Abstract: A test object including: an arrangement of optical elements defining a first partially reflecting surface and a second partially reflecting surface, at least one of the first and second partially reflecting surfaces being curved, wherein the first partially reflecting surface is arranged to receive a substantially collimated input beam and produce therefrom a first transmitted beam that passes on to the second partially reflecting surface, wherein the second partially reflecting surface is arranged to receive the first transmitted beam from the first partially reflecting surface and produce a collimated second transmitted beam and a first reflected beam therefrom, wherein the first partially reflecting surface is arranged to receive the first reflected beam and produce a second reflected beam therefrom, and wherein the first and second reflecting surfaces are configured to cause the second reflecting beam to converge onto a spot on a back surface to produce a diverging beam traveling in the same direction as

Abstract: A point diffraction interferometer for measuring properties of a spatial impulse response function, the interferometer including: a source for generating a source beam; an optical system; an optical element including a test object located in an object plane of the optical system, the test object including a diffraction point for generating from the source beam a measurement beam that passes through the optical system, wherein the optical element also generates from the source beam a reference beam that is combined with the measurement beam to generate an interference pattern in an image plane of the optical system, the interference pattern representing the spatial impulse response function of the optical system.

Abstract: An interferometery system for making interferometric measurements of an object, the system including: a beam generation module which during operation delivers an output beam that includes a first beam at a first frequency and a second beam at a second frequency that is different from the first frequency, the first and second beams within the output beam being coextensive, the beam generation module including a beam conditioner which during operation introduces a sequence of different shifts in a selected parameter of each of the first and second beams, the selected parameter selected from a group consisting of phase and frequency; a detector assembly having a detector element; and an interferometer constructed to receive the output beam at least a part of which represents a first measurement beam at the first frequency and a second measurement beam at the second frequency, the interferometer further constructed to image both the first and second measurement beams onto a selected spot on the object to produce

Abstract: A method of operating a wavefront interferometry system that generates an array of interference signals that contains information about relative wavefronts of measurement and reference beams, the method involving: from the array of interference signals, computing a first array of phase measurements for a first time and a second array of phase measurements for a second time; computing a difference of the first and second arrays of phase measurements to determine an array of rates of phase changes; and from the array of rates of phase changes, computing an array of atmospheric turbulence effect values which is a measure of atmospheric turbulence effects in the wavefront interferometry system.

Abstract: Apparatus and methods for in situ and ex situ measurements of spatial profiles of the modulus of the complex amplitude and intensity of flare generated by an optical system. The in situ and ex situ measurements comprise interferometric and non-interferometric measurements that use an array of diffraction sites simultaneously located in an object plane of the optical system to increase signals related to measured properties of flare in a conjugate image plane. The diffraction sites generate diffracted beams with randomized relative phases. In general, the interferometric profile measurements employ phase-shifting point-diffraction interferometry to generate a topographical interference signal and the non-interferometric measurements are based on flare related signals other than topographic interference signals.

Abstract: An interferometery system for making interferometric measurements of an object, the system including: a beam generation module which during operation delivers an output beam that includes a first beam at a first frequency and a second beam at a second frequency that is different from the first frequency, the first and second beams within the output beam being coextensive, the beam generation module including a beam conditioner which during operation introduces a sequence of different shifts in a selected parameter of each of the first and second beams, the selected parameter selected from a group consisting of phase and frequency; a detector assembly having a detector element; and an interferometer constructed to receive the output beam at least a part of which represents a first measurement beam at the first frequency and a second measurement beam at the second frequency, the interferometer further constructed to image both the first and second measurement beams onto a selected spot on the object to produce

Abstract: A wavefront interferometry system including: a wavefront interferometer that during operation combines a reference beam from a reference object and a measurement beam from a measurement object to generate a combined beam; and a processor system programmed to processes the combined beam to concurrently generate therefrom a control signal and information about the difference in wavefront profiles of the reference and measurement objects, wherein the control signal controls a system parameter so as to maintain an optical path length difference between a spot on the reference object and a corresponding spot on the measurement object at a constant value mod 2?.

Abstract: An imaging system for imaging an object point to an image point, the system including: a beam splitter positioned to receive light rays from the object point and separate each of a plurality of rays into a transmitted portion and a reflected portion, the transmitted portions defining a first set of rays and the reflected portions defining a second set of rays; and an array of independently positionable reflecting elements forming a reflecting surface positioned to receive one of the sets of rays from the beam splitter and focus that set of rays towards the image point via the beam splitter.

Abstract: Methods and apparatus are disclosed for measurement of critical dimensions (CD) of features and detection of defects in reflecting UV, VUV, and EUV lithography masks and in transmitting UV and VUV lithography masks. The measured CD's may be used in the determination of optical proximity corrections (OPC) and/or in mask fabrication process control. The transmitting masks may comprise binary and various types of phase shift masks.

