary [5], by the author [6] and others are the best ones till today. These inverse formulae should be identical, but due to noise and smoothing effects of the transforming and incomplete datasets their numerical pro- perties may be very different and therefore also the results. The principle of the NMR projection will be known to the general reader. In short a magnetic dipole 11 in a field B0 in the vertical z -axis has a torque µ, Bo and the macroscopic moment of magnetization
Implementation of Kern SPACE vision software through a transputer network
G. Zhou
Kern SPACE (System for Positioning and Automated Coordinate Evaluation) is a non-contact 3-D measuring system which utilizes high precision motor-driven theodolites with integrated CCD cameras for image acquisition. The system applies image processing techniques to accurately determine the image coordinates of a predefined target to a subpixel accuracy, the image coordinates are then converted to angular values to adjust theodolite angular readings. A transputer network is an ideal means to implement the current image processing software in a parallel processing mode, thus high-speed surface contouring and automated target tracking using a theodolite-based measuring system will become reality.
Applications of photorefractive crystals to optical information processing at SIOFM
Optical information processing research group at Shanghai Institute of Optics and Fine Mechanics (SIOFM) was engaged in recent years in the research on nonlinear properties of photorefractive crystals and their applications in optical information processing and has achieved some results in this field. We report in this paper a few major results which are esteemed rather important in our opinion. They are some new results of beam coupling in SBN:Ce crystals, and some new methods of spatial light modulation, associative holographic memory and spatial filtering.
An automated microscope system for cell image processing
The screening out of cells specially abnormal cells by microscope is a very useful method for cytology diagnosing. Since inspecting pathological changes of cells by microscope is very slow, thereby study a new auto-microscope system with function of image processing is very necessary. This system has the following functions: 1) the microscope stage should be scanned in x and y directions, and a step distance of scanning is corresponded to a field of view of the microscope. 2) For autofocusing, first the micro-structure is low contrast, otherwise focus depth is very small. Therefore, autofocusing for biological microscope is different to common industrial microscope with low time and high contrast. 3) The microscope must possess image processing functions to recognize and screen out cells. 4) The system possesses function for auto-photograph. Because the field of view of the microscope is very small, if all fields of view are photographed one by one, then several hundred thousands or several millions fields of view will be photographed. But there is no target in most of fields of view, i. e. , only a few is useful, so, it is necessary to screen out and auto- photograph them automatically. On the other hand, transmissivity of different targets is different, so the exposure time must be adjusted automatically. Besides that, this kind of camera must hold sufficient film, i. e. a large cassette must be disigned. The micrscope system with these functions is a complex auto-controlling system.
Study of a modal multidither image sharpening adaptive optics system for solar applications
We propose a modal multidither image sharpening adaptive optical system for a ground-based solar telescope.After a brief introduction of the system structure,we discuss two kinds of image sharpening functions,fitting capability of the zonal deformable mirror to different orders of aberration modes,temporal frequency bandwidth and its limiting factors.
Modulated beams holography and signal processing
The method of using holography with the recorded beams modulated by the plate motion to measure 3D displacement is proposed. Displacements of the plate are determined by the reference object. Image signal is processed with PDS microdensitometer.
An analysis of temperature distribution of heat flash
Yuwen Wang
This paper is to apply the infrared thermography and image processing technique to improve the measured precision for heat flash. In the laboratory and the shooting range,pass through more than hundred times projectile tests,the temperature distribution of heat flash was monited by infrared thermography using the gray thermogram, color thermogram and thermal profile.It is obvious that temperature distribution of heat flash may be measured and calculated to a new lever of reliability previously unobtainable.
Discrete arrays image transfer theory and evaluation technique
Baomin Zhang
This artical sumarizes discrete image developing process and completes a new fundamental image transfer theory of discrete imaging arrays. This theory may provide quantitative analysis for arrays image transfer quality and image recovery. We also put forward a group of testing parameter including real frequency transfer ability, aliasing effect and maximum space information demsity to evaluate the image transfer quality of discrete arrays and set up a discrete arrays imaging quality test equipment. Use this equipment a series of testing has been taken.
