Patent ID: 8157439
Filing Date: 2012-04-17
Classification: G01J,G01K

Abstract:
1. A method of calibrating a temperature measurement device, the method comprising: directing light towards a first side of a calibration wafer, at least part of the calibration wafer having an optical absorption at a first known wavelength that varies with temperature and having an optical path length at a second known wavelength that varies with temperature; heating the calibration wafer; measuring an absorption characteristic of the calibration wafer at the first known wavelength to determine an absolute temperature value; making at least a first measurement and a second measurement of a value of an optical property that is sensitive to the optical path length of the light being directed through at least part of the calibration wafer, wherein the first measurement and the second measurement are performed at different temperatures of the calibration wafer; determining a change in temperature based upon the measured values that are sensitive to the optical path length through at least part of the calibration wafer; and calibrating a temperature measurement device by correlating readings of the temperature measurement device with both the measurement of the absolute temperature value and the measurement of the change in temperature.