Abstract: A laser system includes a beam shaping unit, a random phase plate, and a collimating optical system in an optical path between a solid-state laser device and an excimer amplifier. When a traveling direction of a laser beam entering the excimer amplifier is a Z direction, a discharge direction of a pair of discharge electrodes is a V direction, a direction orthogonal to the V and Z directions is an H direction, a shaping direction of the beam shaping unit corresponding to the V direction is a first direction, a shaping direction of the beam shaping unit corresponding to the H direction is a second direction, an expansion rate in the first direction is E1, and an expansion rate in the second direction is E2, the beam shaping unit expands a beam section of the laser beam such that an expansion ratio defined by E2/E1 is lower than 1.

Abstract: An optical isolator according to an aspect of the present disclosure includes a first polarizer through which incident light transmits, a Faraday rotator configured to rotate the polarization direction of the light, and a second polarizer through which the light transmits. The Faraday rotator includes a calcium fluoride crystal. When a, b, and c axes are the [001], [100], and [010] crystallographic axes, respectively, and x, y, and z axes are obtained by rotating the three axes by a first angle of 40° to 50° about the c axis and by a second angle of 45° to 75° about the b axis rotated by the first angle, the z axis is parallel to the propagation direction of the light, and the calcium fluoride crystal is disposed such that the transmission axis of the first polarizer and the x axis have an angle difference of 0° to 45°.

Abstract: An ultraviolet laser apparatus includes an oscillation-stage laser, an amplifier that amplifies the pulse laser light, and an optical isolator. The optical isolator includes a first Faraday rotator that rotates the polarization direction of the pulse laser light output from the oscillation-stage laser by a first angle in a first rotation direction, a first polarizer so disposed to transmit the pulse laser light that exits out of the first Faraday rotator at normalized transmittance greater than or equal to 0.9, a second Faraday rotator that rotates the polarization direction of the pulse laser light passing through the first polarizer by a second angle in the opposite direction to the first rotation direction, and a second polarizer so disposed to transmit the pulse laser light that exits out of the second Faraday rotator at the normalized transmittance greater than or equal to 0.9.

Abstract: An optical isolator includes a first polarizer arranged such that a transmission axis thereof is set to cause a normalized transmittance with respect to incident light having a wavelength of ultraviolet and linear polarization to be 0.9 or more, a Faraday rotator using a Faraday material configured to rotate a polarization direction of light having transmitted through the first polarizer in a first rotation direction by a first rotation amount by a magnetic field and rotate the polarization direction in a second rotation direction opposite to the first rotation direction by a second rotation amount by optical activity or birefringence, and a second polarizer arranged such that a transmission axis thereof is set to cause a normalized transmittance with respect to the incident light having transmitted through the Faraday rotator to be 0.9 or more.

Abstract: A laser system includes a beam shaping unit, a random phase plate, and a collimating optical system in an optical path between a solid-state laser device and an excimer amplifier. When a traveling direction of a laser beam entering the excimer amplifier is a Z direction, a discharge direction of a pair of discharge electrodes is a V direction, a direction orthogonal to the V and Z directions is an H direction, a shaping direction of the beam shaping unit corresponding to the V direction is a first direction, a shaping direction of the beam shaping unit corresponding to the H direction is a second direction, an expansion rate in the first direction is E1, and an expansion rate in the second direction is E2, the beam shaping unit expands a beam section of the laser beam such that an expansion ratio defined by E2/E1 is higher than 1.

Abstract: 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 ?m to 275 ?m inclusive.

Abstract: A laser system includes a beam shaping unit, a random phase plate, and a collimating optical system in an optical path between a solid-state laser device and an excimer amplifier. When a traveling direction of a laser beam entering the excimer amplifier is a Z direction, a discharge direction of a pair of discharge electrodes is a V direction, a direction orthogonal to the V and Z directions is an H direction, a shaping direction of the beam shaping unit corresponding to the V direction is a first direction, a shaping direction of the beam shaping unit corresponding to the H direction is a second direction, an expansion rate in the first direction is E1, and an expansion rate in the second direction is E2, the beam shaping unit expands a beam section of the laser beam such that an expansion ratio defined by E2/E1 is higher than 1.

Abstract: A laser system includes a random phase plate in an optical path between a solid-state laser device and an excimer amplifier. Cells of a predetermined shape are periodically arranged on the plate, each cell being a minimum unit region of an irregular pattern, regions of depressions or projections in units of the cells being randomly arranged. When a traveling direction of a laser beam is a Z direction, a discharge direction is a V direction, a direction orthogonal to the V and Z directions is an H direction, an in-plane direction of the plate corresponding to the V direction is a first direction, an in-plane direction of the plate corresponding to the H direction is a second direction, lengths of the cell are d1 in the first direction and d2 in the second direction, an aspect ratio of the cell defined by d2/d1 is 1.2 or more.