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- Optical Devices and Instruments
Optical Devices and Instruments
Advances in interferometric surface measurement
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The addition of electronics, computers, and software to interferometry has provided tremendous improvements in the measurement of surface shape and roughness. This talk will describe three such improvements; use of computer generated holograms for testing aspheric surfaces, techniques for performing interferometric measurements more accurate than the reference surface, and two single-shot phase-shifting interferometric techniques for reducing the
sensitivity of an optical test to vibration and measuring dynamically changing surface shapes.
Manufacturing and testing SiC aspherical mirrors in space telescopes
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Reaction Bonded (RB) SiC mirrors due to their excellent specific stiffness and thermal properties have been widely used in space telescopes. However, polishing large SiC aspherical mirrors is difficult compared to other materials such as fused silica or Zerodu. In addition, surface roughness of the polished SiC mirrors is limited by the defects of the materials and needs to be improved by means of surface coating technique.
This paper introduces the current progress of large SiC aspherical mirrors manufacturing and testing in CIOMP. In particular, the procedures of making large off-axis aspherical mirrors were discussed in detail. A proprietary computer controlled optical surfacing (CCOS) technique was utilized to grind and polish the mirrors and the computer aided null test was used to measure the surface figure. As results, a 600mm class off-axis SiC aspherical mirrors was demonstrated with figure error less than 13nm rms.
Design and calibration of large dynamic range optical metrology systems
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Optical metrology requiring a large dynamic range places several requirements on the design and operation on the instrument. In addition to being able to detect the part or wavefront shape to the required range and precision, the measurements must also be calibrated to remove the induced errors associated with operation in a non-null fashion. This paper demonstrates the need for this calibration, and presents the results of a system calibration of a non-null interferometric measurement.
Optical design of the multi-spectral camera (MSC) for high-resolution Earth observation
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The Multi-Spectral Camera (MCS) is the electro-optical imaging isntrument for high-resolution observation of the Earth with push broom scanning in the space. The MSC uses compact and light weighted optical design to tkae image with high MTF (modulation transfer function) performance. The Ritchey-Chretien with focal correct lens is selected to implement enough performance in the wide swath width. The focal plane has one panchromatic (PAN) and four multi-spectral (MS) CCD (charge coupled device) for the imaging of visible and near-infrared wavelength. The PAN and MS have their own focus correct lens to correct field aberration and also to make proper effective focal length. Here we present the optical design and analysis of the MSC.
Optics in Latin America: an update until 2004
Néstor G. Gaggioli
Show abstract
In the introduction it is presented a brief history of the evolution of physics and its professional organizations in Latin
America, how optics is introduced in these countries, the development of the optical community and of its meetings.
The evolution of the optical meetings in which Latin Americans take part and the participation of each country are
described. A clear increase in the number of communications presented in these meetings is observed.
It is shown that Latin American people contribute many more communications than Iberian people to these kinds of
meetings. A study is made of the proportion of co-worked communications presented at these meetings showing the
variations in the quantity of these collaborative works from Latin Americans, from Latin Americans and people from the
Iberian Peninsula and from people outsides these regions. A study is also presented about the amount of papers published
between 1974 and 2004 by people working in the Latin American countries and also in Spain and Portugal, showing the
participation of each country. In particular it is shown that Latin Americans publish only a little more than Iberian people.
Finally, answers are given to some questions about the present situation of optical research in Latin America.
Proposal of a compact repetitive dichromatic X-ray generator with millisecond duty cycle for medical applications
E. G. Bessonov,
M. V. Gorbunkov,
V. G. Tunkin,
et al.
Show abstract
Many practical applications of x-rays lie in the important for the society fields of medical imaging, custom, transport inspection and security. Scientific applications besides of fundamental research include material sciences, biomicroscopy, and protein crystallography. Two types of x-ray sources dominate now: conventional tubes and electron accelerators equipped with insertion devices. The first are relatively cheap, robust, and compact but have low brightness and poorly controlled photon spectrum. The second generate low divergent beams with orders of magnitude higher brightness and well-controlled and tunable spectrum, but are very expensive and large in scale. So accelerator based x-ray sources are mainly still used for scientific applications and x-ray tubes - in commercial equipment. The latter motivated by the importance for the society made an impressive progress during last decades mostly due to the fast developments of radiation detectors, computers and software used for image acquisition and processing. At the same time many important problems cannot be solved without radical improvement of the parameters of the x-ray beam that in commercial devices is still provided by conventional x-ray tubes.
Therefore there is a quest now for a compact and relatively cheap source to generate x-ray beam with parameters and controllability approaching synchrotron radiation. Rapid developments of lasers and particle accelerators resulted in implementation of laser plasma x-ray sources and free electron lasers for various experiments requiring high intensity, shrt duration and monochromatic x-ray radiation. Further progress towards practical application is expected from the combination of laser and particle accelerator in a single unit for efficient x-ray generation.
Generation of aberration polynomials in a Fourier optical processor using a liquid crystal display
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The objective of this paper was to generate Sidel polynomials using a LCD in a Fourier processor. Our proposal was to use this LCD, due to the fact that it is a small device that does not consume too much energy, with several active elements, and we verified the speed with which it is possible to work with optical processing by changing the images on the screen. Since this system is easy to construct, stable and accessible, we want to use it in the future as a corrector system, due to the fact that it can evaluate the system using a program and with the LCD to try to correct the aberrations that it has.
Laser monitoring of the air pollution by aerosols
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Laser particle spectrometry is one of the leading measurement technologies engaged in environmental monitoring, measuring the aerosol contamination of the air inside and outside of urban regions. It has a number of benefits against other methods - e.g. the possibility of real time, in situ measurement with high time resolution. These features make the light scattering based measurement methods superior to others in a mobile environmental laboratory. Our previously developed instruments are based on laser light scattering collected from different angular regions (90°, forward and backward directions) and a special illumination system increase the sensitivity and the resolution of the sizing. A collection of the developed optical instruments and other devices based on different methods were installed into a mobile environmental laboratory for monitoring atmospheric aerosols, which allows the comparison of the results obtained from different measurement methods. This laboratory has been used in 3 measurement campaigns where measurements were performed in 6 different locations.
Sinusoidal wavelength-scanning interferometer for measurement of thickness and surface profile of thin films
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We propose a sinusoidal wavelength scanning interferometer for measuring thickness and surfaces profiles with a thin film. An acousto-optic tunable filter (AOTF) is used to produce sinusoidally wavelength-scanned light from a superluminescent laser diode (SLD) with a wide spectral bandwidth of 46nm. The interference signal contains an amplitude Zb of a time-varying phase and a constant phase α. Two measured values of OPD, which are denoted by Lz and Lα, are obtained from Zb and α. By combining Lz and Lα, an OPD longer than a wavelength is measured with an error less than a few nanometers. When the object has two reflective surfaces, the detected interference signal contains two interference signals which are caused by the front and rear surfaces. In this case we must determine the values of Zb1, Zb2, α1, and α2, where suffixes of 1 and 2 are corresponding to the front and rear surfaces, respectively. We define an error function that is the difference between the detected signal and the theoretical signal, and reduce the value of the error function with the multidimensional nonlinear least-squares algorithm to search the values of Zb1, Zb2, α1, and α2.
Experimental results show that the thickness and surfaces profiles of a silica glass plate of 20μm-thickness are measured with error less than 1.5nm.
Sensitive measurement of water content in dry material based on low-frequency terahertz time-domain spectroscopy
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We proposed sensitive measurement of water content in dry material using low-frequency THz-TDS method. Simultaneous use of bowtie-type photoconductive antennas as a THz emitter and a THz detector achieves specific sensitivity in sub-THz region of ~0.3 THz, in which THz absorption of water is considerably decreased. Effectiveness of the proposed method is demonstrated through water content measurement in instant coffee powder in a glass bottle. The proposed system will be a powerful tool for extract quality control of water content in dry foods.
Construction of a Fourier-transform phase-modulation fluorometer
Hironobu Shibata,
Tetsuo Iwata
Show abstract
We have constructed a Fourier-transform phase-modulation fluorometer (FT-PMF) by which a fluorescence decay waveform can be obtained. In the FT-PMF, the modulation frequency of the excitation light source is swept continuously from a direct current (dc) to a high frequency fmax with a time duration T. The resultant fluorescence signal waveform is Fourier-transformed to obtain its amplitude and phase spectra. The ratio of the amplitude spectrum and the difference of the phase spectrum over those of the reference spectra that are obtained from a non-fluorescent material are calculated, respectively, and the pair of both spectral data is inverse-Fourier-transformed again to obtain the fluorescence decay waveform. The light source used was an ultraviolet light emitting- diode (UV LED) whose typical operating condition was fmax = 100 MHz and T = 10 μs. To demonstrate the performance of the FT-PMF, we carried out (1) measurement of a fluorescent decay waveform of YAG materials packed in a white LED, and (2) determination of fluorescence lifetime of 10 ppm quinine sulfate in 0.1N H2SO4.
Wavelength measurement by polarization method
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The experimental and theoretical results, used for an adjustable quarter wave plate development, are proposed for the light wavelength measurement. To prove that idea propagation of coherent and incoherent light through an adjustable quarter wave plate with different properties was considered. The dependence of the adjustment angle on the light wavelength was obtained for different parameters of single retarder. All calculations were performed for mica retarders. It was shown principal possibility of light wavelength shift detection with accuracy 0.1 nm within wavelength range 3
nm for coherent light. Experimental investigation was performed for an adjustable quarter wave plate made of two mica plates of the same retardation. The qualitative coincidence between experimental and theoretical results has demonstrated.
