Provided is a laser device that includes a laser chamber in which a pair of discharge electrodes are disposed; a line narrowing optical system including a grating disposed in a position outside the laser chamber; a beam expander optical system that increases a diameter of a light beam, outputted from the laser chamber and traveling toward the grating, in a first direction parallel to a discharge direction between the discharge electrodes and in a second direction orthogonal to the discharge direction; and a holding platform that is formed as a component separate from the laser chamber and the grating, holds the beam expander optical system, and forms along with the beam expander optical system a beam expander unit.

A line narrowing module includes a prism that refracts laser light in a first plane, a grating that disperses the laser light in the first plane, first to fourth elements, and a rotation mechanism and narrows the linewidth of the laser light. The second element is supported between the first and fourth elements by the first element. The rotation mechanism rotates the second element relative to the first element around an axis intersecting the first plane. The prism is located between the second and fourth elements and so supported by the second element that the rotation mechanism rotates the prism and the second element. The third element has elasticity and is compressed and located between the prism and the fourth element. The fourth element receives reaction force from the compressed third element. The second element is mechanically independent of the fourth element in the rotational direction of the rotation mechanism.

A laser-beam power-modulation system includes an acousto-optic modulator (AOM) to receive a laser beam and separate the laser beam into a primary beam and a plurality of diffracted beams based on an input signal. The power of the primary beam depends on the input signal. The system also includes a slit to transmit the primary beam and dump the plurality of diffracted beams, a controller to generate a control signal based at least in part on feedback indicative of the power of the primary beam or the power of a beam generated using the primary beam, and a driver to generate the input signal based at least in part on the control signal.

The invention relates to a method for maintaining the synchronism of a Fourier Domain Mode Locked (FDML) laser, the FDML laser comprising at least one dispersion-compensated resonator with at least one variably wavelength-selective optical filter, the laser light circulating in the resonator at a circulation frequency, and the wavelength selectivity of the filter being repeatedly modified at a syntonising rate, the FDML laser being synchronous when the syntonising rate is an integral multiple of the circulation frequency. Said method is characterised by the following steps: a) at least a portion of the laser light is coupled out of the resonator; b) at least a portion of the decoupled laser light is detected by means of a photodetector; c) amplitudes in the measuring signal of the photodetector are counted during successive counting intervals; and d) the circulation frequency or syntonising rate is adjusted such that the ratios of the count value to the lengths of the counting intervals are maintained within a predetermined nominal value interval.

A method includes driving, while producing a burst of pulses at a pulse repetition rate, a spectral feature adjuster among a set of discrete states at a frequency correlated with the pulse repetition rate; and in between the production of the bursts of pulses (while no pulses are being produced), driving the spectral feature adjuster according to a driving signal defined by a set of parameters. Each discrete state corresponds to a discrete value of a spectral feature. The method includes ensuring that the spectral feature adjuster is in one of the discrete states that corresponds to a discrete value of the spectral feature of the amplified light beam when a pulse in the next burst is produced by adjusting one or more of: an instruction to the lithography exposure apparatus, the driving signal to the spectral feature adjuster, and/or the instruction to the optical source.

A spectral feature selection apparatus includes a dispersive optical element arranged to interact with a pulsed light beam; three or more refractive optical elements arranged in a path of the pulsed light beam between the dispersive optical element and a pulsed optical source; and one or more actuation systems, each actuation system associated with a refractive optical element and configured to rotate the associated refractive optical element to thereby adjust a spectral feature of the pulsed light beam. At least one of the actuation systems is a rapid actuation system that includes a rapid actuator configured to rotate its associated refractive optical element about a rotation axis. The rapid actuator includes a rotary stepper motor having a rotation shaft that rotates about a shaft axis that is parallel with the rotation axis of the associated refractive optical element.

A wavelength measuring device configured to detect a wavelength of ultraviolet laser light outputted from a laser resonator with at least one etalon, the wavelength measuring device includes: a first housing having an interior space being sealed and accommodating the etalon, an input window through which the ultraviolet laser light enters to the first housing, the input window being provided at a first opening of the first housing, a first sealing member configured to seal a gap between a rim part of the input window and a circumferential portion of the first opening, a shielding film provided between the rim part of the input window and the first sealing member and configured to shield the first sealing member from the ultraviolet laser light coming from the input window, and a diffusing element provided outside of the first housing and configured to diffuse the ultraviolet laser light before being incident on the input window.

Apparatus for and methods of controlling wavelength in a system for producing laser radiation at more than one wavelength (color) in which one or more actuators control wavelength in response to being supplied with a waveform. The characteristics of the waveform, and/or of a controller for controlling the waveform, are determined based on a current repetition rate of the laser. A current repetition rate is determined and if it is new then a new waveform is commanded. Also disclosed is a system in which a correction depending on repetition rate is applied to an ILC algorithm determining a wavelength.

The laser device includes a laser crystal, a resonator including a pair of mirrors between which the laser crystal is interposed, a Q switch that is disposed on an optical path of the resonator and controls a Q value of the resonator, and a Brewster thin-film polarizer that is disposed on the optical path of the resonator and transmits selectively p-polarized light. The thin-film polarizer has wavelength selectivity in which a p-polarized light transmittance at a first wavelength exhibiting a maximum gain of the laser crystal is 5% or more to 25% or less, the p-polarized light transmittance monotonically increases as a wavelength becomes longer than the first wavelength, and a maximum transmittance is exhibited at a third wavelength. The laser device oscillates laser light at a second wavelength that is a wavelength longer than the first wavelength and shorter than or equal to the third wavelength.

A laser gas regeneration system for an excimer laser includes a first pipe capable of supplying a laser chamber with a first laser gas, a second pipe capable of supplying the laser chamber with a second laser gas having a halogen gas concentration higher than that of the first laser gas, a third pipe allowing a gas exhausted from the laser chamber to pass therethrough, a gas refiner that refines the gas having passed through the third pipe, a branch that causes the refined gas to divide and flow into a fourth pipe and a fifth pipe, a first regenerated gas supplier that supplies the first pipe with a gas having divided and flowed into the fourth pipe, and a second regenerated gas supplier that adds a halogen gas to a gas having divided and flowed into the fifth pipe and supplies the second pipe with the halogen-added gas.