"Off-axis three-mirror anastigmatic telescope without middle image" and "off-axis three-mirror anastigmatic telescope
with one middle image" are both popular in space remote sensing. Working tolerances are analyzed deeply in both
configurations. Compared with "off-axis three mirrors anastigmatic telescope without middle image", "off-axis three
mirrors anastigmatic telescope with one middle image" has bad working tolerances.
TMA (Three Mirrors Anastigmatic) can simplify the configuration of telescope and lighten the weight, so it is very
popular to the design of space-based optical system. According to this concept, an off-axis unobstructed TMA is
calculated. Based on initial configuration parameters, automatic optimization is executed in ZEMAX program, and a new
telescope is obtained with parameters as follow: aperture is 2000mm, f/number is 2.25, FOV is 5°, angular resolution is
better than 7 μrad and image quality meets limited performances.