Bulk damage to optical glasses by repeated laser irradiation

An experimental study was made of the bulk damage to optical glasses by periodically repeated laser pulses of nanosecond duration. Repeated irradiation produced damage at laser pulse energies considerably lower than the damage threshold for single pulses. The cumulative damaged threshold was found to depend on the number and repetition frequency of the laser pulses, laser wavelength, and conditions of focusing of laser radiation inside a sample.