Low-power fast infrared gas sensor, hand held gas leak detector, and gas monitor utilizing absorptive-photo-acoustic detection

Abstract

A gas sensor for sensing the presence of a gas includes an IR source, a microphone, a reference gas substantially similar to the gas to be detected, a reference body defining a reference chamber therein, the reference chamber having a pressure port coupled to the microphone, and a broad-band optical window through which at least IR wavelengths corresponding to absorption peaks of the predetermined gas may pass. The window is disposed between the IR source and reference chamber. The reference gas is contained within the reference chamber between the optical window and the microphone. The sensor can be included in a hand-held gas detection instrument having power supply, an outer shell, a circuit board assembly including sensor circuitry, a suction pump, actuation controls and status indicators. A probe defining a lumen therethrough supplies the sample gas.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of US Provisional Application No. 60 / 928,000 filed May 7, 2007 under 35 U.S.C. §119(e), the entire disclosure of which is hereby incorporated by reference. technical field [0003] The invention relates to the field of gas detection based on non-dispersive infrared absorption (NDIR). Background technique [0004] NDIR technology has existed for many years as a preferred gas detection method. This technique relies on the fact that gases absorb infrared energy (light) at specific wavelengths, and that different gases have peak absorptions at different wavelengths. This absorption follows the Beer-Lambert law: [0005] T = I 1 I 0 = e - αl [0006] Among them, T is visi...

AI Technical Summary

Problems solved by technology

Second, the thermal time constant of the bulb is very long

Then, significant low-pass filtering is required at the output of the sensor to recover the 1Hz signal, which results in a slower response time

Fourth, the sensor size is too large to be suitable for handheld devices (regardless of the noise problems that may result)

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