DETECTING SURFACE STAINS USING HIGH ABSORBANCE SPECTRAL REGIONS IN THE MID-IR

摘要

Methods and systems for detecting the presence of a substance on a surface are provided. The method can include directing a modulated light beam (e.g., having a wavelength of about 3 µm to about 20 µm) from a light source to a beam expander such that the beam expander widens the diameter of the light beam into an expanded beam. The expanded beam can then be directed onto the surface to form an illuminated area. A specular reflection can then be detected from the illuminated area on the surface in each light cycle, and the presence of the substance on the surface can be determined.