PURPOSE: To measure the extent of variation in optical loss with high precision, by splitting light from a light source into two and detecting light passed through a body to be measured and light arriving directly through two photodetectors respectively, and comparing their output ratio with a reference value.
CONSTITUTION: Projection light with power P from the light source 6 is branched by an optical branching device 7 with an N:1 branching ratio; one light component is passed through the body 1 to be measured which has the extent γ of variation in loss and detected by a photodetector 3 with a photoelectric conersion coefficient (k), and the other light component is detected by a detector 3' with a photoelectric conversion coefficient (k'). A divider 9 with a coefficient (d) divides the output of the detector 3 by the output of an attenuator 8 with the extent A of attenuation for the output of the photodetector 3 and a subtracter 5 subtracts the reference voltage E2 of a reference power source 4 from the output V1 of the division to obtain an output V2. The divider is so adjusted that when γ=0, the output of the divider 8 is (d). Further, when V2=0 and N=1, V2=dγ while the body to be measured is disturbed (γ≠0), measuring the amount of optical loss with high precision.
SHIRASAKI YUUICHI
FUJISE MASAYUKI
ASAKAWA KENICHI
| JPS5126080A | 1976-03-03 |
| US3730627A | 1973-05-01 |