基于光栅的大动态范围高精度质心探测方法研究

发布时间：2018-01-21 20:08

本文关键词： 光轴检测衍射光栅动态范围测量精度质心探测　出处：《中国科学院大学(中国科学院光电技术研究所)》2017年硕士论文　论文类型：学位论文

【摘要】：在激光光轴误差检测、光电成像跟踪系统等应用场景中,需要利用聚焦成像远场光斑位置探测器对目标光轴进行探测。远场光斑位置探测器一般采用CCD相机,利用接收到的目标光斑,计算出其质心在靶面的偏移量,从而探测出光轴的倾斜位置。在光轴探测过程中,期望远场成像探测器同时具有大动态范围和高探测精度的能力,其中目标光轴期望具有度级的探测范围,同时需要微弧度级的探测精度。聚焦成像远场光斑位置探测器的动态范围和探测精度均受限于成像透镜的焦距长短。在相同靶面尺寸大小的条件下,采用长焦距的成像透镜能够提高光轴的探测精度,但是会降低光轴的动态探测范围。大动态范围和高精度探测的实现是一对矛盾的过程。本文正是希望解决这一矛盾过程,提出一种基于二维正交衍射光栅的新型光轴测量方法,使得倾斜跟踪探测器具有大动态范围和高精度探测的能力。利用光栅将入射光束分割成具有相同入射方向的多光束,在CCD探测器靶面成像为一个光斑阵列。相对于单个光斑,光斑阵列拥有更多的目标光斑输入信息,由于增加了目标光斑的探测信息,从而可以提高光轴的探测精度。同时,光栅使得光斑阵列分布范围大于CCD靶面大小,当主光斑偏离出靶面区域时,仍可以通过其余光斑阵列强度分布测量出入射光轴偏移量,从而增大光轴的动态范围。本文重点研究了利用光栅分束特性的原理增大光轴动态探测范围和提高光轴探测精度。针对大动态范围和高精度探测两部分内容,分别从理论分析、数字仿真和实验验证三个方面展开了全面深入的研究。首先,本文介绍了光栅的基本特性和分光原理,接着从理论上分析了利用光栅增大光轴动态探测范围的基本原理,并根据大动态范围原理进行了数字仿真分析,仿真分析了利用?1级衍射光斑探测光轴动态范围,仿真结果表明光栅可以增大光轴的动态范围。其次,本文介绍了二维正交光栅的成像原理,利用正交光栅探测高精度光斑质心。在理论上分析了质心探测过程中存在的主要误差来源,利用可探测的光斑阵列,推导出了高精度质心探测方法。根据高精度质心探测原理,进行了数字仿真,仿真结果与理论分析是吻合的。最后,为了验证理论分析与仿真结果的正确性,搭建了一套基于衍射光栅的光学平台进行实验验证。利用CCD相机数据采集软件,获取远场光斑图像数据,对数据处理后得到的实验结果分别验证了光栅能增大光轴动态范围和提高光轴探测精度。总之,利用本文提出的光轴探测方法,聚焦成像远场光斑位置探测器能同时具有大动态范围和高精度光轴误差探测能力,这对于在激光光轴误差检测、光电成像跟踪系统等应用场景中需要探测光轴具有重要的研究意义。
[Abstract]:In the laser optical axis error detection, photoelectric imaging tracking system and other applications in the scene. The focal imaging far-field spot position detector is needed to detect the optical axis of the target. The far-field spot position detector generally uses the CCD camera and the received target spot. The deviation of the center of mass in the target surface is calculated, and the tilt position of the optical axis is detected. In the optical axis detection process, the far-field imaging detector is expected to have the capability of both large dynamic range and high detection accuracy. The target optical axis is expected to have a degree of detection range. At the same time, the detection accuracy of micro-radians is required. The dynamic range and detection accuracy of focusing far-field spot position detector are limited by the focal length of the imaging lens and under the condition of the same target size. The detection accuracy of optical axis can be improved by using long focal length imaging lens. However, the dynamic detection range of optical axis will be reduced. The realization of large dynamic range and high precision detection is a contradictory process. A novel optical axis measurement method based on two-dimensional orthogonal diffraction grating is proposed. The tilt tracking detector has the capability of large dynamic range and high precision detection. The incident beam is divided into multiple beams with the same incident direction by grating. Compared with a single spot, the spot array has more input information of the target spot, because the detection information of the target spot is increased. At the same time, the grating makes the distribution range of the spot array larger than the size of the CCD target, when the main spot deviates from the target area. The offset of the incident optical axis can still be measured by the intensity distribution of the remaining spot arrays. In order to increase the dynamic range of optical axis, this paper focuses on increasing the dynamic detection range of optical axis and improving the precision of optical axis detection by using the principle of grating beam splitting, aiming at the two parts of large dynamic range and high precision detection. From the theoretical analysis, digital simulation and experimental verification of three aspects of comprehensive and in-depth research. First, this paper introduces the basic characteristics of the grating and the principle of light separation. Then the basic principle of using grating to increase the dynamic detection range of optical axis is analyzed theoretically, and the digital simulation analysis is carried out according to the principle of large dynamic range. The first order diffraction spot detects the dynamic range of optical axis. The simulation results show that the grating can increase the dynamic range of optical axis. Secondly, this paper introduces the imaging principle of two-dimensional orthogonal grating. Using orthogonal grating to detect high precision spot centroid, the main error sources in centroid detection are analyzed theoretically, and the detectable spot array is used. The high precision centroid detection method is derived. According to the high precision centroid detection principle, the digital simulation is carried out. The simulation results are consistent with the theoretical analysis. Finally, in order to verify the correctness of the theoretical analysis and simulation results. An optical platform based on diffractive grating is built for experimental verification. The far-field spot image data is obtained by using CCD camera data acquisition software. The experimental results obtained after data processing verify that the grating can increase the dynamic range of optical axis and improve the accuracy of optical axis detection. In short, the optical axis detection method proposed in this paper is used. Focusing imaging far field spot position detector can simultaneously have large dynamic range and high precision optical axis error detection ability, which can be used in laser optical axis error detection. It is of great significance to detect the optical axis in the application of photoelectric imaging tracking system.
【学位授予单位】：中国科学院大学(中国科学院光电技术研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN25

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