2003 Volume 87 Issue 5 Pages 328-333
The tungsten microcavity light source and the tungsten cluster light source have recently attracted interest as nextgeneration light sources that have a high luminous efficacy and a long lifetime. The complex index of refraction of tungsten requires a 2000 to 6500K operating temperature to evaluate the luminous efficacy and lifetime. Little is, known however, about the complex index of tungsten at such high temperatures. We consider that ellipsometry is an effective measuring method because it can measure complex index of refraction without metallic contact at these temperatures. We thus designed and fabricated an ellipsometer and used it to measure the complex index of refraction of tungsten at room temperature. As a result, we established that with an improved ellipsometer the complex index of refraction of tungsten could be measured at 2000-6500K. In this paper, we report on the problems of measuring metallic complex index of refraction precisely using ellipsometry and on the achieved measurement accuracy.
