Fiber laser maker IMRA has come up with a method of writing "hidden" symbols in glass that can be revealed by side-illuminating the panel with a low-power laser diode or LED. The idea came about following an optical waveguide writing experiment, where the team discovered some unwanted features that were scattering light & turned the result into a display application. "Because the marks are written inside the glass, the display can be very rugged, less sensitive to the environment & inexpensive," Alan Arai of IMRA's Applications Research Lab said."There is a trade-off between the transparency of the mark when not illuminated & its visibility when illuminated from the side & this requires more study. For more information please see: www.imra.com/