A method of measurement of polarized light ellipticity only
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A new method of determination of only an ellipticity of a state of polarization of a coherent radiation is proposed. The method is based on a spatial separation of a wave with the arbitrary ellipticity of a state of polarization into two waves with mutually orthogonal circular states of polarization. To part elliptically polarized light into two waves with orthogonal circular polarizations, the optical Magnus effect in a multimode optic fiber and a phase conjugator were used. The main advantage of a method is dealing with light intensities of almost the same values in the case of weekly
elliptically polarized light. It was shown experimentally that precision of measuring increases noticeably for weakly elliptically polarized light. The simple device for the determination of the polarized light ellipticity is proposed.
Moiré deflectometer for measuring distortion in sheet glasses
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In glass casting or shaping processes, some times wavy and distortion defects are developed in glass sheets. Specifying the locations of these defects and measuring the deflections they cause are significant parameters in many applications. There are several techniques for observing and measuring these defects, but the technique we introduce in this work is more simple and flexible and can be easy installed in production line for quality controlling purposes. The presented deflectometer functions in the following way. The imaging system of the device forms an image of large-scale low frequency linear periodical pattern painted on a vertical plane on a transmission grating. The distance between the object grating (painted pattern) and the second grating is so that the frequencies of the image grating and the second (probe) grating are practically the same. There is a small angle between the lines of the latter gratings to form moire fringes. A CCD camera transfers the moire fringes to a PC. By applying phase shifting technique, which is realized by shifting the probe grating in definite steps in its plane in a direction perpendicular to its lines, the phase distribution due to imprecations in optical system and gratings, are specified, At this stage the defected sheet glass is installed between the object grating and the imaging system and the distorted moire pattern is processed as described before. The difference between two-phase distributions is the phase distribution caused by the defects in the glass, which can be easily converted into the required ray deflections. All the processes are carried out automatically in a time less than 30 seconds and the accuracy of the measurement is of the order of 20 arc seconds.
Displacement measurement with a dual-colored sinusoidal phase-modulating interferometer
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Interferometric displacement sensor based on a two-wavelength interferometry is proposed and demonstrated. A combination of time-shared two-wavelength laser diode and sinusoidal phase-modulating interferometry enables us to realize accurate and wide-range displacement measurement with a simple optical setup.
Double frequency of difference frequency signals for optical Doppler effect measuring velocity
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The mathematical model for measuring moving objects (including fluid body, rolled steel materials in the steel works, turbulent flow, vibration body, etc.) velocity or speed by non-contact method is established using light-wave Doppler effect in this paper. In terms of concrete conditions of different optical circuits, and with the correlated conditions substituted, it is easy to obtain the measurement velocity formulas related to optical circuits. An optical circuit layout of difference Doppler effect measuring velocity is suggested in this paper. The fine beam of light emitted by laser is divided into parallel two beam by spectroscope and mirror They are focused on the object point p by a condenser lens respectively. The object point p become a diffuse source. It scatter rays to every aspect. Some rays scattered by the diffuse source p are collected by a lens. Photoelectric detecter receive the lights collected by the lens. This optical circuit layout can realize the double frequency of difference frequency signals in a novel way.
Contactless laser viscometer for flowing liquid films
Alexandre F. Michels,
Thiago Menegotto,
Hans-Peter Grieneisen,
et al.
Show abstract
This work briefly reviews recent progress in interferometric monitoring of spin and of dip coating, from a unified point of view, and its application for contactless viscometry of liquid films. Considering the associated models and measurement uncertainties, the method was validated for both coating processes with oil standards of known viscosities and constant refractive indices. Limitations and perspectives for application of the laser viscometer to liquid films with a varying refractive index are also discussed.
Beam correction optics for laser diodes
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The beam emitted by a laser diode chip is elliptical and astigmatic. Various methods have been proposed and applied to remove the astigmatism and to produce a circular Gaussian beam. In this paper we will further propose the use of the laser diode beam correction optics in an external cavity laser. The light produced by the external cavity laser is not only circular, Gaussian, and non-astigmatic, but its coherence length is also significantly enhanced.
Fiber-optic vibration sensor based on wavefront-splitting interferometry
Hsien-Chi Yeh,
Chun Fan Goh,
Tian Fook Kong
Show abstract
In this paper, we present the working principle and the preliminary results of a novel vibration sensor based on wavefront-splitting interferometry. The interference signal is formed by superposing the radiations within a compact sensor space at which the wavefront is split and reflected by the sample surface. The performance of sensor is determined by the geometrical dimensions, the polarization of the incident light and the optical properties of the sample surface. Due to the grazing incidence of the detecting light, the interference signal is strong and obvious regardless of the material of the sample surface. Therefore, this fiber-optic sensor is more sensitive than the other displacement and vibration sensors, especially when applied for the optically low-reflective samples. The experiments using the OHP transparency and the metal structures demonstrate the static and dynamic measurements of the fiber-optic sensor.
Application of HATR-FTIR spectroscopy to the analysis of nifedipine tablets
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In recent years, FTIR has been found its wider application in analysis processes of pharmaceutical solids. This is, in part, thanks to the development of powerful multivariate quantitative techniques, such as partial least-squares (PLS) modeling software and the emergence of some new reflectance sampling techniques which allow direct measurement of the IR spectrum of solids in their native states. Horizontal Attenuated Total Reflectance (HATR) is a quite popular sampling technique in recent years. In this work, the feasibility of the Horizontal Attenuated Total Reflectance Infrared Spectroscopy (HATR-FTIR) to the quantitative and quantitative analysis of nimodipine tablets is investigated. Quantitative analysis of nimodipine is carried out by using a classical least-squares for areas procedure. Obtained from validated samples of nimodipine, quantitative results demonstrate clearly the strong potential of HATR-FTIR technique through using quantitative analysis of nimodipine content of pharmaceutical tablets.
Design and validation of portable optical instrument for crop diagnose
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In this paper, a portable diagnostic instrument was designed and tested, which can measure the normalized difference vegetation index (NDVI) and structure insensitive pigment index (SIPI) of crop canopy in field. The instrument have a valid survey area of 1 m*1 m when the height between instrument and the ground was fixed to 1.3 meter The crop growth condition can be assessed based on their NDVI and SIPI values, so it will be very important for crop management to get these values. The instrument uses sunlight as its light source. There are six special different photoelectrical detectors within red, blue and near infrared bands, which are used for detecting incidence sunlight and reflex light from the canopy of crop. This optical instrument includes photoelectric detector module, signal process and A/D convert module, the data storing and transmission module and human-machine interface module. The detector is the core of the instrument which measures the spectrums at special bands. The microprocessor calculates the NDVI and SIPI value based on the A/D value. And the value can be displayed on the instrument's LCD, stored in the flash memory of instrument and can also be uploaded to PC through the PC's RS232 serial interface. The prototype was tested in the crop field at different view directions. This paper also provided the method of calibration, the results showed that the average measurement error to SIPI value of instrument was 5.25% and the average measurement error to NDVI value in vegetation-covered region is 6.40%. It reveals the on-site and non-sampling mode of crop growth monitoring by fixed on the agricultural machine traveling in the field.
Study of micro-displacement measuring system with double F-P interference cavities
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A kind of Micro-displacement measuring instrument using double interference cavities is designed. It is based on F-P interference wave length One of interference cavities is reference cavity, the other is measuring cavity. One reflect surface of reference cavity is installed with piezoelectric ceramics, One reflect surface of measuring cavity is erected with an object to be measured. When the central wavelengths in reference Fabry-Perot interference and in measuring Fabry-Perot interference are overlapped, there are the maximum light signal outputs. Based on the relationship between the transmission spectrum central wave length and its interference cavity length, this measuring instrument can be used to realize the real time measurement of Nano-grade micro-displacement. Using simi- conductor laser as the light resource can obtain the required wavelength values and its variation scopes. It can be seen from the measured results that the measured error is not over 1.5nm. Such a precision can satisfy the precision requirements as in the fields of precision mechanical processing, photoelectronic processing and Nano- grade measuring technology.
Vibration insensitive interferometer using sinusoidal phase-modulation and feedback control
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It is easy to extract a signal proportional to a phase fluctuation from a sinusoidally phase-modulated interference signal. This fluctuation is caused by mechanical vibration or air turbulence. In a sinusoidal phase-modulating interferometer using a laser diode (LD) the phase fluctuation is reduced by changing the injection current of the LD with a feedback control system. This control is very useful to a Fizeau type interferometer for surface profile measurement of a large size object. IC wafers of 100 mm diameter are measured with an interferometer insensitive to mechanical vibration and air turbulence. The phase fluctuation with nearly constant amplitude which corresponds to 30nm in surface height is reduced by about 10%. However the reduction in the phase fluctuation is not performed well for an instantaneous and large phase fluctuation. In order to be insensitive to all kinds of phase fluctuations the feedback signal is always observed, so that the interference signal is captured when the amplitude of the feedback signal is less than a specified level during the capturing time of 0.53 s. Thus surface profiles of the IC wafers can be measured with a high repeatability of a few nm even when any kind of vibration exists.
Measurement of optical thickness variation of a multiple-surface object by a wavelength tuning interferometer
Show abstract
Wavelength tuning interferometry can distinguish interference signals from different surfaces in frequency space. The optical thickness variation of each layer of a multiple-surface object was measured by a new tunable phase measuring algorithm which can efficiently compensate for the frequency detuning of the interference signals. A two-layer object consisting of Lithium Niobate (LNB) wafer on the supporting glass parallel was measured by the new tunable algorithm in a Fizeau interferometer. Experimental results show that the optical thickness variation of the top wafer was measured with an error of λPV over a 70 mm diameter aperture.
Generalized theory of dynamical surfaces: experimental verification by speckle correlation
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This work studies rough surfaces that undergo small random morphological changes. In the present paper, rough reflective surfaces are dealt with. Its roughness is larger than the wavelength of the He-Ne laser beam used to illuminate it. Speckle correlation of the scattered light is applied to study changes in the roughness.
A theoretical model, which describes speckle correlation as a decreasing quadratic exponential function of roughness changes and was presented in a previous paper, is used.
New experimental results from rough reflective surfaces in which the changes are simulated through immersion of the samples in liquids with different refraction indices are presented.
