Optical glass for high power digital projection

The light flux of laser based digital projectors is constantly growing. Further, the setup gets more compact. This leads to increasing spatial dependent power densities inside color channel controlling optical systems of high-end laser cinema projectors. It was surprisingly found that high power blue laser irradiation leads to solarization of optical glass, resulting in a decrease of transmission over time. Therefore, SCHOTT started to develop blue laser solarization stable optical glass. A blue laser irradiation setup and spectral photometer measurement facility was established to characterize the solarization effect on optical glass. First very promising results of the development show that it is possible to significantly increase the stability of optical glass against blue laser solarization. This paper discusses the actual status of the development of blue solarization stable optical glass used for digital projection. Solarization results are shown as a function of time and wavelength. Additionally the intensity dependence and saturation of blue laser solarization is addressed.