Li, Xijie; Zou, Chunbo; Yang, Jiating

Image-side telecentric unobscured optical systems have significant application values in the field of space optics. However, off-axis astigmatism increases with an increase of field of view (FOV), relative aperture and image-side telecentricity, so it's very difficult to design image-side telecentric anastigmatic systems with an ultrawide FOV. To solve these issues, this paper proposes an effective method that is based on the coaxial parent mirrors. By calculating the off-axis aberration optical path of the primary mirror (PM), secondary mirror (SM) and tertiary mirror (TM), and introducing even aspheric surface and adding boundary constraints, a prospective system with a focal length of 400 mm, a relative aperture of 1/3, an FOV of 18 degrees x 6 degrees, and a telecentricity of greater than 0.5 degrees is designed. The design results show that the modulation transfer function (MTF) of the system is greater than 0.7 at the Nyquist frequency of 34 lp/mm, which is close to the diffraction limitation. It has a high imaging quality, thereby proving the image-side telecentric off-axis three-mirror anastigmatic (TMA) system to be effective.

The result was published on OPTIK. DOI: 10.1016/j.ijleo.2021.166855