Method for Determining the Optimal Focal Plane Position of Light Source in an Optical Axis Pointing Device

The optical axis pointing device is an important guarantee for star camera to realize high precision measurement, The optimal focal plane position of the light source will affect the accuracy of the optical axis pointing device. This paper deals with the determination of the optimal focal plane position of the light source in the optical axis pointing device, A fast focal plane location determination method based on Gaussian fitting is proposed. The measurement of the focal point of the tiny luminous surface of the light source of the optical axis position recording device is converted to the measurement of the luminosity of the light spot emitted by the light source of the optical axis pointing device. First, a test platform for focal surface position of light source was built, and light source spots under different gaskets thicknesses were obtained by replacing gaskets; Second, the centroid of each light spot is determined, and the DN value of centroid brightness of each light spot is calculated; Thirdly, the least square method is used to fit the centroid brightness of the obtained spot to get the best focal plane position of the light source; Finally, the center of mass standard deviation is calculated to verify the test results. The test results show that the method is effective.