| 摘要 |
PROBLEM TO BE SOLVED: To enable a light level monitoring module and light level monitoring circuit to detect an output light level and a reflected light level by one photodiode. SOLUTION: The module and circuit are equipped with an optical coupler 1 formed of a glass body having a coupler film 11 formed on at least one surface, an attenuating element 2 formed of a glass body having an attenuation film 21 on at least one surface, and one photodiode 3. Then the optical coupler 1 and attenuating element 2 are so arranged that light which is made incident on the optical coupler 1 is branched by the coupler film 11 and exits from the optical coupler 1 toward the attenuating element 2 is made incident on the attenuation film 21 formed on the attenuating element 2 at right angles. Further, the optical coupler 1 and photodiode 3 are so arranged that light which is reflected by the attenuating element 2 and made incident on the optical coupler 11 again is made incident on the sensitive area of the photodiode 3. |
