| 摘要 |
<p>PURPOSE:To-enable a variety of gases to be measured by using only one set of light transmission paths. CONSTITUTION:A plurality of semiconductor lasers 1a and 1b with an absorption line of a single gas as an oscillation line are prepared for a specific gas to be measured and the semiconductor lasers 1a and 1b are modulated at each separate high frequency by laser drive means 17a and 17b. Then, a laser beam from the semiconductor lasers 1a and 1b which are modulated is merged into one light by a branch coupler 11 and then it is guided to a test cell 9 through an optical fiber for outward trip 6, and then a light which is transmitted within the test cell 9 is received by an optical fiber for returning trip 7 and then is guided to a photo detector 12. Furthermore, a specific component within this detection output is subjected to phase-sensitive detection by measuring means 18a and 18b, thus enabling each type of gas concentration within the test cell 9 to be measured simultaneously.</p> |
