Patent ID: 6570650
Filing Date: 2003-05-27
Classification: G01B,G01J

Abstract:
A method of designing an optical spectrum of an illumination light beam within an optical inspection system, the method comprising:determining a set of conditions for inspecting a film on a sample by directing an illumination light beam at the sample, where at least a portion of the illumination light beam is reflected off the sample and used to generate an image of at least a portion of the film on the sample, wherein the determined set of conditions affect color variation in the image; and determining a plurality of peak wavelength values for the optical spectrum of the illumination light beam so as to control color variation in the image of the film portion, the determination of the peak wavelengths being based on the determined set of conditions and a selected thickness of the film, the determined peak wavelengths being wavelengths within the spectrum that have a maximum intensity value as compared to neighboring wavelengths and the determined peak wavelengths being between a wavelength range of a light source of the illumination beam.