| 摘要 |
PURPOSE:To facilitate a supervision over laser light without entailing a loss of laser light, by providing a light polarizer, that can be inserted into and extracted from an optical path, at one part of the optical path between a semiconductor laser and infrared-ray detector. CONSTITUTION:To cause laser light before absorption to enter detector 7 for the measurement of the concentration of pollutional gas in the air, small plane mirror 9 is rotated to the position shown by dotted line 12 by about 135 deg., and consequently the laser light is reflected to the left as shown by dotted lines (d) and then focuses on the photodetection surface of detector 7. Since the optical path in this case is formed only in enclosure A, adsorption of the laser light up to photodetector 7 can perfectly be ignored and the output of detector 7 at this time corresponds to the power of the laser light before the adsorption. To make the laser light, projected out and reflected, to enter enclosure A again, small plane mirror 9 is only put off the optical path. Thus, a supervision over the laser light can be made easy without entailing a loss of the laser light. |
