Optical design of space cameras for automated rendezvous and docking systems

Visible cameras are essential components of a space automated rendezvous and docking (AR and D) system, which is utilized in many space missions including crewed or robotic spaceship docking, on-orbit satellite servicing, autonomous landing and hazard avoidance. Cameras are ubiquitous devices in modern time with countless lens designs that focus on high resolution and color rendition. In comparison, space AR and D cameras, while are not required to have extreme high resolution and color rendition, impose some unique requirements on lenses. Fixed lenses with no moving parts and separated lenses for narrow and wide field-of-view (FOV) are normally used in order to meet high reliability requirement. Cemented lens elements are usually avoided due to wide temperature swing and outgassing requirement in space environment. The lenses should be designed with exceptional straylight performance and minimum lens flare given intense sun light and lacking of atmosphere scattering in space. Furthermore radiation resistant glasses should be considered to prevent glass darkening from space radiation. Neptec has designed and built a narrow FOV (NFOV) lens and a wide FOV (WFOV) lens for an AR and D visible camera system. The lenses are designed by using ZEMAX program; the straylight performance and the lens baffles are simulated by using TracePro program. This paper discusses general requirements for space AR and D camera lenses and the specific measures for lenses to meet the space environmental requirements.