Stray light analysis on helicopter optical landing guidance system

Shipboard helicopter optical landing guidance system can ensure the safety of landing when the helicopter completed missions. Stray light has a great influence on positional accuracy of the optical landing guidance system. In order to improve the imaging quality of the optical system, the sources of stray light in optical landing guidance system were studied in this paper. Moreover, the effects of stray light on the system were analyzed in detail. The model of the optical landing guidance system was established in TracePro software. 16 different off-axis angles were selected to carry out the ray tracing. Through modeling and simulation, the irradiance of stray light in the imaging plane and the point source transmittance (PST) of the system were obtained; And they were used to evaluate the level of stray light. Results show that the PST of the optical landing guidance system can achieve a level of 10(-5)similar to 10(-8) when the off-axis angle is equal to or greater than 49 degrees. At the same time, the solar stray light energy that gets to image plane can achieve a level of 1x10(-4)W/m(2). So the optical landing guidance system can work regularly in this range.