Laser fuze usually adopt an active detection method, which emits laser pulses to the target through the transmitting system. After scattering by the target, the receiving system obtains the return laser signal. By calculating the time delay between the transmitting pulse and the receiving pulse, the target distance can be calculated. Traditional circular-viewing laser fuze typically use four zones for 360 degree detection, with a detection field angle accuracy of only 90 degrees. In order to achieve accurate measurement of target azimuth angle by laser fuze, this paper proposes a method based on the position of laser spot on a photodetector to calculate the target azimuth angle. The effects of proposed method are analyzed by simulation experiment. The results demonstrate that this method can accurately detect the target azimuth angle.
Fresnel zone lens (FZL) telescope is attracting increasing attention owing to its small volume and light weight. However, depending on the fabrication method of FZL, the linewidth and etch depth of FZL may deviate from the set value. It must be considered that the performance of the FZL is influenced by aberrations generated during manufacture. We simulate the effect of fabrication errors on optical performance of FZL and find that the linewidth error of FZL structure is the main cause of image degradation. In addition, we provide a method for correcting aberrations of FZL telescope with adaptive optics system (AOS). This method is verified by the experimental system. The results show that the image resolution is successfully improved after AO correction. The full-width, half-maximum value of a far-field image is improved from 0.065 to 0.038λ. The peak value of image energy after correction has increased by 4.23 times.
Since the phase diversity (PD) wavefront sensor has the advantages of simple structure and high light energy utilization, it is one of most attractive wavefront detection tools. The accuracy of retrieval wavefront depends on the precision of the detective intensity distribution of the CCD camera. However, limited by manufacture craft, the noise data are inevitably recorded, so CCD has only good performance in fixed dynamic ranges. In this paper, we propose a simple modified phase diversity wavefront sensor based on the altered exposure time of camera to improve the dynamic ranges of CCD. The two images are taken under normal exposure time and saturated exposure time of CCD, and then they are stitched to form a perfect image including accurate high space frequency and low space frequency information. Under same signal to noise ratio a comparison between the improved phase diversity wavefront sensor and the traditional phase diversity wavefront sensor is made by using simulation. The results show that this method can significantly enhance the retrieval wavefront accuracy.
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