A radiation system for controlling pulses of radiation comprising an optical element configured to interact with the pulses of radiation to control a characteristic of the pulses of radiation, an actuator configured to actuate the optical element according to a control signal received from a controller, the control signal at least partially depending on a reference pulse repetition rate of the radiation system and, a processor configured to receive pulse information from the controller and use the pulse information to determine an adjustment to the control signal. The radiation system may be used to improve an accuracy of a lithographic apparatus operating in a multi-focal imaging mode.

A laser device may include a chamber accommodating a pair of discharge electrodes, a grating provided outside the chamber, first beam-expanding optics provided between the chamber and the grating and configured to expand a beam width of light outputted from the chamber at least in a first direction perpendicular to a direction of discharge between the pair of discharge electrodes, and second beam-expanding optics having a plurality of prisms provided between the chamber and the grating, the second beam-expanding optics being configured to expand a beam width of light outputted from the chamber at least in a second direction parallel to the direction of discharge between the pair of discharge electrodes.

A narrow band laser apparatus may include: a laser resonator; a pair of discharge electrodes; a power supply; a first wavelength measurement device configured to output a first measurement result; a second wavelength measurement device configured to output a second measurement result; and a control unit. The control unit calibrates the first measurement result, based on a difference between the second measurement result derived when the control unit controls the power supply to apply a pulsed voltage to the pair of discharge electrodes with a first repetition frequency and the second measurement result derived when the control unit controls the power supply to apply the pulsed voltage to the pair of discharge electrodes with a second repetition frequency, the second repetition frequency being higher than the first repetition frequency.

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.

A leak check method for a laser device includes exposing a closed space accommodating laser medium gas to the atmosphere, isolating the closed space from the atmosphere after exposing the closed space to the atmosphere, introducing neon-containing gas containing neon gas to the closed space, and determining whether or not the neon gas is leaking to outside of the closed space.

Disclosed is a laser discharge chamber in which useful lifetime is extended by local electrical tuning using one or a combination of design of the chamber internal geometry, placement and distribution of components within the chamber such as electrodes, current returns, and capacitors, and selective electrical isolation of portions of the components.

A laser chamber of an excimer laser apparatus includes a container including a first member and a second member and configured to accommodate a laser gas in the container and a seal member disposed between two seal surfaces facing each other, a seal surface of the first member and a seal surface of the second member. A laser-gas-side surface of the seal member is made of fluorine-based rubber, and an atmosphere-side surface of the seal member is formed of a film configured to suppress atmosphere transmission.

A high average and peak power single transverse mode laser system is operative to output ultrashort single mode (SM) pulses in femtosecond-, picosecond- or nanosecond-pulse duration range at a kW to MW peak power level. The disclosed system deploys master oscillator power amplifier configuration (MOPA) including a SM fiber seed, outputting a pulsed signal beam at or near 1030 nm wavelength, and a Yb crystal booster. The booster is end-pumped by a pump beam output from a SM or low-mode CW fiber laser at a pump wavelength in a 1000-1020 nm wavelength range so that the signal and pump wavelengths are selected to have an ultra-low-quantum defect of less than 3%.

A semiconductor laser device includes semiconductor laser elements emitting laser beams having different wavelengths from each other and a partial reflection element. The semiconductor laser elements and the partial reflection element constitute respective ends of an external resonator. Further, there is a transmissive wavelength dispersion element located on optical paths of the laser beams between the semiconductor laser elements and the partial reflection element and at a position where the laser beams are superimposed. The transmissive wavelength dispersion element has a wavelength dispersion property, and changes traveling directions of the laser beams in a first plane including the optical axes of the laser beams to combine the laser beams to have one optical axis. Also, there is an asymmetric refraction optical element located on an optical path between the transmissive wavelength dispersion element and the partial reflection element.

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.