Good agreement between the theoretical and experimental results is found.
Measurement of diameter of metal cylinders using a sinusoidally vibrating interference pattern
Show abstract
A method for measuring diameters of metal cylinders is proposed. In this method a sinusoidally vibrating
interference pattern (SVIP) of 100μm-period is used to generate an exact spatial scale along x-axis. Detection of the
amplitude and the phase of the SVIP are carried out easily and exactly with sinusoidal phase-modulating
interferometry. First, phase values of the SVIP on the pixels of the CCD image sensor are measured as the exact
scale along the x-axis. Next, an image of the end-points of the cylinder surface is formed by extracting lights from
the end-points of the cylinder. The phase of the SVIP on the end-point of the cylinder appears at a position where
the amplitude of the image has maximum value along the x-axis. The x-coordinate of the end-point of the metal
cylinder is calculated from the phase value of the end-point and the exact scale. The diameter is obtained from the
x-coordinates of the two end-points. Metal cylinders of 9mm and 8mm-diameters are measured with an error of
about ±2μm.
Development of television camera for detecting oil film floating on the ocean
Show abstract
A television camera system, which automatically picks out exclusive images of the oil at real time, is described. This
system essentially consists of two optical band pass filters (BPFs), two CCD cameras and image processing software.
Due to the multiple-beam interference resulted from the oil film, there is a marked difference of intensity between light
reflected from the surface of the sea and that from oil film. By obtaining these different images, the place with oil can be
distinguished. Emphasis of our work is to compensate the effect of dispersion of sunlight intensity and CCD's quantum
efficiency on oil film detection probability. Laboratory experiments using static glass coated with Al2O3 film have been conducted. The experimental results showed that sensing probability is dependent on the sample thickness, and greatly
on the incident angle. This result is agreed quite well with the simulation done our coauthors in earlier work.
A new type of Shack-Hartmann wavefront sensor using liquid crystal display
Show abstract
In this paper, we present a new and practical method for achieving real-time wavefront measurement, dramatically increasing the resolution, dynamic range of Shack-Hartmann wavefront sensor and improving the wavefront reconstruction quality. In proposal method, a liquid crystal display panel (LCD) for the generation of an array of Fresnel microlenses is used instead of the static microlens array of the conventional Shack-Hartmann type sensor
An off-axis holographic microlens array is designed instead of the normal microlens array to increase the effective array and then the dynamic range. The focus properties of the off-axis lens are studied.
Study on integrated vehicle navigation system of Beidou Double-star/DR
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Vehicle navigation is the corn element of Intelligent Transport System. The integrated system of "Beidou" Double-star/DR is studied in this paper according to the present state of vehicle navigation in our country. "Beidou" Double-star navigation position system is one regional satellite position system built up by our country, which can provide rapidly not only highly precision position and brevity telegram service. However, when the vehicles go around the tall buildings, high mountain area, wayside trees and in the tunnels, all signal may not be received. If the satellite navigation position system is used only, the precision will be reduced. Therefore, this paper proposes a nonlinear self-adaptive Kalman filter model and its algorithm for a Double-star/DR integrated navigation system in land vehicles, and verifies effectively the algorithm and scheme through the means of simulation. Next, this paper introduces map match approach. The roads are segmented and character information is brought out. Then, proper search rules and map match algorithm are adopted. According to the current vehicle position information that Double-Star/DR system provides, the nearest road can be found in the map database. The vehicle position will be matched and displayed on the road. The result of the experiment shows that the Double-Star/DR integrated algorithm and map match can improve reliability and the precision of vehicle navigation system efficiently.
An optical measuring method of high temperature clinker layer's thickness
Show abstract
In this paper, we present a method based on CCD offering the advantages of high sensitivity, no electromagnetic interference and non-contact in order to measure the thickness of the cooler precisely in high temperature and dust atrocious condition online with real-time and reliable parameter for the control system. By analyzing the principle of CCD and the histogram on the grey scale distribution on the layer's image, the thickness measuring model based on the image segmentation method is founded. According to the image characters of clinker layer, both image segmentation and filtering methods before or after the segmentation are selected. The camera cooling system is designed particularly considering the situation where the camera and the clinker cooler work. After analyzing the shortcomings of the measuring method, an improved one named stereopsis thickness measuring method is present, by means of firstly setting up the stereopsis thickness measuring model before determining the homonymic dots recognizing model, then to abstract the characteristic vector to analyze the recognizing method to establish the precise analyzing model, and finally to complete the experimental research of the thickness measurement based on the image segmentation in order to test the feasibility and to show the results to all.
Liquid analysis based on fiber micro-drop sensors
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The fiber micro-drop sensor is a potential tool in different application areas. With the help of a group of fibers, the information of the forming and dripping of a liquid drop is monitored. The fingerprint drop trace provides the information of the liquid to be tested. Some liquids of different types are tested to show the different drop trace. The alcohol solutions of different concentrations are paid more attention to dig the information hiding in the drop trace.
Analysis of various correction factors for MTF measurement with a square object
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In the simultaneous measurement of the sagittal and tangential modulation transfer function (MTF) of an optical system
by using a square object, we analyze various correction factors due to the irregular illumination of the source, the
rotation of the square object, and the off-axis effect by the object size for the precise measurement of the MTF. These
results can be used in the more exact and effective MTF measurement using the square objects instead of an ordinary
pinhole or slit.
A study of high voltage current based on fiber Bragg grating
Show abstract
Recently with the invention of fiber optic Bragg grating (FBG), new kind of sensors based on FBG is increasingly challengingly the dominating position of some traditional sensors, because this new device has some intrinsic capability: Such as multiplexing, self- referencing, optical and mechanical reliability, anti-interference. Especially it brings the significant advantages that they are non- conductive and lightweight, which can allow for much simpler insulation and mounting designs as the application voltage up to 1000kV or more to day. In addition, it doesn't exhibit hysteresis and provide a much large dynamic range and frequency response than iron- core conventional current transformer (CT). In this paper a current sense device based on electromagnetic force is presented. A FBG is held on the armature of an electromagnetism by one end. As current pass through the iron coil, the magnetic force of the coil lengthens the FBG. Then the Bragg wavelength will change via current. By measuring the change of Bragg wavelength of the FBG we can build a relationship between the tested current and the Bragg wavelength. In this paper the configuration of the new device, the theoretical analysis and measurement results are given.
The research of basing on simulative compensator and two-wavelength phase shifting interferometry for testing large departure aspheric surface
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Aiming at null measurement has the flaws of narrow scale and high cost, authors present a novel measure method with large-scale and low cost to test steeper aspheric surface, namely, simulative compensator and two wave-length phase shifting interferometry. Basing on principle of two-wavelength interferometry and computer-stored compensator, we apply the simulative compensator into the two- wavelength phase shifting interferometer, and it will enlarge the measure scale. In order to decrease the high frequency, compare the standard wavefront produced by simulative compensator with interferential pattern produce by interferometer, the departure between the standard wavefront and interferential pattern is processed the least by adjusting standard wavefront. During the date sample and process, we use sub-Nyquist principle to enlarge measure scale. According to computer simulation result demonstrate that the simulative compensator and two wave-length interferometry presented by this paper can test large departure aspheric surface, the departure of aspheric surface from best fitting sphere attain to thousand wave length. The measure scales of the novel metrology is larger several hundred wavelength than conventional non-null interferometry, and overcome the trivial narrow-scale of null interferometry.
The analysis of optical-electro collimated light tube measurement system
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A new type of collimated light tube (CLT) is mentioned in this paper. The analysis and structure of CLT are described detail. The reticle and discrimination board are replaced by a optical-electro graphics generator, or DLP-Digital Light Processor. DLP gives all kinds of graphics controlled by computer, the lighting surface lies on the focus of the CLT. The rays of light pass through the CLT, and the tested products, the image of aim is received by variant focus objective CCD camera, the image can be processed by computer, then, some basic optical parameters will be obtained, such as optical aberration, image slope, etc. At the same time, motorized translation stage carry the DLP moving to simulate the limited distance. The grating ruler records the displacement of the DLP. The key technique is optical-electro auto-focus, the best imaging quality can be gotten by moving 6-D motorized positioning stage. Some principal questions can be solved in this device, for example, the aim generating, the structure of receiving system and optical matching.
A measurement study of refractive-index profile of an optical fiber
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A novel transmitted-light differential interference contrast(DIC)system is used for nondestructive measurement of the refractive-index profile(RIP) of an optical fiber. By means of this system the phase of a measured light beam can be modulated with an analyzer. and the phase distribution of a fiber is obtained by calculation of the various interference patterns. The measurement theory and structure and some typical applications of this system are demonstrated. The results of measuring RIPs in graded-index are presented. Both the experimental results and theoretical analysis show that the system takes the advantage and high index resolution and of sufficient measurement analysis show that the system takes the advantage of high index of the optical fiber. The system has strong ability to overcome environmental disturbance because of its common-path design. Moreover, one can use the system to measure the RIP along the fiber axis and acquire an image of the three-dimensional RIP of the fiber.
Study of the frequency spectrum characteristics of ultra-fast photoconductive semiconductor switches
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According to microwave and circuit theory, the transient response model is established after optically
controlled photoconductive semiconductor switches (PCSSs) are radiated by ultra-short light pulse. A method
for characterizing frequency spectrum characteristics of PCSSs is presented. A deep investigation of the effect
of some structural and physical parameters on the frequency characteristics of PCSSs is made. The findings
show that the carrier life and absorption coefficient of the photoconductive material for manufacturing the
switches, the width of the gap, the pulse width of the incident light, the gap capacitance, lead and parasitical
inductance have a great effect on the frequency characteristics of PCSSs. PCSSs have ability to produce THz
electromagnetic radiation and can be as Teraherz radiation source.
