Patent ID: 9188486
Filing Date: 2015-11-17
Classification: G01J

Abstract:
1. A computer implemented method for correcting light reflectance measurements made by a spectrometer of a sample by determining the portion of the light reflectance measurement values due to second-order-diffracted light, the method comprising: performing obtaining, with a spectrophotometer at plurality of wavelengths in a wavelength range, a first plurality of measurements values of light reflected off of a first calibration tile, wherein the wavelength range includes wavelengths of light that, when passed through a diffraction grating, produce second-order diffracted light at another wavelength within the wavelength range and storing the first plurality of measurements in a first memory location accessible by a processor; performing, with the spectrophotometer at the plurality of wavelengths in the wavelength range, a second plurality of measurements values of light reflected off of a second reflection calibration tile, where the second reflection calibration tile is configured to reflect fewer wavelengths of light than the first calibration tile and storing the second plurality of measurements in a second memory location accessible by a processor; determining, with a processor, for a portion of the wavelength range subject to second-order-diffracted light, the relationship between the obtained first reflection measurement values within the wavelength range and the second reflection measurement values; generating, with a processor, using the determined relationship, at least one compensation value used to correct the first reflection measurement values to eliminate the effects of second-order-diffracted light in the first reflection measurement values; performing with the spectrometer a plurality of sample measurements for a sample at different wavelengths in the wavelength range; correcting with a processor, the sample measurements using the compensation values for each of the plurality of sample measurements to obtain corrected light reflectance measurement values that only include first-order-diffracted light; and transmitting, with a processor, to a user an updated record of the corrected sample measurements for the sample.