To research the attenuation performance of the AlGaN photocathode, three samples with same structures grown by metalorganic chemical vapor deposition (MOCVD) were activated with three different activation methods, which are Cs-only, Cs-O and Cs-O-Cs activation, respectively. The spectral responses and attenuated photocurrents of three AlGaN photocathodes were measured, the result shows that the Cs-O activated AlGaN photocathode have the lowest attenuation speed in the first few hours, the next are Cs-O-Cs and Cs-only activation, respectively. After the Cs-O-Cs activation sample has attenuated 90 min, its attenuation photocurrent curve is coincident with the Cs-O activation sample in the next measurement. The main factor which affects the photocurrent attenuation is Cs atom desorbed from the photocathodes surface.
Based on the study of the current technology of MCP electron rinse and parameters testing, a new electron rinse and testing system with four working stations for large area MCP is developed. In this system, electron rinse for various large area MCP of diameter less than 100mm can be conducted on each station at the same time, and parameters could be tested at one of the stations in the process of the electron rinse at different stages. Four stations in the vacuum system can be converted to each other quickly and accurately by operating the mechanical transmission structure designed. The system's superior performance was shown by a series of tests and data.
High-energy area source electron gun is a key component in image intensifier screen testing instrument. On the basis of
the analysis of relationship between thermal emission characteristics, the shape of filament and the density of thermal
electron emission, high-energy area source electron gun is designed. The distribution of electric field and electronic
tracks are theoretically analyzed and calculated to make it has features of dispersing, uniform, converging and
submerging. By testing a standard screen, correct the structure of high-energy area source electron gun to meet the
requirements of test indexes and obtain reasonable high-energy area source electron gun. Its successful development
provides effective technical support to the luminous screen test for uniformity, brightness, luminescence efficiency and
afterglow and to the examination of other components (such as MCP parameters)of Low-light Image Intensifier.
A system of signal-to-noise ration (SNR)tester for LLL image intensifier is reconstructed . To realize SNR tester for UV
image intensifier,the signal processing module and measurement software of the tester are reconstructed.The system of
UV optical path is used. Based on photoemission mechanism of photocathode, noise factor of photocathode is concerned
with quantum yield. In a range,noise factor of micro-channel plate(MCP) is decreased with the increase in gain. For a
fixed size micro channel,the gain of MCP is increased as the voltage of MCP rises. The analyzed results show that when
the voltage of MCP is in the range of -700V~-850V,the noise factor is monotonically decreased,when it exceed -850V,
MCP is saturated. Although gain has continued to increase, noise factor is in the state of saturation. Experiment platform
is builded according to SNR tester principle diagram of UV image intensifier.The results are given and analyzed. The
conclusion is proved that the effect of voltage of MCP on the SNR of UV image intensifier is compatible with the
analysis of theory.
The core components of Image intensifier is microchannel plate (MCP) and fluorescent screen component. The present paper deeply studies output signal-to-noise ratio (SNR) characteristics of MCP and fluorescent screen component. A tester system using to the evaluation of characteristics of the output SNR of MCP and fluorescent screen component, consists of a vacuum system, a surface electron source, mechanical mechanism components ,a high-voltage power supply system, a signal processing system, communication interfaces, a data acquisition and control system, computer system, and testing software. a hot cathode used as an electron source, generates a surface electron flow to provide the input signal. A photomultiplier tube is used to detection faceplate output brightness of the light spot. Then, the output SNR of MCP and fluorescent screen component is processed with a combination of methods of the hardware filter and digital filtering software. The output SNR of MCP and fluorescent screen component is measured under different conditions, and the results are analyzed. This test system Provide a technical to promote the image intensifier research, and experience to testing other parameters or in other areas of research.
In the field of applied optics, the evaluation of imaging quality in optical systems has been a problem of public attention.
From the 1970s, with the development of the large-capacity high-speed digital computer and improvement of
high-precision optical testing technology, the calculations and measurements of MTF are maturing and began to promote
the practical application. After years of development, The MTF has been an important evaluating indicator of image
quality of an optical system.
