Design of Cassegrain optical system with wide field of view based on diffractive optics

To ameliorate the field of view Cassegrain optical system, a diffractive optical element (DOE) is successfully introduced to the system and the design scheme is provided in this paper. Two correcting lenses with a diffractive surface on the front surface of the first lens are placed after the second reflecting mirror in this Cassegrain system This system could achieve fine imaging quality that approaches the diffraction limit over 3.6° field of view, and the wave-front aberration of each field is less than 1/4 wavelength, so that the modulation transfer function (MTF) is approached to the diffraction limit. The results of the design show that DOE has a great effect on ameliorating the field of view of the Cassegrain optical system The design scheme reduces the demand for high technical levels and cost, and has a compact structure and better aberration character.