Online calibration of laser performance as a function of the repetition rate at which the laser is operated is disclosed. The calibration can be periodic and carried out during a scheduled during a non-exposure period. Various criteria can be used to automatically select the repetition rates that result in reliable in-spec performance. The reliable values of repetition rates are then made available to the scanner as allowed values and the laser/scanner system is then permitted to use those allowed repetition rates.

A laser device includes a first laser medium and a second laser medium that have a first surface and a second surface opposite to the first surface, and receive input of excitation light and seed light from the first surface side to amplify the seed light, a holder that holds the first laser medium and the second laser medium; and a pair of cooling units that cool the first laser medium and the second laser medium according to change in volume of a refrigerant.

A laser apparatus that can generate a high-quality laser beam is provided. The laser apparatus is provided with a laser medium and an insulation layer. The laser medium has a first surface and a second surface. Incident laser light is incident on the first surface. The second surface totally reflects the incident laser light that is incident to the second surface at an incident angle equal to or larger than a critical angle. The insulation layer covers a second area of the second surface that surrounds a first area of the second surface, the first area totally reflecting the incident laser light. The laser medium is exposed in the first area.

A laser system including: A. a laser apparatus configured to output a pulse laser beam; B. an optical pulse stretcher including a delay optical path for expanding a pulse width of the pulse laser beam; and C. a phase optical element included in the delay optical path and having a function of spatially and randomly shifting a phase of the pulse laser beam. The phase optical element includes a plurality of types of cells providing different amounts of phase shift to the pulse laser beam and arranged irregularly in any direction.

A system includes a laser source operable to provide a laser beam, a laser amplifier having a gain medium operable to provide energy to the laser beam when the laser beam passes through the laser amplifier, and a residual gain monitor operable to provide a probe beam and operable to derive a residual gain of the laser amplifier from the probe beam when the probe beam passes through the laser amplifier while being offset from the laser beam in time or in path.

A method of additive manufacture utilizing a uniform laser beam is disclosed. A seed laser projects a laser beam having a first laser beam shape. At least one pre-amplifier is positioned to receive the laser beam and amplify laser beam power. A homogenizer is positioned to receive the amplified laser beam from the at least one pre-amplifier and alter the first laser beam shape into a second laser beam shape. A main amplifier is positioned to receive the amplified laser beam having the second laser beam shape from the homogenizer and amplify laser beam power.

An argon fluoride (ArF) laser system for inertial nuclear fusion energy production with lower required laser energy than other laser drivers. An Argon fluoride laser system uniformly illuminates a spherical capsule comprising an outer ablator wall surrounding an inner shell comprising the fusion fuel. The laser beams are adjusted spectrally to achieve a bandwidth of up to 12 THz and a coherence time as low as 80 femtoseconds that in combination with the short wavelength (193 nm) suppress laser plasma instabilities. Uniform spherical acceleration causes the inner shell of the target capsule to form a spherical assembly of compressed fuel surrounding a hot spot that has sufficient temperature, density and size to ignite and initiate a thermonuclear burn.

An optical system element includes a first enclosure designed for receiving in circulation a functional fluid and at least one inlet and/or outlet window located on the first enclosure and through which a light beam can pass. The inlet and/or outlet window includes two viewports which delimit a spacer cavity adjacent to the first enclosure. The spacer cavity is designed to receive a second fluid with a predetermined optical index and is equipped with a device for adjusting the pressure therein. Degradation of a beam during its passage through the inlet and/or outlet window can be limited by careful selection of the optical index of the second fluid and the pressure in the spacer cavity.

A laser oscillator unit includes an amplification unit configured to amplify laser light and emit amplified laser light from an emitting portion; a case covering the amplification unit; and an outer support mechanism and an inner support mechanism provided on the case. The case is formed with a window portion. An outer movable leg allows the case to slide in a radial direction around an outer fixed leg. An inner movable leg allows the amplification unit to slide in the radial direction around an inner fixed leg. A straight line passing through a center of the outer fixed leg and a center of the inner fixed leg intersects with a straight line passing through the emitting portion and the window, and a laser optical axis emitted from the emitting portion and a laser optical axis emitted from the window portion coincide with each other.

Online calibration of laser performance as a function of the repetition rate at which the laser is operated is disclosed. The calibration can be periodic and carried out during a scheduled during a non-exposure period. Various criteria can be used to automatically select the repetition rates that result in reliable in-spec performance. The reliable values of repetition rates are then made available to the scanner as allowed values and the laser/scanner system is then permitted to use those allowed repetition rates.