A test system of MTF is designed in the paper; theoretical study related to the MTF testing is introduced, such as
specifying the physics concept of MTF, summarizing the testing methods of MTF and analyzing the testing principle. On
the base of introducing the theory which are related, the framework of system has been established. The devices which
are used in the experiment are also introduced. Testing software has been developed. How to manipulate the testing
system is introduced and the factors which affect the result are pointed out. The experiment is carried out to measure the
optical lens sample in the axis, and the result is given.
To test the parameters of image intensifier screen is the precondition for researching and developing the third generation
image intensifier. The picture of brightness uniformity of tested fluorescence screen shows bright in middle and dark at
edge. It is not so direct to evaluate the performance of fluorescence screen. We analyze the energy and density
distribution of the electrons, After correction, the image in computer is very uniform. So the uniformity of fluorescence
screen brightness can be judged directly. It also shows the correction method is reasonable and close to ideal image.
When the uniformity of image intensifier fluorescence screen brightness is corrected, the testing instrument is developed.
In a vacuum environment of better than 1×10-4Pa, area source electron gun emits electrons. Going through the electric
field to be accelerated, the high speed electrons bombard the screen and the screen luminize. By using testing equipment
such as imaging luminance meter, fast storage photometer, optical power meter, current meter and photosensitive
detectors, the screen brightness, the uniformity, light-emitting efficiency and afterglow can be tested respectively.
System performance are explained. Testing method is established; Test results are given.
The micro-channel plate (MCP) is an important part to imaging quality of image intensifier. In order to obtained high
quality of optoelectronic image devices, the microchannel plate (MCP) should be evaluated before assembled in the
devices. A new method for noise power factor determination of MCP is described in this paper. The measurements are in
accordance with theory and experiments reported. The system consists of vacuum chamber, electron gun, high voltage
supply, imaging luminance meter, control units, signal processing circuit, A/D converter, D/A converter, communication
unit, industrial computer and measurement software.
The paper introduces the structure of Cs2Te ultraviolet image intensifier. The manufacturing procedure is introduced
briefly, include the procedure of front group and back group. Its spectral response characteristic is measured with a
specially designed spectral response measuring system, the quantum efficiency is calculated, the diffusing length of the
minor carriers is analyzed. Some other parameters are tested with testing devices. At last some opinions are brought to
improve the technique.
Gallium Nitride (GaN) photocathodes are potentially attractive as UV detective materials and electron sources. Based on
the activation and evaluation system for GaAs photocathode, which consists of ultra-high vacuum (UHV) activation
chamber, multi-information measurement system, X-ray photoelectron spectroscopy (XPS), and ultraviolet ray photoelectron
spectroscopy (UPS), the control and measurement system for the activation of UV photocathodes was
developed. The developed system, which consists of Xenon lamp, monochromator with scanner, signal-processing
module, power control unit of Cs and O source, A/D adapter, digital I/O card, computer and software, can control the
activation of GaN photocathodes and measure on-line the spectral response curves of GaN photocathodes. GaN materials
on sapphire substrate were grown by Metal-Organic Chemical Vapor Deposition (MOCVD) with p-type Mg doping. The
GaN materials were activated by Cs-O. The spectral response and quantum efficiency (QE) were measured and
calculated. The experiment results are discussed.
Image intensifier is a device to observe in night. To evaluate the quality of Image intensifier, there are two important data
which are resolution and SNR. Analyzing the testing principles of resolution and SNR, a test to super second generation
image intensifier is designed. Under the luminance of 1Lx,1×10-3Lx and 1×10-5Lx, test with the same resolution card. It
was found that image quality of Image intensifier has the best quality when in luminance of background 1×10-1Lx to 1×
10-3Lx. When luminance of its background is above 1×10-1Lx the noise will be high, see fig.2. When luminance of its
background is below1×10-3Lx the signal will be weak. It provides a testing foundation for evaluating the quality of an
To obtain high quality optoelectronic image devices, the phosphor screens should be evaluated before assembled in
the devices. The principle and method of measurement are expounded. A measurement system is developed, which
can measure luminous efficiency, luminance, non-uniformity of luminance and persistence of phosphor screen. It
can also detect the flaws of screen. The system consists of vacuum chamber, electron gun, electrostatic lens system,
high voltage supply, imaging luminance meter, luminous flux tester, control units, signal processing circuit, A/D
converter, D/A converter, communication unit, industrial computer and measurement software.
