Range gated imaging has high resolution and long detection range, but it can only image a certain range at a time, so the target search efficiency is low. The detection efficiency of full-range gated imaging can be improved effectively by allocating high repetition frequency laser pulses in different distance slices. In this paper, a coding assignment method for full-range gated imaging is designed, and an underwater laser imaging system is built for experimental testing. Experimental results show that this method can effectively realize underwater laser full gated imaging. The detection performance of full-range gated imaging is inferior to range gated imaging, but it is still far better than underwater continuous light imaging, which can effectively improve the search efficiency of underwater laser imaging.
A portable underwater laser range gated imaging system is realized. The laser uses a fixed electro-optic Q-switched 532nm laser with a pulse width of 2.5 ns and a repetition rate of 20k. The detector adopts domestic second-generation image intensifier coupled with commercial CMOS photosensitive chip, with a limit resolution of 55lp/mm and a maximum gain of 10,000 times. Use FPGA delay chain timing technology to achieve 0.625ns time control accuracy and achieve distance-gated imaging. The overall system weight is less than 15kg, and it is close to zero gravity underwater. The system was measured in a large domestic pool, and the underwater detection imaging distance can reach 5-67AL, and the three-dimensional imaging accuracy is better than 1cm.
An underwater laser imaging system is introduced in this paper. The system has demonstrated underwater imaging capabilities in excess of 3 times the range of visible camera with lights, having three-dimensional (3D) imaging and range gated imaging ability. It also has small size and no gravity in water, can be manually handheld and carried on underwater unmanned platform.
According to the requirement of the full-spectrum camera for detection and warning proposed a camera structure which can cover the ultraviolet (UV, 250-400nm), visible light (480nm-680nm), medium wave infrared (MWIR, 3700nm-4800nm), long-wave infrared (LWIR, 8000nm-12000nm). The camera can utilize the different radiation characteristics of weapons target to achieve the full-spectrum detection and warning. In this structure, a four off-axis reflection system was used as the Primary Optical Systems. Four splitters were utilized to achieve four spectral bands. According to the detector and the corresponding application, the calculation and the design of the four subsystems were completed. After the design, the MTF of the four optical system show as follows: UV MTF>0.7@39lp/mm, visible MTF>0.7@72lp/mm, MWIR MTF> 0.7@17lp/mm, LWIR MTF> 0.7@17lp/mm.
Laser range gating imaging is currently the main means of underwater optical remote detection. The imaging signal-to-noise ratio is the core indicator of the distance gating system, which directly determines the limit detection distance of the system. In this paper, the imaging signal-to-noise ratio of the distance gated imaging system is theoretically analyzed. Based on the theory of laser transport in water, the time and space broadening effect of laser transmission, backscattering and imaging optical modulation transfer function(MTF) decline are all considered. Finally, the final form of the signal-to-noise ratio(SNR) and the simulation results are given.
Solar blind ultraviolet communication has the advantages of non line of sight transmission and low eavesdropping rate. It is a kind of local secure optical communication technology which is especially suitable for the use of the marine communication. This paper briefly describes the principles and characteristics of the solar blind ultraviolet communication system and its potential applications in marine communications. The key technologies of UV communication system, including channel simulation, ultraviolet light source, single photon detector, transceiver optical system, modulation and coding mode, are summarized in this paper.
This paper analyzes the development status of the infrared polarization imaging system. According to the application need of medium wave infrared (MWIR) polarization image, this paper proposes a MWIR polarization coaperture optical system. The system is composed of the front co-aperture optical system and the rear sub-aperture optical system. The rear separate aperture optical system includes four polarization channels. Each channel adopts a 1/4 wave plate and a linear polarizers to obtain three line Stokes polarization components and one circularly Stokes polarization components Thus the system could achieve full polarization imaging. According to the detector and the corresponding application needs, the calculation and optical system design were completed. After the design, the MTF of the optical system is more than 0.3@17lp/mm. The maximum RMS spot diameter is less than the size of detector pixel and a single pixel energy concentration is greater than 80%.