Phase conjugate feedback
Qinghu Shang
In certain instances, the contrast of a photographic transparency needs to be altered to recognize some information from Lhe everpresent background of its image. For example, the contrast of aerial photographs often needs to be reduced,whereas the contrast of X-ray photographs requires an increase.A optical processing system with coherent feedback which was reported by D.P.Jablonowski and S.H.Lee [1,2] is an important device to realize contrast control. To accomplish optical feedback, partially reflecting mirrors and ordinary lenses have been utilized. However, it is difficult to manufacture the optical elements of high quality so that the sizes of the irages processed have been limited.Besides,the input photographs need to be put in a liquid gate to eliminate its phase noises, which increase the complexity of the process. In this paper,a new coherent optical system with phase conjuate feedback using four wave mixing (FWM) with photorefractive crystals is represented, which can be utilized to control the contrast of the optical images of input transparencies in real-time. The feedback can remove the effects of the phase noises of the system on output images. Some results obtained from computer-simulations and experiment are in acreement with our theoretical analyses.
A design of photo-electric analogue-digital computer
Shen-cai Ling
Original of the Subject,the Comparison of Analogue and Digit Computers Obviously, analogue computer and digital computer have certainly a series of respe- ctive features, because of their different methods to reappear or describe the physical rules as two kinds of calculating tools, so there are many differences between them.
The optical-electrical image research on metamerism
Jiyuan Shi
This paper describes that according to the color spectral lightness theory of CIE and spectral character of target, the frequency spectrum of discreted metamerism can serve as the study to metamerism and as the determination of metameric object by optical-electrical image processing and the obtained pseudo image copy. Thus, the information can be extracted and determined accurately, so that it is beneficial to the analysis and judgment in chemical, crystal and biomedical image, etc. in the condition by medium copy. At first, the metamerism area is supposed according to the spectral characteristic, then, the discreted value changed by optical-electrical digital system is input into the image processing system. Under the support of hardware and software, the frequency spectrum of metamerism can be transformed. Having filtered it effectively in the frequency domain and having obtained the spatial domain image, the metamerism analysis can be done and the metamerism object can be determined from metamerism by usin image copy.
Pointwise automatic analysis of speckle photographs
Junjiang Zhang
An automatic system for analyzing specklegrams point-by-point is described. A new method of evaluating Young's fringes is put forward based on making a TV camera to be able to scan horizontally and vertically. Tracking filtering and edge locating techniques are developed to acquire fringe data.?. Experiments show Young's fringes can be determined with the accuracy of 1% in spacing and 1 in orientation and accordingly the displacement can be found out with the accuracy of 1 it m in the range of 20 to 100 p m.
A comprehensive computer-vision system for measuring the surface of large 3D objects
Shiping Zhao
By the use of moire topogarphy method, we developed a comprehensive computer-vision system (CCVS) and firstly put the system into practical industrial use to measure the surface of large 3-D objects, such as the surface of vane of hydraulic turbine. The dimensions of the vane are about 6m X 5m X 3m . In this paper, with the help of Fourier optics theoritical analysis of the forma- tion of moire fringes is given and CCVS is presented.
Applied study of photorefractive crystals to optical image processing
This paper, based on our studying multi-wave mixing in photorefractive crystals Fe: LiNb03[ 1] , we have set up a real-time parallel image, logic " ex OR" operation system, and performed real-time associative memory experiment. The results of our experiment is also given.
Talbot projection Moire topography and it's automatic fringe process using phase shift methods
Ruowei Gu
A novel profilometry---Talbot projection moire topography is demonstrated in this paper, which allows to take 3-D moire measurement under non-dark-room condition while the projecting lens can be eliminated. The moire contours are converted to 3-D data using phase shift methods with an image data processing system. The results of a fundamental experiment and its accuracy analysis are presented also.
The application of improved Fourier transform profilometry
Jian Li
3-D object shape can be profiled by using optical noncontact measurement methods, such as improved Fourier transform profilometry, etc. These methods restore the object shape through analyzing the continuous phase distribution of an optical structured field that is modulated by the shape. However, in practice, many shapes to be measured have steep height variation and may cause shadows in the modulated phase distribution. Such kind of object shape can not be restored. We propose a method to solve this problem. With this method, the improved Fourier transform profilometry can be used in many areas. This paper describes the theory.
