System for separating an optical signal from ambient light

摘要

An arrangement for separating disturbing ambient light from an optical data signal, comprising an interference filter (1), the passband of which matches the wavelength of the optical data signal, and further comprising two photodiodes which are so arranged that one photodiode receives the light (IS, IAT) transmitted through the interference filter, and that the other receives the reflected light (IAR). Adjusting means, e.g., in the form of a settable aperture (4) or an additional simple filter (5) are provided for adjusting the transmitted and reflected portions of the ambient light to each other. Output signal (S1, S2) of both photodiodes are subtracted from each other in compensation circuitry (6). This results in compensation of the ambient light components so that at the output a signal (SR) is available which depends only on the actual data signal (IS).