A laser device includes a laser oscillation device configured to output pulse laser light; a beam intensity distribution measurement device configured to measure a beam intensity distribution of the pulse laser light; a beam angle distribution measurement device configured to measure a beam angle distribution of the pulse laser light; a pulse waveform measurement device configured to measure a pulse waveform of the pulse laser light; a spectrum measurement device configured to measure a spectrum of the pulse laser light; and a laser controller configured to calculate a speckle contrast based on measurement data of each of the beam intensity distribution, the beam angle distribution, the pulse waveform, and the spectrum.

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.

Disclosed herein is a lighting optical system comprising: a light source having a plurality of light-emitting elements configured to emit light from light-emitting surfaces, respectively; a relay optical system configured to convert a luminous intensity distribution of light emitted from each of the light-emitting elements into an irradiance distribution and to superimpose a plurality of the irradiance distributions corresponding to the plurality of light-emitting elements on each other on a superimposed surface; an optical integrator having a plurality of wavefront splitting elements arranged in parallel to each other, the plurality of wavefront splitting elements being configured to wavefront split irradiated light through the relay optical system and to transmit the wavefront split light as a plurality of pencils of light rays; and a condenser optical system configured to superimpose the plurality of pencils of light rays on each other on a surface to be irradiated.

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.

A method of patterning a substrate includes forming a mandrel over the substrate, the mandrel including an extreme ultraviolet (EUV) resist, and depositing a first overcoat layer over the mandrel from a first solution, the first solution including a first solvent, a first polymer, and an agent generator or an acid. The method further includes selectively removing the first overcoat layer leaving a first mandrel portion surrounded by a second mandrel portion, the second mandrel portion being formed by modifying an outer portion of the mandrel by the first overcoat layer. The method further includes depositing a second overcoat layer over the second mandrel portion from a second solution, the second overcoat layer being separated from the first mandrel portion by the second mandrel portion, the second solution including a second solvent, and a second polymer. And the method further includes forming a second mandrel along a sidewall of the first mandrel portion by selectively removing the second mandrel portion relative to the first mandrel portion.