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Optical Engineering

Active surface correction of metallic honeycomb sandwich mirrors
Author(s): Brent J. Backhaus; Steven E. Forman
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Paper Abstract

A common method for correcting wavefront aberrations in an optical system involves using an array of actuators to deform the optical surface of a mirror until the aberrations are reduced or eliminated. Recent interest in metallic sandwich mirrors, where the optical surface is separated from the back surface by a lightweighted core, has created a need for a method to correct wavefront aberrations other than by applying actuator forces. One possible way to deform the optical surface of a sandwich mirror is by independently pressurizing cells within the core of the mirror. A method of active correction utilizing independent pressurized "macrocells" in the core of an 18 in. diameter perforated aluminum honeycomb sandwich mirror has been attempted. This paper describes the experiments and the finite element analyses conducted on 6 in. mirror blanks containing progressively more complex single macrocells and the experiments conducted on two 18 in. mirror blanks, one with a cellular honeycomb core and the other with a machined aluminum core, each containing 19 individual macrocells. Results from the multiple macrocell mirror blanks show that establishing a spatially variable pressure distribution in the core of a sandwich mirror can be an effective active method for deforming the mirror's optical surface.

Paper Details

Date Published: 1 October 1990
PDF: 9 pages
Opt. Eng. 29(10) doi: 10.1117/12.55717
Published in: Optical Engineering Volume 29, Issue 10
Show Author Affiliations
Brent J. Backhaus, John Deere Ottumwa Works (United States)
Steven E. Forman, Massachusetts Institute of Technology (United States)

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