Proceedings Volume 1982

Photoelectronic Detection and Imaging: Technology and Applications '93

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Proceedings Volume 1982

Photoelectronic Detection and Imaging: Technology and Applications '93

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Volume Details

Date Published: 1 April 1993
Contents: 7 Sessions, 87 Papers, 0 Presentations
Conference: Photoelectronic Detection and Imaging: Technology and Applications '93 1993
Volume Number: 1982

Table of Contents

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Table of Contents

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  • Photoelectronic Imaging: Systems and Assessments
  • Photoemitters and Photodetectors
  • Image Tubes and Camera Tubes
  • Design of Photoelectronic Imaging Devices
  • Photoelectronic Detection
  • Image Processing
  • Related Technology and Applications
  • Photoelectronic Imaging: Systems and Assessments
  • Design of Photoelectronic Imaging Devices
Photoelectronic Imaging: Systems and Assessments
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Photonics
Teruo Hiruma
After developing various kinds of photodetectors such as phototubes, photomultiplier tubes, image pick up tubes, solid state photodetectors and a variety of light sources, we also started to develop integrated systems utilizing new detectors or imaging devices. These led us to the technology for a single photon counting imaging and detection of picosecond and femtosecond phenomena. Through those experiences, we gained the understanding that photon is a paste of substances, and yet we know so little about photon. By developing various technology for many fields such as analytical chemistry, high energy physics, medicine, biology, brain science, astronomy, etc., we are beginning to understand that the mind and life are based on the same matter, that is substance. Since humankind has so little knowledge about the substance concerning the mind and life, this makes some confusion on these subjects at this moment. If we explore photonics more deeply, many problems we now have in the world could be solved. By creating new knowledge and technology, I believe we will be able to solve the problems of illness, aging, energy, environment, human capability, and finally, the essential healthiness of the six billion human beings in the world.
High-speed solid state camera imaging systems at LLNL-NTES
Helmut A. Koehler
Strong interest exists at the Lawrence Livermore National Laboratory in studying the physics of transient, high density, high temperature, hydrogen plasmas. Because sequenced imaging is a major part of the diagnostics of these plasmas a continuous effort is made to improve the components of our imaging system and their calibration and to review operating procedures and techniques. The major components of our transient data, optical imaging systems are gated microchannel plate intensifiers (MCPI), solid-state array cameras, and fiberoptic data acquisition systems. Gated MCPIs are currently used with our solid-state cameras to provide sub-nanosecond snapshots of an optical pulse from a radiation-to-light converter. Efforts are made (1) to characterize photocathode response, modulation transfer function, luminous gain, and gating speed of each MCPI during the gating period, and (2) to improve pertinent MCPI parameters such as extinction ratio, gate pulse shape, resolution, and uniformity. A review of our high-speed imaging systems and components and their developments and calibrations is also presented.
Imaging photon-counting detector systems for ground-based and space applications
A family of imaging photon-counting detector systems, the multi-anode microchannel arrays (MAMAs), are now under active development for use on a number of space astrophysics missions at far-ultraviolet and extreme-ultraviolet wavelengths. MAMA detector systems are currently being fabricated for use in instruments on the European Space Agency (ESA)/NASA Solar Heliospheric Observatory (SOHO) spacecraft and for a second generation instrument on the NASA/ESA Hubble Space Telescope. The components of the MAMA detector system consist of, (1) the open or sealed tube assembly containing the photocathode, the high-gain curved-channel microchannel plate, and the readout electrode array, and (2) the associated analog and digital electronics circuits. The configurations of the different MAMA detector systems are described in some detail and the use of custom application specific integrated circuits in the electronics is discussed. The performance characteristics of the MAMA detectors are described and compared with those of alternative imaging photon-counting detector systems. Examples of both ground-based data and flight data from sounding rockets are shown.
Development and current status of photoelectronic image devices in China
The present paper gives an overview on the development and current status of photoelectronic imaging devices in China. Particular emphasis is given to devices aimed at image intensification and image conversion, e.g., image intensifiers, low light level pick-up devices, electronographic tubes, high speed photographic converter tubes, intensified CCDs, infrared detectors, as well as basic theory and design, and components and methods of testing for the photoelectronic imaging systems in China.
Megapixel high-dynamic-range low-energy x-ray imager for synchrotron applications
Jean-Pierre Moy, S. Gibney
New synchrotron facilities such as the European Synchrotron Radiation Facility rely on the development of new detectors to take full advantage of the dramatic increase in the brilliance of their x-ray beamlines. A novel detector system based on modified x-ray image intensifiers (XRII) optically coupled to CCD cameras is described. Different options fit specific requirements, essentially trading resolution against speed. The energy range covers from 5 to 25 keV with the special beryllium windowed XRII, and up to 100 keV with standard medical imager tubes. Input size is 200 mm in diameter, with electronic zooming capability down to (phi) 100 mm. A 50% MTF is reached for 17 line pairs/cm. More important is the extremely narrow wings of the point spread function: full width at 0.1% of maximum is less than 1 mm. Noise is negligible in most applications, being equivalent to a few x-ray photons/s.cm2, so that single x-ray photons are easily distinguished. Commercially available slow scan CCD cameras allow 16 bit dynamic range megapixel images to be read-out in 10 - 20s. Faster designs studied at the ESRF using multi-output CCD already make it possible to acquire several images per second, and ultra fast systems with only 512 X 512 pixels are expected to reach up to 300 images/s while maintaining a dynamic range of 1000:1.
Approach to the image-recording technology of scenes at low light level
Qi Luan Xu
With the development of science and technology in modern society, people have not only the demand of observing scenes at night, but also hope to record them vividly. Practical image recording methods are film photography, cassette or electrostatic recording. This article mainly presents the methods of recording LLL image information with films, the application of LLL image intensifying technology in film recording and the problems of it.
Superhigh-sensitive x-ray video camera and its applications
Tomiyasu Sakamoto, Kenji Suzuki
Two types of new detectors have been developed to pick up faint x-ray image with high resolution in the x-ray energy range of from 3 keV. One is an x-ray image intensifier type video camera. The other is an ultra high sensitive x-ray image intensifier type video camera and this enables us to pick up faint soft x-ray image even in the photon counting region. Features, specification, and applications of these detectors are described.
Ultrafast time-gated imaging techniques
Qingming Luo, Xiande Liu, Shaoqun Zeng, et al.
The propagation properties of an ultrafast laser pulse through breast tissues are simulated in this paper. It has been shown that the use of time-gated imaging techniques could greatly improve the contrast of transmission image of the breast. Then several time-gated imaging techniques are discussed, and a new time-gated imaging technique -- the use of transient stimulated Raman scattering for both rapid time gating and amplification of the image -- is proposed.
