Towards quantification of laser-induced damage phenomena: experimental assessment of absorbed pulse energy via time-resolved digital holography

摘要

In order to correlate laser damaging u001duence with the pertinent theoretical considerations, there were manyattempts in the past to establish reliable damage predicting criterion. Such criterion then could be used toestimate laser u001duence that triggers the damage process in various optical materials. For example, reaching ofmaterials critical property such as - temperature (melting point), - thermoelastic stress, - electron density aregood examples. On the other hand, however, it is already clear that damage mechanism is irradiation condition(wavelengths, pulse duration) and material property dependent. There are no physical restrictions of causingdamage by reaching critical stress without critical electron density and vice versa. Accordingly, total absorbedenergy or absorbed energy density is likely more suited candidate of universal damage criteria as a commondenominator for all critical processes. To our best knowledge, it was never estimated experimentally in thevicinity of the damaging u001duence of optical materials. In this study, we present a novel approach based on pumpprobedigital holographic microscopy that enables quantitative assessment of absorbed energy during the damageprocess in transparent dielectric media. By using this method, a case study is conducted in fused silica glasswith sharply focused infrared laser pulses at 1030 nm central wavelength and 450 fs pulse duration. By doing sowe were able to estimate energy fraction of the incident pulse that is needed to trigger optical damage.