Abstract: Apparatus for measuring the temperature of an electrically heated pot which uses the Planck formula and employs an infrared reflective hemisphere; first and second infrared wave guides, and first and second infrared filters and infrared detectors as well as a calculating device.

Abstract: Apparatus adapted for use in measuring emissivity of a semiconductor wafer having a radiant energy reflecting surface includes a hollow integrating sphere having first and second spaced apart openings and having an inner surface upon which radiant energy can be distributed. The wafer is disposed with its reflecting surface adjacent the second opening. A first radiant energy detector is disposed on the inner surface of the sphere to detect the distributed energy. First means directs a beam of radiant energy through the first opening in the sphere in such manner that the beam passes through the sphere and the second opening to strike the wafer reflecting surface and is thereupon reflected into the sphere, the reflected energy being distributed upon the inner surface of the sphere and being detected by said first detector.