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Chen G.,Luoyang Optoelectro Technology Development Center | Sun W.,Luoyang Optoelectro Technology Development Center | Lv Y.,Luoyang Optoelectro Technology Development Center
Infrared Physics and Technology | Year: 2017

An empirical expression for the energy bandgap as a function of alloy composition x and temperature for In1− xAlxSb was reported. The In1− xAlxSb epitaxial layers were grown by molecular beam epitaxy (MBE) on InSb(1 0 0) substrate, utilizing a p+–p+–n–n+ structure. High resolution X-ray diffraction was used to characterize the epitaxial layers. The Al composition of 2.8% was obtained by assuming the Bragg's formula and Vegard's law. Spectral response measurement of the diodes has been employed to investigate the temperature dependence of the band gap of In1− xAlxSb alloys in the range between 77 K and 260 K. The calculated results for energy gap of InAlSb were in good agreement with the available data and our experimental observation. © 2017


Du B.Y.,Luoyang Optoelectro Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Pulse tube refrigerators have demonstrated many advantages with respect to temperature stability, vibration, reliability and lifetime among cryo-coolers for detectors. Double-inlet type pulse tube refrigerators are popular in GM type pulse tube refrigerators. The single double-inlet valve may introduce DC flow in refrigerator, which deteriorates the performance of pulse tube refrigerator. One new type of DC control mode is introduced in this paper. Two parallel-placed needle valves with opposite direction named double-valve configuration, instead of single double-inlet valve, are used in our experiment to reduce the DC flow. With two double-inlet operating, the lowest cold end temperature of 18.1K and a coolant of 1.2W@20K have been obtained. It has proved that this method is useful for controlling DC flow of the pulse tube refrigerators, which is very important to understand the characters of pulse tube refrigerators for detectors. © 2016 SPIE.


Chao M.,Luoyang Optoelectro Technology Development Center | Yang W.,Luoyang Optoelectro Technology Development Center | Jing P.,Luoyang Optoelectro Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Infrared Detector Dewar Cooler Assembly (IDDCA) is the key component of infrared system, and the reliability of IDDCA determines the reliability of the system and affects the application of the system to a great extent. Reliability research is of great significance for the engineering application of IDDCA. In this paper, research progress of reliability model, failure modes, acceleration factors, and reliability tests on the assemblies are introduced. Optimizing process and life cycle cost during the manufacturing, and evaluating reliability relying on database are described. In addition, the main thought of reliability research on the assemblies is briefly analyzed. This provides a reference for the domestic reliability research of the assemblies. © 2016 SPIE.


Zhang X.,Luoyang Optoelectro Technology Development Center | He Y.,Luoyang Optoelectro Technology Development Center | Li J.,Luoyang Optoelectro Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Infrared focal plane array detector has advantages of strong anti-interference ability and high sensitivity. Its size, weight and power dissipation has been noticeably decreased compared to the conventional infrared imaging system. With the development of the detector manufacture technology and the cost reduction, IRFPA detector has been widely used in the military and commercial fields. Due to the restricting of array chip manufacturing process and material defects, the fault phenomenon such as cracking, bad pixel and abnormal output was showed during the test, which restricts the performance of the infrared detector imaging system, and these effects are gradually intensified with the expanding of the focal plane array size and the shrinking of the pixel size. Based on the analysis of the test results for the infrared detector array chip components, the fault phenomenon was classified. The main cause of the chip component failure is chip cracking, bad pixel and abnormal output. The reason of the failure has been analyzed deeply. According to analyze the mechanism of the failure, a series of measures which contain filtrating materials and optimizing the manufacturing process of array chip components were used to improve the performance of the chip components and the test pass rate, which is used to meet the needs of the detector performance. © 2016 SPIE.


Zhang Z.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Luo S.,Luoyang Optoelectro Technology Development Center
Aerospace Science and Technology | Year: 2013

The terminal guidance problem for missiles intercepting maneuvering targets with terminal impact angle constraints is investigated. Regarding the target acceleration as an unknown bounded disturbance, novel guidance laws based on integral sliding mode control (ISMC) method technique are developed. The first one is a linear integral sliding mode (ISM) guidance law, which can guarantee the line-of-sight (LOS) angular rate and the LOS angle asymptotical convergence with infinite time. To further improve the convergence characteristics of guidance system, a nonlinear ISM guidance law is developed, which guarantees the LOS angular rate and LOS angle finite-time convergence characteristics. However, to guarantee the guidance system has a good performance for dealing with target acceleration, the switch gains of both linear and nonlinear ISM guidance laws need to be chosen larger than the bound of the target acceleration. It will lead to chattering problem. To reduce the chattering phenomenon and improve the performance of system, nonlinear disturbance observer (NDOB) is employed to estimate the target acceleration. The estimated acceleration is used to compensate to actual target acceleration. Then, two novel composite guidance laws combining linear and nonlinear ISM guidance laws with feedforward compensation terms based on NDOB are developed. Finally, simulation comparison results are provided to demonstrate the effectiveness of the proposed methods. © 2013 Elsevier Masson SAS. All rights reserved.


