[2011] Low uncertainty alignment procedure using computer generated holograms

Coyle, L. E., M. Dubin, and J. H. Burge. “Low uncertainty alignment procedure using computer generated holograms.” Optical System Alignment, Tolerancing, and Verification V. Vol. 8131. SPIE, 2011.


We characterize the precision of a low uncertainty alignment procedure that uses computer generated holograms as center references to align optics in tilt and centration. This procedure was developed for the alignment of the Wide Field Corrector for the Hobby Eberly Telescope, which uses center references to provide the data for the system alignment. From previous experiments, we determined that using an alignment telescope or similar instrument would not achieve the required alignment uncertainty. We developed a new procedure that utilizes computer generated holograms to create multiple simultaneous images to perform the alignment. The center references are phase etched Fresnel zone plates that act like thin lenses. We use zero order reflections to measure tilt and first order imaging from the zone plates to measure centration. We performed multiple alignments with a prototype system consisting of two center references spaced one meter apart to characterize this method’s performance. We scale the uncertainties for the prototype experiment to determine the expected alignment errors in the Wide Field Corrector.

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