Ultraviolet warning technology is one of the important methods for missile warning. It provides a very effective way to detect the target for missile approaching alarm. With the development of modern technology, especially the development of information technology at high speed, the ultraviolet early warning system plays an increasingly important role. Compared to infrared warning, the ultraviolet warning has high efficiency and low false alarm rate. In the modern warfare, how to detect the threats earlier, prevent and reduce the attack of precision-guided missile has become a new challenge of missile warning technology. Because the ultraviolet warning technology has high environmental adaptability, the low false alarm rate, small volume and other advantages, in the military field applications it has been developed rapidly. For the ultraviolet warning system, the optimal working waveband is 250 nm ~280 nm (Solar Blind UV) due to the strong absorption of ozone layer. According to current application demands for solar blind ultraviolet detection and warning, this paper proposes ultraviolet warning optical system based on interference imaging, which covers solar blind ultraviolet (250nm-280nm) and dual field. This structure includes a primary optical system, an ultraviolet reflector array, an ultraviolet imaging system and an ultraviolet interference imaging system. It makes use of an ultraviolet beam-splitter to achieve the separation of two optical systems. According to the detector and the corresponding application needs of two visual field of the optical system, the calculation and optical system design were completed. After the design, the MTF of the two optical system is more than 0.8@39lp/mm.A single pixel energy concentration is greater than 80%.
In this paper, we introduce a new method for infrared and UV double color warning system. To increase the recognition ability of enemy targets, the warning system should detect the multiple radiation wave band characteristics of the target at the same time. The optical lens are based on lobster-eye optical system, which could get a large field of view through reflecting. The double color detection is based on AlGaN materials and reasonable band design. In the text, we will give the simulation of the lobster-eye lens and optimize the basic structure of the detectors. The main difficulties for the practical use of the system are also introduced.
Semiconductor photon up-converter that can convert infrared to visible light has great application potential in area of new type infrared imaging, photoelectric alarming, and atmospheric monitoring. Based on its working mechanism, this paper introduced the types of up-convert sensor, displayed its advantage when it was applied to infrared imaging. This paper also gave a detailed review about the development of semiconductor photon up-converter recent years. The organic-inorganic hybrid method can suitably combine the superiority of both material systems and complement each other's advantages. Finally, it may promote the development of low-cost,wavelength variable and imaging directly infrared imaging system.
The effective X-ray single photon detector is one of the key technologies for X-ray pulsar detection and navigation. The detector should have good energy and time characteristics and feasibility to meet the needs of X-ray pulsar single photon detection. In this paper, the main kinds of X-ray single photon detectors at present are introduced. By comparing their advantages, disadvantages and usage in satellite, we will give the development trends for the use of X-ray single photon detectors in X-ray pulsar navigation. Finally, we will introduce other new types of X-ray single photon detectors for the future use.
With the development of modern technology, especially the development of information technology at high speed, the ultraviolet early warning system plays an increasingly important role. In the modern warfare, how to detect the threats earlier, prevent and reduce the attack of precision-guided missile has become a new challenge. Because the ultraviolet warning technology has high environmental adaptability, the low false alarm rate, small volume and other advantages, in the military field applications it has been developed rapidly. According to current application demands for solar blind ultraviolet detection and warning, this paper proposes a reconnaissance and early-warning optical system, which covers solar blind ultraviolet (250nm-280nm) and dual field. This structure takes advantage of a narrow field of view and long focal length optical system to achieve the target object detection, uses wide-field and short focal length optical system to achieve early warning of the target object. It makes use of an ultraviolet beam-splitter to achieve the separation of two optical systems. According to the detector and the corresponding application needs of two visual field of the optical system, the calculation and optical system design were completed. After the design, the MTF of the two optical system is more than 0.8@39lp/mm. A single pixel energy concentration is greater than 80%.
The effective X-ray optics is a key premise for X-ray pulsar detection and navigation. However, it is very difficult to focus the X-ray photons through refraction for the reason that the X-ray photon is very easy to be absorbed by the materials. The most effective ways for the X-ray focusing is reflection. In this paper, we will give a brief introduction of the theory of the grazing incidence and the corresponding optical systems. By comparing the design parameters of main X-ray astronomical telescope in NASA and ESA, we will give the development trend of the X-ray optics for X-ray pulsar navigation and introduce several new technology for the manufacture of the micro-pore optics (MPO).
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