This paper presents two optical systems of descent cameras. These two lens systems have the same parameter whose effective focal length is 14 mm, F-number is F/8, field of view is 72 degree and the working wavelength rang is 0.5-0.8μm. Two different optical structures were used respectively in these two systems. This paper analyses and compares their capacity respectively. Only two kinds of glass material were used in these two optical systems, the difference from the usual imaging system is that this system is required to be fit for the demand of spaceflight environment. It should be small and light enough on the one hand, and the imaging quality should be high on the other hand.
The detector whose image element size is 14 um, its Nyquist cut-off frequency is 35.711p/mm, its diffraction limit MTF is 0.76. Program 1's 1.0 field MTF≥0.58 at the Nyquist cut-off frequency. The biggest relative distortion of this system is+0.2%, Image irradiance at the edge of the field was found to be 50% of the central value. In the design of program 2, MTF approach diffraction limit, the biggest relative distortion in 1.0 field is 0.7%. Because of the structure of telecentric beam path design, the relative illumination in 72° view field is comparatively average.