High-accuracy measurements of the normal specular reflectance.

The French Laser Megajoule (LMJ) is designed and constructed by the French Commissariat à l'Energie Atomique (CEA). Its amplifying section needs highly reflective multilayer mirrors for the flash lamps. To monitor and improve the coating process, the reflectors have to be characterized to high accuracy. The described spectrophotometer is designed to measure normal specular reflectance with high repeatability by using a small spot size of 100 mum. Results are compared with ellipsometric measurements. The instrument can also perform spatial characterization to detect coating nonuniformity.