Fluorescence screen of Image intensifier is the key part to imaging quality of micro light and ultraviolet Image
intensifier. To research the performance testing and analysis of Fluorescence screen seems more important in China. The
research will help to understand the performance of Fluorescence screen, know where improvement should be made
and then a best performance entire tube will be achieved. This article will do the theory analysis to part of testing
instrument, area source electron gun's uniformity. Electron gun consists of taper tantalum filament, vacuum environment
and axial symmetry high pressure static field. The uniformity of hot electron emission of filament has been analyzed.
Upon that, this article will specially analyze the uniformity of electron in the effective area after they go through the axial
symmetry high pressure static field and get accelerated.
Microbolometer focal plane array (FPA), as a popular kind of uncooled infrared detector, has a wide range of low cost
thermal imaging applications due to its high sensitivity and simple micro-fabrication process. The performance of
microbolometer imaging system is determined by many factors such as the property of the FPA, the effect of
nonuniformity correction, the condition of operation and so on. In this paper, the micro-structure and heat transfer
mechanism of microbolometer FPA are analysed to find out the substrate temperature characteristic. The response
nonuniformity of the FPA and corresponding two-point correction method are discussed to find out the calibration
temperature characteristic. And the power dissipation property of the thermal-electrical cooler (TEC) integrated under
the FPA is described to find out the ambient temperature characteristic. According to the simulation and experiment
results obtained from a 320×240 amorphous silicon microbolometer imaging system, it is concluded that all these
temperature parameters have a great influence on the system performance and should be well considered for different
working conditions to gain high system performance and imaging quality.
An infrared target tracking system has been introduced in details for unmanned monitor application and its
corresponding method for extracting and tracking moving targets from real-time infrared video has also been described.
To ensure its real-time implementation on the tracking system, mature motion estimation techniques such as the
time-domain statistics method and the DT method are adopted in the tracking method which includes three stages: target
extracting, target classification and target tracking. A two-strategy classification method is adopted to improve
classification accuracy. The tracking process involves correlation matching between a template and the current motion
regions. The motion region with the best correlation is tracked and is used to update the template for subsequent tracking.
The infrared target tracking system is based on a high-speed DSP chip with an internet interface, which may transmit the
doubtful targets information to monitor center in time. To illustrate the effectivity of the infrared target tracking system,
experimental results has been given in the end of this paper.
When testing the uniformity of Image intensifier fluorescence screen brightness, the million scale CCD brightness meter
is used. Due to the distance between the meter and fluorescence screen, the effect of ambient light on the testing result
is essential to the design of testing system. Test with super second generation tube, input a constant voltage to insure the
fluorescence screen brightness to be constant. Collect the brightness of the same fluorescence screen in different ambient
luminance environment of 1×102Lx, 1×101Lx, 1Lx, 1×10-1Lx, 1×10-2Lx, 1×10-3Lx. Study the results with software
MATLAB. It is concluded as: In ambient luminance environment of 1×10-1Lx the CCD has the best result. The
testing result in ambient luminance environment of above 1×103Lx show untrue image. The testing result in ambient
luminance environment of below 1×10-3Lx shows its own noise image and is unbelievable either.
An uncooled thermal imaging system with multiple working temperatures will be presented. Transient response
performance of α-si microbolometer detectors is simulated firstly when the working temperature varies in the range from
-40deg. to +60deg. Simulating results show that α-si microbolometer detectors have coherent response performance in a
large range of working temperature, which lay basis for designing uncooled thermal imaging system with multiple
working temperatures. Different from traditional thermal imaging systems, this thermal imaging system has three
working temperature with an accuracy range of less than ±0.01deg. When working, the temperature control circuit will
switch between the working temperatures according to the variety of the environmental temperature. To evaluate this
thermal imaging system, we measure its power consumption and NETD in the environmental temperature range from
-40deg. to +60deg. The measurement results are that the total power is less than 2500mW and the NETD is less than
120mk. This indicates that the thermal imaging system has nearly the same imaging quality and obviously lower power,
compared with traditional thermal imaging systems.
