Abstract: Disclosed is an apparatus which includes: an interferometer configured to direct broadband spatially coherent test light to a test surface of a test object over a range of illumination angles and subsequently combine it with reference light to form an interference pattern, the test and reference light being derived from a common source; and multi-element detector; and one or more optics configured to direct at least a portion of the combined light to the detector so that different elements of the detector correspond to different illumination angles of a region of the test surface illuminated by the test light.

Abstract: A method including comparing information derivable from a scanning interferometry signal for a first surface location of a test object to information corresponding to multiple models of the test object, wherein the multiple models are parameterized by a series of characteristics for the test object. The derivable information being compared may relate to a shape of the scanning interferometry signal for the first surface location of the test object.

Abstract: A method including comparing information derivable from a scanning interferometry signal for a first surface location of a test object to information corresponding to multiple models of the test object, wherein the multiple models are parametrized by a series of characteristics for the test object. The derivable information being compared may relate to a shape of the scanning interferometry signal for the first surface location of the test object.

Abstract: Methods and related systems for determining properties of optical systems (e.g., interferometers) and/or optical elements (e.g., lenses and/or lens systems) are described. For example, information related to an optical thickness mismatch of an interferometer can be determined by providing scanning interferometry data. The data typically include obtaining one or more interference signals each corresponding to a different spatial location of a test object. A phase is determined for each of multiple frequencies of each interference signal. The information related to the optical thickness mismatch is determined based on the phase for each of the multiple frequencies of the interference signal(s).

Abstract: In general, in one aspect, the disclosure features a method that includes directing measurement light to reflect from a measurement surface and combining the reflected measurement light with reference light, where the measurement light and reference light are derived from a common source, and there is a non-zero optical path length difference between the measurement light and reference light that is greater than a coherence length of the measurement light. The method further includes spectrally dispersing the combined light onto a multi-element detector to detect a spatially-varying intensity pattern, determining spatial information about the measurement surface based on the spatially-varying intensity pattern, and outputting the spatial information.

Abstract: Disclosed is an interferometry analysis method that includes comparing information derivable from multiple interferometry signals corresponding to different surface locations of a test object to information corresponding to multiple models of the test object, wherein the multiple models are parameterized by a series of characteristics that relate to one or more under-resolved lateral features of the test object; and outputting information about the under-resolved surface feature based on the comparison.

Abstract: Disclosed is a system including: (i) an interferometer configured to direct test electromagnetic radiation to a test surface and reference electromagnetic radiation to a reference surface and subsequently combine the electromagnetic radiation to form an interference pattern, the electromagnetic radiation being derived from a common source; (ii) a multi-element detector; (iii) one or more optics configured to image the interference pattern onto the detector so that different elements of the detector correspond to different illumination angles of the test surface by the test electromagnetic radiation; and (iv) an electronic processor coupled to the detector, wherein the electronic processor is configured to process information measured by the detector to determine information about a test object having the test surface. The measurements made by the detector elements provide ellipsometry/reflectometry data for the test surface.

Abstract: Conical surfaces (and other complex surface shapes) can be interferometrically characterized using a locally spherical measurement wavefront (e.g., spherical and aspherical wavefronts). In particular, complex surface shapes are measured relative to a measurement point datum. This is achieved by varying the radius of curvature of a virtual surface corresponding to a theoretical test surface that would reflect a measurement wavefront to produce a constant optical path length difference (e.g., zero OPD) between the measurement and reference wavefronts.

Abstract: Transparent film measurement techniques are disclosed.

Abstract: A method including: providing a low coherence scanning interferometry data for at least one spatial location of a sample having multiple interfaces, wherein the data is collected using a low coherence scanning interferometer having an illumination geometry and an illumination frequency spectrum, and wherein the data comprises a low coherence scanning interferometry signal having multiple regions of fringe contrast corresponding to the multiple interfaces; and determining a distance between at least one pair of interfaces based on a distance between the corresponding regions of fringe contrast and information about the illumination geometry.

Abstract: A method including comparing information derivable from a scanning interferometry signal for a first surface location of a test object to information corresponding to multiple models of the test object, wherein the multiple models are parametrized by a series of characteristics for the test object. The derivable information being compared may relate to a shape of the scanning interferometry signal for the first surface location of the test object.

Abstract: An apparatus for positioning an object having a substrate and an overlying film and a portion of a photolithography apparatus relative to one another includes a photolithography system, a positioner, an optical system, and a processor. The photolithography system is configured to illuminate a portion of an object with an first light pattern and includes a reference surface. The positioner can change a relative position between the photolithography system and the object. The light projector is configured to project a second light pattern on the overlying thin film of the object. The optical system images light of the second light pattern that is diffusely scattered by the substrate. The processor is configured to determine a spatial property of the object based on the diffusely scattered light and operate the positioner to change the relative position between the photolithography system and the object.