| 摘要 |
The invention relates to an analyzer for analysing the spatial spectrum of fluctuations in the optical index of a transparent fluid, comprising a laser L which produces a main beam Pr directed to a zone Z of the fluid, the light Diff scattered by Rayleigh effect in the zone thus illuminated and collected in a defined direction phi , theta with respect to the direction of the main beam Pr being applied to a detector Det, in conjunction with a reference beam OL of the same direction, having a frequency slightly different from that of the main beam Pr (heterodyne detection method); the apparatus comprises a lens L3 whose image focus is situated in the zone Z and which makes the beams Pr and OL which it receives in a direction parallel to its optical axis OX cross over in this zone at a certain angle theta , the main beam Pr having a position which can be varied using an optical device DD making it possible to adjust its distance d from the beam OL and the angle phi of inclination of the observation plane of the scattering. <IMAGE>
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