Phase-comparison test by means of filling up pulses on dynamic measuring circular grating and its data process
Zhuming Gong
The phase-comparison Test by means of Filling up Pulses introduced in thig paper is a new method of computer applied in dynamic measuring circular grating. Because the digital value is directly used in data sampling and processing, two problems, the read errors from scaling by hand operation, and the lost of high frequent characteristics in the analog signals, are resolved by this method.
A real-time pseudo-color encoding using a liquid crystal light valve
Zhan He
The principle and technique of real-time pseudo-color encoding using a liquid crystal light valve (LCLV) are discussed in detail. We present a simplied hybrid field effect mode of LCLV, and give the mathematical formula of projection light intensity. With this result, the characteristics of this pseudo-coloring method are discussed and the rule of optimum system is pointed out. Some pseudo-coloring images are shown in this paper.
Fiber optic displacement measuring device by microcomputer
Zhenzhong Chen
Facing the facts that the drifts of light source and optoelectronic part are the slow variance of concerned time, the reflection index of the measured surface is the slow variance of concerned space, taking the characteristic that microcomputer can collect and process messages at speed, we may combine two displacement sensors .of intensive optical fiber into a new mode of optical fiber displacement measuring head according to a stated space.
Feature extraction and processing of the signal in opto-electronic image measurement
Wanpeng Ji
Based on related bibliographys and repesences on the image measurement and the practise of author in science and technique research, this paper treat various methods for feature extraction and application for these methods. The indirect binary is a new concept for come up with author. It lends itself to on -line geometric size measurement for heat workpiece in furnace and for glass ribbon width or edge location in the molten tin bath using float process.
The determination of image edge position in image measurement with CCD opto-electronic system
Qixiang Zhu
In order to determinate image size or position in opto-electronic image measurement, it is important to determinate image edge positions. Optical diffraction and the presence of variable filtering process make the image edge blurring, thus the determination of edge position is difficult. The formation and transmission process of electronic image by opto-electronic measuring system using CCD as detector attempt to be analysed, and a mathematical model to be defined in this paper. Edge position will be defined by calculating the point amplitude values of image edge, and the effects of the system parameters on the measurement of edge position will be found out.
Optical implementation of neural network models and photon-echo effect
M. N. Belov
Properties of the photon-echo effect are theoretically investigated for implementation of neural network models in optics. Optical schemes of the HopfieXd's network, the second-order neural network as well as the neural network with retarded response are proposed on this basis. The importance of an additional time coordinate inherent in the photon-echo effect is shown.
Quadratic associative memory hologram prepared by the polarization encoding process
As a higher order correlation model for associative memory, the quadratic associative memory(QAM) is implemented holographically by using the polarization encoding process. The use of polarization encoding to represent sign in the QAM tensor is made by twisted nematic liquid crystal light modulators. Experimental results of retrieving the stored objects from an imcomplete input are presented.
Parallel associative VLSI processor with optical input
P. E. Tverdokhleb
An important property of the optial disk memory systems providing data re(:::oding in the form of 2-D microholograms in their rather fast (0.1 to J. Gbit/s and even faster) speed of data readout and retrieval. It is advisable to perform the data stream processing in this type of memory systems using photoelectron VLSI processors [1], wich provide photoelectric transform and reading of page images reconstructed from microholograms, parallel logical data processing (associative retrieval in particular), writing of "electric" references for comparison and readout of the obtained results via an external fast controller in a computer.
A real time optical neural networks using programmable LCTV spatial light modulator
Shining Yang
A new memory modle of optical neural networks called the reflexive associative memory is implemented in real-time using programmable liquid crystal television (LCTV) in our experiment. In this model the vectors are stored in a memory matrix in the form of vector pairs. Not only a full vector prestored in neural networks can be recalled from a partial information of the vector, but the other vector of the prestored vector pair can also be recalled.
Real-time all-optical associative memory
Tuan-Sun Lu
We have proposed and demonstrated a real-time all-optical associative memory system which combines Fe:LiNbO3 crystal holographic memory element and phase conjugate mirror (PCM). The PCM was produced by BaTiO3 crystal self-pumped phase conjugate whose reflectivity is enhanced by two-wave mixing. Analysis and preliminary experiments are given.
