Modeling and Simulation of Thermo-optic Effects on Star Sensor

The space thermal environment will affect measurement accuracy of star sensor. A model which can be used to analyze the thermo-optic effects on star sensor is built using the software ANSYS, the forward ray tracing algorithm, and aspheric polynomial algorithm. In order to make the aspheric polynomial fitting algorithm suitable for more surfaces and control the numerical accuracy of this algorithm, the algorithms that translating the coordinates and scaling the coordinates are added in this algorithm. The measurement error can be calculated using the model when the temperatures of the optical system change in a uniform value. Then several simulations are done when the temperatures of the optical system increase in different values. And other simulations are done on the condition that the location of the lens in the drawtube is different. The results showed that: the bigger the temperature difference is and the farther the lens is from its fixed surface on the satellite, the bigger the measurement error of the star sensor will be.