19 Sep 2008
Holographic glass with superior transparency and reflectivity will improve the performance of laser projection displays.
Volume Bragg grating (VBG) elements boasting higher transparency in the red, green and blue, along with higher reflectivity in the near-infrared, have been developed by PD-LD,US.
Enhancing the quality of the glass used for production of the VBG elements resulted in more efficient and stable conversion of infrared light into visible light, and could lead to significant improvements in holographic glasses used in laser displays.
"The improved glass leads to higher yield from wafers and VBG elements, and higher power from laser light engines," Uri Abrams of PD-LD told optics.org. "The result is holographic glass suitable for the most demanding display applications, along with lower costs."
The breakthrough was achieved by fine-tuning the actual composition of the glass, as well as some of the process parameters of the VBG development and heat treatment processes. A number of physical changes were necessary before the Bragg grating could be formed. "Controlling the size of the silver clusters in the glass material allows us to maximise transparency while at the same time minimizing scatter," explained Abrams.
Achieving a high level of optical transparency while maintaining the grating's efficiency posed a challenge, according to Abrams. "The optimization of these two factors tend to run in opposite directions, and the trick was to satisfy stringent requirements for the efficiency and transparency at the same time."
PD-LD's next step will be to upscale the newly developed production of the improved glass, in order to meet the cost targets of laser light engine manufacturers for VBG elements used in projection displays.