Patent ID: 7400658

Claim:
Laser apparatus comprising: a laser-resonator arranged to deliver fundamental-wavelength optical pulses having a pulse-duration, the fundamental-wavelength optical pulses being temporally equispaced by a pulse-repetition period τ and delivered at a pulse-repetition frequency (PRF) equal to 1/τ; and an optical delay loop including one or more optically nonlinear crystals and arranged to receive the fundamental-wavelength optical pulses, the optical delay loop being configured and arranged such that each fundamental-wavelength pulse is converted within the optical delay loop into a harmonic-wavelength pulse and further arranged to convert each of the harmonic-wavelength pulses into a plurality of replicas thereof, with the replicas of each harmonic-wavelength pulse being temporally spaced apart by τ/N±Δτ, where N is an integer equal to or greater than 2 and Δτ is about equal to or greater than the pulse-duration of fundamental-wavelength optical pulses, the optical delay loop being further arranged to deliver bursts of the harmonic-wavelength pulse-replicas at a burst-repetition frequency equal to the PRF of the fundamental-wavelength optical pulses multiplied by N, with each burst including replicas of different ones of the harmonic-wavelength optical pulses.