Measurement of magneto-optical constants of RE-TM films by frequency doubling method
Frequency doubling method has been applied to measure polar Kerr rotation and ellipticity. Magneto -optical (MO) constants of some GdCo and TbFeCo films were obtained. The optical performance of A1N TbFeCo / glass bilayer structure calculated with the measured MO constants agrees quite well with the experimental results.
Investigation on the microscopical readout characteristics of optical recording media
Zhongjun Wu
This paper reports a novel experimental method for investigating the microscopical readout characteristics of optical recording media in conjunction with optical and electron microscopy. The leaf spring-supporting guide is employed for reading out the written bit information by scanning the recording medium surface with a focused laser beam. The relationship between the readout signal wave- form and the shape and structure of the written bits has been investigated for several examples of phase change optical recording media.
Study of theory and experiment on signal to noise ratio (SNR) in magneto-optic disc readout system
Ruan Yu
In magneto-optic storage, increasing of SNR in readout system is pragmatically one of the key techniques. This paper analyzes the signal and noise sources in readout system, puts forward the concept of optimum SNR, sets up analytical-function expression of SNR under the action of complex factors, and obtains some important results. It provides the basis for optimizing system. Theoretic analysis is identical with experiment results.
Holographic storage of transparency by holographic element
Meiwen Yu
A kind of holographic element with storage lens and speckle random phase-shifter is proposed. It used as an illuminating element of one-step-microfilm high density holographic storage. the experiment results are also presented.
Two beam optical head for erasable phase change media
Ma-li Gong
A new type of the erasable optical head with two beams, that one is circle spot, the other ellipse, have been developed. The boundary combination method( BCM) combines / isolates the beams of two different wavelength. A simple autofocuse method named as offset axis has been described. The focusing error is less than 0. 5/1 m, the tracking error, less than 0. 1p m. The size of the head is 35 x 35 x 40 mm, weight less than 60g.
Optical fibre-CCD area endoscope image measuring system
Yunxiang Zhang
An endoscope image measuring system, which employs optical fibre as image transmission unit and CCD area camera as image sensor, is described in this paper.
Optical and spectral properties of VO2 thin films prepared by the sol-gel method
Songwei Lu
V02 thin films have been prepared by the sol-gel dip-coating process followed by vacuum heat treatment. The transmittance(T), reflectivity(R) and thickness(d) of these films were measured at room temperature(20°C) and 100°C respectively, and the absorption coefficient( d),refractive index(n) and extinction coefficient(k) were calculated based on the experimen_ tal results. These films show reversible IR transmittance(reflectivity)-Temperature hystere- sis round 67°C, indicating the occurence of phase transition in the films. The IR absorption spectra of the films during heating and cooling were also measured and compared. The possi- bility of using these films for optical storage is discussed.
Design of grin objective lens for CD system
Yong Xu
In this paper, the focusing characteristics of Gaussian beam through the GRIN lens with spherical end surfaces are analyzed. Some design problems of GRIN objective for C. D. system are discussed.
Holographic storage of colour films with high density and colour fidelity
Jingfang Zhang
A new method of eliminating colour cross-talk with spatial multiplexing is presented. In our experiments subtractive filters, a speckle randodi phase shifter and processing of diluting deve- lopment are adapted to obtain high quality reconstructed images.The advantages of the method are high storage density and colour fidelity.
A device detecting optical disc primary bursting error rate
Tao Pan
We designed a device detecting optical disc primary bursting error rate to solve the problem of high transfer speed of optical disc to the low speed of computer. The satisfied characteristics was presented.
Structural change characteristics of the vapour deposited Al-Cu alloy films
Haibo Yan
Structural changes of vapour quenched Al-Cu films induced both by thermal and pulse laser annealing were investigated. An unique crystallization was observed and a structural change mechanism was discussed based on the results.
Optical bistability in silicon on sapphire thermo-optical seed element
We present optical bistability in silicon on sapphire (SOS) thermooptical SEED structures at a visible wavelength of A = 514nm. Theoretical analysis and experimental results show that bistability is due to increasing absorption and thermally induced change of the internal resistance.
