| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a light attenuation type smoke detector of which little attenuation is given in reflection light reflected by a reflection mirror before reaching a reception element for smoke detection, and of which laser light source may not be adversely affected due to that reflection light reflected by a reflection mirror is irradiated by the laser light source. SOLUTION: The q-wave of the light from a light source 10 is transmitted and the p-wave of the light from the light is reflected. To the polarization beam splitter PBS1 provided inside a sensor body B1 and the p-wave reflected by the polarization beam splitter PBS1, phase difference of 1/4 wave length is given to emit. The detector has 1/4 wave length plate 50 provided in the sensor body B1, a mirror M1 is placed on the path of the p-wave in which the phase difference of 1/4 wave length is given by the 1/4 wave length plate 50 progresses, and a light receptor for smoke monitoring is placed on the path where the q-wave having reflected at the reflection mirror M1 and passed the 1/4 wave length plate 50 passes the polarization beam splitter PBS1 after passing and progresses.</p> |