Scanning laser microscopy and laser thermal imaging
Guanqi Yue, Yungang Nie
Besides some advantages over conventional optical microscopes, a scanning laser imaging system is the basis of developing another kind of imaging system i.e., a laser-thermal imaging system. The latter provides thermal images reflecting distribution of thermal properties, such as thermal conductivity of the sample, thus it makes imaging of some material parameters other than optical properties possible. Principle and structure of such a laser-thermal imaging system is described and images of ion implantation dose density in crystal obtained from this system are given.
Research on CCD long-range automatic collimating technique
Dingtao Zhu, Bin Zheng, Xingxing Wu, et al.
This is a research report on developing a CCD long-range automatic collimator. It presents the application of a new photoelectric detector CCD to initial alignment of the inertial platform in launching large rocket and space craft and describes the principles of the system, design features, and the key technique analysis. Finally, the measured results and applications of the prototype are presented.
ISEC imaging system and its applications
Minju Zhang, Jinian Li, Xin-Zhi Jia
This paper reports a novel type of photoelectronic imaging system consisting of laser, image intensifier, secondary electron conduction (SEC) camera, computer, image sample, and hold system, then it sets forth operational principles of the system imaging fluorescence under the control of a computer. Experiment studies on fluorescence detection of biologically organized structure and latent fingerprints also are presented, and a satisfactory result of fluorescence image is obtained. For the use of a first GEN intensifier and integration ability of the SEC target, the system can realize excellent sensitivity and image even in a 10-7 lx illumination environment. Compared with a traditional fluorescence microscope system, the system developed in our laboratory has many good features that the former does not have, such as ultra-high sensitivity, convenience of image processing, quantitative measurement, and display of the spatial distribution of fluorescence intensity.
Theoretic analysis of photoelectronic-imaging delay
Yisong Zou, Yudan Li, Shanfeng Hou
There are some delay elements in photoelectronic imaging processes, such as phosphor screen, photoconductive target, etc., and these lead to the time delay. The former originates from the transience capture of carriers which is produced before recombination luminescence in the luminous crystal excited process, and the time dispersion of the electrons release in trap level determines the delay of the luminous delay process. Whereas, the latter originates from the lifetime dispersion of semiconductor minority carriers and the capacitive delay of scanning electron beam charging the target. It can be fairly well verified by theoretic analysis and experiment that photoelectronic imaging delay can be approximately divided into: proportionality functional delay type, exponential functional delay type, and hyperbolic functional delay type. The three kinds of delays have different temporal modulation transfer functions. In this paper, we give the concrete analysis of them.
Visual range prediction and revision of temperature difference in thermal imaging systems
Zhiyun Gao, Jing Zhang, Yue Gao, et al.
A mathematical model for the visual range prediction of thermal imaging systems, various factors affecting the visual range, as well as the relevant methods of computation are the topics covered. It is suggested that further revision is needed in consideration of the non-linear change of power versus temperature difference when the observed targets are involved in larger temperature difference cases. The concept of equivalent temperature difference is proposed.
Threshold of detectability of image-intensifier optically-coupled CCD (I2-CCD) at low light level
Yudan Li, Zebin Wei, Yisong Zou, et al.
The threshold detectivity of I2-CCD is studied based on the new concept of TV signal modulation transfer (STF) and noise modulation transfer function (NTF). The image detective ability equation of I2-CCD is established using the STF and NTF, as well as the theory of image threshold detectability. The detectability of I2-CCD cameras under several different conditions are calculated according to the equation. The theoretical calculation results fit well the experiment results. After analyzing the theoretical results several means to improve detective ability of I2-CCD are available.
Multiple target infrared-/visual-image tracking system
Chengjun Sun
We developed an infrared/visual image tracking system. The system consists of a longwave FLIR and TV camera combined sensors, a special image processing system, and some other subsystems. The system passed some field tests. Targets such as airplanes, tanks, and cars were detected, recognized correctly, and tracked stably during day and night. The system might track 15 targets in the field of view simultaneously.
High-resolution CCD camera at Yunnan Observatory
Zhaowang Zhao, J. Xu, H. S. Tan, et al.
A CCD camera system has been constructed and is in regular use at the Yunnan Observatory. A Texas Instruments-Japan 1024 X 1024 CCD is employed. The TI-Japan CCD is a virtual-phase with high quantum efficiency, 8 electrons rms readout noise, and excellent charge-transfer properties under low-level light. The CCD controller is designed to operate with multi-functions, the pixels of CCD can be binned into any format. The dewar is cooled by a three stage thermoelectronic device.
Test and analysis on variable-integration low-light-level CCD camera signal and noise properties
Lianfa Bai, Qian Chen, Yinghui Li, et al.
Video signal-to-noise ratio (SNR) is an important combination performance index of the low light level (LLL) camera, test and analysis on it play a very important role in evaluating and designing new LLL cameras. It is an innovation in our teaching and research section that we test video SNR by using digital storage oscilloscope (DSO) combined with a computer and set up a perfect LLL camera signal and noise property test and analysis system. Using this system, we test and analyze the signal and noise properties of the `variable integration low light level CCD camera' which our teaching and research section developed.
Control methods of CCD imager characteristics for dynamic image detection
Andrey A. Mancvetov
The structure of CCD imagers and peculiarities of their operation modes allows us to realize the control of such CCD characteristics as sensitivity and resolution, and to minimize spurious signals from image sensors which appear in the image detection process. In many cases there is an apriory information about parameters of dynamic images, for example, the velocity vector or the law of objects brightness variation, allowing us to optimize CCD sensor operation mode. The following control methods of CCD imager characteristics are considered in the paper: (1) shift compensation methods, time delay and integration mode, which are met for detection of moving objects images; (2) increase methods of time resolution of CCD imagers which are aimed at quick process detection; (3) control methods of CCD sensitivity in the integration process for the false components rejection in the image caused by insufficient field frequency. Experimental data obtained during the research of considered methods are given in the paper.
Photoemitters and Photodetectors
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Thin-film high-gain photodetector and switching devices using a-Si:H and a-SiC:H multilayers
Yoshinori Hatanaka, Narihiro Morosawa, Masakazu Suzuki, et al.
High quality amorphous silicon carbon (a-SiC:H) films with the wide bandgap of 2.4 eV are developed by using rf glow discharge deposition from highly hydrogen diluted C2H4 and SiH4. It has been shown that multi-layer photo-diodes using a-Si:H and a-SiC:H tend to have higher gain than 10, and special constructions of three multi-layers presented switching phenomena like a thyrister switch.
Photoemissive thin film with strange property for laser pulse detection
Q. D. Wu, W. M. Liu, J. L. Wu, et al.
A kind of photoemissive thin film which can be exposed or stored in the atmosphere and can be used again in a vacuum system without any activation process for laser pulse detection is presented. They are different from usual photoemissive materials, since they do not contain alkali elements. They consist of metallic oxide thin film or other material thin film embedded with metallic ultrafine particles. A main interesting material is barium oxide thin film embedded with Ag ultrafine particles. This thin film can detect single laser pulse or laser pulses with high repetition frequencies (approximately 108 pulses/sec.), pulse duration ns to ps, and energy mJ to nJ per pulse.
