Thermal stability technology of signal processing circuit infrared sight is studied under temperature shock. Model parameters and geometry is configured for FPGA devices (EP1C20F400C8), solder material and PCB. Signal circuit boards of full array BGA distribution are simulated and analyzed by thermal shock and waveform through engineering finite element analysis software. Because solders of the whole model have strong stress along Y direction, initial stress constraints along Y direction are primarily considered when the partial model of single solder is imposed by thermal load. When absolute thermal loads stresses of diagonal nodes with maximum strains are separated from the whole model, interpolation is processed according to thermal loads circulation. Plastic strains and thermal stresses of nodes in both sides of partial model are obtained. The analysis results indicate that with thermal load circulation, maximum forces of each circulation along Y direction are increasingly enlarged and with the accumulation of plastic strains of danger point, the composition will become invalid in the end.
Negative electron affinity (NEA) GaN photocathode has many virtues, such as high quantum efficiency, low dark current, concentrated electrons energy distribution and angle distribution, adjustive threshold and so on. The quantum efficiency is an important parameter for the preparation and evaluation of NEA GaN photocathode. The varied doping GaN photocathode has the directional inside electric field within the material, so the higher quantum efficiency can be obtained. The varied doping NEA GaN photocathode has better photoemission performance. According to the photoemission theory of NEA GaN photocathode, the quantum efficiency formulas for uniform doping and varied doping NEA GaN photocathodes were given. In the certain condition, the quantum efficiency formula for varied doping GaN photocathode consists with the uniform doping. The activation experiment was finished for varied doping GaN photocathode. The cleaning method and technics for varied doping GaN photocathode were given in detail. To get an atom clean surface, the heat cleaning must be done after the chemical cleaning. Using the activation and evaluation system for NEA photocathode, the varied doping GaN photocathode was activated with Cs and O, and the photocurrent curve for varied doping GaN photocathode was gotten.
High and low temperature activation experiments were carried out for a transmission-mode GaAs photocathode sample, and the activation photocurrent curves were recorded. The variety of the activation photocurrent curves between high and low temperatures was studied. By using fitting calculation, the surface potential barrier parameters of NEA photocathode after high and low temperature activations were obtained, respectively, and the change of the surface potential barriers between high and low -temperature activations is indicated. Besides, The NEA cathode surface after high-temperature activation and low temperature activation were analyzed respectively by using angle-dependent X-ray photoelectron spectroscopy (XPS). Above investigation results indicate that, with contrast to high-temperature activation, the thickness of surface potential barriers after low-temperature activation become thin and the vacuum level is reduced further. As a result, the cathode spectral sensitivity is improved remarkably.
The development of infrared optical materials is always closely related to the research and exploration of material science. The infrared optical domes bears shock and produces stress when the infrared optical domes mounted on the missile moving at a high speed is shocked by high temperature. According to aerodynamics theory and thermo shock theory, the surge current will be transferred to optical parts through holding up layer and warms the surface of optical parts when infrared optical parts are shocked by high temperature. A compress stress is formed on the hot external surface of optical parts forms and a tension stress is formed on the internal surface or optical parts under the circumstance of the edge of optical parts being fixed. The windows of optical parts become curvature radius of lens with the function of pressure difference which can cause aberration change. The brittle fracture of material will be caused if peak stress is beyond the strength which is permitted for infrared materials. Therefore, limits to design of windows thickness is proposed in this paper.
For varied doping GaN photocathode, from bulk to surface the doping concentrations are distributed from high to low. The varied doping GaN photocathode may produce directional inside electric field within the material, so the higher quantum efficiency can be obtained. The photoemission surface of varied doping GaN photocathode is very important to the high quantum efficiency, but the forming process of the surface state after Cs activation or Cs/O activation has been not known completely. Encircling the photoemission mechanism of varied GaN photocathode, considering the experiment phenomena during the activation and the successful activation results, the varied GaN photocathode surface model [GaN(Mg):Cs]:O-Cs after activation with cesium and oxygen was given. According to GaN photocathode activation process and the change of electronic affinity, the comparatively ideal NEA property can be achieved by Cs or Cs/O activation, and higher quantum efficiency can be obtained. The results show: The effective NEA characteristic of GaN can be gotten only by Cs. [GaN(Mg):Cs] dipoles form the first dipole layer, the positive end is toward the vacuum side. In the activation processing with Cs/O, the second dipole layer is formed by O-Cs dipoles, A O-Cs dipole includes one oxygen atom and two Cs atoms, and the positive end is also toward the vacuum side,thus the escape of electrons can be promoted.
The development of infrared optical materials is always closely related to the research and exploration of material science. The infrared optical domes bears shock and produces stress when the infrared optical domes mounted on the missile moving at a high speed is shocked by high temperature. According to principle of energy balance in fracture mechanics proposed by D.P.H. Hasselman, the author analyzed the crack extension and derived the relationship between Infrared optical materials window model and thermal shock quality factor. Meanwhile, strong or weak of thermal shock for different samples whether they are thin or thick are compared through the operation of queuing algorithm. The conclusion is the internal surface of the domes isn’t heated when the window model is the thermal shock quality factor of thick sample and the heating time is between heating time constant and diffusion time constant. On the other hand, the internal surface of the domes is being heated when the window model is the thermal shock quality factor of thin sample and the heating time is between the two time constants. The most optical domes parts in practice is belong the thin model. For the thin model, reducing the thickness of optical parts can improve their thermal shock ability but mechanical impact stress factor should be considered comprehensively to design optical parts.
