With the development of infrared imaging technology, especially high resolution imaging instrument for space remote sensing, the requirement of suppressing stray light the optical system is more and more high, thus suppression of stray light of IR detector module as the core device of target detection and imaging is important. The design and processing cold shield is the key of infrared focal plane detector dewar for suppressing stray light, which mainly play a role in suppressing stray light outside of field view and improving background limited detectivity of IR detector. The structure of the cold shield is mainly effect Geometry Composing Function (GCF) of the stray radiation transmission, while Black coatings of cold shield influence bidirectional reflectance distribution function (BRDF) of stray radiation transmission. This paper mainly study suppressing stray light of cold shield with black phosphating process and black nickel plating and point source transmittance (PST) is used as the evaluation index for suppression of stray light, which can be measured accurately. A PST test system in near infrared wave band has been set up for measurement of cold shield’s PST, which coupling infrared light source with light guide tube for greatly improving the uniformity of infrared light source, while the dynamic range of test system decrease slightly. After testing and verification, light source instability is less than 1% , Non uniformity of light source at the exit of the parallel light tube is 7.4%@ 87.5mm×87.5mm.and dynamic range of test system is 0~1.5×10-5, thus the test facility can satisfy PST test of stray light. The PST curve with angle for one stage cold shield with black phosphating process and black nickel plating are measured and consistent with numerical simulation, which first decrease rapidly with increase of the angle, then slowly vary after 35 angle for the structure of one stage cold shield, the results is useful for optimizing design of infrared detector modules for control of stray light.
Inert gas packaging and vacuum packaging are the main packaging method of photodetectors. A multi-stage thermoelectric cooler (TEC) is used to provide low temperature environment for extended wavelength InGaAs focal plane. A gas charging device is established to study nitrogen and krypton gas packaging. The performance of multi-stage TEC under different packaging atmospheres is tested, and the temperature field distribution is simulated by finite element analysis using FLoEFD software. The results show that in inflatable environment the cold side of TEC can achieve low temperature below 220K for the extended wavelength InGaAs detector. Gas conduction heat loss and gas convection heat loss are introduced into the inflatable packaging compared with vacuum packaging, and the relationship between temperature difference and input current under different packaging atmosphere is obtained. The cooling effect of TEC in krypton gas packaging is superior to that in nitrogen packaging, and the temperature of the cold platform can reach 211K and 215K respectively under the same input current of 4.5A. The results of FLOEFD finite element analysis are basically in agreement with the measured results, and the temperature uniformity of the focal plane is good. Because of without using the getter, Inert gas packaging is an economical packaging method for infrared detector.
High-quality InAs1-xSbx films with x=0.06 have been successfully grown on InAs (100) substrates by liquid phase epitaxy. Two methods are used to characterize the electrical properties of InAsSb film. One is to grow InAsSb epilayer on p-type InAs substrate, which, in combination with the n-type epilayer, forms a p-n junction to prevent the parallel conduction from the substrate. The other is that both the conductive InAs substrate and the dislocation layer between InAs and InAsSb are removed completely by chemical mechanical polishing method to get InAsSb film glued onto insulating sapphire substrate. The influence of conductive InAs substrate on the electrical properties of InAsSb film is eliminated effectively.
The self-assembled type-II GaSb quantum dots (QDs) were successfully grown on semi-insulting GaAs (100) substrate by the liquid phase epitaxy (LPE) technique with growth temperature ranging from 520 to 580 oC. The morphology of GaSb QDs including size, shape and density was investigated by atomic force microscopy measurement and scanning electron microscope measurement, respectively. The cap layer with scores of nanometers, which is characterized by Profile-system, is obtained for the photoluminescence measurement and device fabrication.
The noise of photoconductive detector is so weak that the PAR 124A lock-amplifier is main test facility despite of discontinuation by long-gone manufacturer for decades. The paper uses 124A and 7124 lock-in amplifier system to test noise and response signal of several photoconductive detectors while use the SR830 internal oscillator and thermal noise of pure resistance as standard signal and noise source respectively. The results indicate that the data of two test system can fit each other except the background noise. The 124A lock-in amplifier with 116 transformer is 0.2nV/√Hz and 7124 lock-in amplifier with 5184 preamplifier is 0.8 nV/√Hz at 1kHz. The impedance of 116 transformer is small and the impedance of 5184 preamplifier is 5MΩ, so the signal of 116 transformer will decay and the 5184 preamplifier won’t in case of testing the performance of photoconductive detector with larger source resistance. Finally we suggest to use 7124 lock-in amplifier system in case of testing photoconductive detector with larger source resistance and use 124A lock-in amplifier system prior to 7124 lock-in amplifier system in case of testing photoconductive detector with small source resistance.
Space infrared detector is the core component of photoelectric conversion in the infrared system, the indicator of which, such as sensibility and reliability, limits the optimum performance of the detection system. In the reliability research of infrared detector, the operating life of the device is a very important index and also a significant subject in the engineering application. In the accelerated life test of space infrared detector, it was difficult to periodically measure blackbody response signal of infrared detector, due to equipment limitations for a long time. Accordingly, it was also hard to get abundant failure data of devices for statistical analysis. For this problem, we designed a novel multi-station testing system for accelerated life test of space infrared device, in which response signal as well as temperature can be measured in-situ and recorded for further analysis. Based on theoretical calculation and analysis of actual measured data, we studied and designed the mechanical structure of the equipment and the key component of the testing system, such as the displacement platform, illustrated the control algorithm and put up a system design proposal which meet the testing requirements well. This work technically supports the accelerated life test of space infrared device.
The paper mainly investigate the abnormal occurrence of no Photo current response at performance test of
detector after coupling of circuit and chip. At the beginning, we find that detector module is out of the way, while
preamplifier circuit and photosenstive chip operate well separately. Then we carry on various experiments such as
I-V measurement of chip, simulated magnification test of circuit, replace of high resistence chip, at various
background measurement and so on. All these experiments and theoretical calculation demonstrate that the large
background dark current resulting in the circuit's overload is the cause of detector's no Photo current response. By
means of adding optical filter and aperture slot to reduce the background radiation, consequently the reduction of
background dark current, and the detector finally works well without the circuit's overload.
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