Many applications in materials research and production require accurate, non-contact surface temperature measurements on various materials under a variety of conditions. All such sur-faces emit radiation, which may be used as a measure of their surface temperature, providing the surface's emissivity is known. Emissivity values are usually uncertain leading to errors in conventional radiation pyrometry. This project concerns a new active pyrometer method, wherein the ratio of target reflectances at two separate wavelengths is measured together with the target radiances at these same wavelengths. From these values the surface emissivity may be determined and the target temperature accurately measured for materials having arbitrary surface textures. Researchers are developing a twowavelength actirve pyrometer suitable for a very wide range of temperatures, and for targets having arbitrary surface textures, thereby greatly extending the applications of active pyrometer technology.The potential commercial application as described by the awardee: The new pyrometer would be very useful in materials research on new semiconductor materials, superconducting materials, and others, as well as in the commercial production of many metals, plastics, semiconductors, foods, textiles, etc., needing accurate noq-contacting temperature measurements where conventional pyrometry is not suitable.