Thermal noise and steady performance of infrared sight has always been the concern of military production under
temperature test conditions. According to military optical instrument environmental test standard of GJB1788-93 and
MIL-STD-810F in infrared detector test method, the test procedure and test method of 320×240 α-Si micro-bolometer
array of UL01011-type were given in detail. By using thermal noise theory and mathematical model analysis method, the
noise models of Johnson noise, 1/ f noise, noise caused by electrothermal effect in temperature shock test condition, preamplifier noise and other noise models of micro-bolometer array were established and analyzed. Noise models
under temperature environment were analyzed. The results are as follows: the basic noise of micro-bolometer array is the
temperature fluctuating noise (thermal noise) which consists of background radiation fluctuation noise and thermal
conductivity noise. In addition, there is Johnson noise, 1/ f noise, noise caused by electrothermal effect and
preamplifier noise etc. Among them thermal noise, Johnson noise and 1/ f noise is the main noise source which
determines the limited performances of micro-bolometer array.
Testing device TST-05B, which is suitable for adaptability test of semiconductor devices, electronic products and other
military equipment under the condition of the surrounding air temperature rapidly changing, is used here for temperature
shock test.Thermal stability technology of thermoelectric cooler control circuit infrared sight under temperature shock is
studied in this paper. Model parameters and geometry is configured for ADI devices (ADN8830), welding material and
PCB which are used in system. Thermoelectric cooler control circuit packaged by CSP32 distribution are simulated and
analyzed by thermal shock and waveform through engineering finite element analysis software ANSYYS. Because
solders of the whole model have much stronger stress along X direction than that of other directions, initial stress
constraints along X direction are primarily considered when the partial model of single solder is imposed by thermal load.
When absolute thermal loads stresses of diagonal nodes with maximum strains are separated from the whole model,
interpolation is processed according to thermal loads circulation. Plastic strains and thermal stresses of nodes in both
sides of partial model are obtained. The analysis results indicates that with thermal load circulation, maximum forces of
each circulation along X direction are increasingly enlarged and with the accumulation of plastic strains of danger point,
at the same time structural deformation and the location of maximum equivalent plastic strain in the solder joints at the
first and eighth, the composition will become invalid in the end.
Low-level-light ( LLL ) aiming sight-glass measurement technologies based on multiple circumstances testing
conditions are always concerned by military equipments manufacturers. The article puts forward the concrete steps and
method of shock circumstances testing measurement according to military optical equipments circumstances testing
standard. Using shock theory and mathematical modeling analysis, shock model of LLL aiming sight-glass based on
shock testing conditions is constructed and analyzed. Without considering resistances and under instantaneous half-sine
shock pulse, the ratio of system response amplitude and half-sine pulse peak value is related to system inherent
characteristic (inherent frequency, cycle T, etc.) and shock pulse duration D. The results indicate that given D/T⪆
10.5, / 1 max / A = , half-sine shock pulse is transmitted by 1:1. Testing device response acceleration is equal to shock
pulse peak acceleration. Testing device response is more intense under this condition. LLL aiming sight-glass structural
performance and reticle zero point moving are influenced. Optical lens offset of LLL aiming sight-glass testing parts is
impacted. Optical path parameters change and light transmission is influenced. What is more serious is that objective
lens will be broken due to shock pulse transmission.
Low-level-light (LLL) sight-glass measurement technologies based on multiple environmental testing conditions are
always concerned by military equipments manufacturers. The article puts forward the concrete steps and method of
vibration environmental testing measurement according to military optical equipments environments testing standards.
Using vibration theory and mathematical modeling analysis, vibration modal of LLL aiming sight-glass based on
vibration testing conditions is constructed and analyzed. In order to study dynamic characteristic of vibration system,
coordinates of the physical model are converted to modal coordinates. By means of equating system modal, vibration
modal is impacted by damping coefficient. Emulating the system under the damping coefficientξ from 0.1 to 1 and
natural frequency n
ωn is 89, the results indicate that damped systems is influenced by coordinates conversion of transfer
function. The structure with less damping usually can be regarded as the proportional damping system otherwise can be
considered as the general damping system.
In order to solve the problem of zero displacement momentum of Low-level-light (LLL) sight device, it requitres to
provide regulating structure of LLL sight device reticle. Through force analysis of the adjusting screw thread mechanism
of reticle under load conditions in shoot test, especially through the calculation of the accumulating value of the
circumference torque Tz when the equivalent frictional angle ρ changes, it reveals the zero displacement momentum
mechanism of the LLL sight device under the load functions in the shoot test. Applying CMETS005 computer-controlled
mulit-environment test of LLL sight device detection systems of this study for practical test, error precision is less than
0.05 mil and the measuring range is greater than 40 mil, which presents that the testing data are reliable and provide
theoretical analysis basis for the production of other direct vision sight devices.
