Patent ID: 7352463

Claim:
A method of measuring the concentration level of a preselected gas in an environment, comprising: (1) continuously moving a stream of sample gas from the environment through a confined testing area within a detecting instrument; (2) energizing a light source to emit a light beam of a frequency that is highly absorbed by the preselected gas; (3) splitting said light beam into three components; (4) passing a first component of said light beam to a first photo detector for providing a first electrical signal indicative of the intensity of said light beam; (5) passing a second component of said light beam multiple times through said confined testing area and thence to a second photo detector for providing a second electrical signal indicative of a concentration measurement corresponding to a lower concentration level; (6) passing a third component of said light beam over a reduced length path through said confined testing area and thence to a third photo detector for providing a third electrical signal indicative of a concentration measurement corresponding to a higher concentration level; and (7) employing said first, second, and third electrical signals for determining the concentration level of said preselected gas in said stream of sample gas.