초록 ▼

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

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.

대표청구항 ▼

[ We claim:] [1.] A photo-acoustic leak detection system for detecting a gas leaking from a component, comprising:at least one laser beam for optically exciting the gas, wherein said beam is incident on at least a portion of the component and having a wavelength which is absorbed by the gas, the gas

[ We claim:] [1.] A photo-acoustic leak detection system for detecting a gas leaking from a component, comprising:at least one laser beam for optically exciting the gas, wherein said beam is incident on at least a portion of the component and having a wavelength which is absorbed by the gas, the gas emitting a photo-acoustic signal when the gas absorbs light from said beam;said beam being pulsed at a pulse frequency, said pulse frequency selected such that the magnitude of background acoustic noise at said pulse frequency is at a predetermined low level, wherein said predetermined low level of background acoustic noise creates a photo-acoustic signal to background acoustic noise ratio which is greater than one-to-one, said pulse frequency being related to a detection frequency of said photo-acoustic signal;acoustic sensor means, for receiving said photo-acoustic signal and for providing a sensor signal indicative of said photo-acoustic signal; anda signal processor, which receives said sensor signal and provides an output signal indicative of the leak in the component.