The contrast of a fiber-optic heterodyne interferometer using 50 μm graded index fibers is investigated as a function of three different fiber optic beam combiners. It is shown that with a beam splitter-type beam com-biner the contrast is 10 dB lower than in a single mode interferometer.
W. L. Glomb,
F. M. Mottier,
"A Multimode Fiber Heterodyne Interferometer", Proc. SPIE 0514, 2nd Intl Conf on Optical Fiber Sensors: OFS'84, (12 November 1984); doi: 10.1117/12.945090; https://doi.org/10.1117/12.945090