On-line calibration of phase-shifter in phase-shifting interferometer
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Phase-shifting interferometry (PSI) as a high accuracy measurement method is widely used in modern measurements. Accurate calibration of phase-shifter is very important if good measurement results are expected from PSI. A new method of on-line calibration for phase-shifter is presented. By constructing a mathematic model for intensity of interferogram associating with the phase-shifter's characters, the coefficients of the function can be solved by introducing Damped-Least-Square methods. Results of computer simulation show a high accuracy after several fast iterations. Experimental results are presented for on-line phase-shift calibration.
Measurement of the birefringence distribution in high resolution laser scanning lenses
Show abstract
We present a polarization analysis system to measure the birefringence of scanning lens. This technique is based on
rotating-analyzer ellipsometer. The liquid immersion method is applied to measure the birefringence distribution
regardless of the shape of the test lens. In this report, the principle of the two dimensional measurement system and the
result of 2-D birefringence distribution in scanning lens are presented.
Iris image acquirement and preprocessing in biometrics
Xing Ming,
Zhihui Li,
Yuanning Liu
Show abstract
As a biometrics, iris recognition is becoming an active topic in recent years. Due to constriction and dilation of iris
sphincter muscle affected by illumination, iris images should be captured under steady illumination. The principles of
our homemade iris capture device and real product are introduced first. This device can be used to capture fine iris
images and store them into the computer. Due to changes of head orientation and binocular vergence at different iris
acquirement time, a preprocessing method including iris location, normalization, image enhancement and rotation
correction is then applied to achieve rotation, shift and scale invariance. Finally the correlation measurement is used to
evaluate the performance of this processing.
A nondestructive technique of analyzing chalcogenide phase-change thin films by spectroscopic-ellipsometry
Show abstract
A multiplayer effective-medium (ML-EM) model is proposed to characterize the microstructure of chalcogenide phase-change thin films grown by magnetron sputtering. Spectroscopic ellipsometric (SE) measurements are carried out on the as-deposited Ge2Sb2Te5 films with various thicknesses ranging from 5.8 to 38.9 nm in the photon-energy region 1.5 to 3.1 eV. The measured data of ellipsometric angles (relative amplitude Ψ and phase difference ▵) are compared with the calculated data of ML-EM model with the help of Levenberg-Marquardt (LM) method. The composition depth profiles, including Ge2Sb2Te5, void and Si, are obtained. The dependence of optical constants on the film thickness is attributed to the various distributions of the compositions in the film.
Determining thin film thickness characterization using adaptive simulated annealing algorithm
Show abstract
Thin film is very important in many industries. To perform the functions for which they were designed, the films must have proper thickness, roughness and other characteristics. These characteristics must often be measured, both during and after fabrication. Optical methods used to determining the characteristics of films are usually preferred because they are accurate, nondestructive and require little or no sample preparing. This paper introduces a new method of determining the thickness of thin films using Adaptive Simulated Annealing (ASA) algorithm. Based on the theory of thin film calculating, it uses the spectral reflectance data with the incident light perpendicular to the sample surface over a range of wavelengths to calculate the thickness of thin film. ASA is selected as a global optimization algorithm to characterize the thickness of thin film because it is good at dealing with the multimodal and nonsmooth cost function and it can converge quickly and accurately. The thicknesses of four thin film systems are calculated out to testify the correctness and efficiency of the method and the results are satisfying.
Development of an optical instrument to determine the pesticide residues in vegetables
Show abstract
An optical instrument was developed to determine the pesticide residues in vegetables based on the inhibition rate of
organophosphates against acrtyl-cholinesterase (AChE). The instrument consists mainly of a solid light source with
410nm wavelength, a sampling container to store the liquid, an optical sensor to test the intensity of transmission light, a
temperature sensor, and a MCU based data acquisition board. The light illuminates the liquid in the sampling container,
and the absorptivity was determined by the amount of the pesticide residues in the liquid. This paper involves the design
of optical testing system, the data acquisition and calibration of the optical sensor, the design of microcontroller-based
electrical board. Tests show that the absorption rate is related to the pesticide residues and it can be concluded that the
pesticide residues exceed the normal level when the inhibition rate is over 50 percent.
Measurement of drill grinding parameters using laser sensor
Peng Yanping,
Hiroyuki Kumehara,
Zhang Wei,
et al.
Show abstract
To measure the grinding parameters and geometry parameters accurately for a drill point is essential to its design and reconditioning. In recent years, a number of non-contact coordinate measuring apparatuses, using CCD camera or laser sensors, are developed. But, a lot work is to be done for further improvement. This paper reports another kind of laser coordinate meter. As an example of its application, the method for geometry inspection of the drill flank surface is detailed. Measured data from laser scanning on the flank surface around some points with several 2-dimensional curves are analyzed with mathematical procedure. If one of these curves turns to be a straight line, it must be the generatrix of the grinding cone. Thus, the grinding parameters are determined by a set of three generatrices. Then, the measurement method and data processing procedure are proposed. Its validity is assessed by measuring a sample with given parameters. The point geometry measured agrees well with the known values. In comparison with other methods in the published literature, it is simpler in computation and more accurate in results.
Detection system for film
Show abstract
Film is one kind of important record median. Its quality will affect image quality directly. So, it is necessary to study how to assure its quality. Because the situation of film production in dark room, normal detect method could not satisfied the film. In order to avoid to damage film, an infrared detect system is studied. This system is design to set at the position of spreader head. If the defect of film could be found at this position, the beginner of film production line, worker could tread with it in time and reduce waster.
The infrared detect system include two sub systems. The two sub system need to detect one position all the time. One sub system is used to detect if there is defect. One CCD camera captures film image. The film image will be monitor by worker through screen. The screen should be set in light room. Another sub system is composed of object lens, image intensifier micro-channel plate and eye lens. If worker find defect from screen, he will inform another worker who worker in dark room. Another worker could find the defect through image intensifier system, and treat with it. The communication method between two workers is sound, not alarm light, because there is dark room. All of the two sub systems use infrared light as light source. The wavelength of light source is 940 nm, which is safe to film.
This system is designed for Lekai, the biggest film company of China. This system could find detect early and help worker to deal with it on site, because the detect position is the starting of film production line.
A new three dimension PLMR imaging system
Show abstract
We are developing a new active three Dimension (3D) laser range imaging system based on a pulse light-source and a modulated receiver (PLMR). A double-frequency YAG laser emits light pulses, which are expanded to light cones, with a frequency of 60Hz. A light pulse can illumine a full scene and a modulated image intensifier micro-channel plate (MCP) selects the reflected light with proper optical imaging devices. A Charge Coupled Device (CCD) receives the MCP output signal and generates an intensity image, and two modulated avalanche photo diodes (APD) collects the light splitting from the light pulse as correct intensified values for the intensity image. The system generates a 3D image, which needs a minimum of two different intensity images. These intensity images are obtained with or without illumination of light pulse and with different modulation applied to the MCP. The above imaging times are equal and relate to detection range. We present the best combination of the modulations and illumination conditions, in the meaning of minimum variance, and the relative theoretical analyses. Detection range, measurement resolution and scan frame rate of the system are given considering the influence of background light and circuit noise. Comparing to other 3D imaging systems, our system has the advantage of achieving both long measurement range and high spatial resolution. Potential applications to industry and military of the 3D laser imaging system are also presented.
A novel method for measuring the thickness of optical wave plate
Weiwei Feng,
Lihuang Lin
Show abstract
Based on chromatic polarization interferometry, a novel method for measuring the thickness of optical wave plate is presented. When the resolution power of spectrometer reaches 0.01nm, the measuring precision of the thickness is better than 0.1μm.
The application of fiber-coupling zig-zag beam deflection method on the investigation of plasma shock waves
Show abstract
A novel method, namely, fiber-coupling zig-zag beam deflection method has been proposed to investigate the attenuation
of plasma shock waves in air in this paper. The main innovation of this method is to use a zig-zag laser beam as the
probing beam, instead of a straight beam in traditional beam deflection method. The zig-zag beam is formed by eight
times successive reflections on a pair of parallel mirrors. Shock waves propagate through the space between two mirrors
which contains nine zigzags in the horizontal plane. This space can be designated as the testing field. After the probing
beam leaves the testing field, it is coupled into a single mode optical fiber which guides the beam into a photomultiplier
to complete the process of photoelectrical conversion.
Plasma shock waves are generated during laser ablation of Fe target in air. The laser used in our experiment is a Qswitched
Nd: YAG laser operating at wavelength of 1064nm and pulse width (FWHM) of 7ns. The output of
160mJ/pulse of this laser is focused on the surface of the target which is far exceeds the ablation threshold of Fe. When a
shock wave propagates in the testing field, it will meet the zig-zag probing beam nine times one after another.
Correspondingly, nine deflection signals will be induced by the perturbations of the shock wave, which can be utilized to
illuminate the propagating behavior of the shock wave. The whole attenuation process of the shock wave can be
demonstrated intuitively only through one experimental curve with the nine deflection signals. From the curve, the
average velocity of the shock wave can be calculated out with high and reliable precision. It is found that shock waves
attenuate into acoustic waves within 10mm in air because of the inhalement of environmental media. The development
of this novel optical technology provides a powerful tool for the detection of shock wave propagation and riches
diagnostic methods of shock waves.
Optoelectronic non-contact measuring method for the taper of a bore
Liancun Zhang,
Qingyuan Tian,
Xun Zhou,
et al.
Show abstract
Based on laser optical triangulation displacement and grating displacement inspecting principle, optoelectronic
non-contact inspecting method and inspecting system for the taper of small-calibre bore are presented. In this paper, the
constitute and overall structure of the system are described. Then, the taper inspecting method and principle of the bore
are discussed and theoretically analyzed, and also, the corresponding mathematics model is established. As inner
diameter measurement is an important parameter for the taper of small-bore, an inner diameter laser non-contact
measuring method is presented based on the structure characteristic of the taper of small-calibre bore, which adopted
optoelectronic probe sensitive device (PSD) and laser optical triangulation inspecting principle. And then, the laser probe
inner diameter measuring system is designed based them. Moreover, the measuring principle, the project of optical
system of this measuring system are illuminated in detail in this article. The accuracy of inspecting system is verified
by experiment. The results showed that the measuring error of inspecting system is superior to ±0.005, and the
inspecting repetition is superior to ±0.003. It indicates that the system can fulfill the inspecting accuracy demand for
inspecting the taper of the small-calibre bore, and the inspecting method is applicable.
