ACOUSTIC DEVICE FOR MEASURING DIMENSIONS OF ARTICLES Russian patent published in 1995 - IPC

FIELD: measurement technology. SUBSTANCE: device is realized according to shadow-free technique and has a photodetector made in the form of an optically controlled delay line composed of piezoelectric plate 3 of acoustic line, identical interdigital transducers 4,5 which pins are located on the surface of the plate at a predetermined distance from each other. Odd(even) pins of the interdigital transducers are galvanically coupled with current conducting bus 6 and even(odd) pins are spaced from corresponding buses 7,8 by a gap overlapped by corresponding portions of photoconducting layer 9. Due to photoeffect in layer 9 upon illumination of the surface of plate 2 the pins of interdigital transducers 4,5 beyond the shadow zone from article 10 are switched with buses 7,8. Thus the information of the article dimensions is converted into a delay time of optically controlled delay line 2. Discretization step is reduced due to the fact that accuracy in general is limited only by lithography possibilities at manufacturing the pins of interdigital transducers 4,5. EFFECT: enhanced accuracy due to reduced discretization step of photodetector elements. 2 dwg