A relatively large aperture (375 mm) optical system working at f/1.6 for a low-light-level movable TV camera has been designed. In the process of designing, advantages and defects of a catadioptric system with all spherical surfaces and three kinds of aspherical systems have been compared. The optical system we finally adopted is a reflecting system with two aspherical surfaces. Its primary mirror is hyperboloid and the secondary is a high order planary aspherical surface. Maximal asphericity is 0.048 mm and 0.007 mm, respectively. There are also two small correcting lenses (crown and flint glass) near focus in order to correct curvature of field and astigmatism. Within 2.4 degree(s) field of view, spot diagrams show that the maximal image is 0.035 mm in diameter with a flat focal plane over the wavelength 4861 angstrom to 6563 angstrom. The total weight of the optical elements is about 14 Kg. The optical tube length is about 277 mm and its T/Number is 2.
Xin He, Xin He,
"Large-objective optical system for TV night observation", Proc. SPIE 1780, Lens and Optical Systems Design, 178022 (15 April 1993); doi: 10.1117/12.142873; https://doi.org/10.1117/12.142873