Abstract: Laser-induced damage in an optical material can be mitigated by creating conditions at which light absorption is minimized. Specifically, electrons populating defect energy levels of a band gap in an optical material can be promoted to the conduction band—a process commonly referred to as bleaching. Such bleaching can be accomplished using a predetermined wavelength that ensures minimum energy deposition into the material, ideally promoting electron to just inside the conduction band. In some cases phonon (i.e. thermal) excitation can also be used to achieve higher depopulation rates. In one embodiment, a bleaching light beam having a wavelength longer than that of the laser beam can be combined with the laser beam to depopulate the defect energy levels in the band gap. The bleaching light beam can be propagated in the same direction or intersect the laser beam.

Abstract: A laser for generating an output wavelength of approximately 193.4 nm includes a fundamental laser, an optical parametric generator, a fourth harmonic generator, and a frequency mixing module. The optical parametric generator, which is coupled to the fundamental laser, can generate a down-converted signal. The fourth harmonic generator, which may be coupled to the optical parametric generator or the fundamental laser, can generate a fourth harmonic. The frequency mixing module, which is coupled to the optical parametric generator and the fourth harmonic generator, can generate a laser output at a frequency equal to a sum of the fourth harmonic and twice a frequency of the down-converted signal.

Abstract: An optical system for detecting contaminants and defects on a test surface includes an improved laser system for generating a laser beam and optics directing the laser beam along a path onto the test surface, and producing an illuminated spot thereon. A detector and ellipsoidal mirrored surface are also provided with an axis of symmetry about a line perpendicular to the test surface. In one embodiment, an optical system for detecting anomalies of a sample includes the improved laser system for generating first and second beams, first optics for directing the first beam of radiation onto a first spot on the sample, second optics for directing the second beam onto a second spot on the sample, with the first and second paths at different angles of incidence to the sample surface. In another embodiment, a surface inspection apparatus includes an illumination system configured to focus beams at non-normal incidence angles.

Abstract: A laser for generating an output wavelength of approximately 193.4 nm includes a fundamental laser, an optical parametric generator, a fourth harmonic generator, and a frequency mixing module. The optical parametric generator, which is coupled to the fundamental laser, can generate a down-converted signal. The fourth harmonic generator, which may be coupled to the optical parametric generator or the fundamental laser, can generate a fourth harmonic. The frequency mixing module, which is coupled to the optical parametric generator and the fourth harmonic generator, can generate a laser output at a frequency equal to a sum of the fourth harmonic and twice a frequency of the down-converted signal.

Abstract: A mode-locked laser system operable at low temperature can include an annealed, frequency-conversion crystal and a housing to maintain an annealed condition of the crystal during standard operation at the low temperature. In one embodiment, the crystal can have an increased length. First beam shaping optics can be configured to focus a beam from a light source to an elliptical cross section at a beam waist located in or proximate to the crystal. A harmonic separation block can divide an output from the crystal into beams of different frequencies separated in space. In one embodiment, the mode-locked laser system can further include second beam shaping optics configured to convert an elliptical cross section of the desired frequency beam into a beam with a desired aspect ratio, such as a circular cross section.

Abstract: The passivation of a nonlinear optical crystal for use in an inspection tool includes growing a nonlinear optical crystal in the presence of at least one of fluorine, a fluoride ion and a fluoride-containing compound, mechanically preparing the nonlinear optical crystal, performing an annealing process on the nonlinear optical crystal and exposing the nonlinear optical crystal to a hydrogen-containing or deuterium-containing passivating gas.

Abstract: An improved solid-state laser for generating sub-200 nm light is described. This laser uses a fundamental wavelength between about 1030 nm and 1065 nm to generate the sub-200 nm light. The final frequency conversion stage of the laser creates the sub-200 nm light by mixing a wavelength of approximately 1109 nm with a wavelength of approximately 234 nm. By proper selection of non-linear media, such mixing can be achieved by nearly non-critical phase matching. This mixing results in high conversion efficiency, good stability, and high reliability.

Abstract: A laser for generating an output wavelength of approximately 193.4 nm includes a fundamental laser, an optical parametric generator, a fourth harmonic generator, and a frequency mixing module. The optical parametric generator, which is coupled to the fundamental laser, can generate a down-converted signal. The fourth harmonic generator, which may be coupled to the optical parametric generator or the fundamental laser, can generate a fourth harmonic. The frequency mixing module, which is coupled to the optical parametric generator and the fourth harmonic generator, can generate a laser output at a frequency equal to a sum of the fourth harmonic and twice a frequency of the down-converted signal.

