Abstract: Disclosed is a metrology method and associated devices. The method comprises obtaining a first image, said first image being subject to one or more non-isoplanatic aberrations of an optical system used to capture said image; and non-iteratively correcting said first image for the effect of said one or more non-isoplanatic aberrations by performing one or both of: a field non-isoplanatic correction operation in field space for said first image, said field space corresponding to a field plane of the optical system; and a pupil non-isoplanatic correction operation in pupil space for said first image, said pupil space corresponding to a pupil plane of the optical system. Said one or more non-isoplanatic aberrations comprise a class of non-isoplanatic aberrations describable as a convolution combined with an object distortion and/or a pupil distortion.

Abstract: A projection unit for a level sensor, the projection unit including: a first light pipe having a first inlet configured to receive radiation from a source and a first outlet; and a second light pipe having a second inlet configured to receive the radiation from the first light pipe and a second outlet. The unit may include a lens device configured to receive radiation from the second outlet and to output radiation having a predetermined distribution of intensity and irradiance.

Abstract: Disclosed is a detection apparatus for simultaneous acquisition of multiple images of an object at a plurality of different focus levels; comprising: a modulator for obtaining multiple beam copies of an incoming beam; and a detector operable to capture said multiple beam copies, such that at two of said multiple beam copies are captured at different focus levels. Also disclosed is an inspection apparatus comprising such a detection system.

Abstract: Disclosed is a metrology device operable to measure a sample with measurement radiation and associated method. The metrology device comprises: an illumination branch operable to propagate measurement radiation to a sample, a detection branch operable to propagate one or more components of scattered radiation, scattered from said sample as a result of illumination of the sample by said measurement radiation; and a dispersive arrangement in either of said illumination branch or said detection branch. The dispersive arrangement is arranged to maintain one or more components of said scattered radiation at substantially a same respective location in a detection pupil plane over a range of wavelength values for said measurement radiation.

Abstract: Disclosed is a detection apparatus for simultaneous acquisition of multiple images of an object at a plurality of different focus levels; comprising: a modulator for obtaining multiple beam copies of an incoming beam; and a detector operable to capture said multiple beam copies, such that at two of said multiple beam copies are captured at different focus levels. Also disclosed is an inspection apparatus comprising such a detection system.

Abstract: Disclosed is a detection apparatus for simultaneous acquisition of multiple images of an object at a plurality of different focus levels; comprising: a modulator for obtaining multiple beam copies of an incoming beam; and a detector operable to capture said multiple beam copies, such that at two of said multiple beam copies are captured at different focus levels. Also disclosed is an inspection apparatus comprising such a detection system.

Abstract: An optical inspection apparatus, including: an optical metrology tool configured to measure structures, the optical metrology tool including: an electromagnetic (EM) radiation source configured to direct a beam of EM radiation along an EM radiation path; and an adaptive optical system disposed in a portion of the EM radiation path and configured to adjust a shape of a wave front of the beam of EM radiation, the adaptive optical system including: a first aspherical optical element; a second aspherical optical element adjacent the first aspherical optical element; and an actuator configured to cause relative movement between the first optical element and the second optical element in a direction different from a beam axis of the portion of the EM radiation path.

Abstract: An optical system (OS) for focusing a beam of radiation (B) on a region of interest in a metrology apparatus is described. The beam of radiation (B) comprises radiation in a soft X-ray or Extreme Ultraviolet spectral range. The optical system (OS) comprises a first stage (S1) for focusing the beam of radiation at an intermediate focus region. The optical system (OS) comprises a second stage (S2) for focusing the beam of radiation from the intermediate focus region onto the region of interest. The first and second stages each comprise a Kirkpatrick-Baez reflector combination. At least one reflector comprises an aberration-correcting reflector.

Abstract: Metrology apparatus and methods for inspecting a substrate are disclosed. A source beam of radiation emitted by a radiation source is split into a measurement beam and a reference beam. A first target on the substrate is illuminated with the measurement beam. A second target separated from the substrate is illuminated with the reference beam. First scattered radiation collected from the first target and second scattered radiation collected from the second target are delivered to the detector. The first scattered radiation interferes with the second scattered radiation at the detector. The first target comprises a first pattern. The second target comprises a second pattern, or a pupil plane image of the second pattern. The first pattern is geometrically identical to the second pattern, the first pattern and the second pattern are periodic and a pitch of the first pattern is identical to a pitch of the second pattern, or both.

Abstract: A beam homogenizer for homogenizing a beam of radiation and an illumination system and metrology apparatus comprising such a beam homogenizer as provided. The beam homogenizer comprises a filter system having a controllable radial absorption profile and configured to output a filtered beam and an optical mixing element configured to homogenize the filtered beam. The filter system may be configured to homogenize the angular beam profile radially and said optical mixing element may be configured to homogenize the angular beam profile azimuthally.

Abstract: A measurement system is disclosed in which a first optical system splits an input radiation beam into a plurality of components. A modulator receives the plurality of components and applies a modulation to at least one of the components independently of at least one other of the components. A second optical system illuminates a target with the plurality of components and directs radiation scattered by the target to a detection system. The detection system distinguishes between each of one or more components, or between each of one or more groups of components, of the radiation directed to the detection system based on the modulation applied to each component or each group of components by the modulator.

