In this paper, the influences for one LWIR thermal camera in different integrate time are studied by using surrounding temperature simulator and blackbody of independent research and development, which compared to theoretical results. In experiment, the image of camera is obtained by using different integrate time and same temperature of blackbody at surrounding temperature of-30°C, 0°C and 20°C, the result show that the output voltage is linearly proportion to integrate time in those surrounding temperature. The experiment is studied for different blackbody temperature at surrounding temperature of-30°C, the result shows that: the slope of “integrate time vs. DL value” is increased with the target temperature. The noise of output image is increased with the increasing of integrate time. Whose agree with theoretical result. According to the conclusion, the DL value of random integrate time can be derived by known two integrate time DL for one blackbody temperature. And the calibration in random integrate time between two integrate time whose calibration curve are known, which is verified in experiment: the blackbody brightness deviation between test and derivation is less than 1%, which corresponds to blackbody temperature deviation between test and derivation is less than 1°C. The experiment results show that the measurement efficiency can be improved by using appropriate integrate time.
In the practical application of the laser, it is necessary to use the laser beam shaping technology to shape the output beam of laser device to the uniform light intensity distribution. The shaping divergent optical system of compound eye integrator way is composed of beam expanding mirror group and lens array. Its working principle is to expand the output laser to a certain size of caliber, and then divide the beam with lens array into multiple sub beam, where the lens unit of lens array can control the divergence angle of sub beam through the design of focal length, with mutual superposition of the sub beam in far field, to make up for the nonuniformity of beam, so that the radiant exitance on the radiated surface may become uniform. In this paper, we use a reflective microlens array to realize the laser beam shaping. By through of the practical optical path model established, the ray tracing is carried out and the simulation results for single-mode Gaussian beam with noise circumstance is provided. The analysis results show that the laser beam shaping under different inputs can be effectively realized by use of microlens array. All the energy is within the signal window, with a high energy efficiency of more than 90%; The measured surface has a better uniformity, and the uniformity is better than 99.5% at 150m.
In order to study the near-field target characteristic of the laser fuse, an algorithm based on the relationship of bidirectional reflectance distribution function and laser radar cross section per unit area is proposed to calculate the echo power of laser fuse in the near-field. The main research work in this paper involves the followings (1)Based on the theory of beam division, a mathematical description of the angular distribution of the detonator laser beam is given to depicted the mathematical model of Gaussian beam. (2)By using the scattering characteristics of rough surface as well as the geometry mesh model of the target, the relation formula between received power and transmitted power of remote system for a facet is derived. (3)Establishing the missile-target encounter model though the conversion from different coordinate systems. Then calculate the echo power of laser fuse by integrating those of the geometrical elements which are illuminated by laser beam during missile target encounter. Consequently, the received power in each channels of the laser fuse can be calculated. In addition, the proposed theoretical model in this paper is calibrated by actually-measured data. And the emulation results are with a good agreement with measured results. Based on the theoretical analysis methods proposed in former chapters, we have developed a program to compute the echo power. Finally , we consider a simplified missile model, and compute its echo power under different angle and different material as well as different miss distance and different target miss in azimuth. The results show that scattering peaks correspond to the points of the wings of the missile. In addition, the results change obviously when using different material .For instance, the results with aluminum material are almost 10 times than that of white paint when ignoring the influence of atmospheric attenuation. At the same time, the results are different under the different miss distance as well as target miss in azimuth. Numerical results prove the proposed method high efficiency and preciseness. It would be especially valuable in engineering application.
Micro-Doppler effect and its mathematical model were discussed. The Micro-Doppler effect of vibration and rotation
of moving point target were analyzed. The micro-Doppler frequency shift induced by vibration is simulated and
proceeded by means of the time-frequency analysis. A micro-Doppler Solid-state coherent ladar system for detecting
micro-motion of target was demonstrated to detect the micro-Doppler frequency shifts induced by vibration, complex
micro motion and rotation, and the micro-Doppler frequency shift induced by rotations at 0.2 r/s or vibrations at 0.5Hz
were detected. The information of micro-motion was extracted by the arithmetic of time-frequency analysis. These
results are helpful for target's feature extraction and identification.