An efficient iterative algorithm for subaperture stitching interferometry for aspheric surface
Show abstract
The subaperture stitching testing method provides a cost-effective means for large field of view, high spatial resolution interferometer. Current approaches to subaperture stitching are mostly limited to plano optics, where only the piston and the tilts are considered. Another implied assumption is that pixels corresponding to the overlapping region between pairs of subapertures are exactly known and given by the nominal translation within a spatial tolerance. This is obviously impractical in the case of aspheric surface. We address the problem here and introduce a geometrical approach to formulate it mathematically. It is essentially a large-scale nonlinear optimization problem, which is very complicated and time-consuming to be solved by conventional method. By virtue of the alternating optimization technique and the successive linearization method, we present a novel iterative algorithm for subaperture stitching interferometry for aspheric surface. It differs from others in that the CAD model of the tested surface is used to determine the overlapping region precisely and efficiently. Subapertures are then simultaneously stitched by minimizing deviations among them, as well as deviations from the nominal surface. As a result, precise prior knowledge of the nulling and alignment motion, which is of six degrees of freedom, is no longer required. Numerical simulations are given to test the validity and computational efficiency of the proposed algorithm.
A novel method of measuring convex aspheric lens using hologram optical elements
Yuejing Qi,
Ping Wang,
Jinghui Xie,
et al.
Show abstract
In order to simplify the complexity and improve the accuracy of convex aspheric lens testing, a novel method is proposed in this paper. In this method, convex aspheric lens is tested in transmitted light at the design wavelength by means of a Mach-Zehnder interferometer. Lens under test and its collimating lens are situated in one arm of Mach-Zehnder interferometer, Hologram Optical Elements (HOEs) acting as the compensator is placed in the proper position in another arm of interferometer. The principle of this setup is analyzed. The design and manufacture of HOEs and spatial filter used in this method are described in detail. In comparison with other methods, the advantages using this method are: (1) complex compensation lenses are not required any more, which simplifies the compensating structure and decreases the costs of measurement, (2) HOEs is easier to be fabricated. A convex-plane aspheric lens as an example is experimented.
The replacement of dry heat in generic reliability assurance requirements for passive optical components
Xusheng Ren,
Longsheng Qian,
Guiyan Zhang
Show abstract
According to Generic Reliability Assurance Requirements for Passive Optical Components GR-1221-CORE (Issue 2, January 1999), reliability determination test of different kinds of passive optical components which using in uncontrolled environments is taken. The test condition of High Temperature Storage Test (Dry Test) and Damp Test is in below sheet. Except for humidity condition, all is same. In order to save test time and cost, after a sires of contrast tests, the replacement of Dry Heat is discussed. Controlling the Failure mechanism of dry heat and damp heat of passive optical components, the contrast test of dry heat and damp heat for passive optical components (include DWDM, CWDM, Coupler, Isolator, mini Isolator) is taken. The test result of isolator is listed. Telcordia test not only test the reliability of the passive optical components, but also test the patience of the experimenter. The cost of Telcordia test in money, manpower and material resources, especially in time is heavy burden for the company. After a series of tests, we can find that Damp heat could factually test the reliability of passive optical components, and equipment manufacturer in accord with component manufacture could omit the dry heat test if damp heat test is taken first and passed.
Two structure interleavers with flat-top spectral response
Show abstract
This paper describes two kinds of circuit configuration to design interleaver, which are implemented by a single stage M-Z interferometer whose two arms are connected with ring waveguides. When the two configurations circuits are composed of M rings and N rings, respectively, (2M+2N+1)th-order interleaver characteristics can be realized. For two kinds of structure, design examples including third-order interleaver and fifth-order interleaver and seven-order interleaver are demonstrated. By theoretical analysis of the transmission function, The power transmittances spectrums are calculated, the circuit parameters are gained. Compared the power transmittances spectrums among third-order interleaver, fifth-order interleaver and seventh-order interleaver, it is found that with order of interleaver added, flat-top effect is better, the steeper spectral responses of the stopband and passband are achieved, and power transmittances get closer to square wave.
Development and application of a novel crop stress and quality instrument
Show abstract
In this paper, a portable diagnostic instrument for crop quality analysis was designed and tested, which can measure the normalized difference vegetation index (PRI) and structure insensitive pigment index (NRI) of crop canopy in the field. The instrument have a valid survey area of 1m×1m when the height between instrument and the ground was fixed to 1.3 meter. The crop quality can be assessed based on their PRI and NRI values, so it will be very important for crop management to get these values. The instrument uses sunlight as its light source. There are six special different photoelectrical detectors within red, blue and near infrared bands, which are used for detecting incidence sunlight and reflex light from the canopy of crop. This optical instrument includes photoelectric detector module, signal process and A/D convert module, the data storing and transmission module and human-machine interface module. The detector is the core of the instrument which measures the spectrums at special bands. The microprocessor calculates the NDVI and SIPI value based on the A/D value. And the value can be displayed on the instrument's LCD, stored in the flash memory of instrument and can also be uploaded to PC through the PC's RS232 serial interface. The prototype was tested in the crop field at different view directions. It reveals the on-site and non-sampling mode of crop growth monitoring by fixed on the agricultural machine traveling in the field. Such simple instruments can diagnose the plant growth status by the acquired spectral response.
Nanometer measurement of the planar motion of a magnetic levitation stage based on optical heterodyne interferometry
Show abstract
Nanoscale micromotion stage is a key instrument for the reasarch of nanotechnology that provides one-dimensional, two-dimensional, or three-dimensional nanoscale movement. In this paper, a magnetic levitation stage that can provide large range micromotion with nanometer positioning accuracy is proposed, and a height measurement and calibration of the stage using a triplex heterodyne interferometer is presented. This measurement system is mainly consists of three parts: two-frequency He-Ne laser, three heterodyne interferometers and three phase meters, respectively. Each heterodyne interferometer is used to measure the displacement of the magnetic levitation stage in the vertical direction. Then, the triplex heterodyne interferometer can realize the nanometer measurement of three degrees of freedom motion for the stage, that is, translation in the z-axis and rotations around the x- and y-axes. Furthermore, the three heterodyne interferometers have a common planar reflecting mirror, thus, the advantage of this measurement method is that the heterodyne interference can always produce within the travel range wherever the stage travels, this ensure the stage can always have the same height as that of desired position, and this measurement can give fine height consistency.
Theoretical analysis of sensing character of long period fiber grating coated with gas-sensitive film
Show abstract
Firstly we studied the sensitivity of long-period fiber gratings (LPFG) to the refractive index of ambient medium using the coupled modes theory. Then we presented numerical calculation based on long period fiber grating to show the relationship between the resonant wavelength of transmission spectrum and the ambient refractive index. Secondly we analyzed the optical mechanics of the semiconductor oxide film with gas-sensitivity and found that when touching the thin film gas can make its extinction coefficient, absorption coefficient and corresponding refractive index change. Thus we can coat the grating surface with gas-sensitive film and make use of the character that the refractive index will change with the component and density of ambient gas. Furthermore the change will influence the resonant wavelength of transmission spectrum of LPFG therefore we can get information about the gas component and density by way of monitoring changes of wavelength. The LPFG is more sensitive to ambient refractive index than fiber and the sensed signal is wavelength-modulated so the signal is not reflected by the fluctuation of light intensity and the fiber loss. Therefore the LPFG is more sensitive than intensity-type fiber gas sensor.
Research on dynamic dimensional classifying apparatus with double light paths of laser
Show abstract
This paper described a kind of new method and system in dynamic measurement used to measure the diameter of cylinder. Laser prismatic technology, photoelectric sensor technology, fine machine technology, electronics data processing technology and computer figure control technology were used in this system. It was a system integrated with optics, machine and electronics. This system had some characteristics of high precision, high efficiency, real time, on-line, non-contact and automatic measurement.
Developing of in-suit long trance profiler for testing slope error of aspherical optical elements
Changxin Zhou,
Hengshun Li,
Chukang Chen,
et al.
Show abstract
Profile error of super smooth surface of optical elements at x-ray/EUV in synchrotron radiation (SR) light beam line is described as slope error of them generally. The Long Trace Profiler (LPT) is used for testing surface slope error of SR optical elements in world generally. It is requisite to use In-suit LTP measuring surface thermal distortion of SR optical elements with high heat under high bright SR source. Authors design an In-suit LTP by means of co-path interferometer with pencil light beam. The instrument not only can be used for testing slope error of mirrors in Lab. also in situation test the distortion of mirror with high heat load at synchrotron light beam line. The device can be used to test various absolute surface figures of optical elements such as aspherieal, spherical and plane. It is needless standard reference surface. It is named by LTP-III. This paper describes its basic operating principle, optical system, mechanical constructions, DC serve motor control system, array detector, data acquisition system and computer system for controlling and data analysis of LTP-III. The Instrument has advantages of high accuracy, low cost, multifunction and wide application. Length of surface measured of optical element accuracy is 0.04 arcsec.
The effect of transparent film on its surface 3-D mapping by using vertical scanning white light interferometer
Show abstract
We have investigated the effect of transparent thin film while mapping its surface profile by using vertical scanning white light interferometer. Our theory analysis showed that multiple reflections taking place within the transparent thin film result in an extra phase change. The simulation and experiment results revealed that this extra phase change is also related to the thickness of thin film, the numerical number of microscope interferometer objective and the spectral distribution of light source. As a result of extra phase change, the interferogram has some deviation in its shape or two interference fringes may appears while the thickness of thin film is large.
