Two-axis gimbal for air-to-air and air-to-ground laser communications

Amnon G. Talmor; Harvard Harding Jr.; Chien-Chung Chen

doi:10.1117/12.2218097

15 March 2016 Two-axis gimbal for air-to-air and air-to-ground laser communications

Amnon G. Talmor, Harvard Harding Jr., Chien-Chung Chen

Proceedings Volume 9739, Free-Space Laser Communication and Atmospheric Propagation XXVIII; 97390G (2016) https://doi.org/10.1117/12.2218097
Event: SPIE LASE, 2016, San Francisco, California, United States

Abstract

For bi-directional links between high-altitude-platforms (HAPs) and ground, and air-to-air communication between such platforms, a hemispherical +30°C field-of-regard and low-drag low-mass two-axis gimbal was designed and prototyped. The gimbal comprises two servo controlled non-orthogonal elevation over azimuth axis, and inner fast steering mirrors for fine field-of-regard adjustment. The design encompasses a 7.5cm diameter aperture refractive telescope in its elevation stage, folded between two flat mirrors with an exit lens leading to a two mirrors miniature Coude-path fixed to the azimuth stage. Multiple gimbal configurations were traded prior to finalizing a selection that met the requirements. The selected design was manifested onboard a carbon fiber and magnesium composite structure, motorized by custom-built servo motors, and commutated by optical encoders. The azimuth stage is electrically connected to the stationary base via slip ring while the elevation stage made of passive optics. Both axes are aligned by custom-built ceramic-on-steel angular contact duplex bearings, and controlled by embedded electronics featuring a rigid-flex PCB architecture. FEA analysis showed that the design is mechanically robust over a temperature range of +60°C to -80°C, and with first mode of natural frequencies above 400Hz. The total mass of the prototyped gimbal is 3.5kg, including the inner optical bench, which contains fast steering mirrors (FSMs) and tracking sensors. Future version of this gimbal, in prototyping stage, shall weigh less than 3.0kg.

Citation Download Citation

Amnon G. Talmor, Harvard Harding Jr., and Chien-Chung Chen "Two-axis gimbal for air-to-air and air-to-ground laser communications", Proc. SPIE 9739, Free-Space Laser Communication and Atmospheric Propagation XXVIII, 97390G (15 March 2016); https://doi.org/10.1117/12.2218097

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