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Laser Induced Luminescence

IP.com Disclosure Number: IPCOM000095370D
Original Publication Date: 1965-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Eisenthal, KB: AUTHOR [+2]

Abstract

A giant-pulsed, unfocused laser of approximately 5 to 10 megawatts power induces luminescence in air. This luminescence is attributable to foreign particles. Pure gas, such as helium, nitrogen and oxygen, do not show such an effect. It is not due to the water content in the air.

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Laser Induced Luminescence

A giant-pulsed, unfocused laser of approximately 5 to 10 megawatts power induces luminescence in air. This luminescence is attributable to foreign particles. Pure gas, such as helium, nitrogen and oxygen, do not show such an effect. It is not due to the water content in the air.

This luminescence is in the blue-green region of the electromagnetic spectrum. It has a non-exponential decay with the major component decaying within nanoseconds after excitation. The remainder of the luminescence continues for a few microseconds. Increasing the concentration of foreign particles in the air sample, e.g., smoke particles, substantially increases the luminescence.

By directing the luminescence through a lens to a photomultiplier connected to an oscilloscope, an accurate measurement of the number of particles in the air sample can be made. Moreover, by using a filter or spectrograph, some of the particles can be identified by either their characteristic fluorescent spectra, viz. benzpyrene, or their decomposition luminescence, viz. biphenyl. Some inorganic particles can be recognized by their ionization spectra.

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