Patent ID: 7580132
Filing Date: 2009-08-25
Classification: G01P,G01S,Y02A

Abstract:
1. A device for measuring a Doppler frequency shift, comprising: an optical signal channel delivering an optical signal light beam illuminating a reference medium, a portion of the optical signal light beam illuminating the reference medium being returned by the reference medium; a reference channel delivering a reference light beam for detecting the Doppler frequency shift, the frequency shift being determined from the difference in frequency between the light signal illuminating the reference medium and the portion of the optical signal light beam returned by the reference medium; at least two wavelength-shifted light radiation sources, a first light radiating source generating the optical signal light beam for the optical signal channel and a second light radiating source generating a reference signal light beam for the reference channel, a second optical polarization-maintaining coupler having another first and another second optical coupling input and an optical output connected to an input of a second optical detector followed by a second amplifier, the second polarization-maintaining coupler receiving, at the other first optical coupling input, the optical signal generated by the second light radiation source and, at the other second optical coupling input, the optical signal generated by the first light radiation source, the second optical detector delivering a second beat signal Br between the two light beams generated by the two light radiations sources; and a mixer into which are injected, via respective inputs, the amplified first and second beat signals, Bs and Br, the mixer configured to deliver an analog signal carrying the Doppler shift at an output of the mixer.