The CellaCrystal PA 45 has been developed for optical temperature measurement in the production of graphite, graphene and crystals. The pyrometer, which is based on the quotient measuring method, is characterised by a very large measuring range with a constant high resolution of < 0.1 K over the entire measuring range. With its very high long-term stability, the device fulfils the requirements for the high measuring accuracy needed in production processes. With the help of the through-the-lens sighting or the video camera, the pyrometer can be precisely aligned to the measuring point.