Modern observatories including ultra-stable spectrographs, optical telescopes and gravitational wave observatories rely on ultra-stable structures to meet their science objectives. These structures must exhibit pm to nm level length stability over a few seconds to a few hours and m-level length stability over mission duration of several years in some cases. The use of ultra-low CTE glass substrates provide the required stability while being highly fragile, having limited adaptability while driving turnaround times longer. We characterized structures made using materials that can provide the required stability while improving on the adaptability, turnaround times, structural mass and strength. These include a compound structure made using ALLVAR Alloy, a metal with a negative CTE, a second structure made of HB-Cesic, a full-ULE structure and a metal-ULE hybrid structure. In this work, we present a comparative analysis of the measured length noise and the long-term length stability for these structures.
Laser communication systems promise orders-of-magnitude improvement in data throughput per unit SWaP (size, weight and power) compared to conventional RF systems. However, in order for lasercom to make sense economically as part of a worldwide connectivity solution, the cost per terminal still needs to be significantly reduced. In this paper, we describe a coarse pointing mechanism that has been designed with an emphasis on simplicity, making use of conventional materials and commercial off-the-shelf components wherever possible. An overview of the design architecture and trades is presented, along with various results and practical lessons learned during prototype integration and test.
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