US 5,394,244 A · Ambient air refracture index measuring device

Abstract

An improved laser refractometer (10) employing a interferometer optical component (12), an object mirror (14) and an etalon (16). The etalon (16) is moved in the path of a plurality of reference beams (22, 24) and a plurality of measurement beams (26, 28) such that the reference beams (22, 24) travel through a vacuum within the etalon while the measurement beams (26, 28) travel a like distance through the etalon (16) in ambient air. In varying the distance traveled by the laser beams (22, 24, 26, 28) within the etalon (16) any interference fringes detected by an interference fringe detection device (20) are attributable to differences in the optical paths of the measurement beams (26, 28) as compared to that of the reference beams (22, 24) which, in turn, is entirely attributable to the ambient index of refraction. In a first preferred embodiment of the improved refractometer (10) the angular distance between a pair of plates (30, 32) is varied by rotation of the etalon (16). In an alternate embodiment of the etalon (516), the distance between plates (530, 532) is varied by linear displacement of the etalon (516).

Claims19

Dependent claims

An improved refractometer comprising:

a laser emitting device for emitting a first laser beam and a second laser beam;
an object mirror;
an interference fringe detector for detecting interference fringes caused by changes in the optical path of the first laser beam as compared to the optical path of the second laser beam;
an interferometer optical component for separating the first laser beam from the second laser beam, and further for directing both of the laser beams toward said object mirror, and further for directing the laser beams from said object mirror into said interference fringe detector;
and
an etalon inserted in the path of the laser beams between said interferometer optical component and said object mirror such that the first laser beam passes through an enclosed evacuated passage in said etalon and the second laser beam passes through said etalon and outside the enclosed evacuated passage;
wherein
said etalon is movably mounted in relation to the laser beams such that the length of the path through the enclosed evacuated passage is variable according to the position of said etalon.

5 more elements

Dependencies are inferred from the claim text.

Ambient air refracture index measuring device

Life of this patent

Ambient air refracture index measuring device

Life of this patent

Abstract

Claims19