Patent ID: 6114700
Filing Date: 2000-09-05
Classification: G01N

Abstract:
An instrument for non-dispersive infrared (NDIR) measurement of the concentration of an infrared-absorptive gas species in a gas sample, comprising:an elongated sample cell having an inlet and an outlet, and infrared-transparent windows at opposed ends of said cell;an infrared-emitting lamp juxtaposed to the outer surface of the window at a first end of said cell;a first pyroelectric detector juxtaposed to the outer surface of the window disposed at the opposed end of said cell;means for supplying a square wave drive signal of controllable amplitude to said lamp;means for processing a signal provided by said pyroelectric detector responsive to the intensity of infrared radiation from said lamp incident thereon, to yield an output signal proportional to the infrared absorptivity of a gas sample in said cell; andmeans for determining the concentration of the infrared-absorptive gas species in said cell responsive to said output signal, said means for determining compensating said output signal responsive to a leakage factor L, characteristic of the absorption spectrum of the gas species within the cell with respect to radiation from said lamp.