Ultra-Lightweight, Ultra-Stable RoboSiC Additively Manufactured Lasercom Telescope

Of interest to JPL, GRC and GSFC are laser communications telescopes (LCTs) with 30 to 100 cm clear aperture, wavefront error (WFE) less than 62 nm, cumulative WFE and transmission loss not to exceed 3-dB in the far field, advanced thermal and stray light design for operation while sun-pointing (3-degrees from the edge of the sun); -20° C to 50° C operational range (wider range preferred), and areal density <65kg/m2. Telescope dimensional stability, low scatter, extreme lightweighting, and precision structures are a common theme across the NASA 2017 Physics of the Cosmos and Cosmic Origins Program Annual Technology Reports. Multiple Priority technology gaps can be found that require a solution in time for the next Decadal Survey. A common cited solution of interestis silicon carbide and 3D printing or additive manufacturing. RoboSiC technologies provide both. Team GT proposes purposefully engineered 2nd Generation optical-grade and structural-grade “RoboSiCto provide the degree of passive athermality required for the laser communications telescope wavefront error stability, concomitant with low areal density mirrors (7.75-10 kg/m2) and structures (4-5 kg/m2), and the ability to perform active precision adjustment (if required).The combination of 3D/AM allows the possibility to manufacture high structural efficiency classical truss structures such as the Pratt, Warren and Howe trusses and our gradient lattice cores for the mirrors. Clever design provides the additional stability benefit of damping during slew. We will use a combination of 3D/AM parts to produce inexpensive, bolt-together, athermal telescopes which achieve optical pathlength and wavefront error stability with low-scatter. A Paul-Baker three-mirror anastigmatic telescope may be an ideal laser communications telescope design. We plan to deliver mirror and structures coupons to NASA for testing.