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A dual purpose optical truss laser metrology system for a space-based far-IR segmented telescope: Figure maintenance and pointing controlTo obtain imaging performance as for monolithic mirrors, large segmented reflectors used for astronomy must be actively aligned and pointed to extreme levels of precision. A system concept for a dual purpose optical truss laser metrology system is described which is used for both figure and alignment maintenance and telescope pointing. A two-stage figure active control approach was developed for several proposed spaceborne far infrared segmented telescopes, one of which is the 10-20 meters Large Deployable Reflector (LDR). The first active control stage, the figure initialization control system, aligns the optical elements (i.e., the primary segments, secondary and focal plane assembly) based on images obtained. The second stage, the figure maintenance control system, maintains the alignment between re-initializations using measurements provided by laser interferometers arranged in an optical truss configuration. It measures the relative positions and alignments of the telescope segments so that a controller can reposition them appropriately. The application of this optical truss for figure maintenance control is the subject of the first part of this paper. The second portion of this paper discusses the application of the optical truss to telescope pointing. Here, the laser metrology system is used to transfer pointing information from an external fine guidance sensor (FGS) to the telescope optical boresight as defined by the primary mirror, secondary mirror, and focal plane assembly. Thus, any alignment variations between the two boresights can be observed and accounted for.
Document ID
19950050897
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Lau, Kenneth
(Jet Propulsion Laboratory, California Inst. of Tech., Pasadena, CA US, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publisher: ISTS Editorial Board
Subject Category
Astronomy
Accession Number
95A82496
Distribution Limits
Public
Copyright
Other

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