Send to:

Choose Destination
See comment in PubMed Commons below
Appl Opt. 2013 Jul 10;52(20):4820-6. doi: 10.1364/AO.52.004820.

Determination of the index inhomogeneity of transparent isotropic optical material with a dual Sagnac interferometer.

Author information

  • 1Raja Ramanna Centre for Advanced Technology, Department of Atomic Energy, Indore, India.


A technique for the measurement of inhomogeneity of optical glass, fused silica, etc., using a Sagnac interferometer (SI) has been presented. An SI produces a pair of laterally separated, mutually parallel, collimated beams with orthogonal planes of polarization, i.e., p and s polarizations from an expanded, linearly polarized (45°) collimated He-Ne (632.8 nm) input laser beam. The p and s beams pass through a liquid-filled cell with plane parallel glass windows. The test glass with plane parallel end surfaces is kept in the path of the p beam in the index matching liquid, while the s beam traverses a parallel path through the liquid. Another SI recombines the emergent p and s beams by removing the lateral shear. A quarter-wave plate transforms the state of polarization of the beams to opposite circular polarizations of which the components selected by a linear polarizer interfere to form Fizeau fringes. Polarization phase shifting interferometery has been applied to determine the optical path difference (OPD) variations. The OPD variation without the test glass is subtracted from that with test glass to eliminate the effect of system aberration. The results for a phosphate laser glass sample have been presented.

PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk