Mathematical Corrections Applied to Laser Radar Measurements Made Through a Cryogenic Vacuum Chamber Window

Abstract

The direct sequel to the 2010 chamber-window work. Laser radar measurements were made through a vacuum chamber window for cryogenic metrology of targets on two James Webb Space Telescope alignment fixtures, and the beam passed through as many as four different optical environments on the way: the air outside the chamber, the window itself, the chamber environment, and the glass of a solid glass retroreflector target. The range and pointing errors that imparted reached 22 mm – roughly half the total single-pass glass path. This paper is the correction: custom MATLAB software employing real ray tracing to recover the true coordinates in post-processing.