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Target tracking and pointing for arrays of phase-locked lasers
Author(s): Van P. Macasaet; Gary B. Hughes; Philip Lubin; Jonathan Madajian; Qicheng Zhang; Janelle Griswold; Neeraj Kulkarni; Alexander Cohen; Travis Brashears
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Paper Abstract

Arrays of phase-locked lasers are envisioned for planetary defense and exploration systems. High-energy beams focused on a threatening asteroid evaporate surface material, creating a reactionary thrust that alters the asteroid’s orbit. The same system could be used to probe an asteroid’s composition, to search for unknown asteroids, and to propel interplanetary and interstellar spacecraft. Phased-array designs are capable of producing high beam intensity, and allow beam steering and beam profile manipulation. Modular designs allow ongoing addition of emitter elements to a growing array. This paper discusses pointing control for extensible laser arrays. Rough pointing is determined by spacecraft attitude control. Lateral movement of the laser emitter tips behind the optical elements provides intermediate pointing adjustment for individual array elements and beam steering. Precision beam steering and beam formation is accomplished by coordinated phase modulation across the array. Added cells are incorporated into the phase control scheme by precise alignment to local mechanical datums using fast, optical relative position sensors. Infrared target sensors are also positioned within the datum scheme, and provide information about the target vector relative to datum coordinates at each emitter. Multiple target sensors allow refined determination of the target normal plane, providing information to the phase controller for each emitter. As emitters and sensors are added, local position data allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. Mechanical design and associated phase control that is scalable for target distance and number of emitters is presented.

Paper Details

Date Published: 19 September 2016
PDF: 15 pages
Proc. SPIE 9981, Planetary Defense and Space Environment Applications, 998102 (19 September 2016); doi: 10.1117/12.2237694
Show Author Affiliations
Van P. Macasaet, California Polytechnic State Univ., San Luis Obispo (United States)
Gary B. Hughes, California Polytechnic State Univ., San Luis Obispo (United States)
Philip Lubin, Univ. of California, Santa Barbara (United States)
Jonathan Madajian, Univ. of California, Santa Barbara (United States)
Qicheng Zhang, Univ. of California, Santa Barbara (United States)
Janelle Griswold, Univ. of California, Santa Barbara (United States)
Neeraj Kulkarni, Univ. of California, Santa Barbara (United States)
Alexander Cohen, California Polytechnic State Univ., San Luis Obispo (United States)
Travis Brashears, Univ. of California, Santa Barbara (United States)


Published in SPIE Proceedings Vol. 9981:
Planetary Defense and Space Environment Applications
Gary B. Hughes, Editor(s)

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