This Small Business Innovation Research (SBIR) Phase I project proposes to develop an improved method for measuring temperature during manufacture of visible and ultra-violet light emitting diodes (LED's). Unfortunately, LED substrates such as sapphire do not allow one to use currently available instruments because at wavelengths where the substrate is opaque process gases absorb radiation affecting temperature measurements. In this project it is planned to develop a method to correct for process gas absorption of radiation for use with substrates such as sapphire and silicon carbide. This will allow improved real time in-situ temperature measurement, giving improved manufacturing yields, better data for development work, and lower costs for these materials. The instrument will be initially developed for use with gallium nitride (GaN) processes used for LED manufacture. Improved process temperature measurement will lead to faster development through a better understanding of the process and higher manufacturing yields due to improved temperature control. Commercially, the project could enhance manufacturing productivity and improve national competitiveness in wide bandgap materials manufacturing by providing better process control data. The reduced development and manufacturing costs will improve US competitiveness in this critical technology area. Also, reduced costs of LED components will speed widespread adoption of LED lighting lowering US energy costs and bringing economic and environmental benefits