Optical Design of reflective omnidirectional optical system to be used simultaneously in visible and LWIR wavelength range

摘要

We design an omnidirectional optical system that is composed of pseudo-Cassegrain collecting mirror part making narrow field of view(FOV) and a reverse pseudo-Cassegrain imaging mirror part, which can be used simultaneously in visible and long wavelength infrared(LWIR) light. The FOV is set to 40 ° to 110 ° and the Fumber is 1.55. Because a CMOS sensor (CMOSIS, CMV2000) for visible and a micro bolometer sensor (semiconductor device, Bird 384) for LWIR are chosen, respectively, the common size of image should be determined by 5.9 mm x 5.9 mm. After the optimizing design, the ratio of the image height about two cases of 40 ° and 110 ° is 48.97 %. We can obtain that two MTFs for visible and LWIR at 20 Ip/mm about the FOV of 110 ° are 0.425 and 0.385. respectively. The total length of this system is about 280 mm. When the MTF at 20 lp/mm and 110° is 0.3, the cumulative probabilities of the tolerance in visible and LWIR are 90.69 % and 99.79 %, respectively. After the athermalization analysis in the temperature range of-32 °C to 55 °C, we choose the secondary mirror of the imaging part as a compensator to improve the collapsed MTF.