Measuring the effective pulse duration of nanosecond and femtosecond laser pulses for laser-induced damage experiments

We report on our approach to measure the quantity named effective pulse duration as defined in the ISO 21254-1:2011 standard, which deals with laser-induced damage (LID) threshold measurements. The approach is applied to measure pulses from two laser sources: an injection-seeded electro-optically Q-switched Nd:YAG nanosecond system with 10-Hz pulse repetition frequency, and a fully integrated Ti:sapphire laser with 150–400 fs and 2-kHz pulse repetition frequency. For comparison, the full-width-half-maximum (FWHM) of the same pulses is also measured. The analysis and description of the measurement process, the experimental results, and the corresponding uncertainties are presented. A smaller combined uncertainty is obtained for the effective pulse duration than for the FWHM-defined pulse duration for each time scale involved in experiments. This suggests that the effective pulse duration is the appropriate parameter to characterize the pulse duration in LID experiments.