15 October 2012 Measurement of the accumulation of water ice on optical components in cryogenic vacuum environments
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Abstract
An experiment was performed to study and measure the deposition of water (H2O) ice on optical component surfaces under high-vacuum cryogenic conditions. Water was introduced into a cryogenic vacuum chamber via a hydrated molecular sieve zeolite housed in a valved external chamber, through an effusion cell, and impinged upon a quartz-crystal microbalance (QCM) and first-surface gold-plated mirror. A laser and photodiode setup external to the vacuum chamber monitored the multiple-beam interference reflectance of the ice-mirror configuration while the QCM measured the mass deposition. Data acquired and analyzed from this experiment indicate that water ice under these conditions accumulates on optical component surfaces as a thin film up to thicknesses over 45 microns and can be detected and measured by nonintrusive optical methods based upon multiple-beam interference phenomena. The QCM, a well-established measurement technique, was used to validate the interferometer.
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Trevor M. Moeller, Trevor M. Moeller, L. Montgomery Smith, L. Montgomery Smith, Frank G. Collins, Frank G. Collins, Jesse M. Labello, Jesse M. Labello, James P. Rogers, James P. Rogers, Heard S. Lowry, Heard S. Lowry, Dustin H. Crider, Dustin H. Crider, "Measurement of the accumulation of water ice on optical components in cryogenic vacuum environments", Proc. SPIE 8492, Optical System Contamination: Effects, Measurements, and Control 2012, 849207 (15 October 2012); doi: 10.1117/12.929089; https://doi.org/10.1117/12.929089
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