Appts. altering refractive index of interferometer arm - has second or comparison beam passed to reference mirror while first beam returns to splitter

摘要

The optical length of path of an interferometer arm is changed in interference measurements of relatively short lengths or length changes, by changing the refractive index of the light guiding medium. The refractive index is changed by changing the pressure of this medium. The path of light to be regulated in a recipient is transferred and the internal pressure is changed. Monochromatic light (1) is divided by the beam splitter (2). The first or measuring beam (3) is passed to a mirror (5) and returned to the beam splitter (2). The second or comparison beam (4) is passed to a reference mirror (6) and returned.