A singlet telescope is provided for reshaping the laser beam to a larger
or smaller diameter while maintaining the inherent quality of the beam.
Applications for the singlet telescope include intercavity expansion to
accommodate the damage thresh-old of various components, expansion of
beams to match the size of different wavelengths for final collimation,
and shrinking of beams to provide high irradiance for nonlinear processes
such as optical parametric oscillation and frequency doubling, with the
above applications usually requiring low power magnification or
demagnification. Problems involving the utilization of these telescopes
over wide temperature ranges and ghost reflections in which a light is
reflected back to a pumping laser are minimized with the singlet
construction, with the ghost reflections potentially creating damage of
components including self-damage or breakdown of air, as well as damage
to a Q-switched resonator which causes pre-lasing.