Optical Design and Optimization of Space High-cadence Observing Terahertz-telescope (SHOT)

The Space High-cadence Observing Telescope (SHOT) is proposed to conduct a wide-field survey in 1-3 THz with an aperture of 1-meter class. It will provide complete terahertz and far-infrared photometry with low-resolution spectroscopy throughout the sky, promoting the study of fast radio bursts, the formation and evolution of stars, and other scientific goals. The telescope will adopt a superconducting kinetic inductance detector to achieve a wide survey of terahertz imaging. This work designs the optical system of SHOT to obtain a large FOV of up to 1.5 deg and match the detector with the size of 60 mm\(\times\)60 mm and pixel pitch of 0.8 mm. The quasi-optical system adopts a Ritchey-Chr{\'e}tien design. By adding a corrector lens to the optical system and optimization, the aberrations mainly caused by the optical elements in the detector system are reduced. The influence of each component assigned to different terahertz materials is analyzed. The results show that TPX is more suitable than the other two materials. The performance of the optimized optical system is close to its diffraction limit. It will have the characteristics of high image quality and compact layout.