| 摘要 |
PCT No. PCT/EP91/01855 Sec. 371 Date Jul. 24, 1992 Sec. 102(e) Date Jul. 24, 1992 PCT Filed Sep. 27, 1991 PCT Pub. No. WO92/06389 PCT Pub. Date Apr. 16, 1992.The invention relates to a device for measuring the speed or length of a moved surface, where a measuring light beam from a laser is used. The laser light beam reflected from the surface to be measured is frequency-shifted by the Doppler effect so that the overlaying of the outgoing light beam and the incoming one results in a beat which is a measure of the speed of the surface. Before the speed can be determined, digital signals occurring in large numbers must be processed in an evaluation system. The evaluation system is characterized in that there is downstream of a counter intended for detecting the incoming signals and having a high counting speed an intermediate store which is connected to an adding mechanism for pulse-wise monitoring of the counter contents. A control mechanism handles coordination of the counter, the intermediate store and the adding mechanism, upstream of which is a pulse generator. Counting results are added in the adding mechanism and occur at a substantially lower speed than the individual measuring signals.
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