Field-assisted photoemission from semiconductor heterostructures up to 1.7 um
A. L. Musatov, S. L. Filippov, K. R. Izraelyants, et al.
We present the spectral curves of the photoemission from biased semiconductor heterostructures with Schottky barrier InGaAs-InP-Ag in the region of spectrum up to 1.7 micrometers and consider the main processes that determine the efficiency of photoemission from such structures. We also present the characteristics of dark-current emission from InGaAs-InP- Ag heterostructures and show that it is connected with thermal generation of electrons in the space charge region of InGaAs near the interface.
Photoemission stability of negative-electron-affinity GaAs photocathodes
Tailiang Guo, Huai Rong Gao
Photoemission stability of the negative electron affinity (NEA) GaAs-(Cs,O) photocathode activated with several cycles of alternate Cs and O2 adsorption at room temperature is mainly determined by the stabilization of the cesium and oxygen adlayer on the GaAs surface, and the bonding strength between this adlayer and the GaAs substrate. It is found that the light treatment (incident white light illumination) during or after the Cs and O2 activation process can improve the emission stability of the NEA GaAs-(Cs,O) cathodes. It is also found that the emission stability of the NEA GaAs-(Cs,O) cathodes is closely related to the electronic states of cesium and oxygen before being adsorbed on the GaAs surfaces, best result being obtained with cesium ions and excited oxygen molecules. In addition to the activation procedure and experimental results, some photoinduced reactions, e.g., photoinduced adsorption, desorption, excitation, dissociation, ionization, and surface migration and surface rearrangement of the cesium and oxygen adsorbates on or from GaAs surfaces are analyzed, and their effects on the emission stability of the NEA GaAs-(Cs,O) photocathodes are discussed.
Optimization of the GaAs-delta-doped p-i-n quantum-well APD
Yang Wang, Kevin F. Brennan
We examine the basic design issues in the optimization of a GaAs delta-doped quantum well avalanche photodiode structure using a theoretical analysis based on an ensemble Monte Carlo simulation. The device is a variation of the p-i-n doped quantum well structure previously described in the literature. It has the same low-noise, high-gain, and high-bandwidth features as the p-i-n doped quantum well device. However, the use of delta doping provides far greater control of the doping concentrations within each stage possibly enhancing the extent to which the device can be depleted. As a result, it is expected that the proposed device will operate at higher gain levels at very low noise than devices previously developed.
Study of GaAs-Cs-Sb photoemitter
Libin Zhao, Qing Zhou, Shouzhen Zhao, et al.
It is well known that the defects of the GaAs-Cs-O photocathode are the poor photoemission stability and short life at room temperature. All these defects are caused by cesium desorption from the photosurface. In this paper, for resolving the problem of cesium desorption, a new surface activation material Cs-Sb is proposed to take the place of Cs-O for reducing the cesium release from the GaAs surface. From the experimental results, the following conclusion may be obtained: using the Cs-Sb to replace the Cs-O covering the GaAs surface, the stable negative-electron-affinity (NEA) photoemitter can be prepared.
Tapered rib-waveguide for single sideband modulation at 10.6 um
Hui Wang, Peter K. Cheo
A traveling rib-waveguide structure is proposed for single sideband (SSB) modulation. A low- loss parabolic taper is designed to transmit a large infrared laser beam (10 micrometers ) into a narrow channel at an optimal length of 7500 micrometers where the taper opening is 242 micrometers and the rib-channel width is 100 micrometers . The propagation loss of one taper is about 5 to 10%, and this has been confirmed by experimental results.
Analyzing the thermal stability of CsI photocathodes with XPS
Kaisheng Tan, Zhiyong Pan, Fengqin Liu
The effects of vacuum-baking on the chemical state of CsI photocathodes are studied with x- ray photoelectron spectroscopy (XPS) in this paper. The experimental results indicate that when the vacuum-baking temperature is below 180 degree(s)C the chemical states of CsI photocathode are stable, but there is a sublimation of CsI with low rate in high vacuum. When the vacuum-baking temperature is higher than 180 degree(s)C, chemical shifts will occur.
Optimum optical local oscillator power levels in coherent detection systems
J. Fred Holmes, Badih John Rask
Use of an optical local oscillator for coherent detection with a photoconductor or a photodiode can significantly reduce the responsivity of the detector due to saturation effects. Consequently, local oscillator shot noise limited operation of the detector may not be possible. However, a local oscillator power level can be selected that maximizes the signal to noise ratio.
Various improved techniques for reduction of dark current in silicon photoelectric detector
Guoxiang Zheng
Silicon photodiodes, photoelectric transistor, and other silicon photoelectric devices have many advantages such as high response speed, good linearity of current vs. illuminance, high quantum efficiency over a wide spectrum range, and long life. However, a whole class of photoelectric detectors is based on low dark current. For example, silicon vidicon, silicon blue sensitive photodiode (SPD) and its integrated amplifier, and silicon photoelectric array have special features which depend on dark current. The dark current must be kept low enough. The reduction of the dark current was investigated by the author in making SPD. Dark current can be ascribed to the following causes: diffusion current, extended defects and generation current on the surface and junction depleted layer. The diffusion current is the unavoidable contribution to the dark current. Extended defects in active zones once decorated by metal atoms bring about an increase of dark current. Generation current plays an important part in dark current. Therefore, it is important to reduce density of the generation center and metal atom in surface and junction to obtain low dark current. HCl treatment, gettering techniques, etc., are the efficient methods. The author has improved HCl oxidation, intrinsic gettering, phosphorus diffusion gettering, and Si3N4 film deposition to obtain further reduction of dark current.
Post-annealing effect in HgCdTe photodiodes
Guo Min Yu
The post-annealing effect in HgCdTe photodiodes ((lambda) c < 3 micrometers ) has been reported. After the post-annealing proceeding, the current responsibility of the photodiodes has no change. However, the noise current of the photodiodes has considerable changes. For the photodiodes with small noise current (in < 300 fA) before the post-annealing, the noise current increases after the post-annealing; for the photodiodes with big noise current (in > 300 fA) before the post-annealing, the noise current obviously reduces. The probable mechanism has been analyzed.
Theoretical study on the thickness of polycrystalline semiconductor multialkali photocathodes
B. K. Chang, Yuanzhen Z. Liu, Xu Dagang, et al.
Optimum thickness of polycrystalline semiconductor multialkali photocathodes is studied by the exponential attenuation rate of the radiation intensity and formulas for the quantum yield spectra and optical absorption coefficient of multialkali photocathodes. It has been found that if I(alpha )/IO > 0.4, photocathode optimum thickness D will be in excess of around 1000 angstroms and if I(alpha )/IO increases further, D will tend to increase too, while photoelectrons excited by energetic photons will appear in the inner surface of the photocathode. Furthermore, D should be in the vicinity of 300 angstroms for the first kind of photocathode (S-20, S-20R, and S-25) and 900 angstroms for the second kind of photocathodes (new S-25, Varo, and LEP). It is suggested that the optimum photocathode thickness D be studied by the spectral response peaks of multialkali photocathodes. We came to the conclusion that photoelectron escape depth and incident wavelength tends to increase and along with it the optimum photocathode thickness. It has been calculated that the optimum thickness of multialkali photocathodes possessing good response in visible and infrared light must be in the vicinity of 1200 angstroms.
