Houghton University’s Phase-Shifting Laser Interferometer for the Study of Thin Metal Films
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Date
2025-05-05
Authors
Yelle, Luke
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Houghton University
Abstract
A modified Twyman-Green phase-shifting laser interferometer was built by Houghton University to determine the thickness of thin metal films. A 635 nm beam is split by a cube beam splitter. Lenses expand and culminate the beams to a diameter of 83 mm. One beam reflects off the thin film sample. The other reflects off a 10 cm diameter, 𝜆10 flat, phase-shifting reference mirror moving via piezoelectric ceramic stacks, controlled by an Arduino. Both are then combined to form an interference pattern on a screen. The intensity of a given point on the interference pattern changes sinusoidally with the change of position of the reference mirror. A set of pictures is taken at different reference positions by an HP high-definition camera and is then processed by a Processing code. Each pixel of the image set is fit to determine its effective intensity phase shift, which is then used to map the topography of the film surface.
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