Mechanism of topography formation during CO2 laser texturing of silicate glasses

• Published in: Journal of applied physics 1998-09, Vol.84 (5), p.2897-2905
• Main Authors: Bennett, Ted D., Krajnovich, Douglas J., Li, Lei, Wan, Dujiang
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.368396

A theoretical picture is advanced to explain experimental results of CO2 laser texturing of silicate glasses. Common characteristics among several glass types are found that corroborate observations made by other investigators and establish features of glass laser texture. The principal experimental results include increasing bump height with pulse energy (above some threshold); bump width scales with the bump height; annealing, before or after laser texture, reduces bump heights; and finally, further growth in bump height occurs with a finite number of laser pulses subsequent to the first. Explanations for these results have been unified in terms of a “fictive temperature map” that relates microstructure to the thermal history of the glass. On this map, the glass transition temperature identifies a fictive temperature at which the rate of change of temperature is comparable to the rate of change of the microstructure. Therefore, the time scale imposed by the laser pulse can elevate the transition temperature of the glass, making accessible high fictive temperatures to the heat affected zone. As a result of this description we can offer explanations to important characteristics of glass laser texturing, perhaps most notably the nonlinear threshold dependence of bump height on pulse energy. We can also explain the observed bump growth with multiple laser pulses, the effect of chemical strengthening, and the effect of annealing before or after laser texturing.