Threshold Fluence versus Absorption Coefficient

Jellinek and Si inivasan, assuming photochemical etching, observed diat for homogeneous polymers, Fth decreased in an inversely linear manner wilh die absorption coefficient oc through the relation 

Furzikov proposed a thermal model to describe the etching rate that led to an inverse square root dependence of the threshold fluence on a modified absorption coefficient, which includes possible changes in the singlephoton absorption coefficient owing to thermal diffusion. This inverse square root relation is given by 

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Fig, 2 The threshold fluence (Fq) and axFo versus the absorption coefficient (a) for PMMA doped with pyrene. (T. J. Chuang, H. Hiraoka, A. Modi, 1988)... 

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