| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical level monitor by which lowering of a light receiving level is found at first sight and capable of confirming the range of the light receiving level. SOLUTION: Light to transmit an optical fiber from a light source is received in a PD5, an optical level monitor 9 is connected at an output side of the PD5 and an optical level is measured. The optical level monitor 9 consists of an OP AMP (1) to amplify an output of the PD5, an OP AMP (2) to compare a signal with a reference value, a transistor Tr to output a control signal of display according to a comparison result and a display (LED) 10 to be turned ON or OFF by the control signal. In the OP AMP (2), voltage V2 at an input side is compared with reference voltage V6 , when V6 >V2 , differential voltage V3 becomes positive and the LED 10 is turned ON, when V6 <V2 , the differential voltage V3 becomes negative and the LED 10 is turned OFF. A fact whether the light receiving level is lowered to the reference voltage V6 or not is judged at first sight by the ON, OFF of the LED 10. |
