Owing to the requirement of high resolution of imaging system, such as the infrared imaging system, the imaging laser radar, the compressive sensing is used in the imaging system with low resolution sensors to obtain high quality image information. In this paper, compressive sensing is applied in an imaging system. A random phase mask is placed on the lens of the optical system. The optical wave propagation process of light field from the object plane to the lens, then to the image plane is analyzed and theoretical formula of the propagation with the form of the Fourier transform expression is deduced, thus the reconstruction speed is high by using the fast Fourier transform. The orthogonal wavelet transform and the orthogonal matching pursuit algorithm are employed in the reconstruction. The simulation results prove the good performance of the reconstruction quality and speed.
Background sunlight has more or less influence on optical receiver operating in the wild. Laser receiver usually has poor performance in sunlight than designed. The paper’s intention is to test and evaluate the influence of background sunlight on laser receiver by rule and line. The measurement method was studied and measuring system was put up. The outdoor experiments were carried out at plateau. The sensitivity of laser receiver was tested separately at noon and night. The test proves that the sensitivity of laser receiver at noon is down 37.77 per cent, compared with the sensitivity at night. The analytical model of maximum operating distance was founded. With the model, the maximum operating distances at noon and night were calculated. The calculation proves that the maximum operating distances at noon falls more than 12 per cent compared with the distance at night. The test and calculation show that background sunlight has a great influence on performance of laser receiver. It’s very necessary to consider the impact of sunlight when testing, evaluating, and using laser receiver.
Diffractive optical elements (DOEs) can realize beam shaping with higher light efficiency, strong flexibility of diffraction pattern, and is suitable to be used in optical interconnections to split beams. In order to increase the intensity uniformity of the split beams, a hybrid algorithm merging Gerchberg-Saxton (GS) algorithm with gradient method is presented based on the sampling rule different from the existing optimization algorithms. By controlling N extra points with zero amplitude besides the original N sampling points on the input plane, and finally the sampling pitch on the Fourier plane is half of that of the conventional sampling rule. Then the N extra points on the Fourier plane will be controlled. Finally spot array with high intensity uniformity can be realized with the proposed algorithm. Simulation results demonstrate the good performance of the proposed algorithm.
With the development of infrared focal plane array (IRFPA) technology, the high performance staring infrared imaging system has fully substituted the scanning type, and become the third generation thermal imaging system. Meanwhile the performance evaluation model associated with the device level also should be updated accordingly. This paper compares the traditional distance evaluation model with the latest model that is based on Target Task Performance (TTP) metric, and analyzes the problems and deficiencies when we evaluate a staring imaging system using the traditional model. Taking a certain type of infrared imaging equipment for example, we simulate its performances by using the two models respectively, and analyze the simulation results. Finally we verified the simulation results through field experiments, the results show that the value predicted by the model basing on the rule of TTP is closer to the measured value. This paper suggests that the TTP model is more accurate than traditional model in the design, optimization and evaluation of the high performance staring infrared imaging system.
Background sunlight effect the technical performance of laser detection system significantly. Analyses and experiments were done to find the degree and regularity of effects of background sunlight on laser detection system. At first, we established the theoretical model of laser detection probability curve. We emulated and analysed the effects on probability curve under different sunlight intensity by the model. Moreover, we got the variation regularity of parameter in probability curve. Secondly, we proposed a prediction method of probability curve, which deduced the detecting parameter from measured data. The method can not only get the probability curve in arbitrary background sunlight by a measured probability curve in typical background sunlight, but also calculate the sensitivity of laser detection systems by probability curve at the specified probability. Thirdly, we measured the probability curves under three types of background sunlight. The illumination conditions in experiments included fine, overcast and night. These three curves can be used as reference to deduce other curves. Using model, method, and measured data mentioned above, we finally finished the analyses and appraisal of the effects of background sunlight on typical laser detection system. The research findings can provide the theoretical reference and technical support for adaptability evaluation of typical laser detection systems in different background sunlight.