Browse Prior Art Database

Trace Gas Analyzer Using Diode Arrays

IP.com Disclosure Number: IPCOM000075978D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Onton, A: AUTHOR

Abstract

Most trace gasses of interest in the atmosphere have vibration-rotation energy levels with spacings that correspond to near infrared wave-lengths. These gasses will absorb infrared radiation at characteristic wavelengths to an extent that is proportional to trace gas concentration. Measurement of the absorption constants of the atmosphere at these characteristic wavelengths will give a direct measure of trace gas concentration.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 62% of the total text.

Page 1 of 2

Trace Gas Analyzer Using Diode Arrays

Most trace gasses of interest in the atmosphere have vibration-rotation energy levels with spacings that correspond to near infrared wave-lengths. These gasses will absorb infrared radiation at characteristic wavelengths to an extent that is proportional to trace gas concentration. Measurement of the absorption constants of the atmosphere at these characteristic wavelengths will give a direct measure of trace gas concentration.

Fig. 1 shows a side view of a spectrometer, while Fig. 2 is a top view of this spectrometer. The device is simple and portable, using electroluminescent (EL) diodes. A baffled box 1 eliminates external light. Inside the box, pairs of EL diodes 2 are mounted symmetrically with respect to the axis of symmetry of spherical mirror 3, so that each diode of a pair is focussed at the other member of the pair. A screwdriver adjustment is used to bring the diodes into mutual fine focus. One diode of each pair is utilized as an emitter at a wave-length in an absorption band of the trace gas, while the other is used as the detector.

Detector current can be calibrated as a function of trace gas concentration in the laboratory, with given voltages on both the emitter and the detector. To measure different gasses, the device is switched to other pairs of diodes which have emission peak centered on the absorption band of other trace gasses.

To account for light scattered by particulate matter in the gas, the emitter-...