Abstract: A test object including: an arrangement of optical elements defining a first partially reflecting surface and a second partially reflecting surface, at least one of the first and second partially reflecting surfaces being curved, wherein the first partially reflecting surface is arranged to receive a substantially collimated input beam and produce therefrom a first transmitted beam that passes on to the second partially reflecting surface, wherein the second partially reflecting surface is arranged to receive the first transmitted beam from the first partially reflecting surface and produce a collimated second transmitted beam and a first reflected beam therefrom, wherein the first partially reflecting surface is arranged to receive the first reflected beam and produce a second reflected beam therefrom, and wherein the first and second reflecting surfaces are configured to cause the second reflecting beam to converge onto a spot on a back surface to produce a diverging beam traveling in the same direction as

Abstract: A method of processing a substrate on which a layer of photoresist has been applied, the method involving: exposing the layer of photoresist to radiation that carries spatial information to generate exposure-induced changes in the layer of photoresist that form a pattern having one or more features; and before developing the exposed photoresist, interferometrically obtaining measurements of the pattern in the exposed layer of photoresist for determining at least one of (1) locations of the one or more features of the pattern and (2) magnitudes of the exposure-induced changes.

Abstract: A method of detecting non-uniform ellipsometric properties of a substrate surface involving: directing a measurement beam onto a spot at a selected location on or in the substrate; for each orientation of a plurality of different orientations of the reference beam relative to the scattered measurement beam, interfering the scattered measurement beam with the reference beam to produce a corresponding interference beam, wherein each of the different orientations of the reference beam is selected to produce a peak sensitivity for a portion of the scattered measurement beam that emanates from the object at a corresponding different diffraction angle of a plurality of diffraction angles; for each orientation of the reference beam, converting the interference beam into an interference signal; and using the interference signals to determine whether any non-uniform ellipsometric properties are present anywhere within a region on or in the substrate.

Abstract: A method of measuring properties of a substrate, the method involving: illuminating a spot on the substrate with a standing wave measurement beam to generate a return measurement beam, the standing wave measurement beam characterized by a standing wave pattern; generating an electrical signal from the return measurement beam; causing the standing wave pattern to be at a succession of different positions on the surface of the substrate; and for each of the succession of different positions of the standing wave pattern, acquiring measurement data from the electrical signal.

Abstract: Methods and apparatus based on optical homodyne displacement interferometry, optical coherent-domain reflectometry (OCDR), and optical interferometric imaging are disclosed for overlay, alignment mark, and critical dimension (CD) metrologies that are applicable to microlithography applications and integrated circuit (IC) and mask fabrication and to the detection and location of defects in/on unpatterned and patterned wafers and masks. The metrologies may also be used in advanced process control (APC), in determination of wafer induced shifts (WIS), and in the determination of optical proximity corrections (OPC).

Abstract: A multiple source array including a guided-wave structure having a dielectric core and a cladding covering the dielectric core; and an array of dielectric-filled, guided-wave cavities in the cladding extending transversely from the dielectric core and forming an array of apertures through which optical energy that is introduced into the core exits from the core.

Abstract: An interferometric method including: generating a variable frequency source beam; from the source beam, generating a collimated beam propagating at an angle ? relative to an optical axis; introducing the collimated beam into an interferometer that includes a reference object and a measurement object, wherein at least a portion of the collimated beam interacts with the reference object to generate a reference beam, at least a portion of the collimated beam interacts with the measurement object to generate a return measurement beam, and the reference beam and the return measurement beam are combined to generate a combined beam; causing the angle ? to have a first value and at a later time a second value that is different from the first value; and causing the variable frequency F to have a first value that corresponds to the first value of the angle ? and at the later time to have a second value that corresponds to the first value of the angle ?.

Abstract: A wavefront interferometry system including: a wavefront interferometer that during operation combines a reference beam from a reference object and a measurement beam from a measurement object to generate a combined beam; and a processor system programmed to processes the combined beam to concurrently generate therefrom a control signal and information about the difference in wavefront profiles of the reference and measurement objects, wherein the control signal controls a system parameter so as to maintain an optical path length difference between a spot on the reference object and a corresponding spot on the measurement object at a constant value mod 2?.

Abstract: A method of operating a wavefront interferometry system that generates an array of interference signals that contains information about relative wavefronts of measurement and reference beams, the method involving: from the array of interference signals, computing a first array of phase measurements for a first time and a second array of phase measurements for a second time; computing a difference of the first and second arrays of phase measurements to determine an array of rates of phase changes; and from the array of rates of phase changes, computing an array of atmospheric turbulence effect values which is a measure of atmospheric turbulence effects in the wavefront interferometry system.

Abstract: An interferometric system including: an interferometer that directs a measurement beam at an object point to produce a return measurement beam, focuses the return measurement beam to an image point in an image plane, and mixes the return measurement beam with a reference beam at the image point to form a mixed beam; a beam combining layer located at the image plane which is responsive to the mixed beam and produces an optical beam therefrom, wherein the layer comprises a thin film with an array of transmissive openings formed therein and further comprises a fluorescent material associated with each of the openings of the array of openings; a detector that is responsive to the optical beam from the beam combining layer; and an imaging system that directs the optical beam from the beam combining layer onto the detector.

Abstract: An external cavity structure including: a light source for generating a light beam; a dispersive system which in combination with the light source defines a cavity, the dispersive system for directing a selected wavelength of the light beam back into the light source, the dispersive system including a grating for selecting said wavelength of the light beam; and a beam-conditioner positioned within the cavity along a light path between the light source and the dispersive system, the beam conditioner including a beam deflecting element for changing the direction of propagation of the light beam as that light beam that travels between the light source and the dispersive system.