Minimizing Thermal Distortion in Mirrors for Dual Mode Active-Passive Seeker Applications

The U.S. Army Space and Missile Defense Command is responsible for the Advanced Discriminating LADAR Technology Program to develop LADAR seeker technology to augment sensors of Exoatmospheric Kill Vehicle seekers. The dual mode LADAR has a high power transmit beam that uses the same primary optical path as the receive beam. The transmit beam is steered to one side of the primary mirror to avoid any obscuration due to support structures. This results in uneven heating of the primary optic and consequential thermal distortion. The Army needs a passively cooled mirror that can mitigate this distortion. The system wavefront error for dual mode LADAR systems can be minimized using low figure error/surface finish, low print-through, SLMST technology with high-reflectivity very low absorption (VLA) coatings. SLMST technology provides the highest structural efficiency for high-bandwidth (> 1kHz) fast steering mirror applications (e.g. ABL), and for the sensor telescopes of Ground Based Midcourse Defense EKV, while mitigating the thermal effects of the high-energy laser and fast-X-rays, respectively. SLMST can dramatically exceed the thermal performance and match or exceed the 1st frequency of lightweighted beryllium mirrors at the same weight, while at substantially lower cost, and without the health risks associated with processing beryllium