公开(公告)号：CA1124798A

公开(公告)日：1982-06-01

申请号：CA339220

申请日：1979-11-06

Applicant: IBM

Inventor： BAPST URS H ,  GFELLER FRITZ ,  VETTIGER PETER

IPC: G01J1/42 ,  G01J1/44 ,  G02F2/00 ,  G02F2/02 ,  G06K7/10 ,  H04B10/114 ,  H04B9/00

Abstract: ARRANGEMENT FOR SEPARATING AN OPTICAL SIGNAL FROM AMBIENT LIGHT An arrangement for separating ambient light from an optical data signal, comprising an interference filter having a passband which matches the wavelength of the optical data signal, and two photo diodes which are so arranged that one photo diode receives the light transmitted through the interference filter, and the other receives the light reflected from the filter. A variable aperture or an additional simple filter (5) is provided to adjust the transmitted and reflected portions of the ambient light to one another. Output signals of the photo diodes are subtracted from each other in a compensation circuit. This results in compensation of the ambient light components so that an output signal from the compensation circuit only depends on the actual data signal. SZ9-78-003