A sensor (200, 900) comprising an illuminator (212, 500, 804, 832, 858,
904), a receiver (216, 400, 420, 460, 480, 808, 836, 862, 924) and an
analyzer (240) for detecting and identifying an analyte having a
characteristic absorption band that is present in a sample region (208,
812, 824, 874, 922). The illuminator includes an illumination source
(220) for illuminating the sample region with spectral energy across at
least a portion of the characteristic absorption band. The receiver
includes a detector (228, 404, 424, 460, 484, 866, 928) for sensing
predetermined portions of the spectral energy band and for creating a
sample spectral data vector (236). The analyzer uses the spectral data
vector and known characteristic data to detect and identify the analyte.