The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 16, 2002
Filed:
Mar. 29, 1999
Donald W. Phillion, Dublin, CA (US);
The Regents of the University of California, Oakland, CA (US);
Abstract
A constant volume gas cell optical phase-shifter, particularly applicable for phase-shifting interferometry, contains a sealed volume of atmospheric gas at a pressure somewhat different than atmospheric. An optical window is present at each end of the cell, and as the length of the cell is changed, the optical path length of a laser beam traversing the cell changes. The cell comprises movable coaxial tubes with seals and a volume equalizing opening. Because the cell is constant volume, the pressure, temperature, and density of the contained gas do not change as the cell changes length. This produces an exactly linear relationship between the change in the length of the gas cell and the change in optical phase of the laser beam traversing it. Because the refractive index difference between the gas inside and the atmosphere outside is very much the same, a large motion must be made to change the optical phase by the small fraction of a wavelength that is required by phase-shifting interferometry for its phase step. This motion can be made to great fractional accuracy.