A measuring device for measuring of transverse speed and length of a measurement object

摘要

The speed/size measurement involves one or more laser beam transmitters (2a,2b), each with an intensity modulator (1a,1b) using a different frequency, and a receiver (3), positioned on the same side of the object being measured (4) as the transmitters, which detects the reflected beams (13,14). In the receiver, a frequency selector separates the optical signal from superimposed electrical signals. A narrow-band filer may be used to amplify the signals. The distance in time between the reflected signals, in relation to the known time intervals of the transmissions, indicates the speed (17) and the duration of the signals the length (18) of the object being measured. The method allows for detection of very weak reflected signals via a lock-in technique.