2009 Vol. 2, No. 4
Warplane optoelectronic platforms, which own the outstanding feature of high-resolution and anti electronic jamming, have been modern military aircraft essential equipment and remarkable sign. This paper according the foreign published data, firstly, centers on the electrooptical pod and multisensor platform of unmanned aerial vehicle photoelectric load, manned fixedwing aircraft and manned rotorcraft, all of which are serviced after 2000. Especially the electro-optics active in local wars assembling on the new generation combined attacker F-35, ”Predator” unmanned scout/attacker RQ-1A/B ,then, analysis the main advantages of the modern military aircraft’s photoelectric system, point out the bottleneck and deficiency of related photoelectric technology and equipment. This paper also discusses the development of the airborne military photoelectric system. At last, probes into some current urgent need solved technology difficult points. Expecting that our country military aircraft photoelectric system can develop faster, for catching up with the same level as the developed country earlier, devoting my spark effort.
Bessel beams have received a wide number of applications in many fields, from metrology, classical optics to nonlinear optics and life science, owing to their special beams properties which the core of the beam is small and invariant propagation, self-healing and realized bottle beam。 The generation and transformation of the nondiffracting beam is an active research field nowadays。The propagation properties of the Bessel beam were described based on interferential theory, diffraction theory and geometrical optical theory。 The generation methods of nondiffracting Bessel beams can be divided into active and passive。 In this paper, three new passive generating methods have been given。 By analyzing the advantages and disadvantages of these generating methods, we proposed the scope of their applications。
The iris recognition technology as the biometrics with the best prospect is introduced. Based on the introduction of the technology from the whole, the representational algorithms are described in detail. At last, aimed at the problems existed in the process of iris recognition, the trend for the future is put forward——the localization algorithms with high accuracy, fast speed and good robustness, high effective feature extraction methods, machine learning methods, the evaluation of iris image quality, the iris recognition under incomplete and non-cooperative situation, and the detection of live iris.
The paper analyzes the advantages and disadvantages of dispersion method between prism and grating from some different points of view. The result indicates that the prism is more suitable for space-borne high resolution hyper-spectrum imager. The transmission efficiency of spectrometers with prisms is 95.24%(VNIR) and the diffraction efficiency of grating is between 60% and 70%. Moreover, the stray light of spectrometers with prisms is 10－4 and that of spectrometers with grating is 10－2. Furthermore the spectrometers with prisms is better than the spectrometers with grating between 0.4 －2.5 .In the dispersion linearity aspect, the spectrometers with grating are linear. The nonlinear problem of shortwave for spectrometers with prisms can be solved through double-prisms. Spectrometers with prisms are more reliable than Spectrometers with grating. In the spectrum bandwidth and cost aspect, Spectrometers with prisms and grating are equivalent.
The Hyper-spectral Imager (HSI) is a kind of new optical remote sensor that can simultaneously obtain imaging and spectral information of ground targets. Onboard calibration is the basis for space-borne HSI to obtain accurate quantified spectral imaging data. In this paper, we firstly presented the principles of onboard calibration for HSI; then made a classification of the onboard calibration technologies according to the different calibration references, and reviewed the onboard radiometric and spectral calibration technologies for HSI; finally, made an expectation to the development of the onboard calibration technologies in the future. Absolute radiometric calibration has already been the basic requirement of the radiometric calibration of HSI, and solar radiance will gradually take place of onboard lamps to be the absolute radiometric calibration reference. The calibration accuracy and reliability will be greatly enhanced by the combination of multi calibration technologies based on different calibration references. With the enhancement of the calibration accuracy, ground spectral calibration assembly will be used in the space and detector-based radiometric calibration systems will be generally taken into application in the onboard radiometric calibration.
Both fluorescence lifetime and time resolved fluorescence spectra are very important in time-resolved fluoroimmunoassay. This article describes a CPLD-based high-speed data acquisition system.In this design,the fluorescence lifetime from a few hundred nanoseconds to more than a dozen milliseconds can be measured. VHDL language had been used in this design of CPLD’s internal logic. There are 13 sampling frequencys can be changed from one to another.The number of sampling can be changed from 1 to 8192 ,also sampling time and delay time can be set arbitrarily, Measurement indicates that the system does well in the measurement of fluorescence lifetime and time-resolved fluoroimmunoassay.
