| 摘要 |
PROBLEM TO BE SOLVED: To realize a resolution high enough to detect a smoke particle one by one by receiving a scattering light efficiently regardless of the intensity distribution pattern of laser light. SOLUTION: The light source image, i.e., the near field pattern, of the exit face of a laser diode emitting a laser light having a field component E in a given direction is focused through a focus lens 9 at a position 10 in a smoke detecting region where a suction air flow 13 passes. A photodetector 6 is disposed on an optical axis 12 being set on a plane substantially parallel with the direction of the field component E of laser light passing through the light source image focus position 10 in the smoke detecting region. The photodetector receives the light scattered on smoke particles passing through the light source image focus position 10 or thereabout. |
