Bichannel radiation detection method

A method for accurately determining in non-destructive, non-contacting manner the temperature within a processing chamber of an object that is selected from a population of similar objects using a plurality of pyrometers that operate in different wavebands on the radiation received through a wall of the processing chamber from an object within the chamber, the method comprising the steps of:

• substantially calibrating the responses of each pyrometer on a reference object within the chamber to yield corrected responses at at least one reference temperature;
• selecting a master object from the population of objects;
• determining master emissivities of the master object at a reference temperature within the chamber from the corrected responses of each of the calibrated pyrometers;
• altering the corrected pyrometer responses relative to the master emissivities to provide extreme values of emissivity from the corrected pyrometer responses to radiation at the reference temperature from within the chamber of each of a set of objects selected from said population which exhibit emissivities near extremes of the range of emissivities of objects in the population;
• providing signal values determined for each of said set of objects selected from said population from the responses of the corrected pyrometers which are altered i accordance with the master emissivities;
• determining a correlation between said signal values and the emissivity values of the objects providing the extreme values;
• elevating another object selected from said population to a temperature within the chamber near the reference temperature;
• calculating the emissivity values of said another object from the corrected responses of the pyrometers in accordance with said correlation;
• and
• altering the emissivity values of said another object within the chamber in accordance with the calculated emissivity values of said another object for determining the temperature of said another object within the chamber.