Stephen L Day

US Patent:

48915181, Jan 2, 1990

Filed:

Aug 21, 1987

Appl. No.:

7/087872

Inventors:

Stephen Day - Trumbull CT

Assignee:

The Foxboro Company - Foxboro MA

International Classification:

G01J 100

US Classification:

250339

Abstract:

A gas detector for detecting a combination of at least three gasses employs an optical filter having a spectral passband shaped and positioned to produce substantially equal responses from a single detector to a given concentration of any single one of the gasses or to a concentration any two or more of the gasses. A filter spectrum encloses substantially equal areas of the absorption spectra of the gasses. The filter includes a spectral bandwidth, cut-on maximum wavelength, cut-on slope, cut-off maximum wavelength and cut-off slope, adjusted for controlling the areas of the gas absorption spectra enclosed therein.