| 摘要 |
The invention relates to an electro-optical device for measuring absolute distances in relation to a target. Apart from a modulation of the beam polarisation required by the Fizeau method, the invention provides that the modulation means has a modulator crystal (8; 7) with electrodes which are connected to a variable direct current voltage force (11; 10). A control device (19) is provided which triggers determination of the value of the modulation phase in the range of minimal luminosity when the associated modulation frequency is obtained in steps for different direct current voltage values over a complete period of basic polarisation of the modulator crystal. Said device also stores and averages the values measured and when there is an average value deviating from zero repeats the measurement at a slightly changed modulation frequency; it also determines by interpolation the modulation frequency associated with the modulation phase mean value zero. The measuring device is particularly suitable for connection with a tracking system based on interferometry.
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