Image Tubes and Camera Tubes
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Femtosecond streak tube
Katsuyuki Kinoshita, Motohiro Suyama, Yoshinori Inagaki, et al.
A new magnetic focusing streak tube with a traveling wave deflection electrode has been developed. In the operation, a pulse voltage is applied between the photocathode and the accelerating mesh electrode. The limiting time resolution of approximately 180 fs has been experimentally obtained.
Development of the 12-inch high-definition x-ray image intensifier
Tetsuro Endo, Masafumi Tanaka, Yoshitoshi Ishihara, et al.
A high definition x-ray image intensifier (II) has been developed which has a 60 mm large diameter output phosphor screen. This new tube also has another improvement in conjunction with the output phosphor screen, electric lens, and input phosphor screen, it resulted in more than 50% higher resolution than conventional types.
Preliminary study of supersensitive camera tube
Pan-Ao Chen, Chun-Lin Shen
For lack of sensitivity, conventional HDTV cameras can't obtain satisfactory picture quality. A super-sensitive HDTV camera tube, HARPICON (10 times as sensitive as the Saticon), and a new camera tube (more sensitive than the HARPICON) are proposed. The later combines a microchannel plate (MCP) as the electron image storage, a field emission array cathode (FEAC), and high-performance electron-optics. The performances of two experimental Saticon are also given in this paper.
New progress in high-performance x-ray image intensifiers
Yves R. Beauvais, Paul M. de Groot, Jean-Charles Chen
The primary feature of x-ray image intensification is to allow a substantial reduction of the necessary x-ray dose, by offering a luminance gain of about 104 compared to direct view fluoroscopic screens. Such a luminance gain has made possible real time video recording and display of radiological images, by optically coupling a video camera to the output of the screen of the XRII tube. However, the observable field of view of the XRII was initially limited to approximately 15 cm, and the image resolution was not as good as the resolution achievable with radiological films. Progressively, the size of XRII tubes has been increased, and modern tubes can offer useful image diameters up to 40 cm. In addition to that, the electronic zoom, introduced at the beginning of the seventies as a feature of the XRII tubes, allowed the user to achieve an observable resolution very close to that of the radiological films, but at the expense of the observable field of view. Continuously, the manufacturing technology of the most critical parts of the XRII tubes have been improved resulting, for modern tubes, in such an imaging quality that most of the radiological modalities of diagnostic are directly achievable through video observation. Furthermore, the recent progress made in electronics and image processing offers powerful means to make the best possible use of the electronically recorded radiological images. A review is made, hereafter, of the latest progresses in XRII performances and applications.
Image tubes for measurements in extreme region
Our research has been performed by aiming at the measurement in the extreme regions, such as at extreme low light level or ultra high speed. Image tubes are key devices for these purposes, therefore two-dimensional low light level detection tubes and streak tubes have been developed. The low light level detection tubes have realized imaging in the photon-counting region, and the streak tubes have reached the femto second temporal resolution range. These devices have been utilized in various fields.
New gateable SEC camera tube
Xin-Zhi Jia, Ji-Tian Li, Xianfu Ban, et al.
In this paper, a newly developed gateable SEC tube is presented. Structure, operating principle, and performance of the tube are introduced in detail. Features and preparation of a new mesh-supported target are described. An experiment system, in which combination of selectable switching on and integrating capability of the new gateable SEC tube is used for fluorescence image detection, is given.
Novel x-ray image intensifier with catadioptric electron optics
A. G. du Toit
A novel experimental x-ray image intensifier tube with simple catadioptric electron optics is presented and its imaging properties are analyzed theoretically by the use of a few simplified relations. The introduction of catadioptric electron optics in an x-ray image intensifier makes it possible to use a unique output phosphor structure which alleviates the imaging defects suffered by most conventional state-of-the-art x-ray image intensifiers. Several important advantages of the novel intensifier are exemplified. A brief theoretical analysis of the x-ray conversion factor, signal-to-noise ratio, modulation transfer characteristic and other imaging properties of the new tube is given to indicate the improved performance that can be realized by the new intensifier. Preliminary results obtained from an experimental tube with a diameter of 18 mm are presented to verify the theoretical analysis and predict the performance of tubes with larger diameters. The characteristics of the x-ray images of test objects recorded with the experimental tube coupled with a relay lens to a CCD camera and video frame grabber are displayed and analyzed.
New type of x-ray-wafer image intensifier with CsI-CsI/MCP photocathodes: its design and assessment
Shiming Xiang, Hong Zhao
The article introduces a new type of x-ray wafer image intensifier with a double proximity focusing system, (Phi) 50 CsI-CsI/MCP photocathode, and a series of welding constructions of glass window or ceramic components with metal rings. This kind of x-ray image intensifier has been widely used in the field of medical diagnosis and industrial non-destructive detection by means of sophisticated portable x-ray diagnoscopes, featuring a number of satisfactory performances such as low x-ray dosage, miniature x-ray tube and power supply, high output brightness and good resolution, light weight, small volume, low cost, and easy operation without any condition constrained by working environment and illumination. In the paper, the authors have given a series of formulae to determine characteristic parameters of the device, i.e., the quantum detection efficiencies of both reflection mode (CsI/MCP) and transmission mode (glass window CsI/MCP) photocathode, the brightness conversion factor, and resolution. The relations of the mentioned parameters with the performances of constituent components, which include CsI photocathodes layer thickness, MCP bias angle and gain, phosphor screen conversion efficiency, and double proximity focusing distances, are also briefly analyzed. The analysis thought and methods mentioned in the paper have been successfully used for the optimal design and assessment work of our devices and shows that they have a good coincidence with experimental results.
Design of Photoelectronic Imaging Devices
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Optimization design of image tubes with electrostatic focusing
Zhiquan Zhang, LiWei Zhou, Weiqi Jin, et al.
The present paper applies a constrained variable metric method (CVMM) for the optimization design of image tubes with electrostatic focusing, and a multigrid method (MGM) for the computation of the electrostatic field in designing image tubes, thus to improve the efficiency of field computation and to reduce the time of computation. For the design of diode tubes, triode tubes, zoom tubes, and gated tubes, we have investigated the objective function having a least-square-fit form with weight factors to carry out the optimization computation. The result of optimization has shown that the suggested method for designing image tubes given in the present paper ia a practical and effective one.
Computational aspects of photomultiplier design
Khadija Tahir, John A. Rouse, Xieqing Zhu, et al.
