Abstract: A laser frequency conversion system with ultraviolet-damage mitigation includes a nonlinear crystal for frequency converting a laser beam, and a one-dimensional beam expander arranged to receive the laser beam from the nonlinear crystal and expand a first transverse dimension of the laser beam. This expansion protects subsequent optical elements from ultraviolet damage. To mitigate ultraviolet damage to the nonlinear crystal and the beam expander, the system also includes one or more translation stages configured to translate the nonlinear crystal and the beam expander along a translation direction that is orthogonal to the first transverse dimension of the laser beam and non-parallel to a propagation direction of the laser beam through the nonlinear crystal and the beam expander.

Abstract: In harmonic-generating laser apparatus, plane-polarized fundamental radiation of a laser is converted to harmonic radiation by an optically nonlinear crystal. The power of harmonic radiation generated by the apparatus is selectively varied by selectively rotating the plane of polarization of fundamental radiation entering the optically nonlinear crystal.

Abstract: In harmonic-generating laser apparatus, plane-polarized fundamental radiation of a laser is converted to harmonic radiation by an optically nonlinear crystal. The power of harmonic radiation generated by the apparatus is selectively varied by selectively rotating the plane of polarization of fundamental radiation entering the optically nonlinear crystal.

Abstract: A laser system includes an optically pumped laser resonator that produces a fundamental-wavelength beam. A temperature-tuned frequency converter outside the laser resonator converts a portion of the fundamental-wavelength beam to a frequency-converted beam. The frequency converter includes at least one temperature-tuned optically nonlinear crystal. The power and position of the frequency-converted beam are dependent on the temperature of the optically nonlinear crystal and the optical pumping power. The power and position of the frequency-converted beam are monitored. The temperature of the optically nonlinear crystal is adjusted to maintain the frequency-converted beam at a predetermined position. The optical pump power is adjusted to maintain the power of the frequency-converted beam at a predetermined level.

Abstract: A method of operating a continuously pumped, Q-switched laser to provide trains of pulses for laser operations is disclosed. The laser includes a solid-state gain-medium that exhibits a thermal-lensing effect on being optically pumped. Pulse delivery is controlled by a Q-switch that is in a normally-open state when the laser is not delivering pulses. This allows the laser to deliver CW laser radiation when pulses are not being delivered. A train of pulses is delivered by repeatedly interrupting the CW operation by closing then reopening the Q-switch. When the Q-switch reopens after the interruption, the laser delivers a pulse of laser radiation, then resumes delivery of CW operation until the next interruption. The interruption periods may be varied to provide pulses of different peak power in a pulse train.

Abstract: A method for operating an extracavity frequency-converted solid-state laser for performing a laser processing operation is disclosed. The laser has a laser-resonator including an optically-pumped gain-medium. The resonator is configured to compensate for a predetermined range of thermal lensing in the gain-medium. An optically-nonlinear crystal located outside the resonator converts fundamental laser radiation delivered by the resonator into frequency converted radiation. The laser processing operation is performed by a train of pulses of the frequency-converted radiation having sufficient power to perform the processing operation. The power of frequency-converted radiation is dependent on delivery parameters of the laser radiation from the laser-resonator. The laser is operated in a manner which provides that the resonator delivers effectively the same average power of fundamental laser radiation before and during the laser processing operation.