Multi-frame infrared image restoration is concerned with the improvement of imagery acquired in the presence of varying degradations. The degradations can arise from a variety of factors: common examples include undersampling of the image data, uncontrolled platform or scene motion, system aberrations and instabilities, noise characteristic of the infrared detector. In this paper, the mathematic models of infrared image blur and sampling and noise models are discussed. The multi-frame infrared image restoration problem is discussed, too. We show the origin and restoration
infrared images which are used in the application of multi-frame infrared image restoration. By assessing subjectively
and objectively to restoration images, we have verified this kind of model and the feasibility of the multi-frame infrared
Reasons that thermal imaging systems consume power have been analyzed, and a low-power design scheme of thermal
imaging systems has been presented with multiple working temperature points. Transient response performance of α-si
microbolometer detectors is simulated firstly when the working temperature varies in the range from -40°C to +60°C.
Simulating results show that α-si microbolometer detectors have coherent response performance in a large range of
working temperature, which lay basis for designing uncooled thermal imaging system with multiple working
temperatures. Different from traditional thermal imaging systems, this thermal imaging system has three working
temperature with an accuracy range of less than ±0.01°C. When working, the temperature control circuit will switch
between the working temperatures according to the variety of the environmental temperature. To evaluate this thermal
imaging system, we measure its power consumption and NETD in the environmental temperature range from -40°C to
+60°C. The measurement results are that the total power is less than 2500mW and the NETD is less than 120mk. This
indicates that the thermal imaging system has nearly the same imaging quality and obviously lower power, compared
with traditional thermal imaging systems.
Microbolometer detector is very competent as uncooled infrared detector for a wide range of thermal imaging
applications, since it has been found to be more sensitive and has the advantage of using standard Si micro-fabrication
process compared with pyroelectric or ferroelectric technology. The heart of microbolometer detector is a two
dimensional array of thermal sensitive thin-film layers, which can change their temperatures and resistivities depending
on the radiation absorbed. During the entire thermal imaging process, the microbolometer detector's substrate
temperature, calibration temperature and ambient temperature are the key parameters which determine the thermal-electrical
performance and the ultimate imaging quality of the microbolometer detector. In this work, based on the
analysis of the characteristics of these parameters, the experiment has been conducted with the uncooled infrared thermal
imaging system based on 320×240 amorphous silicon microbolometer detector working at different substrate
temperatures, adopting different calibration temperatures for different ambient temperatures. The corresponding
measurement results of the system's NETD, residual nonuniformity and power consumption, as well as the system's
imaging results are presented, which all have a great agreement of the theory analysis above.
Recent advances of microelectromechanical system (MEMS) technology have opened new opportunities for amorphous
silicon (α-Si) microbolometer focal plane arrays (FPAs) both for military and civil applications. α-Si membrane is
chosen for sensitive material of microbolometer FPAs due to its high temperature coefficient of resistance (TCR), high
resistivity and good mechanical properties. However, α-Si membrane also has the disadvantage of high 1/f noise, strict
preparation conditions and metastable effect. So nowadays, researches are focused on properties of α-Si membrane to
gain high performance of microbolometer FPAs. Since the pulsed bias readout mode of microbolometer FPAs causes a
non-steady-state of α-Si membrane during the operation, the transient thermal-electrical response process of the sensing
pixel is analyzed detailedly in this paper to predict the thermal and electrical performance of α-Si microbolemeter FPAs
such as responsivity, noise equivalent temperature difference (NETD), detectivity and power dissipation. Numerical
simulations are presented to investigate the factor which affects the performance of α-Si microbolometer FPAs. The
imaging experiment results obtained from a 320×240 α-Si microbolemeter FPA are in good agreement with the
theoretical analysis. The way to improve the performance of α-Si microbolemeter FPAs is given in the end of this paper.
Recent advances in MEMS and focal plane array (FPA) technologies have led to the development of manufacturing
microbolometers monolithically on a readout integrated circuit (ROIC). Since the response of microbolometer detectors
depends on the modification of temperature in micromachined bridge structures, it is useful to model and simulate
thermally the corresponding structures in order to predict their performance parameters. In this work, finite element
methods are performed to simulate the transient temperature field of thermistor films of microbolometer detectors. The
varisized supporting legs' impacts on the performance of detectors are discussed and the transient response for three
microbolometer configurations was investigated. At the same time, variation of the operation temperature's impacts on
total noise, noise equivalent to temperature difference (NETD) and detectivity (D*) are also discussed in details. These
performance analyses are helpful for optimum design of microbolometer infrared detectors' structure and rational choice
of operation temperature of infrared focal plane arrays.
