PURPOSE: To enable real-time measurement while not affected by extraneous light, by incorporating laser transmitting and receiving sections into the same substrate while a laser beam shaped into a square wave with a chopper is used to perform a synchronous detection.
CONSTITUTION: Laser transmitting and receiving sections are incorporated into the same substrate while a laser light 41 from a laser oscillator 4 is shaped into a square wave with a chopper 5. It is made to irradiate a corner cube reflection mirror 8 and the reflected light thereof is received with a light receiving element 74. A reference signal B and a measurement signal A as obtained by synchronous detection of outputs of the light receiving elements 72 and 74 by a reference signal of the chopper 5 are processed with a division circuit 103 and the concentration of dust in a measuring space is measured from a propagation loss. Thus, outputs of the light receiving elements 72 and 74 are measured as AC components thereby eliminating effect of extraneous light while processing circuits of the measuring light are incorporated into the same substrate thereby enabling real-time measurement.
TAKAHASHI HIDEMI
YAMADA OSAMU
NAITO HIROYUKI
| JPS6123947A | 1986-02-01 | |||
| JPS6123943A | 1986-02-01 |