The Stray Light Analysis And Control In Star Sensor

In the aerospace field,star sensors for aircraft attitude are widely used.Due to the complex space light environment,the stray light entering the star sensor is more complicated,and the level of stray light suppressed determines the positioning accuracy of the star sensor.Stray light has a great influence on the detection of weak targets.The stray light reaching the surface of the detector will reduce the contrast of the image surface and increase the background noise.In severe cases,the detection target signal will be annihilated,resulting in system failure.Based on the above background and a large number of literature,this paper analyzes the source and path of complex space light environment,determines the steps of stray light analysis,introduces the scattering model affecting the stray light path and proposes the evaluation function of stray light suppression level.After reading a large amount of literature,the following aspects of research work were carried out.1)Different types of baffle and vanes design principles are proposed,as well as the distribution of vanes at different positions.The baffle and vanes are designed by MATLAB software,and the relevant parameters are quickly obtained according to the design requirements and imported into the ASAP software for modeling.Analyzed three different types of baffle in the system by using the two evaluation methods of extinction ratio and point source transmittance,and plot the curves of extinction ratio and point source transmittance with respect to the off-axis angle of the light.Provide theoretical analysis basis for baffle and vanes.2)Propose two methods used in the simulation analyses of Monte-Carlo method and important area sampling method.The scatter characteristics of the structure are measured by the scatter characteristic measuring instrument and then establish the polynomial scattering model.The accuracy of the scatter model is seriously affected by the accuracy of the stray light simulation analysis.Discuss the establishment of the scatter model of the lens and the selection of the scattering model equation of the structural.The ASAP software is used to analyze the stray light of simple systems and complex systems in star sensor which work in the visible light band,and the values of the point source transmittance under different off-axis angles are simulated under the premise of verifying accurate modeling,accurate scattering model and accurate selection of important areas,compared with design parameter.3)Propose the point source transmittance test method based on double-column tanks which is a commonly used test method in foreign countries.Introduce the equipment,methods and test steps for point source transmittance testing.Through the actual measurement of the point source transmittance of the visible optical system,the measured data of the point source transmittance is obtained and the curve is compared with the simulated analysis value to analyze the error.After comparison,the simulation index and the analysis value are mutually verified by the evaluation index of the verification analysis,and the actual measurement indicates the correctness of the simulation analysis.