High speed lapping paraboloid by means of a lapping tool bending method
Show abstract
This paper discusses a new lapping paraboloid method which combines high speed lapping technology with solid abrasives and lapping tool bending method. In this method a bending moment is acted on lapping tool with solid abrasives, which makes the tool bend and form a shape on its working surface which is same the as generant of workpiece shape. This kind of tool is used to form lap.
Performance and progress of daylight tracking for SLR in Changchun station
You Zhou,
Cunbo Fan,
Xinwei Han,
et al.
Show abstract
The paper introduces the performance and progress for Satellite Laser Ranging (SLR) system daylight tracking in
Changchun station. This paper first briefly summaries the Changchun SLR data quality and quantity from data
analysis centers: single shot rms, NP rms, long and short-term stability, data percentage and its rank in ILRS
after the system improvement. Second it introduces the problems and difficulties facing this system for daylight
tracking-mount model, the separation of emitting and receiving parts of the telescope, control range gate,
installing narrower filter. Third it presents some work which were done in the system for daylight tracking: system
stability improvement, laser stability improvement, mount model adoption, control system, etc. From these
analysis and work which have been done, daylight tracking in Changchun SLR system will be possible in the near
future.
Self imaging technique for refocusing an aerospace camera
Show abstract
A novel auto-focusing technique using a self imaging approach is developed for an aerospace camera having large aperture and long focus. Its optical system consists of an emitting system, receiving system, and two penta-prisms. Emitting system has three parts: a light source, beamsplitter, and aim slit. The receiving system includes a field lens, two separate lenses, and CCD. Using two little penta-prisms instead of a large planar mirror makes the autofocus system simple and compact. CCD was used as photoelectric converting device. A defocused signal is acquired by measuring the change of the two slit self-images position imaged on the CCD. A simple and compact construction of the auto-focusing system was proposed. The algorithm to calculate the moving of the slit-self images position was analyzed in order to achieve subpixel position estimation. The results of the experiments show a ±10μm focusing precision. The system demonstrates high resolution, easy adjustment and high reliability.
Mechanical interleaving assembly of TDICCD focal plane for space camera
Xing-Xiang Zhang,
Jian-Yue Ren
Show abstract
TDICCD assembly is a major method of acquiring wide field for space camera. For the demand of space camera's wide
view field and high resolution, the technique of mechanical interleaving assembly is discussed. Its principle, method of
adjusting and testing as well as the structure of focal plane are described. Using mechanical tangent-screws adjusting
method, the assembly with TDI CCDs for wide field space camera focal plane is finished on the facility which is
composed of a long work-distance microscope and a negative pressure and adsorption guide apparatus. The assembly
length of TDICCD focal plane for wide field space camera reaches 560mm, and the measuring error is not more than 3.2μm, the mechanical interleaving assembly method has effect of zero clearance and can achieve good image quality.
Lightweight tip-tilt mirror in correlation tracker system of the Space Solar Telescope
Show abstract
To compensate the image motion caused by random atmospheric turbulence and mechanical vibration, a high
performance correlation tracker designed for the Space Solar Telescope (SST) has been realized in National
Astronomical Observatories. Correlation tracker is to stabilize the image and provide the stabilized objective to CCD.
The main optical telescope can obtain the highest spatial resolution and ensure the image processing. Tip-tilt mirror is the
crucial element of the correlation tracker. The lightweight mirror is to adapt to work normally with space using and
satisfy the space environmental requirement. Tip-tilt mirror's material is SiC. Confirming the appropriate joint with the
platform and supporting mode through Finite Element Method. Then calculating the surface shape quality value (RMS)
of the mirror effected by inertial load and temperature. The calculation results show that the tip-tilt mirror has enough
stiffness and intensity. The mirror's surface shape quality value can satisfy the optical requirement of the correlation
tracker system.
Satellite trajectory simulator for inter-satellite laser communication system APT test
Show abstract
The characteristics of the terminals for the inter-satellite laser communication must be tested and verified on ground
before flight test. A pair of terminals for inter-satellite laser communications was developed for principle demonstration.
A terminal has two main subsystems. The first is one for the laser communications and the second one for acquisition,
pointing and tracking (APT). The optical methods and related system test-beds to measure and verify the performance of
the terminals in the lab room. In these programs, several novel ideas are proposed. With these ideas, whole programs can
be tested on ground in near-contacted field. The dynamic APT performances of an inter-satellite laser communication
terminal can be tested and verified by the combination of satellite trajectory simulator and a collimator-like laser
communication.
Opto-mechanical design and analysis of the MSC on the KOMPSAT-2
Eung-Shik Lee,
Deog-Gyu Lee,
Seung-Hoon Lee
Show abstract
The Multi-Spectral Camera (MSC) is the payload of KOMPSAT-2 which is designed for earth imaging in
visible and near-infrared spectral region on a sun-synchronous orbit. The telescope in the MSC is a
Ritchey-Chretien type with large aperture. The telescope structure should be well stabilized and the optical
alignment should be kept steady so that best images can be achieved. However, the MSC is exposed to
adverse thermal environment on the orbit which can give impacts on optical performance.
In order to meet those stability requirements in addition to fundamental structural ones telescope structure
was designed with newly developed graphite-cyanate composite which has high tensile modulus, high thermal
conductivity and low moisture absorption compared with conventional graphite-epoxy composite. In this
paper, space-borne telescope structure with new composite material will be presented and fulfillment of
stability requirements will be verified with designed structure.
Study on distortion control technology of the active stressed lap polishing deeper aspherical mirror
Show abstract
A special computer controlled polishing machine and a 450mm diameter active stressed lap have been developed
in NIAOT, and the lap has been successfully applied on polishing a f/2, Φ910mm paraboloidal mirror. This paper briefly
introduces the control structure of the polishing system. The deformation technology is an important part of the stressed
lap. This paper puts emphases upon discussing the deformation technology. On the base of experiments on f/2 mirror,
deformation experiments on f/1.5, f/1.2 have been done also. As the asphericity becomes faster, the dynamic response
of the lap's deformation becomes slower and the error of shape becomes bigger. In order to solve this problem and
improve deformation precision, we analyse the reason for the error of the lap and discuss the dedormation emendating
problem. In the end according to the result of deforming experiments, several considerations for optimization of
mechanic-electric design of the stressed lap are given.
Analysis and design of a precise omnidirectional stereo vision optical device utilizing a single camera
Show abstract
A catadioptric optical system is one that employs both lens and mirror components in the optical path, and can be used to capture a nearly 360° field of view. Such a system had the advantages of processing only one image, and with this image being continuous, not having to deal with discontinuities at the boundaries of view as a ring of conventional cameras would introduce. This paper presents a novel configured catadioptric sensor, a precise omnidirectional stereo vision optical device (OSVOD) based on a common perspective camera coupled with two hyperbolic mirrors. As the hyperbolic mirrors ensure a single viewpoint (SVP) the incident light rays are easily found from the points of the image. In our system the two hyperbolic mirrors, which aligned coaxially and separately, share one focus that coincides with the camera center. So the geometry of our system naturally ensures matched epipolar lines in the two images of the scene. The separation between the two mirrors provides a large baseline and eventually leads to a precise result. The properties mentioned above make the system especially suitable for omnidirectional stereo vision because depth estimation is simple, fast and precise. This proposed system can be used for detecting obstacles by mobile robots, automatic mapping of environments and machine vision where fast and real-time calculations are needed.
Optical system design of descent camera
Show abstract
This paper presents two optical systems of descent cameras. These two lens systems have the same parameter whose effective focal length is 14 mm, F-number is F/8, field of view is 72 degree and the working wavelength rang is 0.5-0.8μm. Two different optical structures were used respectively in these two systems. This paper analyses and compares their capacity respectively. Only two kinds of glass material were used in these two optical systems, the difference from the usual imaging system is that this system is required to be fit for the demand of spaceflight environment. It should be small and light enough on the one hand, and the imaging quality should be high on the other hand.
The detector whose image element size is 14 um, its Nyquist cut-off frequency is 35.711p/mm, its diffraction limit MTF is 0.76. Program 1's 1.0 field MTF≥0.58 at the Nyquist cut-off frequency. The biggest relative distortion of this system is+0.2%, Image irradiance at the edge of the field was found to be 50% of the central value. In the design of program 2, MTF approach diffraction limit, the biggest relative distortion in 1.0 field is 0.7%. Because of the structure of telecentric beam path design, the relative illumination in 72° view field is comparatively average.
Mechanical design of the stressed-lap polishing tool
Show abstract
We present an overview of the engineering design of stressed lap developed at Nanjing Institute of Astronomical Optics and Technology. Stressed lap consists of two parts: active deformable lap, driving-adjusting mechanism. The finite element model for active deformable lap is constructed, and the performance of lap deforming is discussed. Descriptions about mechanical structure of driving-adjusting mechanism are given. Now, stressed-lap polishing tool has been used to accomplish a fast parabolic mirror in Nanjing. The φ910mm F/2 parabolic mirror has been figured to an accuracy of 22 nm.
The application of auto-controlled liquid crystal light valve arrays to photolithography shutter
Yun Chen,
Lihui Liang,
Huiyang He
Show abstract
Photolithography shutter is usually used to control exposure in order to obtain patterns of code disc and metrology grating which are the core components of optical shaft encoder. But perforated film as photolithography shutter has many disadvantages such as taking too long time to perforate, easily making wrong code, lower reusable ratio. Mathematical models for resist property, luminous efficiency and exposure have been established by deducing their relations for avoiding the disadvantages, which provides the theory of using liquid crystal light valve (LCLV) replacing proforated film. Based on operating principles of LCLV and control theories of photolithography shutter, the principle diagram of control circuit of LCLV arrays has been designed according to theirs control principles. In the control system, LCLV arrays as photolithography shutter are realized by adopting DS75451 to drive them and using AT89C51 chip to control them. By photolithographic experiment, the patterns of code disc are good, the edges of lines are vertical, it indicates LCLV arrays as photolithography shutter may control exposure and light passing accords with the intending requires. It proves using LCLV arrays replacing perforated film as photolithography shutter is feasible completely.
