US 7,514,268 B2
Method for identifying contaminants
Paul H. Shelley, Lakewood, Wash. (US); and Diane R. LaRiviere, Seattle, Wash. (US)
Assigned to The Boeing Company, Chicago, Ill. (US)
Filed on Nov. 24, 2003, as Appl. No. 10/720,766.
Prior Publication US 2005/0124074 A1, Jun. 09, 2005
This patent is subject to a terminal disclaimer.
Int. Cl. G01N 24/00 (2006.01); G01N 21/62 (2006.01); G01T 1/167 (2006.01); G01T 1/169 (2006.01); G01J 5/02 (2006.01)
U.S. Cl. 436—173  [436/171; 250/339.01; 250/301] 160 Claims
 
1. A non-destructive method for identifying a contaminant on a substrate, the method comprising:
exposing the substrate to a multi-frequency infrared energy source;
determining at least two infrared energy absorbance peaks, the first absorbance peak at a first wavenumber, and the second absorbance peak at a second wavenumber; and
identifying the contaminant on the surface by correlating the at least two absorbance peaks to the known absorbance peaks of a contaminant at the first and second wavenumbers.