Abstract: A line narrowing laser device includes an optical element and a diffractive optical element positioned on an optical path of an optical resonator, a wavelength actuator configured to change an incident angle of light incident on the diffractive optical element by moving the optical element, a wavelength driver configured to drive the wavelength actuator, a processor configured to output a wavelength control signal to the wavelength driver so that a wavelength of pulse laser light output from the optical resonator periodically changes, and a notch filter arranged in a path of the wavelength control signal and configured to operate at a notch frequency different from a drive frequency of the wavelength actuator.

Abstract: A pulse width expansion apparatus according to an aspect of the present disclosure includes a polarization beam splitter and a transfer optical system. The transfer optical system includes ¼-wavelength and reflection mirror pairs. The ¼-wavelength mirror pair include first and second ¼-wavelength mirrors. The first ¼-wavelength mirror provides ¼-wavelength phase shift and reflects a pulse laser beam. The second ¼-wavelength mirror provides ¼-wavelength phase shift and reflects the pulse laser beam reflected by the first ¼-wavelength mirror. The reflection mirror pair are disposed on an optical path before and after or between the ¼-wavelength mirror pair. The transfer optical system transfers an image of an input pulse laser beam on the polarization beam splitter to the optical path between the ¼-wavelength mirror pair at one-to-one magnification as a first transfer image and transfers the first transfer image to the polarization beam splitter at one-to-one magnification as a second transfer image.

Abstract: A laser apparatus includes an output coupling mirror; a grating that constitutes an optical resonator together with the output coupling mirror; a laser chamber in an optical path of the optical resonator; at least one prism in an optical path between the laser chamber and the grating; a rotary stage including an actuator that rotates the prism to change an incident angle of a laser beam from the laser chamber on the grating; a wavelength measuring unit that measures a central wavelength of the laser beam from the laser chamber through the output coupling mirror; an angle sensor that detects a rotation angle of the prism; a first control unit that controls the actuator at a first operation frequency; and a second control unit that controls the actuator at a second operation frequency.

Abstract: A wavelength control method in a laser apparatus including a wavelength actuator configured to cyclically change the wavelength of pulse laser light output in the form of a burst includes reading data on a wavelength target value, determining from the data a first target wavelength and a second target wavelength shorter than the first target wavelength, and setting wavelengths of at least one first-period long wavelength pulse and at least one first-period short wavelength pulse contained in a first period at a start of a burst to a first set wavelength shorter than the first target wavelength and a second set wavelength longer than the second target wavelength, respectively, by using the first target wavelength and the second target wavelength to control the wavelength actuator.

Abstract: An optical pulse stretcher includes a first delay optical system including a plurality of concave toroidal mirrors; and a beam splitter including a first surface and a second surface, causing a part of pulse laser light incident on the first surface to be transmitted in a first direction and output as a first beam and another part thereof to be reflected in a second direction and enter the first delay optical system, and causing a part of pulse laser light incident on the second surface from the first delay optical system to be reflected in the first direction and output as a second beam.

Abstract: A pulse width extension device includes a first delay optical system having a first loop optical path formed on a first plane and configured by a first beam splitter and a plurality of first concave mirrors, a second delay optical system having a second loop optical path formed on a second plane parallel to and different from the first plane and configured by a second beam splitter and a plurality of second concave mirrors, and a first beam rotation mechanism arranged on an optical path between the first delay optical system and the second delay optical system and configured to rotate a beam of pulse laser light having passed through the first delay optical system so that a longitudinal direction of a beam cross-sectional shape of the pulse laser light traveling on the second loop optical path is perpendicular to the second plane.

Abstract: A laser apparatus according to an aspect of the present disclosure includes a laser oscillator configured to emit a pulse laser beam, and a first optical pulse stretcher, a second optical pulse stretcher, and a third optical pulse stretcher that are disposed on an optical path of the pulse laser beam. When L1 represents an optical path length of a delay optical path of the first optical pulse stretcher, L2 represents an optical path length of a delay optical path of the second optical pulse stretcher, L3 represents an optical path length of a delay optical path of the third optical pulse stretcher, and n represents an integer equal to or larger than two, L2 is an integral multiple of L1 by an integer equal to or larger than two and L3 satisfies the following condition: (n?0.75)×L1?L3?(n?0.25)×L1.

Abstract: A pulse width expansion apparatus according to an aspect of the present disclosure includes a polarization beam splitter and a transfer optical system. The transfer optical system includes ¼-wavelength and reflection mirror pairs. The ¼-wavelength mirror pair include first and second ¼-wavelength mirrors. The first ¼-wavelength mirror provides ¼-wavelength phase shift and reflects a pulse laser beam. The second ¼-wavelength mirror provides ¼-wavelength phase shift and reflects the pulse laser beam reflected by the first ¼-wavelength mirror. The reflection mirror pair are disposed on an optical path before and after or between the ¼-wavelength mirror pair. The transfer optical system transfers an image of an input pulse laser beam on the polarization beam splitter to the optical path between the ¼-wavelength mirror pair at one-to-one magnification as a first transfer image and transfers the first transfer image to the polarization beam splitter at one-to-one magnification as a second transfer image.