Configuration optimization of a kind of sparse-aperture system
Show abstract
The quest for finer angular resolution in space-borne systems leads to larger aperture of the optical systems. Unfortunately, the primary mirror diameter for space telescopes is limited by volume and mass constraints of current launch vehicles as well as the scaling laws of manufacturing costs. The goal of sparse-aperture systems is to synthesize a larger effective collection aperture with a configuration of smaller sub-apertures. The modulation transfer function (MTF) of the sparse-aperture systems is depressed, resulting in a low-contrast and unsatisfactory SNR image. The optimization of the aperture is necessary to achieve a sparse-aperture configuration with more uniform MTF. In this paper, a novel sparse-aperture system composed of dual three sub-apertures is proposed. The optimization criterion of dual three sub-aperture is given, which is directly linked by the maximum spatial frequency ρR (or practical resolution) and the diameters of the sub-apertures. An optimized sparse-aperture configuration and the parameters of the configuration are given, i.e. the sites of each aperture, which varies with the different fill factor. Simulation images both optimized and un-optimized configuration for dual three sub-aperture are shown. Wiener filter is applied to restore the detail in the images of sparse-aperture systems. The loss of mid-spatial frequency information is irretrievable corresponding to the frequency (ρR) that MTF is a zero. So configuration optimization is a key aspect of the design for sparse-aperture systems.
A novel CNC aspheric grinding machine
Jianjun Hu,
Junhua Pan
Show abstract
Aspheric surface can be thought as being enveloped by a series of spherical surfaces with their centres on the same axis but having different positions. These spherical surfaces are tangent with the aspheric surface. We have manufactured a Φ600 CNC aspheric grinding machine with this novel operating principle. We choose δp , ε and αp as the key parameters of our grinding machine. δp is the distance between the cup-shaped tools' bottom and the vertex of the aspheric surface. αp is the rotational angle of the cup-shaped tool. ε is the space angle of the cup-shaped tool during the fabrication process of convex aspheric surface. Using this grinding machine, we can fabricate a conic concave aspheric surface continuously about three hours. But we need change the cup-shaped tool one time when we fabricate a conic convex aspheric surface in also about three hours. Our grinding machine can also be used to fabricate high-order aspheric surface. We used this machine fabricating a RC telescope system's primary and the secondary mirror. The PV-value is less than 5μm for the primary Φ350 concave hyperbolic aspheric surface which departure is about 55μm. We can polish and finish this aspheric surface with these residual errors easily. The manufacturing cost of the machine is about 300,000 RMB which is 1/10 of the LOH's product with the same maximum aperture of workpiece.
A novel method of calculation-separating second order spectrum in grating spectrometers
Hong-sheng Li,
Bing-xi Yu,
Yang Xiang
Show abstract
In grating spectrometers, according to wavelength, short-wave second-order spectrum superimposes on long-wave spectrum with the wavelength twice as long as the short-wave. Usually spectrum of long-wave range is got via preventing the superimposition of short-wave second-order spectrum by cut-off filters. This paper analyses the characteristic of the ratio of short-wave second-order spectrum in long-wave superimposing spectral range to first-order spectrum in short-wave free spectral range of diffraction gratings. The paper studies a novel method of obtaining long-wave spectrum via calculation-separating short-wave second-order spectrum from mixed spectra in long-wave superimposing spectral range by data processing with the spectrum of free spectral range and the ratio (instrumental parameter) of short-wave second-order spectrum to first-order spectrum measured beforehand. Spectrum-measurement experiments were carried out by VIS-NIR spectrometers (0.36~1.0μm). That the spectrum data got via calculation-separation coincide with those got via cut-off filter indicates that spectrum can be obtained by processing the measured date without filters in whole operating wavelength.
Hygrothermal design of high stability telescope structure
Deoggyu Lee
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Structural and hygrothermal analysis for a composite tube is carried out in this study, that provides critical parameters for the design of a highly dimensionally stable space telescope. Carpet plots for laminate effective engineering constants are generated and used for the best tube lay-ups with high elastic modulus and highly insensitive to thermal and moisture expansion, which is essential for maintaining optical alignment of opto-mechanical system under random force applied during a launch campaign and orbital thermal load. Despace in the longitudinal direction under hygrothermal load of the tubes constructed with the selected lay-ups is calculated for the validation of lay-up designs on the dimensional stability. Dynamic analysis is also carried out to feature the resonant behaviour. A zig-zag triangular element accurately representing through thickness stress variations for laminated structures is developed in this study and incorporated into the structural and hygrothermal analysis.
Smart camera with extended depth of field
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A smart camera is studied that combines the blurring logarithmic asphere lens and maximum entropy processing to extend the depth of field 10 times over that of a conventional lens and to provide near diffraction-limited performance. For this camera, a circularly symmetric logarithmic lens with radially varying focus length provides an image with distance invariant blur; a newly developed digital deconvolution technique, the accelerated maximum entropy processing, is thereafter applied to recover the sharp image providing an extended depth of field. Three types of logarithmic aspheres are described together with the effect of aperture apodizations. We show that the central obscuration of the aperture improves the overall performance of the smart camera, especially the near distance performance. The performance of the maximum entropy processing is greatly improved by introducing a new metric parameter into the algorithm. In the presentation, I will demonstrate the novel maximum entropy algorithm that has been devised, and also demonstrate the lens manufacturing technique of magnetorheological finisher that we used.
A new instrument for fiber connector endface measurement
Zongtao Ge,
Fumio Kobayashi
Show abstract
A new instrument for measuring end surface geometrical parameters of APC connectors is described. In this apparatus, a
Mirau type interferometric objective is employed to measure a small area of the connector end surface and generate
interferogram corresponding to the surface profile. Various new technologies are used to ensure high performance and
high measurement repeatability. A multi-point method is proposed to adjust the inclination of the PC sample stage. APC
angle of the sample stage is adjusted directly on the instrument using a special tool whose angle is calibrated by using the
reversal method. Measurement results of important parameters of fiber connector end faces are compared with those
inspected by commercial profiler or a standard sample. Optical insertion losses of connectors inspected by the developed
system are also evaluated.
Interferometric thickness calibration of 300 mm silicon wafers
Show abstract
The "Improved Infrared Interferometer" (IR3) at the National Institute of Standards and Technology (NIST)
is a phase-measuring interferometer, operating at a wavelength of 1550 nm, which is being developed for measuring
the thickness and thickness variation of low-doped silicon wafers with diameters up to 300 mm. The purpose of the
interferometer is to produce calibrated silicon wafers, with a certified measurement uncertainty, which can be used as
reference wafers by wafer manufacturers and metrology tool manufacturers. We give an overview of the design of the
interferometer and discuss its application to wafer thickness measurements. The conversion of optical thickness, as
measured by the interferometer, to the wafer thickness requires knowledge of the refractive index of the material of
the wafer. We describe a method for measuring the refractive index which is then used to establish absolute
thickness and thickness variation maps for the wafer.
Nonlinear imaging applied to the visualization of flow patterns
Show abstract
Flow visualization refers to a method used for qualitatively obtain information in the field of fluid mechanics. In this work, we show a simple single lens system using laser light illumination to observe flow dynamics using a setup similar to the schileren setup. As we will detail, it is based on a phase contrast technique in which the filter is made of a nonlinear optical material, therefore it is self-aligned and depends mainly on the illuminating intensity. Due to these characteristics, the resulting setup is extremely robust and builds up within a few milliseconds.
Vacuum annealing effects on properties of ITO films prepared by reactive low voltage ion plating technique
Ying Xu,
Jinsong Gao,
Xuanming Zheng,
et al.
Show abstract
With reactive low voltage ion plating technique, ITO (indium oxide doped with tin) films were deposited on glass
substrates by using ITO pellet with a composition of 90 wt.% In2O3 and 10 wt.% SnO2 without extra heating. The post
annealing process was done in vacuum with different annealing temperature at 100, 200, 300 and 400°C for 2 hours,
respectively. The effects of vacuum annealing on structural, optical and electrical properties of the ITO film deposited by
RLVIP were studied in detail. The results showed that the crystalline of the film was improved with the higher
temperature. The increase of the annealing temperature improved the infrared reflectivity from 30% to 80% over
8~14μm of the infrared atmosphere window, and a simultaneous variation in the optical transmission of the visible
spectral region occurred. In addition, sheet resistance of ITO films had contrary changing trend with the IR reflectance,
as well.
Dimension effect in lattice absorption of silicon carbide
Show abstract
We report high-sensitive experimental investigations of the SiC powders transmission spectra in the lattice oscillations region. For the SiC powders with the grain size of the order of the wave length the transmission minimum is shifted to the low-frequency range with respect to the transverse oscillation frequency of a single crystal ωT orresponding to phonon absorption with greater wave vectors. The decrease of the grain size leads to the shift and narrowing of the lattice absorption band to the high-frequency region. The observed change in the form and position of an absorption band corresponds to the narrowing of an optical phonon band due to decrease of the crystalline grain size, and approaching the lattice oscillation frequency to the frequency of molecular oscillations of Si-C in carbosilane owing to the surface energy contribution increase.
Application of photoresist melting method to the fabrication of holographic grating
Wenhao Li,
X. Bayanheshig,
Chengshan Zhang,
et al.
Show abstract
A new technique of reducing surface roughness of photoresist grating is presented. In this paper, photoresist melting method, which is low-cost, short-period and easy realization, is presented. In addition, the influence of photoresist melting on the groove profile of the photoresist grating is investigated. Experimental results show that the surface roughness reduces due to surface tension, when developed photoresist is heated to be melting state by this method. In experiment, when the melted photoresist grating is etched by ion beam, the surface relief grating possessing preferable groove profile is obtained on K9 glass substrate, then the surface is evaporated by aluminum using vacuum evaporation, holographic grating with preferable groove profile is successively fabricated.
