INTERFEROMETER AND METHOD FOR MEASURING THE REFRACTIVE INDEX AND OPTICAL PATH LENGTH EFFECTS OF AIR

摘要

A method and apparatus for measuring fluctuations in the refractive index of a gas, such as air, in measurement path (298) comprising light sources (1) for providing two light beams (9, 10) with different wavelengths along the measurement path (298) of an interferometer (260) which are substantially harmonically related to each other and the output beams (103, 104) of the detectors (85, 86) are electronically processed by an electronic processor.