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Proceedings Paper

Near-field optical model for directed energy-propelled spacecrafts
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Paper Abstract

Directed energy is envisioned to drive wafer-scale spacecraft to relativistic speeds. Spacecraft propulsion is provided by a large array of lasers, either in Earth orbit or stationed on the ground. The directed-energy beam is focused on the spacecraft sail, and momentum from photons in the laser beam is transferred to the spacecraft as the beam reflects off of the sail. In order for the beam to be concentrated on the spacecraft, precise phase control of all the elements across the laser array will be required. Any phase misalignments within the array will give rise to pointing fluctuations and flux asymmetry in the beam, necessitating creative approaches to spacecraft stability and beam following. In order to simulate spacecraft acceleration using an array of phase-locked lasers, a near field intensity model of the laser array is required. This paper describes a light propagation model that can be used to calculate intensity patterns for the near-field diffraction of a phased array. The model is based on the combination of complex frequencies from an array of emitters as the beams from each emitter strike a target surface. Ray-tracing geometry is used to determine the distance from each point on an emitter optical surface to each point on the target surface, and the distance is used to determine the phase contribution. Simulations are presented that explore the effects of fixed and time-varying phase mis-alignments on beam pointing, beam intensity and focusing characteristics.

Paper Details

Date Published: 5 September 2017
PDF: 9 pages
Proc. SPIE 10401, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems, 1040107 (5 September 2017); doi: 10.1117/12.2274692
Show Author Affiliations
Amber Sucich, California Polytechnic State Univ. (United States)
Tomas Snyder, California Polytechnic State Univ. (United States)
Gary B. Hughes, California Polytechnic State Univ. (United States)
Prashant Srinivasan, California Polytechnic State Univ. (United States)
Philip Lubin, Univ. of California, Santa Barbara (United States)
Qicheng Zhang, Univ. of California, Santa Barbara (United States)
Alexander Cohen, Univ. of California, Santa Barbara (United States)
Jonathan Madajian, Univ. of California, Santa Barbara (United States)
Travis Brashears, Univ. of California, Santa Barbara (United States)
Nic Rupert, Univ. of California, Santa Barbara (United States)


Published in SPIE Proceedings Vol. 10401:
Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems
Tony B. Hull; Dae Wook Kim; Pascal Hallibert, Editor(s)

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