| 摘要 |
A gas sample chamber that is particularly advantageous for use with a semiconductor laser has the form of an elongated hollow tube (44) with a specularly reflective inside surface (50), a semiconductor laser (12) located at one end of the tube and a detector (34) located at the opposite end of the tube. In one embodiment, apertures (52, 54) in the wall of the tube permit a gas to enter and leave the sample chamber by free diffusion. In another embodiment the gas flows into the hollow tube (44) from a pressurized source through a port (64) or is drawn through the tube by a suction pump. In other embodiments, the tube is partitioned into two successive sections by means of a window (70) located within the tube. The window is transparent to radiation of two different wavelengths that coincide with the absorption bands of two different gases. The semiconductor laser is tuned to these wavelengths successively so that two gas components can be detected and measured simultaneously. |
