Method and device for Doppler laser velocimetry with homodyne detection

摘要

The laser velocimeter with homodyne detection is constructed from a laser 1 whose linearly polarised radiation is applied in 10 to an optical system 2 of the Mach-Zender interferometer type. The measurement beam strikes the object, whose velocity is to be measured, either directly or through a telescope 8. The signal beam S and the local oscillator beam OL are produced with a slight angular offset between them before striking a double detector 5. The angular offset is chosen so that the wavefronts of the two beams are offset by a half wavelength over the whole surface of the double detector 5. A comparison of the phases of the signals received by the two detectors gives the sign of the velocity. <IMAGE>