Td. Bennett et al., MECHANISM OF TOPOGRAPHY FORMATION DURING CO2-LASER TEXTURING OF SILICATE-GLASSES, Journal of applied physics, 84(5), 1998, pp. 2897-2905
A theoretical picture is advanced to explain experimental results of C
O2 laser texturing of silicate glasses. Common characteristics among s
everal glass types are found that corroborate observations made by oth
er investigators and establish features of glass laser texture. The pr
incipal 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 h
ave been unified in terms of a ''fictive temperature map'' that relate
s microstructure to the thermal history of the glass. On this map, the
glass transition temperature identifies a fictive temperature at whic
h the rate of change of temperature is comparable to the rate of chang
e of the microstructure. Therefore, the time scale imposed by the lase
r pulse can elevate the transition temperature of the glass, making ac
cessible high fictive temperatures to the heat affected zone. As a res
ult of this description we can offer explanations to important charact
eristics of glass laser texturing, perhaps most notably the nonlinear
threshold dependence of bump height on pulse energy. We can also expla
in the observed bump growth with multiple laser pulses, the effect of
chemical strengthening, and the effect of annealing before or after la
ser texturing. (C) 1998 American Institute of Physics. [S0021-8979(98)
05317-1].