Process and apparatus for performing differential refractive index measurements using interference of modulated light beams passing through reference and test samples

摘要

PCT No. PCT/FR93/01054 Sec. 371 Date Aug. 19, 1994 Sec. 102(e) Date Aug. 19, 1994 PCT Filed Oct. 27, 1993 PCT Pub. No. WO94/10552 PCT Pub. Date May 11, 1994.The invention relates to the measurement of the difference between refractive indexes of two media, traversed by a light beam the beams produce an interference figure consisting of fringes having a displacement which is measured. According to the invention, the displacement of the fringes of the interference figure is detected with a photosensitive device and a phase modulation is performed on at least one of the beams and the modulation is controlled in order to obtain a movement of the fringes of the interference figure.