Brightness transformation of low-level-light images, which only depends on the characteristics of every pixel, can change the brightness of pixels. In this paper we firstly analyze the low-level-light images, proposing two ways to transform the brightness of pixels: brightness correction and gray-scale transformation. And during the brightness correction is changing the brightness of pixels, it is necessary to consider something such as the brightness it used to have and its position in the image. While gray-scale transformation doesn't need to consider its position in the image during it's modifying the brightness of pixels.
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.
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.
Taking GaAs and GaN as representation, negative electron affinity (NEA) photocathode has many virtues,
such as high quantum efficiency, low dark current, concentrated electrons energy distribution and angle distribution,
adjustive long-wave threshold, great potential to extend the long-wave spectral response waveband. Therefore it plays
more and more important effect in high performance image intensifiers and polarized electron sources. GaN NEA
photocathode and GaAs NEA photocathode are very similar because they all belong to III-V compound. But, GaN
photocathode and GaAs photocathode have many difference in such aspects as preparation process, activation manners,
stability and application field etc. In this paper, using the multi-information measurement and evaluation system of
photocathode, the preparation processes of native reflection-mode GaN photocathode and GaAs photocathode are
studied. The different activation manners of GaN photocathode and GaAs photocathode are compared and analyzed. The
spectral response and stability of the two kind of photocathode are compared also. The experiments indicate: the
atomically clean degree of NEA photocathode surface and the structure of activation layer are the main factors that
influence photocathode sensitivity and stability after activation. GaN photocathode and GaAs photocathode have good
NEA property and large quantum yield. Compare with GaAs photocathode, GaN photocathode has high stability, and the
decay of the quantum yield is comparatively slow.
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
image intensifier.
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
image restoration.
A new algorithm which is suitable for FPGA to the real-time infrared image enhancement is proposed in this paper. In
order to reduce Infrared image noise, we use the accumulation of the combining sequential neighbor frames, and use the
nonlinear expanding of gray histogram to enhance contrast ratio. This kind of algorithm has considered infrared image
characteristic and vision characteristic of the human eye synthetically, and guarantee real-time character of image
process, at the same time, also give consideration to the advantage of the FPGA design. This method can be realized
easily on hardware without damaged enhancement result. Finally, quality of enhanced image is evaluated through a
model. It has verified the enhancement result of this kind of algorithm, and offered reliable assurance for further
treatment of the infrared image. Use in the image system of the infrared video, the effect of image Enhancement is
obvious.
Iterative infrared image restoration is concerned with the improvement of infrared imagery acquired in the presence of
varying degradations. The degradations can arise from a variety of factors: common examples include undersampling of
the infrared 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 iterative infrared image restoration problem is discussed, too. We show the origin and restoration infrared
images which are used in the application of iterative infrared image restoration. By assessing subjectively and
objectively to restoration infrared images, we have verified this kind of model and the feasibility of the iterative infrared
image restoration.
Low-level-light (LLL) sight devices measurement technologies based on multiple environments testing conditions
are always concerned by military equipments manufacturers. Because vibration, shooting, shock, drop and high
low-temperature environment, etc. are under loaded function, the machinery, optics structure and electric
performance parameter change to make LLL sight instrument, causing the LLL sight instrument can't be worked
and used normally while taking aim. We have designed the measure and test system of LLL sight instruments
under multiple environmental experimental conditions, provided and made up the operation principle of the
detection system by CCD. Have analyzed the image of LLL sight devices, have brought forward algorithm of
median filter, and have already confirmed its accurate number value. Have combined actual project application, the
measure precision which is less than 0.05 mil. And the measure range which is greater than 40 mil. It can meet the
project requirements.
Low-level-light (LLL) weapon sight measurement technologies based on Low-high temperature environments testing
conditions are always concerned by military equipments manufacturers. Because low-high temperature environment, etc.
are under loaded function, the electric performance parameter change to make LLL weapon sight, causing the LLL
weapon sight can't be worked and used normally while taking aim. Generally believed that many photocathode is n-type
and p-type doping of the inner surface layer comprising more photocathode not light sensitive, but also sensitive to
temperature. To image intensifier is non-working state at the temperature 70°C ±2°C test boxes and thermostats time
one hour, five minutes to image intensifier into -50°C±2°C Test Box temperature one hour, then five minutes again
placed 70°C ±2°C high temperature test box for three cycle question image intensifier restore normal temperature
after the test. The experiments show that, when the temperature rises, the heat semiconductor photocathode current
density, thermal current rise in the temperature range 0 to 70°C, 4°C temperature is increased, almost twice its
current heat. Of course, image intensifier imported the equivalent background illumination will also increase, resulting in
night vision systems observed at the scene image contrast and differential rates were lowered, target detection system
performance last night caused the decline. A study of the reasons is the photo-cathode materials and fabrication of
thermal electron emission standards restricting the ability.
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
estimated motion.
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 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
mathematic model.
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.
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