Abstract: Laser-induced damage in an optical material can be mitigated by creating conditions at which light absorption is minimized. Specifically, electrons populating defect energy levels of a band gap in an optical material can be promoted to the conduction band—a process commonly referred to as bleaching. Such bleaching can be accomplished using a predetermined wavelength that ensures minimum energy deposition into the material, ideally promoting electron to just inside the conduction band. In some cases phonon (i.e. thermal) excitation can also be used to achieve higher depopulation rates. In one embodiment, a bleaching light beam having a wavelength longer than that of the laser beam can be combined with the laser beam to depopulate the defect energy levels in the band gap. The bleaching light beam can be propagated in the same direction or intersect the laser beam.

Abstract: Laser-induced damage in an optical material can be mitigated by creating conditions at which light absorption is minimized. Specifically, electrons populating defect energy levels of a band gap in an optical material can be promoted to the conduction band—a process commonly referred to as bleaching. Such bleaching can be accomplished using a predetermined wavelength that ensures minimum energy deposition into the material, ideally promoting electron to just inside the conduction band. In some cases phonon (i.e. thermal) excitation can also be used to achieve higher depopulation rates. In one embodiment, a bleaching light beam having a wavelength longer than that of the laser beam can be combined with the laser beam to depopulate the defect energy levels in the band gap. The bleaching light beam can be propagated in the same direction or intersect the laser beam.

Abstract: Improved laser systems and associated techniques generate an ultra-violet (UV) wavelength of approximately 193.368 nm from a fundamental vacuum wavelength near 1064 nm. Preferred embodiments separate out an unconsumed portion of an input wavelength to at least one stage and redirect that unconsumed portion for use in another stage. The improved laser systems and associated techniques result in less expensive, longer life lasers than those currently being used in the industry. These laser systems can be constructed with readily-available, relatively inexpensive components.

Abstract: The present invention includes an exposure chamber configured to contain a passivating gas having a selected hydrogen concentration, the exposure chamber further configured to contain at least one NLO crystal for exposure to the passivating gas within the chamber, a passivating gas source fluidically connected to the exposure chamber, the passivating gas source configured to supply passivating gas to an interior portion of the exposure chamber, and a substrate configured to hold the NLO crystal within the chamber, the substrate further configured to maintain a temperature of the NLO crystal at or near a selected temperature, the selected temperature being below a melting temperature of the NLO crystal.

Abstract: An improved solid-state laser for generating 193 nm light is described. This laser uses the 6th harmonic of a fundamental wavelength near 1160 nm to generate the 193 nm light. The laser mixes the 1160 nm fundamental wavelength with the 5th harmonic, which is at a wavelength of approximately 232 nm. By proper selection of non-linear media, such mixing can be achieved by nearly non-critical phase matching. This mixing results in high conversion efficiency, good stability, and high reliability.

Abstract: A mode-locked laser system operable at low temperature can include an annealed, frequency-conversion crystal and a housing to maintain an annealed condition of the crystal during standard operation at the low temperature. In one embodiment, the crystal can have an increased length. First beam shaping optics can be configured to focus a beam from a light source to an elliptical cross section at a beam waist located in or proximate to the crystal. A harmonic separation block can divide an output from the crystal into beams of different frequencies separated in space. In one embodiment, the mode-locked laser system can further include second beam shaping optics configured to convert an elliptical cross section of the desired frequency beam into a beam with a desired aspect ratio, such as a circular cross section.

Abstract: A pulse multiplier includes a polarizing beam splitter, a wave plate, and a set of mirrors. The polarizing beam splitter receives an input laser pulse. The wave plate receives light from the polarized beam splitter and generates a first set of pulses and a second set of pulses. The first set of pulses has a different polarization than the second set of pulses. The polarizing beam splitter, the wave plate, and the set of mirrors create a ring cavity. The polarizing beam splitter transmits the first set of pulses as an output of the pulse multiplier and reflects the second set of pulses into the ring cavity. This pulse multiplier can inexpensively reduce the peak power per pulse while increasing the number of pulses per second with minimal total power loss.

Abstract: Laser-induced damage in an optical material can be mitigated by creating conditions at which light absorption is minimized. Specifically, electrons populating defect energy levels of a band gap in an optical material can be promoted to the conduction band—a process commonly referred to as bleaching. Such bleaching can be accomplished using a predetermined wavelength that ensures minimum energy deposition into the material, ideally promoting electron to just inside the conduction band. In some cases phonon (i.e. thermal) excitation can also be used to achieve higher depopulation rates. In one embodiment, a bleaching light beam having a wavelength longer than that of the laser beam can be combined with the laser beam to depopulate the defect energy levels in the band gap. The bleaching light beam can be propagated in the same direction or intersect the laser beam.