Abstract: The present invention is directed to an apparatus and process for filtering light in a thermal processing chamber. In particular, the apparatus of the present invention includes a first spectral filter spaced apart from a second spectral filter. The first spectral filter is spaced apart from the second spectral filter so as to define a cooling fluid channel therebetween through which a cooling fluid can be circulated. In order to prevent thermal radiation being emitted by the light source from interfering with the operation of a radiation sensing device contained in the chamber, the first spectral filter absorbs most of the thermal radiation being emitted by the light source at the operating wavelength of the radiation sensing device. The second spectral filter, on the other hand, is substantially transparent to thermal radiation at the operating wavelength of the radiation sensing device.

Abstract: The present invention is generally directed to a system and process for accurately determining the temperature of an object, such as a semiconductive wafer, by sampling from the object radiation being emitted at a particular wavelength. In particular, a 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. Through this method, the emissivity of the wafer has only a minor influence on the calculated temperature.