| 摘要 |
<p>A laser (10) of the type having a cavity (11), front window (12) and Brewster window (13) is tuned to its characteristic lines in its gain envelope by the angular rotational and/or longitudinal movement of grating (14) relative to the cavity axis. The grating (14) is mounted on a turn-table (15) and the angular and longitudinal position of the grating (14) is tuned to one of its characteristic lines as determined by the detector (18). The photoacoustic cell (22) receives a portion of the output beam of the laser (10) and from the absorption characteristics of the gas in the photoacousting cell (22), the identity of the characteristic line of the laser (1) can be determined, together with the corresponding position of the grating (14) for that line.</p> |