Abstract: A wavelength control method of a laser apparatus includes sequentially obtaining target wavelength data of a pulse laser beam, sequentially saving the target wavelength data, sequentially measuring a wavelength of the pulse laser beam to obtain a measured wavelength, calculating a wavelength deviation using the measured wavelength and the target wavelength data at a time before a time when the measured wavelength is obtained, and feedback-controlling the wavelength of the pulse laser beam using the wavelength deviation.

Abstract: An optical pulse stretcher includes a first delay optical system including a plurality of concave toroidal mirrors; and a beam splitter including a first surface and a second surface, causing a part of pulse laser light incident on the first surface to be transmitted in a first direction and output as a first beam and another part thereof to be reflected in a second direction and enter the first delay optical system, and causing a part of pulse laser light incident on the second surface from the first delay optical system to be reflected in the first direction and output as a second beam.

Abstract: 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.

Abstract: A laser apparatus includes an output coupling mirror; a grating that constitutes an optical resonator together with the output coupling mirror; a laser chamber in an optical path of the optical resonator; at least one prism in an optical path between the laser chamber and the grating; a rotary stage including an actuator that rotates the prism to change an incident angle of a laser beam from the laser chamber on the grating; a wavelength measuring unit that measures a central wavelength of the laser beam from the laser chamber through the output coupling mirror; an angle sensor that detects a rotation angle of the prism; a first control unit that controls the actuator at a first operation frequency; and a second control unit that controls the actuator at a second operation frequency.

Abstract: A wavelength control method of a laser apparatus includes sequentially obtaining target wavelength data of a pulse laser beam, sequentially saving the target wavelength data, sequentially measuring a wavelength of the pulse laser beam to obtain a measured wavelength, calculating a wavelength deviation using the measured wavelength and the target wavelength data at a time before a time when the measured wavelength is obtained, and feedback-controlling the wavelength of the pulse laser beam using the wavelength deviation.

Abstract: 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.

Abstract: A laser apparatus includes first and second wavelength dispersion elements, an optical element, first and second actuators, and a control unit. The first wavelength dispersion element generates wavelength dispersion in a direction orthogonal to an electric discharge direction between a pair of electric discharge electrodes. The second wavelength dispersion element generates wavelength dispersion in a direction parallel to the electric discharge direction. The optical element corrects wavelength dispersion generated by the second wavelength dispersion element. The first actuator drives the first wavelength dispersion element. The second actuator drives the optical element. The control unit controls the first actuator so that the center wavelength of the laser light approaches to a target wavelength and controls the second actuator so as to correct the wavelength dispersion generated by the second wavelength dispersion element.

Abstract: 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.

Abstract: 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.

Abstract: A laser apparatus includes: a laser chamber in which a pair of discharge electrodes is provided; a first beam expander configured to expand a beam width of a beam outputted from the laser chamber at least in a first direction substantially parallel to a direction of electric discharge between the discharge electrodes; and a line narrow optical system including: a second beam expander configured to expand a beam width of the beam outputted from the laser chamber at least in a second direction substantially perpendicular to the first direction, the second beam expander including at least one optical element; and a grating configured to perform wavelength dispersion of the beam expanded by the first and second beam expanders, the wavelength dispersion being performed in a plane substantially parallel to the second direction, wherein at least one of the grating and the at least one optical element is arranged so as to compensate for wavelength dispersion caused by the first beam expander.

Abstract: A grating for line-narrowing a laser beam that is outputted from a laser apparatus at a wavelength in a vacuum ultraviolet region may include: a grating substrate; a first aluminum metal film formed above the grating substrate, the first aluminum metal film having grooves in a surface thereof; and a first protective film formed by an ALD method above the first aluminum metal film.

Abstract: A laser apparatus includes first and second wavelength dispersion elements, an optical element, first and second actuators, and a control unit. The first wavelength dispersion element generates wavelength dispersion in a direction orthogonal to an electric discharge direction between a pair of electric discharge electrodes. The second wavelength dispersion element generates wavelength dispersion in a direction parallel to the electric discharge direction. The optical element corrects wavelength dispersion generated by the second wavelength dispersion element. The first actuator drives the first wavelength dispersion element. The second actuator drives the optical element. The control unit controls the first actuator so that the center wavelength of the laser light approaches to a target wavelength and controls the second actuator so as to correct the wavelength dispersion generated by the second wavelength dispersion element.