Method for determining the temperature of a semi-transparent radiating body

The present invention is generally directed to a system and process for accurately determining the temperature of an object, such as a semi-conductive wafer, by sampling from the object radiation being emitted at a particular wavelength. In one embodiment, a single reflective device is placed adjacent to the radiating object. The reflective device includes areas of high reflectivity and areas of low reflectivity. The radiation being emitted by the object is sampled within both locations generating two different sets of radiation measurements. The measurements are then analyzed and a correction factor is computed based on the optical characteristics of the reflective device and the optical characteristics of the wafer. The correction factor is then used to more accurately determine the temperature of the wafer. In an alternative embodiment, if the radiating body is semi-transparent, a reflective device is placed on each side of the object, which compensates for the transparency of the object.