Optics and Photonics Society of Iran

Stray light has a damaging effect on the contrast and image quality in optical system. To reduce these effects Mechanical structures are needed to control stray light. After designing mechanical structures, it is necessary to detect effect of the structures in stray light of the system. The aim of this study is determination of the stray light performance of the INO 340 telescope system and identification of the changes that improve the off-axis rejection characteristics of the system. In this paper, the principle of stray light analysis by using Zemax Software is presented. The Point Source Transmittance (PST) curve of the system is plotted versus different fields. The results show the PSTs are less than 10-5 when off-axis angles are larger than 9 degree, which satisfies the system requirement. Also, the special fields of stray light control by using baffle and vane are discussed.