The finite difference method (FDM) is used to compute electrostatic potential distributions in photomultipliers. New Fortran packages, using both successive over-relaxation (SOR) and incomplete Choleski conjugate gradient (ICCG) techniques, have been developed for solving the finite difference equations. The effects of the mesh size on the accuracy of the results and the difference between the two methods are highlighted. The electron trajectories are computed by direct ray tracing with a power series method. The software can handle electron transparent grids as well as dynodes. It has been used to characterize the performance of many photomultiplier tubes. The results agree very well with experimental measurements. In addition, the advantages of using three-dimensional field computation in the design of certain PM tubes are illustrated.
Development of all-electrostatic camera tubes with pattern yoke
Yonggui Guan, Guowei Yang, Yaqiang Dong
The all-electrostatic camera tube with pattern yoke is a new type of vacuum camera device. It has the following advantages: compactness, light weight, low power consumption, and variable scanning rate. The ultracompact camera tubes are able to compete with solid-state imagers. This paper introduces the method of design optimization of its electron optics system and describes the properties of a 2/3 inch, all-electrostatic camera tube designed and fabricated in our laboratory.
New study on permanent-magnet focusing image detectors for space astronomy
GuoQiang Ni, Weiqi Jin, LiWei Zhou, et al.
From the practical requirements of new astronomical photoelectronic imaging detectors, much attention has been paid to the design of new permanent magnet focusing field systems, in which curved input-image and demagnification are allowable. The constrained inverse design of the focusing magnetic field in electrostatic and magnetic imaging systems applying new permanent magnet materials is discussed and investigated using the constrained optimization constrained variable metric (CVM) method.
New electron optic for widescreen Gen. I image intensifiers: practical realizations
Alexander L. Surovegin, Boris Efimovich Dashevsky
The family of widescreen Gen. I image intensifiers with a photocathode active area of 40 mm developed in the RADIAN R&D Centre is reported. There are four types of image intensifiers with different magnification (1:1, 1:0.62, 1:0.46, 1:0.33), monoframe gateable intensifier, streak tube, and a special chronographic intensifier in this family. The exclusive features of all tubes are extremely low in homogeneous distortion, the possibility to combine in different configurations for solving a wide set of scientific and applied tasks. The latest model of chronographic intensifier named SCANCROSS has unique parameters for registration of low intensive, shot light phenomena. This tube is most suitable for employment in laser remote sensing devices. All of those tubes have the possibility to operate either cw, or pulse regimes. Besides, they are relatively cheap.
Performance of the phototube in which the photoelectron train is stretched to extend the timebase
Yuji Kiuchi, Takashi Sakusabe
To observe a waveform of a very fast photoevent, a special phototube is developed. A short photoelectron train produced by the incident light from the photoevent is stretched during its runs through a long drift electrode of the phototube due to the difference of the velocity of each photoelectron which is instantaneously accelerated by a step voltage of the photocathode rapidly raised during the light incidence. In order to discuss the limitation of the stretching operation the performance of the phototube such as spreading of the pulse width, influence of the electron lens, both induction noise and random noise are described. As a consequence the time resolution is estimated to about 10 ps at present.
Photoelectronic Detection
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Real-time photocentroid detection for photon-counting and wavefront-sensing cameras
F. Fidouh, Alain Blazit, Gerard Lelievre
For fast photon counting cameras and their applications, present centroiding electronics are not fast enough to match the pixel rate. We are designing a new architecture for the centroiding process. The basic principle is to select only the useful pixels where photoevents occur in order to compute the photocenters and to discard the others. The selected pixels are sent to a digital signal processor (DSP) for photocenter computations. The maximum photon rate is only limited by the DSP speed.
Solar spectroscopy with a Tektronix scientific CCD
The performance of a TeKtronix scientific grade (Grade 1) CCD TK512CF with the METACHROMERII coating, applied as a detector for a solar spectroscopy, and the detailed description of the system configuration for operating the CCD are presented in this paper. The laboratory evaluation is made to the chip and the system prior to its installation on the solar spectrograph. Both the lab test and solar observation results show that the chip is a prospective powerful detector for modern solar spectroscopy.
Image sensor used in displacement measuring with high resolution
Xianghui Yuan, Guolin Lu, Tingchao Zhao
A kind of specially designed MOS image sensor (IS) with high sensitivity is introduced in the paper. The IS is used to receive moire signals to form a phase-modulated signal. With dynamic phase discriminating and subdivision, a very high resolution and precision can be achieved. This special image sensor is valuable in practical designing of high resolution (<EQ 0.1 micrometers ), high precision, and low cost grating displacement transducer.
Photoelectronic detection of optical surface defects of optical system
Shou-Cheng Cheng, Fu Wang
This paper introduces an auto-photoelectronic instrument for evaluating the surface defects of the optical parts inside an optical instrument. By analyzing the effects of defects on image quality, we can present the possibility of evaluating the surface defects and its damage objectively and quantitatively by measuring stray-light. Detailed discussion is given about the physical procedure for generating and measuring stray-light. On the basis of this theoretical research a new type of auto-photoelectronic instrument used to evaluate the defects on the optical surface inside the optical system is given. In this instrument the technology of photoelectronics and microcomputer is applied, so a test result is given automatically.
Detection of radiation direction of CO2 pulsed laser by the use of a pyroelectric camera
Qianyang Yu, Keyong Wu, Xianfu Ban, et al.
Operation principles of the detection of radiation direction of a CO2 pulsed laser by the use of pyroelectric camera are described. The basic analysis, computation, and field test results are given, some theoretical and technical problems as well as some potential applications are discussed.
Measurement system for scanner angular linearity
Li Wang, Haochen Liang, Wei-Li Qiu
This paper describes a measurement system for scanner linearity of angle vs. time. Because the techniques of pinhole filter, high-speed data acquisition, and CCD elaborate division have been successfully used, the system has a high measurement accuracy (2 micrometers ) and powerful data processing capacity.
Investigation on the correction for the cooling nonuniformity of IR detector arrays
Jianxun Zhou, Dianxiu Wei, Shicai Liu, et al.
In this paper we have deduced the theoretical formulae which describe the correction of detectivity nonuniformity introduced by cooling -- nonuniformity of the detector array, and we point out that the fixed pattern noise arising from the difference of D* may be corrected by amending the magnification of each detector element respectively. However, the color noise relating spectrum distribution of input image and spectrum detectivity nonuniformity of the detector element cannot be corrected by a similar method. According to the varying tendency of D* ((lambda) , T) in different temperature, we have explored the method of the cut-off filter, which makes use of the linear relation between D* ((lambda) , T) and T in certain spectrum range, and the probability of removing color noise arising from cooling nonuniformity. We have also analyzed the characteristic of this method and its limitation of practical applicability.
Two-dimensional photoelectronic intelligent autocollimator
Zhaoxiang Ge, Xiaoping Wu
The importance of 2-D photo-electronic measurement has been discussed. A new method to realize 2-D displacement and angle measurement with only one linear CCD array is given. And a low price, high performance 2-D real-time photo-electronic autocollimator is designed.
