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Title: In-lab calibration and testing of adaptive secondary mirrors using phase measuring deflectometry
An adaptive secondary mirror (ASM) with novel actuator technology is being designed and built for the UH88 telescope as a demonstration of a new generation of ASMs that might be deployed at ground based observatories such as Keck, Subaru, and TMT. Before putting the ASM on the telescope, a set of calibrations and character- izations need to be made in the lab. The crucial lab characterizations of the ASM are to measure its influence functions, and its surface shape when powered and unpowered. To measure these, we develop a novel and inexpensive optical metrology approach using phase measuring deflectometry. This paper describes the simulations we wrote to model the deflectometry method, our data acquisition/analysis pipeline, and a lab prototype sys- tem we built that demonstrates its feasibility on a microelectromechanical systems (MEMS) deformable mirror. Based on the information gained through the deflectometry simulation and the setup prototype, we conclude that phase measuring deflectometry is a reasonable method for obtaining the influence functions but that the absolute surface shape of the ASM will be limited by our knowledge of the placement of components within the deflectometry setup itself. We discuss challenges with extending this approach to larger convex adaptive secondary mirrors.  more » « less
Award ID(s):
Author(s) / Creator(s):
Schmidt, Dirk; Schreiber, Laura; Vernet, Elise
Date Published:
Journal Name:
Proc. SPIE 12185, Adaptive Optics Systems VIII
Page Range / eLocation ID:
Medium: X
Sponsoring Org:
National Science Foundation
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