| 摘要 |
PROBLEM TO BE SOLVED: To measure a current value with no error without being affected by an influence of return light based on a return loss of an optical fiber transmission path.SOLUTION: A photoelectric transducer 20 includes a DC correction processing section 32 between a first DC extraction section 24 and a first division processing section 27. The DC correction processing section performs processing of subtracting a correction value DCset in a DC correction value setup section from an output of the first DC extraction section. Thereby, DCis input in the first division processing section by subtracting the correction value from a DC component (DC+DC) of an optical signal that is input in the photoelectric transducer 20 via a first optical fiber transmission path 15a by a sensor head 12. A degree of modulation calculated by the first division processing section can compensate an error caused by the return loss of the optical fiber transmission path 15a. Consequently, both of degrees of modulation of two signals provided in an addition processing section 30 are free from the influence of the return loss (the return light) of the optical fiber transmission path. |
