US Patent 7316969 Method and apparatus for thermally treating substrates

The object of the disclosure is to measure temperature using pyrometers, in a simple and economic way, enabling precise temperature measurement, even for low temperatures. The disclosure presents an apparatus and method for thermally treating substrates, wherein the substrate is exposed to at least a first and at least a second radiation; the predetermined wavelengths of the first radiation are absorbed between the first radiation source and the substrate; a radiation from the substrate is measured in the predetermined wavelength using a radiation detector arranged on the same side as a second radiation source; the second radiation from the second radiation source is modulated and determined.