| 摘要 |
<p>PURPOSE:To accurately detect the existence of normal-temperature gas in the space of long distance by emitting laser light beams having the same power from the end of a branched fiber which is brached by an optical fiber coupler every detected space. CONSTITUTION:The pulse-state laser light beams A and B are alternately generated from laser light sources 1 and 2 respectively and transmitted to an optical fiber 20 through an optical coupler 8 and a main optical branching device 9. The laser light beams A and B are branched to the branched fibers d1-dn by the optical fiber couplers K1-Kn and emitted to a target from collimator lenses L1-Ln respectively. The reflected laser light beams made incident from the ends of the branched fibers d1-dn are con nected to the main optical fiber 20 by the couplers K1-Kn and transmitted to the optical branching device 9. The reflected laser light beams which return are transmitted to a photoelectric converter 10 by the optical branching device 9 and converted into an electrical signal. Next, the converted signal is amplified 11 and amplified 12 in synchronism with the emitting timing of the laser light sources 1 and 2. Then, the laser light beams A and B are averaged 13 and 14 separately and divided 15. The presence or absence and the existing quantity of the gas are detected from the magni tude of the output from the divider 15.</p> |
