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3 November 1999 Real-time holographic compensation of large optics for space deployment
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Large deployable space-based optical systems will likely require complex structure position controls in conjunction with an adaptive optic to maintain optical tolerances necessary for near diffraction-limited performance. A real- time holographic (RTH) compensation system can greatly reduce the requirements and complexity of the position control system and enable the use of novel or imperfect optical components for large mirror surfaces. A hologram of the distorted primary is recorded with a local beacon at 532 nm (approximately 100 nJ/exposure) on an optically addressed spatial light modulator and transferred as a phase grating to a ferroelectric liquid crystal layer. The hologram is played back with target light containing the same optical distortion. A corrected image is obtained in the conjugate diffracted order where the phase of the optical distortion is subtracted from the distorted image. We report recent test results and analysis of a RTH-compensated deformed mirror of 0.75 m diameter. The short exposure hologram is recorded at video frequencies (30 Hz) at bandwidths up to 5 kHz. Correction for tens of waves of static and dynamic optical distortions including mechanical and thermal warp, mechanical vibration, and air turbulence are shown for monochromatic (532 nm) and broadband (532 +/- 40 nm) illuminated targets.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dennis M. Guthals, Daniel Sox, Michael D. Joswick, and Paul J. Rodney "Real-time holographic compensation of large optics for space deployment", Proc. SPIE 3760, High-Resolution Wavefront Control: Methods, Devices, and Applications, (3 November 1999);

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