GB1379769A - Distance measurement systems - Google Patents

Abstract

1379769 Photo-electric profilometers SIEMENS AG 31 Jan 1972 [19 March 1971] 4357/72 Heading G1A [Also in Division H4] A system for determining a profile 8 comprises a laser transmitter 1 coupled to an acousto-optical light deflector 4, a detector 9 and computing means supplied by signals representing the angles α and # or α and the transit time of the light from transmitter to detector. The transmitter comprises laser oscillator 2 and devices 3, 5 to expand the beam. The detector comprises an entry diaphragm 10, optical system 12 and grid 13 made of individual light-sensitive elements 14 to determine angle #. The light is deflected at various angles by deflector 4 according to the ultrasonic frequency being propagated through the deflection crystal, the beam being made to scan profile 8. Knowing α, # and the distance between transmitter and detector along reference line 15, distance 16, and hence the profile, can be determined. In the embodiments of Figs.2, 4 (not shown) the angle α and the transit time are used. The embodiment of (Fig.2) utilizes an amplitude modulator 17 to give the signal in Fig.3a (not shown), the phase ## of the received signal, Fig.3b (not shown) with respect to the transmitted signal being used to determine the transit time. A further embodiment, (Fig.4), utilizes an axially mode coupled laser to measure the transit time. The beam may be deflected in two planes to determine a three dimensional contour and the laser may be pulsed.