INTENSITY MODULATION TYPE PHOTO-SENSOR AND PHOTO-CURRENT/VOLTAGE SENSOR

摘要

[PROBLEMS] To minimize affect given to a sensor output and improve measurement accuracy even when a light source has a ripple. [MEANS FOR SOLVING PROBLEMS] In an intensity modulation type photo-sensor, light from a light source (1) is introduced to a sensor head (6) and the light intensity is modulated according to an AC measurement object (such as current i) changing temporally. The modulated light is received by a light reception element (81) and converted into an electric signal. From the ratio of its AC component As and DC component Ds, a normalized reception signal Xs indicating the modulation degree is obtained to acquire a value of an AC measurement object. Furthermore, a part of the light coming into a sensor head (6) is separated/received to obtain a reference signal Vr. From the ratio of the AC component Ar and the DC component Dr of the reference signal, a normalized reference signal Xr is obtained. This normalized reference signal Xr is subtracted from the normalized reception signal Xs so as to reduce the noise component and improve accuracy.