Detour-phase holographic interconnects
Jari Turunen
A novel concept of detour-phase kinoform is introduced here, which opens up the possibil- ity to generate, by standard lithographic techniques, holographic optical interconnects with arbi- trary image array, excellent diffraction efficiency (F.), 75 - 95%) and negligible reconstruction error (a few per cent).
Hybrid semiconductor devices for optical and optoelectronic signal processing
D. Jaeger
Two-dimensional arrays of nonlinear optoelectronic devices or optical bistable elements may be the key building blocks of future digital optical signal processors. This paper examines special hybrid semi- conductor components based upon the concepts of conventional photodetectors and passive or active modulators. Smart pixels and SEED structures are considered as well as novel vertically integrated devices and travelling-wave components for 2D-applications.
Parallel architectures for digital optical computing and their design principles
Kuan-Tsae Huang
Some architectural characteristics of digital optical computing systems are discussed. F.issential issues such as functional architectures, machine levels, instruction steps, and instruction complexities in the design of parallel digital optical computers are presented. `I he design of an optical cellular logic computer gives an example.
Optical interconnect for a circularly distributed processor array
George Eichmann
A nove I optical interconnect scheme for a circularly distributed processor array is pi oposed. This unexplored optical interconnect topology promises several important advantages over the conventional rectangular array topology, such as the use of space-invariant optical elements, identical interconnect latency, and network reconfigurability.
Non-holographic content addressable memory based arithmetic processor
A new scheme for digital optical computing, utilizing a non-holographic opto-electronic content addressable memory (CAM), is discussed. To illustrate the performance of a CAM based arithmetic processor, an optical binary carry look-ahead adder (CLA), a binary and a residue multiplier were designed. Experimental results are also presented.
Submilliwatt optical bistability in nematic liquid crystals at 1.3pm
C. H. Wang
The design and optimisation of devices displaying microwatt switching levels is considered with respect to an improvement in response times and extension of the operating range from the visible to the infrared, with experimental results presented for 1.3 am.
Optical triple matrix product processor
Versions of opto-elektronic processors have been suggested 1nrecent years, which can perform algebraic vector and matrix operations and realise pipeline and parallel processing algorithms. The paper presents the results of studies connected with the development of matrix processors have be.en carried out at the Institute of Automation and Electror metry since 1972. In 1 1975 a parallel version of optical triple matrix product pro- cessor was developed" The new optical system for parallel computing of three N x N matrices product D=BAC is analysed in detail.
Optical digital integrated computing devices
Valentin M. Egorov
Physico-technological peculiaritice of the construction of optical digital computers in the integrated execution based on the principles of electrooptical modulation of the light beam are considered. The optical commutative element in which the functional completeness is achieved by the flexible optical connections is described.
Optoelectronic bistability at low temperature avalanche breakdown in GaAs epitaxial films
O. A. Ryabushkin
The object of this report is a new type of optoelectronic bistability in n-GaAs epitaxial films at helium temperatures based on the phenomenon of low-temperature impurity breakdown. The bistability mechanism is related with the following two factors: 1. The films possess an S-shaped current-voltage characteristic (CVC) that is light-sensetive (Fig. 1) [ 1] . Light illumination changes the characteristic point Ith, Vao I., V. of the CVC which limit the region of negative differential resistence, here Ith, Va-current and voltage of the threshold points, I., Vi--those of the sustaining points. Under photoexcitation Vlh falls to the value Vtia and Tot increases to Ina . This property of the CVC allows to realize the light-induced electric switching when the external circuit is properly chosen. . _ .•
Optical nonlinearities, optical bistability and optical phase conjugation in semiconductors, composites and thin films
Jianguo Zhang
In this paper, we give new explanations of optical nonlinearities of band filling in semiconductors for different recombinations and semiconductor-glass composites made up of small semiconductor particles embedded in an insulating glass matrix, and experimental results of quantum effects of semiconductor doped glasses(SDG). We present a new kind of ZnS film doped ZnSe and Cu, which is waterproof and dampproof, and study its optically bistable characteristics and structure. We also report the experiment of low power phase conjugation in thin film of saturable absorber.
