Design of long focal length terahertz optical system

Terahertz imaging has significant development prospects in terahertz technology due to its strong penetration and high spatial resolution. Currently, optical system designs are generally limited to the visible light range. To design an optical system suitable for terahertz imaging, an analysis of optical materials and system structures has been conducted. TPX (4-methylpentene-1) material and inverse telephoto structure were selected as the design basis. A terahertz optical system with a full field angle of 50°, a relative aperture of 1/4 and a focal length of 100 mm is designed using ZEMAX. The optimization results show that the root mean square radius of the spot in each field of view is smaller than the airy disk radius, indicating good imaging quality of the system.