A design of portable high-speed near-infrared grating spectrometer based on linear array CCD and USB2.0 data acquisition system was introduced. Plan grating, collimator system and imaging system with the spherical reflector were used, which made the spectrum plane and little curved (﹤4.2%), and the CCD was used to detected the spectrum. Hardware structure was optimized by using the FPGA and USB2.0, and the speed of data acquisition was improved greatly, the fastest up to 2MB/S. Analyzing the measuring data, the wavelength calibration was given. By the result, the spectrometer is portable and high-speed, and the wavelength accuracy is up to 1nm.
Fourier Telescope as a new technology for opto-electronic surveying has become one of the first-select technology for surveying deep space target with high precision. For advance the engineering evolve of practices system, the segment support module of Fourier Telescope field experiment collecting light mirror is designed in this paper. Mirror support and angle adjust framework are designed individually in series. Axial support adopts three flexible diaphragm balanced along 120°, in this way, the influence of thermal deformation to mirror surface figure can be reduced well. Central diaphragm flexure provides Lateral position to the segment and the gravity is loaded by six point lever hammer. Angle adjust framework drived by three screw pair and three FOD are realized. With the finite-element analysis, PV is 200nm and PMS is 40nm, the change of curvature radius is less than millimeter. It also has some reference values for support of thin mirror.
In order to solve the difficult problem of determining the value of the thermal contact resistance, a calculation method for space camera is brought up from the view of conduction and radiation among the contact surfaces. According to the material, machining, assembly and the actual operating environment, a reasonable range for thermal contact coefficient is obtained. The vertical camera, a sample to show the method, is reasonably meshed into finite element model with some simplification. Its temperature field is computed at low temperature steady-state equilibrium case with I-DEAS / TMG. And then temperature distribution, which is induced by the fluctuations of thermal resistance, is checked. The result of thermal analysis and the data of thermal environment simulation test are consistent very well and the maximum deviation is 0.45 ℃. It is shown that the calculation method of thermal contact resistance is reasonable and it could predict the thermal contact resistance of dry contact precision-machined surfaces in the space environment.
In order to satisfy the need of acquiring clear image in area CCD aerial camera, an automatic light adjustment control system based on digital signal processer TMS320F2812 as the core light adjustment controller was designed. The control system consisted of programmable logic device EPM7128 worked as logic operation and electric level conversion, integrated photodiode and amplifier OPT301M worked as detective light device, A/D converter AD7865 which converted analog signal to digital signal, direct circuit motor which controlled curtain type shutter speed, photoelectric encode which fed back speed signal, program code which realized automatic light adjustment arithmetic and control. The experiment results show：with the input step signal of 180r/min, the adjustable time is 0.095s, speed error 1.08r/min, which meets the need of system.
Photoelectric encoder CAN bus interface is put forward in order to make photoelectric encoder used in the system which adopts CAN Bus as data transmission method. Firstly, CAN bus interface hardware circuit of photoelectric encoder is designed which is composed of singlechip, CAN bus controller SJA1000, CAN bus transceiver TJA1050 and high-speed optical coupling TLP113 ; secondly, the paper introduces the design of CAN bus interface software consisted of the design of initialization, receiving message and sending message; lastly, the feasibility of photoelectric encoder CAN bus interface is proofed by “USBCAN1”CAN interface card produced by ZLG company. In the test, communication speed rate is 800kbps and one-meter shield twisted pair line is used as the transmission medium; the results show that the photoelectric encoder with CAN bus interface overcomes communication line’s shortcomings of classical photoelectric encoder system . The system can work in automatic measuring and controlling system better as a result of the advantages of more real-time and reliability , high transfer rate , long transfer distance and high resistance.
On the basis of actual demand for long-distance transmission of high definition LED screen, In order to solve the problem that the longest transmission of 1000BASE-T is 100 meters, using optical fiber which has longer transmission distance instead of 1000BASE-T. In the light of cost, the original structure of the sending and receiving system was not changed. A design of fiber converter of gigabit Ethernet was presented, which has implemented the conversion of UTP and fiber with the design of conversion of data format and control module based on FPGA. This converter is used for real-time digital video transmission system of high definition LED screen with reasonable effects, implementing real-time digital video transmission up to 10km，meeting the needs of users in a certain future, achieving the expected target of this design.