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Proceedings Paper

Design of an inertially stabilized telescope for the LLCD
Author(s): Jamie W. Burnside; Stephen D. Conrad; Allen D. Pillsbury; Catherine E. DeVoe
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Paper Abstract

The Lunar Laser Communication Demonstration (LLCD) program will demonstrate the first high-bandwidth optical communication payload on a NASA space mission. The inertially stabilized 108 mm aperture telescope will fly on NASA's LADEE spacecraft and is fabricated nearly entirely of beryllium, providing a high stiffness-to-weight ratio. The telescope consists of a two-axis fine positioning stage using inertial sensors and coarse and fine optical tracking. The stabilized telescope uses a two-axis coarse positioning gimbal to provide a large field-of-regard. Inertial stabilization provides local disturbance rejection while allowing modest optical uplink power to provide an absolute pointing reference. The telescope is a three-wavelength design providing separate uplink acquisition and communication wavelengths, and a downlink communication wavelength. Acquisition and coarse tracking of the uplink beacon is via a photodiode quadrant detector, while fine tracking is via nutation tracking and piezoelectric actuation of the receive fiber. Control of the downlink point-ahead angle is via piezoelectric actuation of the transmit fiber. The telescope is thermally stabilized during normal operations. The transmit and receive beams are fiber-coupled to a separate optoelectronic module and the telescope line-of-sight will be stabilized to better than 2.5 microradians during normal operations. Provision for self-test and boresighting during on-orbit operations is provided.

Paper Details

Date Published: 1 March 2011
PDF: 8 pages
Proc. SPIE 7923, Free-Space Laser Communication Technologies XXIII, 79230L (1 March 2011); doi: 10.1117/12.878926
Show Author Affiliations
Jamie W. Burnside, MIT Lincoln Lab. (United States)
Stephen D. Conrad, MIT Lincoln Lab. (United States)
Allen D. Pillsbury, MIT Lincoln Lab. (United States)
Catherine E. DeVoe, MIT Lincoln Lab. (United States)

Published in SPIE Proceedings Vol. 7923:
Free-Space Laser Communication Technologies XXIII
Hamid Hemmati, Editor(s)

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