Testing an optical window of a small wedge angle: effect of multiple reflections
Wyant College of Optical Sciences(University of Arizona)
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Testing an optical window of a small wedge angle: effect of multiple reflections
- Author:
Chiayu Ai, James C. Wyant
Multiple reflections between two surfaces of a window introduce a fixed pattern error in optical measurements. Spurious reflections usually introduce errors into the measurement results obtained with laser phaseshifting interferometry. For a Fizeau interferometer, work has been done to reduce or eliminate the effect of the multiple reflections between the test and reference surfaces. One way to remove these spurious reflections is to use a reasonably large wedge so that the interference fringes formed by the two surfaces are too dense for the detector to resolve. However, this method does not work if the wedge angle is small, e.g., several arcseconds. By tilting both the window and the return mirror properly, it is possible to remove the effect of multiple reflections of a window.