Applications of optoelectrical imaging in automatic inspection of mechanical components
Lian Duan, Zhonglian Zhang, Liudi Liu
With the recent development of modern mechanical industry, automatic inspections have been playing more and more important roles. Optoelectric inspection is a major one among them. This article is to discuss a system which can inspect contour sizes of mechanical components in real time by using the method of optoelectric image. This system adopts the methods of optical projection of the `tolerance zone' of components as well as image preprocessing and analysis. According to the different positions of the reflector group, a variety of parameters of a component, such as outer diameter, length, width, height, taper, and thread can be measured. In this article, we first discuss the structure of the system and then analyze its principle and applications in inspecting outer diameter, taper, and thread. In this inspection system, we use image processing and analysis in the process of automatic inspection. We control the complete system and the processing of information with the help of a computer so that the high speed and high precision are obvious. Meanwhile, due to the optoelectric method in getting optical information, the system is of noncontact inspection. And also it can inspect several parameters of a component at the same time since it adopts projection of the tolerance zone of components. For the same reason, the inspection efficiency is high and the system can be made compact.
Measurement of temperature field of combustion flame by CT and the middle-IR spectral-region optical-fiber-sensor technique
Jiaming He, Zaixuan Zhang, GuoGuang Yang
After discussing the principle of CT technique, the paper develops a thermometry to measure the temperature field of combustion flame, using CT and middle IR spectrum fiber technique. In addition, the temperature distribution of a practical flame temperature field, obtained by the system dependent on the method, demonstrates the feasibility of the method.
Detecting defects and showing their position in a deep hole by means of CCD camera
Muxing Liu, Zhenying Liu, Qian Mi, et al.
The small, put-in, optical testing head described in the paper is available to detect the inner surface defects in a deep hole. It is composed of the following advanced techniques: CCD camera, step motor, grating displacement measurement unit, etc. It can be put in a hole thats diameter is larger than 40 mm and can scan in axial and diametrical directions, recording the image by intermittent CCD camera. The detecting position and image data can be memorized by computer to analyze and process. The resolution of the testing head is better than 0.04 mm.
TV system for detection of latent fingerprints
Ping Li, Xianfu Ban, Shaowu Liu, et al.
A fingerprint is reliable evidence for recognizing criminals in detecting cases. There are many conventional chemical and physical methods in detecting fingerprints. In this paper, a newly developed portable TV system for detecting a latent fingerprint is described. This system is suited for field reconnaissance of cases as well as for laboratory testing. It can display a latent fingerprint, which is hard to identify and even cannot be displayed by conventional methods, and it can detect prints or stamps which are faded, altered, or falsified, etc.
Image Processing
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Methodology base and problems of information technologies
Boris Ya. Sovetov
Information product qualitative forming and effective use is the aim of any information technology. Information technology as a system provides both computer-aided problem solving for the user and automation of information processes, which in turn support the problem solving process. That's why the information technology methods are the methods for data transmission, processing, and storage. The tools of methodology, mathematics, algorithms, hardware, software, and information are the tools of information technology. We propose to differ between global, basic, and applied information technologies depending on information product significance and characteristics of models, methods, and tools used. The global technology is aimed to use information resources in the social sphere as a whole. The basic technology is oriented on the application sphere (industry, scientific research, design, training). Transition towards new information technology should have in its concern business area model merged with the formal model of problem solving: computing organization based on the data concept; user's intellectual interface development.
Statistical problems of color-image-recognition theory
Robert E. Bykov
Methods of analysis and calculation of chromater thresholds for a multizone image processor have been discussed. Functions of radius-vector sensitivity to variations in color separated signals within color space have been established. The results obtained allow us to describe the procedure of forming windows with minimum dimensions preassigned by probabilities of correct identification of image elements by their chromaticities. Calculation procedures are exemplified and the structural schemes of components which have been used in synthesis of color image recognition systems are demonstrated.
Wavefront sensing and deconvolution of turbulence-degraded photon-counting images
J. Sebag, Gerard Lelievre
We present the focal instrumentation set up on the 2-m telescope at Pic du Midi, France developed to achieve third order aberration corrections on turbulence-degraded images using a photon-counting detector, a wavefront sensor, and a deconvolution method. This instrument is called DIVAS for visible image deconvolution using wavefront analysis. Our goal is to determine the necessary compromises to adopt in order to obtain high resolution images of low luminosity objects recorded in a photon-counting mode. In addition to the recording of short- exposure images at the telescope focus, a wavefront sensor measures simultaneously the incoming distorted wavefronts. In post-processing, the optical transfer function is calculated from the phase retrieval. The object is then reconstructed through a deconvolution process of the short-exposure images with the corresponding point spread functions.
Recent advances in guided-wave correlators for real-time optical processing
Mario Nicola Armenise, Vittorio M. N. Passaro, Anna Maria Matteo, et al.
In this paper a review of recent advances in the field of guided-wave correlators for real-time optical processing is presented. These advances refer to some configurations which are extremely attractive for reducing hardware complexity problems and power consumption in on-board applications, involving airborne or satellite platforms and focused on remote sensing and synthetic aperture radar (SAR) systems.
Design of computer-generated holographic optical elements for detection and imaging
Ming-Wen Chang
A computer generated holographic optical element (CGHOE) has wider use than a holographic optical element (HOE). The latter which is generated with recording beams of different vergences is less controllable than the former which is generated by a computer as a binary computer hologram with amplitude and phase recorded. There are two main problems in making the latter. One is to make it of high spatial frequency and the other is to design a special phase transfer function for special use. The first problem can be overcome by using e- beam for plotting. The second problem can be solved by optimizing the phase transfer function and minimizing the mean-squared wavefront deviation of the output wavefront. Ways and techniques to do them are analyzed. These lead to the improved performance of the elements. Ray tracing can be used to analyze the image properties of the system. Two design examples for detection and imaging are given. One is the designing of a variable spacing grating to have linear effect for measuring of displacement and thickness. The other is the designing of a lens to have extended field of view for copy machine, facsimile machine, or scanner.
Multiprocessor data acquisition system for a 256x256-pixel infrared camera
Luis Fernando Rodriguez-Ramos, A. Rodriguez-Mora, Nicolas A. Sosa, et al.
The Department of Detectors of the Instituto de Astrofisica de Canarias, Spain is developing a data acquisition system (DAS) for an infrared camera based in a 256 X 256 InSb detector. The camera is going to work from 1 to 5 microns wavelength, with a scale on the sky of 0.5 arcsec per pixel, and will be installed as a common user instrument at the Carlos Sanchez Telescope in the Observatorio del Teide (Canary Island, Spain). A multiprocessor architecture has been chosen for the DAS, due to the very tight requirements on real time processing, and high speed storage capability (20 images per second readout rate, 2 images per second storage rate). The complete system is split into two main parts, the front end electronics and the user workstation. They are interconnected through an ETHERNET link.