Applications of electro-optical hybrid optical bistable devices
The hybrid optical bistable devices with electro-optical feedback have many potential important applications for controlling light by light or electricity, such as optical modulator, optical switch, optical logic, optical limiter, optical stabilizer, optical amplifer, optical oscillator and optical sensor. Some examples which have been done by us are shown in this paper.
Simultaneous realization of auto- and hetero-AM: a modification of Hopfield model
It is interesting to realize auto- & hetero- AM simultaneously as human brain acts. In this paper, a modification of basic Hopfield neural network model is proposed. This model can function simultaneously both as two classes of associative memory with less increase in memory. The result of computer simulation and analysis of the SNR is given.
Optical bistability in nematic liquid crystals
Shuchao Chen
Optical bistable behaviour of nematic liquid crystals in Fabry-Perot cavity has been discussed. The normal and abnormal bistable loops were also discussed. Considering thermal conductivity in F-P cavity, a theory to get very low critical switching power optical bistability was developed.
An optical neural network used for content addressable two-dimensional associative memory
Yanping Sun
An optical neural network system used for content addressable 2-D associative memory has been demonstrated. A liquid crystal light valve (LCLV) is employed as a 2-D parallel thresholding and feedback device. The interconnections of the network are realized with a specially prepared hologram. When one of the stored images, even if only less than half of the image, appears at the input plane, the system can recognize and give a complete retrieval of the input image.
Parallel optical latching switch using bistable devices for symbolic substitution
M. T. Tsao
This paper indicates that the optical bistable devices can be exploited to act as memory bank for parallel optical latching switch. The 4 by 2 array of optical latching switch have been performed in the experiment. When it is used in an optical arithmetic system of symbolic substitution logic, the optical hardwares of arithmetic units are greatly reduced, the optical circuit is much more simplified.
A hybrid optical-digital system for computing superposition integral
Yansong Chen
In this paper, a hybrid optical-digital system, consisting of a holographic mask, two Fourier lenses, a CCD detector and a microcomputer, is presented for computing a superposition integral, which is expressed as the integral of input data and impulse response or point-spread -function. In principle, the system can be used for performing an arbitrary linear transform and multiplication of matrices, as well as extracting the features of a pattern. In this system all the spacings between the input, lens, mask and output planes are equal to the focal length of the Fourier lens, The point-spread function is represented by the process of lightwave propagating through the optical system and modulating in the mask. The mask is produced by using computer-generated-hologram techniques. In experimental research, the system is tested by Walsh-Hadamard transform, matrix multiplication and geometric moment integral. The experimental results show that, the measured values of the above integrals are in agreement with the theoretical calculations.
Spatial encoded pattern array logic and design of 2D-encoding device for optical digital computing
Lichen Zhong
This paper presents some results of theoretical and experimental research on a new method of implementing optical spatial encoded pattern array logic. For the first time, we have deigned a novel spatial polarization pattern encoding device using photo-refractive crystal for executing the parallel array logic operation. The experimental results show the applicability of our design.
On computer optics optimization software system
Xun Yang
On the basis of the canonical coordinate optics theory, by the use of the optical construction method a random function method has put forward by the authors. The computer optics optimization software system has been accomplished both in micro computer Apple and in CEC (The China Education Computer) There are four parts included in the computer optics optimization software system; (1). The fundamental optics optimization education software system. (2). The optical lens optimization design software system. (3). The optical system assemble and management software. (4). The optical system data bank. In the following paper, some of the key concept and the fundamental method used in the computer optics optimization software system will be summed up and discussed.
Optical full-parallel three matrices multiplication
Qiuming Qian
Optical systems are capable of performing high parallel computations at very high speed. This suggests the use of optical computing methods for •achieving matrices multiplication that requires handling large arrays of number in parallel manner. From this point of view, many efforts have made to implement matrix-matrix multiplications in full parallel. However, most of them require some special optical elements, such as scanning system, cylindrical lens array or some undesirable elements, only two optical systems for multiple matrices multiplication are constructed by some common optical elements such as spherical lens or cylindrical lens, but they are still very complicated.
Study of switching in dispersive optical bistability
Dejin Yu
The semiclassical theory is used to study the switching in the dispersive optical bistability. In the mean-field approximation, the equations of OB system are solved numerically. It is shown that the dispersion has remarkable influence on the output intensity and the risetime of switching. In the "bad cavity case', it is more striking. Under the different cavity conditions, the dispersive spectra of switching output are given.
