The present invention provides a blue laser transmitter operating at the H-beta Fraunhofer line at 486.13 nm wavelength. The subject blue laser is based on pulsed lasing action in thulium doped into lutetium sesquioxide (Tm:Lu.sub.2O.sub.3). The laser wavelength is restricted by volume

Bragg grating to the vicinity of 1944 nm wavelength. The laser is operated with a q-switch to generate high-energy pulses within the nanosecond regime. The output at the 1944 nm wavelength is then frequency quadrupled in a single pass through non-linear crystals to a wavelength near the center of the H-beta Fraunhofer line. The operation at the 1944 nm wavelength in Tm:Lu.sub.2O.sub.3 is very efficient because this wavelength is located on a shoulder of a substantially broad emission peak at 1945 nm. In addition, at the 1944 nm wavelength, Tm:Lu.sub.2O.sub.3 has only a modest saturation fluence of about 15 J/cm.sup.2, which allows for efficient energy extraction.

A light source apparatus includes a gas discharge stage, a sensing apparatus, an optical arrangement, an adjustment apparatus, and a control apparatus. The gas discharge stage includes an optical amplifier including a chamber configured to hold a gas discharge medium outputting a light beam, and a set of optical elements configured to form an optical resonator around the optical amplifier. The optical arrangement is configured to image light from a plurality of distinct object planes within the gas discharge stage onto the sensing apparatus. The adjustment apparatus is in physical communication with one or more optical components within the gas discharge stage and is configured to modify at least one geometric aspect of the optical components. The control apparatus is communication with the sensing apparatus and the adjustment apparatus and is configured to provide a signal to the adjustment apparatus based on an output from the sensing apparatus.

Apparatus and methods for altering one or more spectral, spatial, or temporal characteristics of a light-emitting device are disclosed. Generally, such apparatus may include a volume Bragg grating (VBG) element that receives input light generated by a light-emitting device, conditions one or more characteristics of the input light, and causes the light-emitting device to generate light having the one or more characteristics of the conditioned light.

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.

The present disclosure is directed to systems and methods for controlling a center wavelength. In one example, a method includes estimating a center wavelength error. The method also includes determining a first actuation amount for a first actuator controlling movement a first prism based on the estimated center wavelength error. The method also includes actuating the first actuator based on the actuation amount. The method also includes determining whether the first prism is off-center. The method also includes, in response to determining that the first prism is off-center, determining a second actuation amount for the first actuator and determining a third actuation amount for a second actuator for controlling movement of a second prism. The method also includes actuating the first actuator and the second actuator based on the second and third actuation amounts, respectively. The method finds application in multi-focal imaging operations.

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.

An exposure method includes reading data representing a relationship between a first parameter relating to an energy ratio between energy of first pulsed laser light having a first wavelength and energy of second pulsed laser light having a second wavelength longer than the first wavelength and a second parameter relating to a sidewall angle of a resist film that is the angle of a sidewall produced when the resist film is exposed to the first pulsed laser light and the second pulsed laser light, and determining a target value of the first parameter based on the data and a target value of the second parameter; and exposing the resist film to the first pulsed laser light and the second pulsed laser light by controlling a narrowed-line gas laser apparatus to output the first pulsed laser light and the second pulsed laser light based on the target value of the first parameter.

A laser apparatus according to an aspect of the present disclosure includes a master oscillator configured to emit a laser beam, an amplifier including an optical resonator and configured to amplify the laser beam emitted by the master oscillator in the optical resonator, and a phase shift structure disposed on an optical path between the master oscillator and the amplifier at a position closer to the amplifier than a middle point of the optical path. The phase shift structure includes a plurality of cells having different phase shift amounts for the laser beam. The cells have a disposition interval of 80 μm to 275 μm inclusive.

A system includes: an optical source including a plurality of optical oscillators; a spectral analysis apparatus; and a controller. Each optical oscillator is configured to produce a light beam. The controller is configured to: determine, based on data from the spectral analysis apparatus, whether the spectral property of the light beam of one of the optical oscillators is different than the spectral property of the light beam of at least another of the plurality of optical oscillators. If the spectral property of the light beam of the first one of the optical oscillators is different than the spectral property of the light beam of another of the optical oscillators, the controller is configured to adjust the spectral property of the light beam of the first one of the optical oscillators or of the light beam of at least one other of the optical oscillators.

A line narrowing device includes first and second prisms disposed at positions different in a wavelength dispersion direction of any of the first and second prisms, a third prism disposed on the optical path of an optical beam and through which the beam width of the optical beam is enlarged and first and second parts of the optical beam are incident on the first and second prisms, respectively, a grating disposed across the optical path of the first part having passed through the first prism and the optical path of the second part having passed through the second prism, a first actuator configured to adjust the incident angle of the first part on the grating, a second actuator configured to adjust the incident angle of the second part on the grating, and a third actuator configured to adjust an energy ratio of the first and second parts.