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Yang X.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Zhong S.,Huazhong University of Science and Technology
Proceedings - 2015 Chinese Automation Congress, CAC 2015 | Year: 2015

Dynamic target tracking technology has been widely used in airborne fire control systems, airborne warning systems, onboard systems and battlefield surveillance target tracking. The dynamic target tracking technology is used in automatic target detection, identification and positioning to control the movement of the camera. High-sensitivity CCD camera system is widely used in Modern high-speed camera. When the camera is used in the scene that target is too bright and ground is in large variation, the images are easily saturated. The gray of collected images is directly related to the amount of light enter the camera, so the image gray relies on the adjustment of light amount through an optical system. The means of the exposure control focuses on the adjustment of image brightness, and the amount of light through an optical system relies on the integration time to adjust the brightness of the images, in our system, we adjust the integration time to change the image gray. We propose a method for automatically adjusting the gray of image, which takes the image gray as the feedback signal of FID system to adjust the camera's exposure time. So we can get stable and desirable image gray under high image frame rate in restricted time. In different environment with different illumination, this technology is mainly used in adjusting the image gray to an appropriate value. Furthermore, the tracking camera attaches importance not only on the dimming range but also on the dimming speed. Our algorithm can guarantee a quick adjustment and get a stable and desired image gray. © 2015 IEEE.


Tong Q.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Lei Y.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Zhang X.,Huazhong University of Science and Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

As we all know, because the index of refraction of the conventional microlens array (MLA) is not variable, the wavefront sensor based on the conventional MLA can only obtain the intensity image with low-resolution when it is used to measure the wavefront information simultaneously. In this paper, we use the dual-mode photosensitive arrays based on the liquid crystal (LC) MLA and CMOS sensors to obtain both intensity images with high-resolution and wavefronts. The dual-mode photosensitive arrays can work between an imaging mode and a wavefront sensor mode by switching the voltage off and on. In the experiment, we compare the composite wavefront of the object exposured in a white light with the wavefronts of the same object in tricolor laser. Because using the monochromatic light to measure the wavefront of an object may loss some information, it is a better method to use the white light for obtaining the wavefront information of the single object in the black background. We also discussed how to mix the wavefronts of the red green and blue laser to make the mixed wavefront which is closer to the composite wavefront. © 2015 SPIE.


Zhang H.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Zhang H.,Huazhong University of Science and Technology | Muhammmad A.,Huazhong University of Science and Technology | Luo J.,National Key Laboratory of Science and Technology on Multispectral Information Processing | And 11 more authors.
Applied Optics | Year: 2014

An electrically tunable infrared (IR) filter based on the liquid crystal (LC) Fabry - Perot (FP) key structure, which works in the wavelength range from 5.5 to 12 μm, is designed and fabricated successfully. Both planar reflective mirrors with a very high reflectivity of ∼95%, which are shaped by depositing a layer of aluminum (Al) film over one side of a double-sided polished zinc selenide wafer, are coupled into a dual-mirror FP cavity. The LC materials are filled into the FP cavity with a thickness of ∼7.5 μm for constructing the LC - FP filter, which is a typical type of sandwich architecture. The top and bottom mirrors of the FP cavity are further coated by an alignment layer with a thickness of ∼100 nm over Al film. The formed alignment layer is rubbed strongly to shape relatively deep V-grooves to anchor LC molecules effectively. Common optical tests show some particular properties; for instance, the existing three transmission peaks in the measured wavelength range, the minimum full width at half-maximum being ∼120 nm, and the maximum adjustment extent of the imaging wavelength being ∼500 nm through applying the voltage driving signal with a root mean square (RMS) value ranging from 0 to ∼19.8 V. The experiment results are consistent with the simulation, according to our model setup. The spectral images obtained in the long-wavelength IR range, through the LC - FP device driven by the voltage signal with a different RMS value, demonstrates the prospect of the realization of smart spectral imaging and further integrating the LC - FP filter with IR focal plane arrays. The developed LC - FP filters show some advantages, such as electrically tunable imaging wavelength, very high structural and photoelectronic response stability, small size and low power consumption, and a very high filling factor of more than 95% compared with common MEMS-FP spectral imaging approaches. © 2014 Optical Society of America.


Tong Q.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Tong Q.,Huazhong University of Science and Technology | Zhang X.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Zhang X.,Huazhong University of Science and Technology | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The liquid crystal (LC) device with the circle aperture electrode can be used as a convex lens. The index of refraction of the LC lens can be easily changed by the voltage signal; the arrayed LC lens can be used in the imaging sensors. Comparing with the traditional optical lens, the LC lens has a more effective architecture. In this paper, we present an imaging sensor with a new type LC structure composed of three layers of top electrodes and a joint bottom electrode, and simulating the tunable spatial resolution architecture carried out by applying voltage signal over different ITO electrode in LC lenses coupled with arrayed imaging sensors. From the result of the simulation, we can find that changing the spatial resolution by our architecture can be achieved. © 2013 SPIE.


Lan X.-J.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Lan X.-J.,Huazhong University of Science and Technology | Liu L.,National Key Laboratory of Science and Technology on Multispectral Information Processing | Liu L.,Huazhong University of Science and Technology | And 2 more authors.
Acta Astronautica | Year: 2016

A guidance scheme has been proposed based on a new online trajectory planning algorithm for an unpowered reusable launch vehicle (RLV) in the terminal area energy management (TAEM) phase. The trajectory planning algorithm is able to rapidly generate a feasible path from the current state to a desired state at approach and landing interface (ALI) based on the dynamic pressure profile and new ground track geometry. Simple guidance laws are used to keep the RLV flying along the reference path which can be adjusted online by five related parameters. Then, the effectiveness and adaptability of the proposed TAEM guidance scheme is demonstrated by numerical trials with variations in the initial energy, position and aerodynamic performance. © 2015 IAA. Published by Elsevier Ltd. All rights reserved.

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