초록 ▼

The invention provides an apparatus for the detection of a selected species in a gas sample and includes a photo-acoustic detector coupled to an infrared radiation source with an acousto-optic tunable filter disposed between the source of infrared radiation and photo-acoustic detector. This combinat

The invention provides an apparatus for the detection of a selected species in a gas sample and includes a photo-acoustic detector coupled to an infrared radiation source with an acousto-optic tunable filter disposed between the source of infrared radiation and photo-acoustic detector. This combination is capable of measuring concentrations of controlled vapors in the parts-per-million range. These measurements may be performed in a few seconds via the portable gas detection and measurement device of this invention.

대표청구항 ▼

An apparatus for the detection of a selected species in a gas sample comprising: a photo-acoustic detector means including walls defining an enclosed chamber with valve means operatively associated with said walls for introducing the gas sample into said chamber and for vacating the gas sample there

An apparatus for the detection of a selected species in a gas sample comprising: a photo-acoustic detector means including walls defining an enclosed chamber with valve means operatively associated with said walls for introducing the gas sample into said chamber and for vacating the gas sample therefrom, and with means for detecting an acoustic disturbance within said chamber, and with window means on opposite sides of said chamber for the passage of infrared radiation therethrough, said enclosed chamber being resonant at 4 kHz; an infrared radiation source means operatively associated with said photo-acoustic detector means wherein a narrow bandwidth portion of infrared radiation is directed through said chamber for interaction with the sample gas in said chamber to generate an acoustic disturbance within said chamber in the presence of a selected species; and an acousto-optic tunable filter disposed between said photo-acoustic detector means and said infrared radiation source means comprising an optically aligned acousto-optic crystal through which infrared radiation is passed, an acoustic transducer means coupled to a variable frequency energy source pulsed at a rate of 4 kHz and to the acousto-optic crystal in order to pulse said acousto-optic tunable filter at a rate of 4 kHz at a selected frequency to launch acoustic waves in the crystal in order to interact with a selected narrow bandwidth portion of the infrared radiation to make said portion distinguishable from the remaining infrared radiation, which narrow portion is a function of the selected frequency of the rf energy and the acoustic waves launched into said crystal wherein the acoustic disturbance within said chamber is a pulsed disturbance at a rate of 4 kHz.