Image processing in the compound eye of insects
Shizhe Shang
In this paper, a new type of multiaperture optical system, optical compound eye lens (OCEL), is described. There are short focus, large field of view, and mosaic structure of optical lens and detectors in this new type of optical system. The application of multiaperture optical systems for pattern recognition, locating the position of the target and measurement of the direction and velocity is discussed. Multiaperture optical systems inherently perform some degree of optical preprocessing which reduces the amount of information offered to the system to a manageable level and so simplifies pattern recognition. It is pointed out in this paper that the resolving power is equal to the angle between two neighbor lenslets. The clear aperture of OCEL is defined and the concept of overlapping image is advanced.
Adjacent-event detection in intensified CCDs using a Hopfield neural network
Tony Prud'homme
Classical peak detection methods, used for event detection in intensified CCDs, do not permit the location of events in two adjacent pixels of a single frame, dramatically reducing the spatial resolution of the observations. To overcome this limitation, in the context of real time processing, a Hopfield neural network for event detection is proposed. A n2 neuron network is designed so that each neuron is associated with a corresponding pixel of a n X n window scanning the CCD frames. The n2 pixel values of the window are inputs to the network which evolves dynamically according to the propagation rules of the Hopfield model. At convergence, the activation state of each neuron is a binary value, 0 or 1, operating as an event flag for the associated pixel. The network parameters are determined by formulating the event detection problem as a signal decision problem, assuming a model of shape for the photon splashes in the detector. Digital implementation of the network has been studied and simulation results are presented.
Visualization of real-time color-debugging pseudocolor-encoded phase variation with a photoelectronic processing technique
Tiequan Cai, Hui Wang, Yixing Tang, et al.
A photoelectronic processing technique for visualization of real-time color debugging pseudocolor encoded phase variation has been proposed. It is based on the spatial filtering operation, the polarized modulation of linear polarization read out light passing through liquid crystal light valve (LCLV), real-time processing ability of the liquid crystal light valve, and manifold color debugging measures. The principle of this technique is discussed by using a simplified hybrid field effect mode of the liquid crystal light valve. Some color photographs of typical pseudocolor encoding phase variations using this technique are also presented.
Imaging with phase diversity: simulations with a neural network
Nancy A. Miller, Alice V. Ling
The technique of phase diversity was proposed for estimating telescope aberrations for an unknown extended object. The original version of phase diversity requires extensive processing due to a nonlinear optimization algorithm which is prohibitive in a real-time system. Therefore, neural networks were explored as an alternative solution of the problem and this paper shows the modification of the traditional phase diversity method to employ neural networks to estimate aberrations of point source and extended scene data. Simulations indicated aberrations could be estimated to an average error of 0.02 waves rms.
Computer simulation studies of atmospheric turbulence
Hongzhi Zhao, Dazun Zhao
Two methods are described in this paper: the first one, which is based on the strict constraints of the structure function of atmospheric turbulence, is used to generate random wavefronts; the other method is used to measure the atmosphere correlation length from the long-exposure degraded image. Simulation results verify the effectiveness of the two methods.
Wiener filter restoration of high-energy flash x-ray radiograph
Tianfu Wang, Weishen Dong, Guangzhi Yang
Wiener filter restoration is a good method in the linear space, but it requests the signal to noise ratio be over a certain threshold. In the flash x-ray radiographs the signal to noise ratio is often low. In this paper, we hope to study how to apply the Wiener filter restoration method in the low signal to noise ratio case, and then discuss how to choose the parameter k.
Real-time low-light-level image-processing system
Zebin Wei, Huien Zhang, Min Zhou, et al.
A real time low light level image processing and tracking system has been developed in our photoelectronic system laboratory. The system contains five basic parts: a low light level (LLL) CCD camera, several special real time image processing hardware function blocks, processed image output lookup table transfer, target tracking function block, and a controlling CPU. The image (512 X 512 X 8 bits) can be processed and tracked at video rates (25 frames per second).
Related Technology and Applications
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Another definition of resolution for the electron microscope
Jon H. Orloff
Resolution of an electron microscope is often estimated by adding the aberrations of the optical system in quadrature with the diffraction disk and the source size. It is known that this is not particularly accurate and that it is not really theoretically justified. In the case of large aberrations, such as when the beam limiting aperture angle is large, there is the possibility of ambiguity in the estimate of system performance because the optical transfer function may have significant structure. It was shown by Fellgett and Linfoot together, and by Linfoot alone, that it is possible to define the information transmitting capacity of an optical system in terms of the optical transfer function. If one makes use of their result then the resolution of an optical system can be defined by comparing it with the resolution of a diffraction limited system having the same information transmitting capacity. The method gives results that agree well with measurements made on a high resolution scanning electron microscope. In addition, it emphasizes the importance of the current density distribution for understanding the performance on an electron (or ion) optical instrument.
Optically addressed liquid-crystal phase-only modulating spatial light modulator
Narihiro Yoshida, Naohisa Mukohzaka, Haruyoshi Toyoda, et al.
An optically addressed liquid crystal phase only spatial light modulator has been developed. The transfer characteristics and the diffraction efficiency of the device are discussed theoretically and experimentally.
Application of CCD in biorheology: novel microrheometer
Qilian Yu, Shirong Liu
The rheological behavior of human somatic liquids is important in biological and medical studies. Today the rheological measurement of biofluids trends toward minimization of fluid samples. This paper deals with a microrheometer able to test a small sample less than 1 ml. The instrument, as a next generation of the oscillating magnetic microrheometer, features incorporation of CCD photoelectronic detection, white noise, and digital signal processing techniques. Using the instrument a high-resolution measurement and a real time analysis of signals may be achieved. The results measured by the instrument are very accurate.
Analysis of the influence factors of infrared response of fiber optical plate
Jingjiao Yie, Ji Wang, Liangmin Ling, et al.
Fiber optic plate (FOP) has the characteristics of high light-collection ability and clear image transmitting ability. It can transmit image from one end to the other. In the image intensifier, FOP is usually used as the window material, as well as the base of the photocathode. So the sensitivity of polyalkaline photocathode relates not only to the making technology of the photocathode but also to the materials of the FOP and its transmission.
Analysis of accuracy for locating target with an ATR system
Ding-Zi Zhang
This paper presents theoretical analysis and quantitative estimation for the accuracy of location with a scanning IR sensor. Factors that introduce errors into the system are discussed and compared. Suggestions about improving the accuracy are given.
Color-image large-screen display with single liquid-crystal light valve
Hui Wang, Tiequan Cai, Xiaogang Yao, et al.
The information of a color image is coded in the brightness of the black and white TV CRT. By writing this brightness into an LCLV, we can readout a color image the same as the original color image from the LCLV if this coding is proper. In this paper, we discuss the principle of this technique and demonstrate the large screen color image display using only single LCLV experimentally.