Zhang Z.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Luo S.,Luoyang Optoelectro Technology Development Center
Transactions of the Institute of Measurement and Control | Year: 2013

For the terminal phase of tactical missiles intercepting maneuvering targets, the terminal guidance problem is studied. Based on an integral sliding mode (ISM) control method and nonlinear disturbance observer technique, a novel composite guidance law is designed in the case of constrained impact angle and a first-order-lag autopilot. Regarding the target acceleration and the external disturbance of autopilot as unknown bounded disturbance, a nonlinear ISM guidance law is designed. The obtained guidance law guarantees the line-of-sight (LOS) angular rate and LOS angle a finite-time convergence characteristics. Then, to alleviate the chattering problem and guarantee the disturbance rejection performance, the composite guidance law combining the ISM guidance law with feedforward compensation terms based on nonlinear disturbance observers is obtained. Finally, simulation comparison results are provided to demonstrate the effectiveness of the presented methods. © The Author(s) 2013.


Wei P.,Luoyang Optoelectro Technology Development Center | Wei P.,CAS Shanghai Institute of Technical Physics | Li X.,CAS Shanghai Institute of Technical Physics | Li T.,CAS Shanghai Institute of Technical Physics | And 4 more authors.
Infrared Physics and Technology | Year: 2014

The surface passivation of low-temperature-deposited SiNx films has been investigated in PIN type In0.83Ga0.17As photodiodes. In contrast to SiNx films (330 C) fabricated by PECVD (Plasma enhanced chemical vapor deposition), the low-temperature-deposited SiNx films (75 C) fabricated by ICPCVD (Inductively coupled plasma chemical vapor depositon) have a good effect on passivation of In 0.83Ga0.17As photodiodes, which caused reductions of dark current as large as 2-3 orders of magnitude at the same test temperature 200 K. The effects of low-temperature-deposited SiNx passivations with lowrate (∼16 nm/min) model were compared to the ones with highrate (∼100 nm/min) model. SiNx films with lowrate model have a better effect on reducing dark current of the photodiodes. The different SiNx films were studied by SIMS. The results show that the content of oxides in SiN x layer fabricated by PECVD is 2 orders of magnitude more than that in SiNx layer fabricated by ICPCVD which could be the reason that low-temperature-deposited SiNx passivation leads to higher performance. Further, the dark current density of the photodiodes with lowrate-deposited SiNx passivations does not show the dependence on the perimeter-to-area(P/A) of the junction. © 2013 Elsevier B.V. All rights reserved.


Lv H.,Luoyang Optoelectro Technology Development Center
IET Conference Publications | Year: 2013

This paper proposes a novel alternating least squares (ALS) method for joint angle and Doppler frequency estimation in bistatic multiple-input multiple-output (MIMO) radar. Via iteratively estimating the transmitting, receiving and Doppler steering vectors of multiple targets from the received signals, ALS can simultaneously obtain the two-dimensional (2-D) angles and Doppler frequency of the target. Simulation results illustrate the rapid convergence rate and high estimation accuracy of this method.


Zhang L.,Luoyang Optoelectro Technology Development Center | Zhang X.,Luoyang Optoelectro Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

InAs/GaSb superlattice material was grown on GaAs substrates by Molecular-beam epitaxy(MBE). To study the Ohmic contact and electrical property of InAs/GaSb superlattices, the Au//Ti/InAs/GaSb superlattices contact was fabricated using heated electron evaporation methods on the surface of InAs/GaSb superlattices. The Au//Ti/InAs/GaSb superlattices contact character was analyzed by transmission line model. The results show that Au//Ti/InAs/GaSb superlattices contact is the Ohmic contact with good contact resistivity. And it meets requirement of Ohmic contact with the perfect quality. The electrical properties of InAs/GaSb superlattices were tested by Van Der Pauw. That means the leak current decrease as the carriers density reaches to a lower level. At the meantime, the detector obtains a better background noise and energy resolution. © 2012 SPIE.


Guo C.,Northwestern Polytechnical University | Liang X.-G.,Luoyang Optoelectro Technology Development Center
International Journal of Aeronautical and Space Sciences | Year: 2014

This paper proposes a novel guidance law based on the block backstepping sliding mode control and extended state observer (ESO), which also takes into account the autopilot dynamic characteristics of the near space interceptor (NSI), and the impact angle constraint of attacking the maneuvering target. Based on the backstepping control approach, the target maneuvers and the parameter uncertainties of the autopilot are regarded as disturbances of the outer loop and inner loop, respectively. Then, the ESO is constructed to estimate the target acceleration and the inner loop disturbance, and the block backstepping sliding model guidance law is employed, based on the estimated disturbance value. Furthermore, in order to avoid the "explosion of complexity" problem, first-order low-pass filters are also introduced, to obtain differentiations of the virtual control variables. The stability of the closed-loop guidance system is also proven, based on the Lyapunov theory. Finally, simulation results demonstrate that the proposed guidance law can not only overcome the influence of the autopilot dynamic delay and target maneuvers, but also obtain a small miss distance. © The Korean Society for Aeronautical & Space Sciences.

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