An optical pulse extender includes a delay loop formed by a plurality of mirrors
and a graded reflectivity beamsplitter. The mirrors and the beamsplitter are configured
and aligned such that a pulse to be broadened makes a predetermined number of round
trips in the delay loop and is incident on a different zone of the beamsplitter
after each round trip. The different zones of the beamsplitter have different reflection
values and different transmission values. These values are selected such that the
pulse extender delivers a plurality of temporally and spatially separated replica
pulses each thereof having about the same energy. The delivered replica pulses
together provide an extended pulse having a longer duration than the input pulse.
The replica pulses may be passed through a beam homogenizer to spatially homogenize
the temporal characteristics of the extended pulse.