Chanan, Gary and Troy, Mitchell and Dekens, Frank and Michaels, Scott and Nelson, Jerry and Mast, Terry and Kirkman, David (1998) Phasing the Mirror Segments of the Keck Telescopes: The Broadband Phasing Algorithm. Applied Optics, 37 (1). pp. 140-155. ISSN 0003-6935 http://resolver.caltech.edu/CaltechAUTHORS:CHAao98
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To achieve its full diffraction limit in the infrared, the primary mirror of the Keck telescope (now telescopes) must be properly phased: The steps or piston errors between the individual mirror segments must be reduced to less than 100 nm. We accomplish this with a wave optics variation of the Shack–Hartmann test, in which the signal is not the centroid but rather the degree of coherence of the individual subimages. Using filters with a variety of coherence lengths, we can capture segments with initial piston errors as large as ± 30 µm and reduce these to 30 nm—a dynamic range of 3 orders of magnitude. Segment aberrations contribute substantially to the residual errors of ~75 nm.
|Additional Information:||© 1998 Optical Society of America Received 11 January 1997; revised manuscript received 29 July 1997.|
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|Deposited On:||06 May 2006|
|Last Modified:||26 Dec 2012 08:51|
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