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.