| 摘要 |
A photo-acoustic leak detection system for detecting a gas leaking from a component (30), includes at least one laser beam (20), incident on the component (30) and having a wavelength which is absorbed by the gas, the gas emitting a photo-acoustic signal (36) when the gas absorbs light from the beam (20), the beam (20) being pulsed at a pulse frequency, the pulse frequency being related to a detection frequency of the photo-acoustic signal and being a frequency at which the magnitude of background acoustic noise at the detection frequency is at a predetermined low level, at least one acoustic sensor (40), which receives the photo-acoustic signal (36) and provides a sensor signal on the line (42) indicative thereof to a filter (44) and a synchronous detector (18), which provide a filtered signal on a line (50) to a signal processor (52). The processor (52) provides an output signal on a line (54) indicative of the leak in the component. Setting such pulse frequency to a low level acoustic noise frequency allows the signal-to-noise response to be greatly increased. |
