Robert H. Koch’s Work on Lightweight Medium-Aperture Mirrors
After a visit by Peter Waddell from the University of Strathclyde, Glasgow, UK in 1991, Robert H. Koch launched a program at the University of Pennsylvania to build lightweight pneumatic membrane mirrors, initially for balloon flight observations where weight is at a premium. Mirror cells were fab...
Main Authors: | , |
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Format: | Article |
Language: | English |
Published: |
The Korean Space Science Society
2012-03-01
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Series: | Journal of Astronomy and Space Sciences |
Subjects: | |
Online Access: | http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2012/v29n1/OJOOBS_2012_v29n1_79.pdf |
Summary: | After a visit by Peter Waddell from the University of Strathclyde, Glasgow, UK in 1991, Robert H. Koch launched a program
at the University of Pennsylvania to build lightweight pneumatic membrane mirrors, initially for balloon flight observations
where weight is at a premium. Mirror cells were fabricated from sizes 0.18 m to 1.77 m, and experiments conducted
to characterize the mirror figure and stability. Most of the work stopped after Prof. Koch’s retirement in 1996 until 2006
when the authors expressed an interest in building an array of medium-aperture portable telescopes. The program restarted
in earnest at Gravic, Inc. in Malvern, PA in 2008 with Koch using his extensive observational astronomy experience
to guide the fabrication of a fully operational 1.07 m membrane mirror telescope with an optical tube assembly weighing
under 45 Kg. Residual wavefront aberrations remediation resulted in Koch and the authors investigating membrane
tensioning techniques with different cell designs, active secondary wavefront correction, photometric algorithms for aberrated
images, and the use of additional lightweight mirror substrates from the Alt-Az Initiative Group, such as foamed
glass. The best result for the lightweight mirrors was a point spread function spot size of several arc seconds. A lightweight
1.6 m cast aluminum cell alt-az telescope was subsequently designed by Koch and the authors for prime focus use. |
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ISSN: | 2093-5587 2093-1409 |