This article introduces motion detection and estimation of low-level-light video sequence, and, motion detection, motion
estimation and variational problem. Low-level-light video sequence different form others, the time and space domain
noise in the signal not only limit the lowest illuminance of the system but also make the image show random glitter. In
this paper how to improve the signal-to-noise ratio (SNR) of low light level image is discussed too. The results show that
models and estimation algorithms in low-level-light video sequence can lead to improve reliability and accuracy of the
The three elements of photoelectrical cathode, microchannel plate and fluorescence screen are important parts to imaging
quality of low light and ultraviolet Image intensifier. To do research and analysis work on the Fluorescence screen
parameter testing have practical significance to the understanding of the performance of fluorescence screen and then can
help to know where improvement should be made and then achieve a best performance entire tube, This article mainly
introduce the testing theory of the brightness uniformity of fluorescence screen of Image Intensifier and how to build a
The novel approach to the image noise problem of reticle images based on impact condition in low-level-light weapon
sight is proposed in this paper. The condition and process of the low-level-light weapon sight impact experiment were
analyzed, and then averaging algorithm of reticle images consists of two parts has been applied on the experiment. First
averaging and smoothing using a rotating mask methods were operated on Gaussian noise, to obtain a matching precision
with in 0.05 mil. Second the well known efficient median filtering smoothing method is performed to obtain the higher
matching precision. The potential of this averaging method is shown in the experimental results of reticle images in low-level-light weapon sight based on impact condition.
The edge detector operator of image intensifier is a key problem for fluorescent image processing. This paper is intended
to serve for three purposes: (1). To present the general problem of Fluorescent image in a sufficient depth and extent, (2)
to present a complete algorithm for image processing including image sharpening and gradient operator. (3). to search
for a edge detector optimal for fluorescent image processing of image intensifier. It is expected that a edge detector
operator could provide a generic and robust solution to the reticle fluorescent noise images matching problem, which
could be an important breakthrough in computer vision, photogrammetry, and pattern recognition.
The responding time delay characteristic of the detector of PIN photodiode is caused by the different intensity of the signal received by the detector. The responding time delay usually is less several tens nano-seconds. Aaccording to the principle of the responding time delay, the testing system is designed to measure the responding time delay. The test of responding time delay with different laser powers is carried on, and the result of the responding time delays is given.
The combination photo electronic sighting device usually composed of different optical devices, including telescope and low light level night vision device or infrared thermal imaging system. Every optical axle of the optical device of the combination sighting device is needed to be parallel. When a target away enough from the sighting device is observed, if the images of the target locate on the center of the field of the vision of the different optical devices, it shows that the axis are parallel. According to this principle, a rectifying device for optical axis of sighting device is designed. It includes off-axle paraboloid reflector, the target of cross line, light sources, precision modifying devices and other devices. The target of cross line is put on the focus of the off-axle paraboloid reflector, thus it forms a parallel light beam through the off-axle paraboloid reflector, the sighting device is immerged in the parallel light beam. The observing effect is like a target of long distance. The target is connected with a precision modifying device, by moving modifying device, until the image of the target coincide with the center of the field of vision of every optical device, whose degree of deviation of the optical axle can be calculated. The paper gives the structure of the rectifying device and the way of testing. The parameters of the device is given too.
The paper introduces the principle and structure of the PIN diode detector, and then describes the researching background and the responding characteristic of the detector. The high responsibility of photodiode response characteristic is important. The paper designs a set of testing device to measure the responsibility. The optical part can produce a laser pulse of 1.06μm with a certain frequency and energy, with the aid of white light source and CCD camera, the laser beam can focus on the surface of the photon detector of PIN diode. The signal-testing instruments can measure the responding characteristic of the photon detector, and the average noise power. The paper gives the waveforms of the laser pulse and the responding signals.