An apparatus (10) for increasing a pulse length of a pulsed radiation beam, the apparatus comprising: a beam splitter (16) configured to split an input radiation beam (18) into a first beam (24) and a second beam (22); an optical arrangement (12, 14), wherein the beam splitter and the optical arrangement are configured such that at least a portion of the first beam is recombined with the second beam into a modified beam after an optical delay of the first beam caused by the optical arrangement; and at least one optical element (30) in an optical path of the first beam, the at least one optical element configured such that the phase of different parts of a wavefront of the first beam is varied to reduce coherence between the first beam and the second beam.

Apparatus for and method of aligning optical components such as mirrors to facilitate proper beam alignment using an image integration optical system is used to integrate images from multiple optical features such as from both left mirror bank and right mirror bank to present the images simultaneously to the camera system. A fluorescent material may be used to render a beam footprint visible and the relative positions of the footprint and an alignment feature may be used to align the optical feature.

An optical system includes a first optical system, a second optical system, and a third optical system. The first optical system divides an input beam into a first light and a second light. The second optical system includes a concave reflective surface which reflects the first light. The third optical system directs at least one of the first light reflected from the second optical system and the second light from the first optical system to an output optical path of the third optical system.

A laser apparatus according to an aspect of the present disclosure includes a laser oscillator that outputs pulsed laser light, a deformable mirror including a deformer that deforms a reflective surface, a first processor that drives the deformer during the period for which the reflective surface reflects the pulsed laser light, a homogenizer that homogenizes the pulsed laser light reflected off the deformable mirror, and a spectrum measuring instrument that measures the spectrum of the pulsed laser light homogenized by the homogenizer.

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.

A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.

Disclosed is a metrology device (1600) configured to produce measurement illumination comprising a plurality of illumination beams, each of said illumination beams being spatially incoherent or pseudo-spatially incoherent and comprising multiple pupil points in an illumination pupil of the metrology device. Each pupil point in each one of said plurality of illumination beams has a corresponding pupil point in at least one of the other illumination beams of said plurality of illumination beams thereby defining multiple sets of corresponding pupil points, and the pupil points of each set of corresponding pupil points are spatially coherent with respect to each other.

Disclosed is a metrology device (1600) configured to produce measurement illumination comprising a plurality of illumination beams, each of said illumination beams being spatially incoherent or pseudo-spatially incoherent and comprising multiple pupil points in an illumination pupil of the metrology device. Each pupil point in each one of said plurality of illumination beams has a corresponding pupil point in at least one of the other illumination beams of said plurality of illumination beams thereby defining multiple sets of corresponding pupil points, and the pupil points of each set of corresponding pupil points are spatially coherent with respect to each other.

An apparatus (10) for increasing a pulse length of a pulsed radiation beam, the apparatus comprising: a beam splitter (16) configured to split an input radiation beam (18) into a first beam (24) and a second beam (22); an optical arrangement (12,14), wherein the beam splitter and the optical arrangement are configured such that at least a portion of the first beam is recombined with the second beam into a modified beam after an optical delay of the first beam caused by the optical arrangement; and at least one optical element (30) in an optical path of the first beam, the at least one optical element configured such that the phase of different parts of a wavefront of the first beam is varied to reduce coherence between the first beam and the second beam.

An optical system, in particular for microlithography, comprises a laser light source for generating a multiplicity of light pulses, and a control unit configured to control the laser light source in such a way that, for a light pulse sequence generated by the laser light source, the time period between respectively successive light pulses varies across the light pulse sequence. A method comprises operating the optical system.