Design of an IRI track system
Lan Tao
This paper presents the algorithm of an IR image track system, its hardware and software design. TMS32020 (or C25), as the main tools of image processing, makes the IRI track experiment system closed-loop. Track algorithm and processing speed are tested in the dynamic tracking situation. The experiment results show that the system can track the target in real-time, the period from collecting data to the output of the track control signal is less than 8.5 ms, and with a good ability to resist noise and disturbance.
Graduation value judgment of mercurial thermometer by CCD imaging technique
Jiaming He, Zaixuan Zhang, GuoGuang Yang
For the manufacturer and metrological department, the accurate judgement of a mercurial thermometer is very important. Because of the eye's limited resolving ability, the judgement value obtained by man's eye can only reach the accuracy of about 0.1 mm graduation linewidth. Moreover, in the measurement of a mercurial thermometer's graduation value, the operator must estimate, compare, and revise each graduation value. The heavy and complicated job, and the operator's disturbance factor of fatigue and absentmindedness lead to erroneous readings. In order to increase the efficiency of measurement, this paper puts forward a method to solve the graduation value judgment of the mercurial thermometer in which the CCD imaging technique is used. This method is also advantageous to the achievement of automatic measurement of a mercurial thermometer's graduation value.
Photon-counting shearing interferometer
Guomao Tang, Mingquan Li, Jiaxi Huang, et al.
We have designed and built a photon-counting shearing interferometer which is capable of performing the wavefront gradient measurement of photon levels in real-time. This paper describes its principle and configuration, and analyzes its capability of wavefront sensing. The shearing interferometer has been used in the adaptive optics image compensation system for astronomical observation and successfully tested on the 1.2 m telescope of Yunnan Observatory in China from 1990 to 1992.
Research on amorphous-silicon liquid-crystal light valve and its performance
Yuhan Hai, Xingshi Li, Baocui Zang, et al.
Using the amorphous silicon (a-Si:H) film, which is cheap and has a small lag, as the photoconductive layer of the liquid crystal light valve (LCLV) is an ideal selection. With the method of impedance matching, we have designed and fabricated an a-Si:H LCLV and have obtained a clear image on a large screen projection system. The resolution of the valve was 20 lp/mm. The sensitometry measurement showed that the projection light level varies linearly with the writing light level when the latter is below 100 (mu) W/cm2. The measurement of the transient response at the writing light level of 100 (mu) W/cm2 indicated that the rise time and the decay time were 60 ms and 80 ms, respectively.
Single-mode fiber optic in electronic speckle pattern interferometry
Wei Liu, Yushan Tan, Xianglin Wang, et al.
A new technique has been developed for applying fiber optics to electronic speckle pattern interferometry (ESPI) to measure unbonded faults in the carbon/epoxy honeycomb composite. The fiberized ESPI system we designed is introduced in detail. This paper also develops the theoretical and experimental approach of singlemode fiber optics phase-step ESPI. This approach produces a significant improvement in fringe contrast and in reducing image processing computational effort. We adapted the singlemode fiber piezoelectric transducer as modulator and the two-step phase shifting method.
New method of designing CCD driver
Wei Yu, Daoyin Yu, Yimo Zhang
A new method of designing CCD driver circuits is introduced in this paper. Some kinds of programmable logic device (PLD) chips including generic array logic (GAL) and EPROM are used to drive a CCD sensor. The driver runs stably and reliably. It is widely applied in many fields with its good interchangeability, small size, and low cost.
New technology and measurement of L2MCP
Lichen Fu, Jingquan Tian, Baifu Zhang, et al.
This paper describes the characteristics of long life microchannel plate (L2MCP), analyzes the reason why the lifetime of common MCP becomes short, gives the principle and technique of the new method which can lengthen the operating lifetime of MCP, and introduces an electron scrubbing experiment, UV-photoelectric testing method, and the results. Finally, the advantage and the application prospect of the technology are pointed out.
Technique of real-time measuring of high temperature and its distribution
Dong Wang, Shenjun Zhao, Zhonglian Zhang
The high temperature and its distribution are measured by using a CCD camera as a detector based on two-color thermometer technique and image processing technique. The rotary frequency of the filters located on a motor is synchronized with the vertical frequency of the camera. The camera receives the energy emitted from the object at wavelength (lambda) 1 and (lambda) 2. Through an A/D converter, the video signal is digitalized into 8 bit. After processing by operational circuit and a pseudo color processing unit, the digital signals are converted into three channels standard video signals. By inputing those signals into a color monitor, the temperature distribution can be displayed.
Electron scrubbing of microchannel plates
Xuhui Zhou, Shicai Liu, D. Chen, et al.
In this paper the electron scrubbing and life tests for microchannel plates used in second generation image intensifiers are studied. It presents the test apparatus developed specially for such tests and inquires into the proper schemes for the scrubbing process. Test results are analyzed and relevant conclusions drawn.
Microcomputer system of detecting and recognizing inner walls of pipes
Baoxing Bai, Xilong Wang
This paper describes the architecture design and executive points of hardwares and softwares for a detecting and recognizing system. In the system IBM-PC/AT-286 is used for the main controller, and the advanced techniques and functions of CCD, AD-7821, and AD-585 are effectively applied to the devices. It is primarily used for automatically detecting the inner walls of pipes, and performing a number of fundamental functions which include digital conversions of the input information, image processing and recognition, classification, and output display.
Photoelectronic Imaging: Systems and Assessments
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Photoelectronic techniques for subnanosecond evaluation of laser-material interactions and dynamic material properties
Photoelectronic techniques provide the highest temporal resolution for dynamic material interaction studies. Optical signals from a velocity interferometer (VISAR) are coupled by fiber optics to the slit plane of an electronic streak camera. Temporal resolution of < 100 ps has been realized. Laser-launched miniature flat plates as thin as 1 micrometers have been launched to 4 km/s resulting in an impact pulse duration of approximately 0.3 ns at > 30 GPa. Miniature plates are being used to study grain and sub-grain size effects of metals and ceramics. The small size of the experiment permits evaluation of: (1) spall strength at strain rates > 107, (2) local grain size effects, (3) grain boundaries, (4) shock and release all within one grain thickness, (5) small samples of valuable or toxic materials, (6) bond strengths between similar or different materials, (7) Hugoniot elastic limits, and (8) separation of elastic-plastic shock velocities. Dynamic properties of metals at grain and sub-grain size affects are just now being investigated experimentally. This presentation discuses the status of work in progress and the application of photoelectronic techniques for data collection and analysis.
Design of Photoelectronic Imaging Devices
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Intersection-point calculations for electron-optical devices
Jerzy M. Woznicki, Jacek Grzegorz Puchalski
A method for computing the intersection point of a ray in a potential field for electron-optical devices is presented. This method is applied for three or four component ray trace schemes which are based on the electron-optical analogy. The method requires only three adjacent integration points of ray trajectory where the last point is located behind the given surface. In this way the best possible accuracy for numerical ray-trace schemes of the fourth order can be obtained.