Lidar can accurately collect the distance and speed information of the target, and can realize the target detection and imaging, so it has important application prospects in the fields of intelligent transportation, UAV obstacle avoidance, smart home, satellite mapping and navigation. Firstly, the basic principles, mainstream technical solutions and research necessity of laser detection are introduced. Secondly, according to the application requirements of solid-state and miniaturized integration of lidar, the technical development trends of international optical phased array lidar, mechanical scanning lidar and flash lidar are introduced. Meanwhile, the technical, product and commercial development status of lidar in China are expounded. Finally, the challenges and possible solutions of lidar technology are proposed, and its development trend is prospected.

The investigation of low resistance ohmic contact on GaAs/AlGaAs quantum well infrared detector is introduced. Combined with the heat treatment process, through testing the I--V characteristics, experiments are conducted on different combinations of Ni/AuGe/Au metal systems to determine the electrode system suitable for n+GaAs/AlGaAs. The heat treatment conditions after metal deposition are preliminary studied. Under the annealing conditions of 400 ℃, nitrogen atmosphere and 60 s, the transmission line model is used to obtain the specific ohmic contact resistance of 3.07×10-5 Ω·cm2 on n+GaAs(1×1018 cm-3).

Infrared band-pass filters are important components of infrared detectors to determine spectral response range. But cutoff wavelengths of the spectrum of infrared band-pass filters drift at low temperature, which influences spectral response range of infrared detectors. In order to explore the spectrum drift of the filters at low temperature, several typical infrared band-pass filters are selected and the self-made low temperature spectral test dewar is used to carry out spectral test at room temperature and 77 K respectively. The results show that the front cutoff wavelengths of tested filters all drift toward short wavelength direction at low temperature, and the drifts are mainly related to the waveband of filters. The drifts increase as the waveband increases. The drift of the cutoff wavelength of the medium band-pass filter is less than 100 nm at low temperature. The substrate material has little influence on the cutoff wavelength drift. The conclusion has important reference value for the spectral design of infrared detector filters.

This paper briefly discusses the classification of eavesdropping technology and the principle of infrared thermal imaging, analyzes the feasibility of applying infrared thermal imaging technology in the field of anti-eavesdropping, and emphatically introduces a design scheme of the anti-eavesdropping equipment based on cooled infrared focal plane detector. The scheme has certain technical advantages and good detection effect for some eavesdropping devices. The design of this scheme is based on users and usage scenarios, and focuses on man-machine adaptability, so it has a certain market prospect.

Aiming at the problem of inaccurate temperature measurement of the common infrared thermal imager caused by the thermal radiation of the surrounding high temperature objects, according to the principle of the temperature measurement and the infrared thermal radiation theory, a high temperature compensation measurement method based on this type of infrared thermal imager is designed. Shielding materials with emissivity of 0.5 can fully compensate the effect of the high temperature radiation. When the emissivity is equal to 1, it is equivalent to ignoring the thermal radiation of the high temperature object, which does not play a compensating role. The higher the emissivity is above 0.5, the higher the measured temperature is than the real temperature； and the more 0.5 exceeds the emissivity, the higher the real temperature is than the measured temperature.

In order that the optical spectrum analyzer can accurately measure narrow spectral signals, the grating is required to distinguish 2 million points in one cycle. A high-resolution grating positioning system based on diffraction grating, brushless direct current motor and photoelectric encoder is designed. A high-precision closed-loop speed control technology based on PID is realized which can drive the rotation of the grating. Meanwhile, the high-precision photoelectric encoder can quickly detect and feedback the angle position of the grating, and the subdivision circuit can further subdivide the output signal of the encoder. The resolution of the output signal is improved from 16000 to 2048000 per cycle, which greatly improves the overall resolution of the grating positioning system. The performance indexes such as the scanning speed, wavelength repeatability and wavelength accuracy of the grating are tested by experiments, and the positioning accuracy and resolution of the grating are verified.

In the development, production and maintenance of polarization-maintaining sensing systems, high-speed electro-optical modulation systems and passive optical devices, the requirement for the polarization extinction ratio is gradually increasing. For this purpose, a measuring technology of polarization extinction ratio with high speed and wide dynamic range is proposed. First, the basic principle of the rotation analysis method is described, then the power detection method of the logarithmic amplifier used in this technology is introduced, and finally the test results of the ordinary polarization extinction ratio tester and the improved polarization extinction ratio tester are compared. The results show that the new measuring technology of polarization extinction ratio improves the speed and dynamic range of the extinction ratio test, solves the problems of the current measuring technology, and therefore meets the relevant needs in the market.

The inter-frame difference method was applied to ship target image recognition, and a target recognition method in ship images based on the statistics features of the image was proposed. The demo software was written to verify the scheme by using the OpenCV computer vision library and the MFC dialog development tool in Visual C++. The results show that the method can quickly and accurately identify the target images and provide an objective basis for the commander to make decisions.