GB653887A - Optical apparatus for determining the distribution of the refractive index in a medium - Google Patents

Abstract

653,887. Optical apparatus. STAUB, H., and LABHART, H. Sept. 16, 1948, No. 24364. Convention date, May 31. [A Specification is laid open to inspection under Sect. 91 of the Acts, March 17, 1949.] [Class 97 (i)] In apparatus for determining by interference the distribution of refractive index in a non-homogeneous medium and comprising a plane - parallel transparent plate arranged obliquely to a collimated monochromatic light beam, to divide the latter into two separated beams, one of which passes through a cell adapted to contain the medium, a second plane parallel plate is arranged behind the cell perpendicular to the beams, the front face of which plate reflects one of the beams and the rear face the other, so that one beam returns through the cell, and the two beams are superposed at the first plate to form a combined beam producing interference effects. As shown in Fig. 2, the collimated beam A is divided by the plate P into beams A<SP>1</SP>, A<SP>2</SP>, directed towards the second plate F which, in this case, is formed with a cell Z for the medium. Mirrors F<SP>1</SP>, F<SP>2</SP> return the beams to the plate P to form a combined beam W. A portion F<SP>3</SP> of the plate P may be rendered reflecting. Alternatively the cell Z may be located between the plates P and F. The Specification as open to inspection under Sect. 91 of the Acts describes also modifications in which the mirrors F<SP>1</SP>, F<SP>2</SP> are mounted on a single block or are coplanar, a transparent medium being inserted in one beam to equalize the optical paths. Alternatively one beam may be reflected by the plate P and the other transmitted, mirrors being provided to return the beams to the plate P. The modification shown in Fig. 1 (Cancelled), comprises a collimator L<SP>1</SP> and a vertical slit B<SP>1</SP> producing a narrow monochromatic beam divided by a plate P<SP>1</SP> into beams S<SP>1</SP>, S<SP>2</SP>, one passing through a control cell Z<SP>2</SP> and the other through a cell Z<SP>1</SP> containing the medium under test. A diaphragm B<SP>2</SP> allows the beams S1<SP>1</SP>, S1<SP>2</SP> recombined by a plate P<SP>2</SP> to be focused by lenses L<SP>2</SP>, L<SP>3</SP> on to a photographic plate P. This subject-matter does not appear in the Specification as accepted.