Simulation of anisoplanatism of adaptive optical system in inhomogeneous turbulent atmosphere
Show abstract
The software is presented for simulation of anisoplanatic effect and its influence on performance of adaptive optical phase conjugation system in inhomogeneous turbulent atmosphere. Atmospheric turbulence was simulated with the help of a set of moving random phase screens with arbitrary statistics. Both reference and target are supposed to be the point light sources. To simulate atmospheric turbulence we applied the concept of a number of moving random phase screens with Kolmogorov spectrum. In our investigations we used the model of Shack-Hartmann wavefront sensor and the ideal model of wavefront adaptive mirror that is assumed to reproduce a given number of Zernike polynomials without time delays. The designed software allows to calculate instantaneous and average values of phase correction errors at a different angle between a reference beacon and target source. Simulations can be made with a broad range of parameters of adaptive system and atmospheric turbulence. The approach enables us to estimate residual aberrations as well as to calculate instant parameters of system performance - point spread function (PSF), optical transfer function (OTF) - and system isoplanatic angle. The model of system allows to change the control algorithm of phase corresction. Both common phase conjugation and weighted phase conjugation algorithm have been tested.
Research of on-axis tracking technology based on equal acceleration model
Show abstract
On-axis tracking technology is an ideal tracking mode with high tracking precisions. The author constructed an on-axis tracking system through assuming the target maneuvers with equal acceleration model, filtering and predicting the position and velocity with Kalman fiter. The analysis results show that the constructed on-axis system not only improves tracking precision dramatically, but also decreases the noise simultaneously.
The advanced position compensation to improve the dynamic tracking ability for fast moving target in an optoelectronic tracking system
Nengwei Wu,
Lirong Zhao,
Hui Zhou,
et al.
Show abstract
The servo control system of the optoelectronic tracking equipment usually is a kind of SISO. When the fast moving target is tracked, the over-tune of the servo system is the main representation for the dynamic tracking error. As the result, the tracking ability may be improved by limiting the over-tune. We put forward a method, the advanced position compensation (called as APC in short), which is to check the speed-overtune by applying the advanced position information. For the large accelerate target, small over-tune tracking is achieved, but it lowers the ability for tracking the sine signal at low frequency area. While the dynamic high-type can improve the tracking precision for the sine signal at low frequency area, we work out a brand-new method, which combines the advantages of the both. It increases the tracking precision in the whole frequency band at large scale for the optoelectronic tracking system. The simulation results show that when the target moves with the largest accelerate 120°/s2, 120°/s, the maximum static tracking error is about 0.6".
INS’s error compensation on the base of the celestial theodolite
Hai-bo Zhao,
Li-hong Guo
Show abstract
In recent years there has been a major upsurge of interest in the integrated inertial navigation system (INS)/celestial navigation system (CNS) as a cost-effective way of providing accurate and reliable navigation aid for civil and military vehicles (ships, aircrafts, land vehicles and so on). One of the disadvantages of INS is its errors will grow unbounded. The CNS can be used to improve position estimation resulting from INS measurement. This paper describes the design of this. An error model developed earlier is used for CNS/INS filter (Kalman filter) mechanization. In CNS, celestial theodolite acquires an image of the sky, recognize the most brilliant stars in the image, creates with them a "constellation", and searches for this pattern in an on board star catalogue of the observed region to get the precise position and attitude information of vehicles. The Kalman filter method is used to fuse measurement from the system. We can use this information to compensate INS's error. The tests carry out with this system show that system will get accurate navigation information.
Image rotation of two-axis line-of-sight stabilization system
Yingfeng Feng,
Yun Zhu
Show abstract
In connection with the vector analysis and coordinate conversion, this paper theoretically analyzes the image rotation of the line-of-sight (LOS) stabilization system and derives the image rotation formula, and it also analyzes all possible factors which have impact on the image rotation.
Analysis movement feature about spindle and relevant points on stressed lap
Bilie Gao
Show abstract
Niaot (Nanjing Institute of Astronomical Optics & Technology) had made a stressed lap1 and finished a Φ910mm, F/2 paraboloid2, and also analyzed its feature about deformation and tilt of stressed lap on proceeding condition3. In this paper, according to the spindle tilt and no tilt, assuming the spindle moving velocity along the crossbeam, or the spindle tilt velocity around its tilt shaft, or apex of lap moving tangential velocity along the paraboloid surface is uniform, Author analyzes the movement feature of each relevant point and the removal efficiency for mirror on each condition for Φ2200mm, F/2, F/1 and F/0.6 paraboloid. And proceed to consider: when the lap on tilt condition, the normal pressure on mirror will change in succession and it will reduce removal efficiency. So Author put forward another linkage moving type to reduce its effect, it will become a uniform removal efficiency from mirror center to edge on one period. On spindle no tilt class, the rotative velocity of lap isn't uniform, in this paper author also analyzes the difference of their angle and angular speed between spindle and lap, and how to correct this error. All these analyses is just for stressed lap working on axial symmetry paraboloid mirror. On removal proceeding, all movements, including the spindle translation on horizontal crossbeam and on vertical slider; the spindle tilt; the spindle rotation; the lap deformation etc., must work together to become a linkage under computer control. It is to say, in any twinkling, all relevant points must be on specific position and have specific velocity and specific acceleration. So this analysis is the mathematical basis for using stressed lap too.
Maintenance consideration for the mirror systems of LAMOST telescope
Show abstract
The Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) is the largest of this kind in China and it will be put into operation in two years. To secure its smooth operation, each component, especially the mirror system needs to be maintained in a good condition. Some equipment is needed and the operation must be considered at early stages. In this paper, a feasible approach is put forward in which the concept of human and machine cooperative work is used to assure the successful operation at lower cost. An electrical driven forklift with some special fixtures designed for this work is used for MB mirror system and a special designed crane is used for the assembly and disassembly of MA mirror system. Procedures and methodologies for the identification of assembly and disassembly sequence, special tool design, time and cost analysis, and human factors analysis of the assembly and disassembly sequence are presented.
Application of linear CCD for position measurement
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A method that measures relatively position relation between two vehicles fleetly and accurately that are both on a horizontal plane is proposed in the article. When manipulator rotates horizontally, the linear CCD vidicon that is on the end of manipulator on the loading vehicle scans two point targets that are on the launching vehicle, and then we can utilize spatial intersection principle and trigonometry theorem to get relatively position relationship. I.e. the coordinate parameters: x, y, z, α. Error analysis and the simulation on computer validate: the measurement error of length is less than ±0.84mm; that of angle is less than ±2'6'', which satisfies technical requests. So the method is feasible. The research is not only significant for missile of automatic transshipment, but also is valuable in theoretic research on method of measuring spatial position relationship.
Detectors of UV and x-ray irradiation on the base of metal-zinc selenide contact
Victor P. Makhniy,
Volodymyr V. Mel'nyk,
Peter N. Gorley,
et al.
Show abstract
The paper presents results of experimental investigations of electric and photoelectric properties of the diodes, obtained by thermal sputtering of semitransparent Ni layers over monocrystalline wafers of zinc selenide. It was found that parameters of diode structures studied are very similar to those of "ideal" metal-semiconductor contact. Influence of temperature, UV- and x-ray radiation on diode parameters is discussed.
A two incoherent sources resolution criterion in the phase space
Show abstract
The aim of this work is to propose a positiveness constraint on the Wigner Distribution Function (WDF) of the detected image of two incoherent point sources: if WDF lacks of zeroes along the frequency coordinate the object can not be resolved by imaging and detected systems; otherwise, it can. This criterion can be applied without preference for a circular clear diffraction limited aperture and for complex apertures with small aberration values; furthermore, it holds if the intensity of each source is different or even when the sources are not points.
Design, fabrication, and characterization of an ultraviolet silicon sensor
Show abstract
In this work a Silicon/Silicon Rich Oxide (SRO) Ultraviolet detector is designed, fabricated and characterized.
This device increases the silicon detection range to the ultraviolet region (200-300nm). Besides the fabrication
process of this detector is compatible with standard silicon technology that makes it cheaper than commercial UV
detectors.
Analyzing tolerance of grazing angle for hard x-ray Kirkpatrick-Baez microscopes
Show abstract
K-B microscope intended for the use in inertial confinement fusion experiments was designed. The microscope operates at the 8keV x-ray energy and provides the 8X magnification. The parameters of the microscope are decided by requirements of ICF experiments. Ray tracing software (Zemax) is used to simulate optical system performance. Grazing angle range on the surface of mirrors and the assembly tolerance of centre grazing incident angle were both calculated. For the working energy is 8 keV, in order to obtain sufficient reflectivity at about 1° grazing angle on each mirror, multilayer should be coated on the mirrors. Two kinds of multilayer, periodic multilayer and non-periodic multilayer (supermirror), are discussed in the paper. Take into account the grazing angle ranges on the mirrors and the grazing angle tolerance, it is necessary to have a fairly constant reflectivity over a wide angular domain. Periodic multilayer has narrow bandpass, which cannot fulfill the requirement of such wide angular domain. The non-periodic structure multilayer was designed and fabricated. The results show this kind of non-periodic multilayer can be used in K-B microscope.
Design and fabrication of soft X-ray blazed diffraction gratings
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Diffraction gratings are designed for grazing-incidence operation in the soft x-ray spectral region. The efficiencies for various diffraction orders are simulated as a function of angle of incidence and blazed angles. According to the beat phenomenon, the grating pattern with double-frequency on the same substrate is recorded in a holographic way. The blazed grating will be fabricated using holography and ion beam etching method. The primary experimental results are presented. This kind of blazed grating is a key element used as a beam splitter of soft x-ray Mach-Zehnder interferometer, which is a new tool to diagnose the plasma generated by the laser-based inertial confinement fusion.