Abstract: Disclosed are an optical system for conditioning a beam of radiation, and an illumination system and metrology apparatus comprising such an optical system. The optical system comprises one or more optical mixing elements in an optical system. The optical system defines at least a first optical mixing stage, at least a second optical mixing stage, and at least one transformation stage, configured such that radiation entering the second optical mixing stage includes a transformed version of radiation exiting the first optical mixing stage. The first and second optical mixing stages can be provided using separate optical mixing elements, or by multiple passes through the same optical mixing element. The transformation stage can be a Fourier transformation stage. Both spatial distribution and angular distribution of illumination can be homogenized as desired.

Abstract: Devices and methods for processing a radiation beam with coherence are disclosed. In one arrangement, an optical system receives a radiation beam with coherence. The radiation beam comprises components distributed over one or more radiation beam spatial modes. A waveguide supports a plurality of waveguide spatial modes. The optical system directs a plurality of the components of the radiation beam belonging to a common radiation beam spatial mode and having different frequencies onto the waveguide in such a way that each of the plurality of components couples to a different set of the waveguide spatial modes, each set comprising one or more of the waveguide spatial modes.

Abstract: An optical system (OS) for focusing a beam of radiation (B) on a region of interest in a metrology apparatus is described. The beam of radiation (B) comprises radiation in a soft X-ray or Extreme Ultraviolet spectral range. The optical system (OS) comprises a first stage (S1) for focusing the beam of radiation at an intermediate focus region. The optical system (OS) comprises a second stage (S2) for focusing the beam of radiation from the intermediate focus region onto the region of interest. The first and second stages each comprise a Kirkpatrick-Baez reflector combination. At least one reflector comprises an aberration-correcting reflector.

Abstract: A beam (542, 556) of inspection radiation is generated by focusing infrared (IR) radiation (540) at a source location so as to generate the inspection radiation (542) by high-harmonic generation in a gas cell (532). An illumination optical system (512) focuses the inspection radiation into a spot (S) of radiation by imaging the source location onto a metrology target (T). In one embodiment, the same illumination optical system forms a spot of the IR radiation onto a target material. A spot of visible radiation is generated by second harmonic generation at the metrology target. The visible spot is observed by an alignment camera (564). A special alignment target (592) may be provided, or material present in or near the metrology target can be used. In another embodiment, the spot is imaged using a portion (758) of the inspection radiation reflected by the target.

Abstract: An illumination system has a microLED array 502. The microLED array 502 is imaged or placed very close to a phosphor coated glass disc 504 which upconverts the light from the microLED array into a narrow band emission. The plate has at least two different photoluminescent materials arranged to be illuminated by the microLED array and to thereby emit output light. The different photoluminescent materials have different emission spectral properties of the output light, e.g. different center wavelength and optionally different bandwidth. Illumination of different photoluminescent materials by the illumination sources is selectable, by selective activation of the microLEDs or by movement of the photoluminescent materials relative to the illumination sources, to provide different illumination of the different photoluminescent materials. This provides tunable spectral properties of the output light.

Abstract: A measurement system is disclosed in which a first optical system splits an input radiation beam into a plurality of components. A modulator receives the plurality of components and applies a modulation to at least one of the components independently of at least one other of the components. A second optical system illuminates a target with the plurality of components and directs radiation scattered by the target to a detection system. The detection system distinguishes between each of one or more components, or between each of one or more groups of components, of the radiation directed to the detection system based on the modulation applied to each component or each group of components by the modulator.

Abstract: Metrology apparatus and methods are disclosed. In one arrangement, a substrate is inspected. A source beam of radiation emitted by a radiation source is split into a measurement beam and a reference beam. A first target is illuminated with the measurement beam, the first target being on the substrate. A second target is illuminated with the reference beam, the second target being separated from the substrate. First scattered radiation is collected from the first target and delivered to a detector. Second scattered radiation is collected from the second target and delivered to the detector. The first scattered radiation interferes with the second scattered radiation at the detector. The first target comprises a first pattern. The second target comprises a second pattern, or a pupil plane image of the second pattern.

Abstract: An optical inspection apparatus, including: an optical metrology tool configured to measure structures, the optical metrology tool including: an electromagnetic (EM) radiation source configured to direct a beam of EM radiation along an EM radiation path; and an adaptive optical system disposed in a portion of the EM radiation path and configured to adjust a shape of a wave front of the beam of EM radiation, the adaptive optical system including: a first aspherical optical element; a second aspherical optical element adjacent the first aspherical optical element; and an actuator configured to cause relative movement between the first optical element and the second optical element in a direction different from a beam axis of the portion of the EM radiation path.

Abstract: Devices and methods for processing a radiation beam with coherence are disclosed. In one arrangement, an optical system receives a radiation beam with coherence. The radiation beam comprises components distributed over one or more radiation beam spatial modes. A waveguide supports a plurality of waveguide spatial modes. The optical system directs a plurality of the components of the radiation beam belonging to a common radiation beam spatial mode and having different frequencies onto the waveguide in such a way that each of the plurality of components couples to a different set of the waveguide spatial modes, each set comprising one or more of the waveguide spatial modes.