Laser polishes silica micro-optic components

Although much research has been performed on the use of carbon-dioxide (CO2) lasers for polishing glass and fused-silica bulk optics, researchers in the Department of Physics at Heriot-Watt University (Edinburgh, England) have demonstrated, for what they believe to be the first time, efficient surface polishing of fused-silica micro-optic components.

Well-controlled pulses from a planar-waveguide CO2 laser with a wavelength of 10.59 µm-guided by an x-y translation stage-are delivered to the optical surface in two phases: a preheating pulse, followed by a train of pulses with an adjustable duty cycle over the remaining pulse length. The preheating pulse provides a laser-induced surface-temperature increase to melt the silica surface and initiate surface-tension-driven mass flow, while the subsequent polishing pulses control the surface temperature to avoid a loss of material by evaporation with no cracking. Optimization of pulse delivery allows for reduction of micron-scale surface roughness to below 1 nm while preserving the shape of the micro-optic component. In related work, the researchers have also developed a laser-machining technique for the fabrication of custom micro-optic elements. Contact Krzysztof Nowak at[email protected].

Editor’s note: This is a corrected version of a newsbreak that appeared in April 2006 LFW with technical errors.