A laser radiation system according to a viewpoint of the present disclosure includes a first optical system configured to convert a first laser flux into a second laser flux, a multimirror device including mirrors, configured to be capable of controlling the angle of the attitude of each of the mirrors, and configured to divide the second laser flux into laser fluxes and reflect the laser fluxes in directions to produce the divided laser fluxes, a Fourier transform optical system configured to focus the divided laser fluxes, and a control section configured to control the angle of the attitude of each of the mirrors in such a way that the Fourier transform optical system superimposes the laser fluxes, which are divided by the mirrors separate from each other by at least a spatial coherence length of the second laser flux, on one another.

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.

In a laser system according to a viewpoint of the present disclosure, a first amplifier amplifies first pulsed laser light outputted from a first semiconductor laser system into second pulsed laser light, a wavelength conversion system converts the second pulsed laser light in terms of wavelength into third pulsed laser light, and an excimer amplifier amplifies the third pulsed laser light. The first semiconductor laser system includes a first current controller that controls current flowing through a first semiconductor laser in such a way that first laser light outputted from the first semiconductor laser is caused to undergo chirping and a first semiconductor optical amplifier that amplifies the first laser light into pulsed light. The laser system includes a control section that controls the amount of chirping performed on the first pulsed laser light in such a way that excimer laser light having a target spectral linewidth is achieved.

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.

A high-voltage pulse generation device configured to apply a pulsed high voltage to the space between a pair of discharge electrodes disposed in a laser chamber of a gas laser apparatus includes n transformer cores that form a transformer, where n is a natural number greater than or equal to two, n primary electric circuits of the transformer, the n primary electric circuits each having a first terminal connected to a reference potential and a second terminal connected to a charger, the n primary electric circuits each including one or more primary coils, one or more diodes connected in parallel to the one or more primary coils, and one or more pulse generators connected in parallel to the one or more primary coils, and a secondary electric circuit of the transformer, the secondary electric circuit including a secondary coil and connected to the pair of discharge electrodes.

A high voltage pulse generation device includes n transformer cores configuring a transformer, n being a natural number of 2 or more, each of the n transformer cores being configured to form a magnetic circuit along a first plane and to have a width in a first direction parallel to the first plane larger than a width in a second direction parallel to the first plane and perpendicular to the first direction; n primary electric circuits of the transformer connected in parallel to each other, each of the n primary electric circuits including at least one primary coil, and m pulse generation units connected in parallel to the at least one primary coil, m being a natural number equal to or more than 2; and a secondary electric circuit of the transformer including a secondary coil and connected to a pair of discharge electrodes.

In accordance with some embodiments, a method of controlling an extreme ultraviolet (EUV) radiation in lithography system is provided. The method includes generating a plurality of target droplets. The method also includes generating a pre-pulse and a main pulse from an excitation laser module to generate EUV light and reflecting the EUV light by a collector mirror. The method further includes measuring a separation between a pre-pulse and a main pulse. Moreover, the method includes determining whether the separation between the pre-pulse and the main pulse in the y-axis is changed, if not adjusting a configurable parameter of the excitation laser module to set the variation in the energy of the EUV light within an acceptable range.

A wavelength conversion system including: A. a first nonlinear optical crystal to which first pulsed laser light having a first polarization state and a first wavelength and second pulsed laser light having a second polarization state and a second wavelength are inputted and which is configured to output in response to the input the second pulsed laser light and first sum frequency light having the second polarization state and a third wavelength produced by sum frequency mixing of the first wavelength with the second wavelength; and B. a second nonlinear optical crystal to which the first sum frequency light and the second pulsed laser light outputted from the first nonlinear optical crystal are inputted and which is configured to output in response to the input third pulsed laser light having a fourth wavelength.

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.