Energetic pulses write and draw inside glass

17 Jun 2002

Shine the focus of a pulsed laser beam inside a block of glass and the energy the pulse delivers will mark the point where the focus falls with a little ball of cracks.

Move the pulsed beam and it will write security marks in vehicle window, leave an abstract design to create a paperweight, or a draw a three-dimensional building or a portrait inside a block of glass.

Vitro, a glass company in Minden, Germany, has just installed the latest diode-pumped solid-state lasers for marking glass. The lasers, developed by the Fraunhofer Institute for Laser Technology in Aachen, are well suited to life in industry because they are compact and robust.

When the diode pumps flash they excite a bar containg a lasing material to emit a pulse of light. Diodes are more robust than flashlamps and the solid-state lasing material contains no gas that needs replacing.

These solid-state lasers emit an average power of 100 kW. They produce pulses of 20 ns at a rate of 500 Hz. That means a laser can write 500 points every second each 0.05 to 0.3 mm across. In tests, one laser drew a picture of Aachen cathedral inside a 10 x 10 x 10 cm glass block in a few minutes. JB