| 其他摘要 | In the satellite laser ranging system, the characteristics of the laser spot emitted through the telescope is a very important factor restricting the success of the ranging.In order to accurately grasp the characteristics of the laser spot emitted by the telescope, after extensively studying the common laser spot measurement methods ,such as: ablation method, photosensitive method, scanning method, CCD imaging method and array detector method, this article designed a device to measure the characteristics of the laser spot emitted by the 1.2m telescope based on CCD imaging method. In this paper, the principle of laser spot measurement, the design of the measuring device, and the processing method of the spot data are given in detail, and the focus is on the design of the spot measuring device and the study of the data processing method.In the design of the spot measuring device, the CCD camera and the energy meter were used to collect images and energy of the same laser spot at the same time. The distribution characteristics of the light field of the diffuse reflection screen were carefully studied, and the CCD camera and the energy meter were fully considered Optically matched to the outgoing laser beam.Finally, during the installation of the measuring device, the distance from the camera to the diffuse reflection screen was also strictly calculated. In the study of laser spot data processing methods, The gray value of the image area is calculated cleverly by the method of equal-circle area.According to the measured energy value of the energy meter, the energy calibration coefficient of the measured energy value to the gray value of the spot image is accurately calculated.The spatial distribution of the energy density of the light spot is also calculated by the energy scaling factor.Then, according to the definition of the spot radius, characteristic parameters of the spot are calculated.In addition, in the processing of spot data, this article also considers the influence of atmospheric turbulence and free diffraction of the ring laser beam on the measured value of the spot. Finally, according to the designed spot measuring device, the laser beam emitted from the 1.2-meter telescope was subjected to a spot measuring experiment.And the laser spot radius, divergence angle, average energy density distribution and other parameters after exiting through the telescope are calculated.The experimental results show that the 1.2-meter laser ranging system of Yunnan Observatory works normally, the laser divergence angle is small, and the laser beam quality is good.It also proves that the developed spot measuring device has the advantages of accurate energy standard, fast response speed, simple operation, easy control, etc.And the measurement method has important application prospects in laser spot measurement.Keywords:Spot measurement, CCD imaging,Diffuse reflection, Laser parameters, Laser Ranging |
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