In order to meet the requirements of spacecrafts for autonomous navigation systems with light small

cheap and reliable performance

a wide-angle static infrared horizontal system was designed. The system chose the operating wavelength range of 14 to 16.25 μm to keep a stable radiation

and its full field of view was set as 136° and

F

number as 0.61. By using a retrofocus structure in image space

the back working distance has been 15 mm in the optical system. On the basis of the design principle of a

f-θ

lens

the aspheric surface was used to rationally optimize the wide-angle system

then the related error of linear characteristics of the

f-θ

len is less than 0.5%

and the modulated transfer function is higher than 0.6 at 15 lp/mm in the image plane(approaches diffraction limit). In a circle with radius of 20 μm

the radial energy is higher than 85%. Furthermore

a telecentric optical path was used in the system

which improves the relative illumination to more than 99%. These results show that the designed lens has the advantages of simplicity

compactness and long back working distance

and can balance the correctness of off-axis aberrations.