FIELD: physics.
SUBSTANCE: proposed device comprises laser radiation source, first optical transducer and second optical transducer. Laser radiation source is arranged on first lateral side to emit coherent laser beam towards second lateral side. First optical transducer is arranged on second lateral side to receive coherent laser beam and measure its intensity. Second optical transducer is arranged on one of the sides, top or bottom. Note here that with foreign object present in cash acceptor laser beam intensity received by first optical transducer is reduced and, at least, a portion of coherent laser beam reflected, retracted, diffracted or dissipated by foreign object is received by second optical transducer.
EFFECT: higher resolution of detection.
19 cl, 12 dwg