Thermal optical bistability in CdSSe doped glass
Zizhong Cha
In this paper we report the observation of thermal optical bistability in CdSSe doped glass. Advantages and disadvantages of the device for optical computing is analysed. The sign of nonlinear refractive index is deduced to be positive from the experimental results. Moreover, far-field interference fringes caused by self-focusing are observed.
A new optoelectronic hybrid method of spatial frequency spectrum analyzing and its application in computer vision
Yibin Sun
A new optoelectronic hybrid method of spatial frequency spectrum analyzing (SFSA) is put forward and a complete system of SFSA is set up. A lot of experiments show that this method and system can be used widely in the field of computer vision, pattern recognition and on-line products inspection.
An automated reconstruction method for 360° shape of 3D objects
An automated reconstruction method for 3600 shape of 3-D objects is presented. The method is based on the simple principle of triangulation with a structured illumination. By using an advantageous data acquisition scheme and algorithm, a high data acquisition rate and measuring accuracy can be achived. The system contains simply a structured lighting projector, a 2-D detector, and a microcomputer for control and processing. Experimentals results for 3-D objects are offered.
Pattern recognition with a phase-only matched filter made from outline features
Minhua Liang
Pattern recognition with a phase-only matched filter made from outline features is reported. Computer simulation of discrimination capabilities of this method and other methods are presented. The results show that our filtering method has a better discrimi- nation capability than Horner-Gianino filtering method.
Beacon recognition in omni-vision guidance
The beacon recognition approach based on the omni-vision characteristics is presented. The proposed method using a color lights arranged in a given spatial pattern is described. A recongnition logic using color features added spatial dimensions was developed. The navigation software integrating the beacon recognition with robot positioning is provided. The developments of the nr,w method will lead to practical module in omni-vision guidance for mobile robots.
Real-time optical implementation of the synthetic discriminant function
Rutong Hong
A digital-optical hybrid processing system is successfully applied to perform real-time 3-D distorted invariant correlation with projection Synthetic Discriminant Function Matched Spatial Filtering (pSDF-MSF) technique. The pSDF-MSF filter is produced and used to perform rotation scale and shift simultaneously invariant correlation and optical pattern recognition (OPR). A sharp correlation peak with good S / N and improved light efficiency is obtained.
An implementation of 360° shape measurement of 3D object using single point projection
Guanshen Zhang
An implementation of 360* shape measurement of 3-D object using single point projection is presented. Several algorithms determining the center position of the light spot are compared, and the method to adjust the sensitivity of the detector is discussed. The experimental results of 360 Shape reconstruction of a last used in footwear industry is presented.
In situ determination of oil-spills using a laser fluorosensor
An experiment research for determination of oil-spills on the sea surface was performed by using a shipboard laser fluorosensor in Jiaozhou Bay. The laser-induced fluorescence(LIF) spectra of five kinds of oils were obtained. The results show that the LIF spectra of the in situ measurement are basically consistent with those of the laboratory measurement, and these spectra can be discriminated.
The optical head of a far-middle distance TV tracking camera
Congzhong Zhao
An optical head of seeing at a far-middle distance for TV tracking camera is described in this report. It analyses and discusses about some main technique questions. A test proved that the standoff range of the instrument reaches to 33km.
Description and recognization of 3D moving objects
Jian Dong
A recognition scheme of 3-D objects is proposed in this paper. A new data structure is presented to improve the approach of volumetric descirption of objects from multiple views. The Monte Carlo method is adopted to ac- quire test data. The HTR descriptor is proposed to describe shapes. A "coarse- fine retrival" strategy is used to re- trieve the matching library. Fair results have been obtained in the analogous experiments.
Intellegent spectrum analyzer detected with photodiode array (PDA)
Caitao Guo
In this Intellegent Spectrum Analyzer ,PDA is used as a detector , and a micro - computer is used for control and process. PDA is capable of parallel detecting and serial outputing the spectral information. Therefore , this sys- tem can rapidly acquire the spectral lines produced at the same time with dif- ferent wavelengths, realize the real-time spectral researching to kinetic pro- cesses, and the detection on line in manufacture.