| 摘要 |
This invention provides a long open path optical gas analyser having broad band light emitting and detecting means. Light of selected wavelengths are produced from the light source by wavelength selecting means, passed through an open space sample, are reflected back through the sample area and are directed to detecting means where signal processing means are provided to indicate the presence of a particular gas or gases and the concentration thereof. In a preferred embodiment the broad band input light beam is directed into an acousto-optic cell to which acoustic signals are applied and which interact with the input beam to diffract a selected band width of light which is subsequently directed through said open path. |
