1. Articles from Xavier Colonna De Lega

    1-17 of 17
    1. Analyzing surface structure using scanning interferometry

      Analyzing surface structure using scanning interferometry

      A method includes comparing a scanning interferometry signal obtained for a location of a test object to each of multiple model signals corresponding to different model parameters for modeling the test object, wherein for each model signal the comparing includes calculating a correlation function between the scanning interferometry signal and the model signal to identify a surface-height offset between the scanning interferometry signal and the model signal and, based on the identified surface-height offset, calculating a height-offset compensated merit value indicative of a similarity between the scanning interferometry signal and the model signal for a common surface height. The method ...

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    2. Interferometer utilizing polarization scanning

      Interferometer utilizing polarization scanning
      In one aspect, the disclosure features methods that include using a microscope to direct light to a test object and to direct the light reflected from the test object to a detector, where the light includes components having orthogonal polarization states, varying an optical path length difference (OPD) between the components of the light, acquiring an interference signal from the detector while varying the OPD between the components, and determining information about the test object based on the acquired interference signal.
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    3. Interferometry for lateral metrology

      Interferometry for lateral metrology
      A method is disclosed which includes: using a scanning interferometry system, generating a sequence of phase-shifted interferometry images at different scan positions of an object comprising a buried surface, identifying a scan position corresponding to a position of best focus for the buried surface based on the sequence of phase-shifted interferometry images of the object, and generating a final image based on the phase-shifted interferometry images and the scan position, where the interferometric fringes in the final image are reduced relative to the interferometric fringes in the phase-shifted interferometry images.
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    4. Interferometry method and system including spectral decomposition

      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 ...
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    5. Generating model signals for interferometry

      A method is disclosed which includes, for each of multiple areas of a test surface on a test object having different reflectivities, using an interferometry system to measure each area in a first mode of operation that measures information about the reflectivity of the area over a range of angles and wavelengths; using the same interferometry-system to measure the test surface in a second mode of operation that interferometrically profiles a topography of the test surface over a range including at least some of the multiple areas; and correcting the profile based on the information about the reflectivity of the ...
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      Mentions: FDA
    6. Interferometer with multiple modes of operation for determining characteristics of an object surface

      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; and (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. The apparatus is configured to operate in a first mode in which the combined ...
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    7. Interferometer for determining characteristics of an object surface

      BACKGROUND The invention relates to interferometry.Interferometric techniques are commonly used to measure the profile of a surface of an object. To do so, an interferometer combines a measurement wavefront reflected from the surface of interest with a reference wavefront reflected from areference surface to produce an interferogram. Fringes in the interferogram are indicative of spatial variations between the surface of interest and the reference surface. A scanning interferometer scans the optic
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    8. Interferometer for determining characteristics of an object surface, including processing and calibration

      BACKGROUND The invention relates to interferometry.Interferometric techniques are commonly used to measure the profile of a surface of an object. To do so, an interferometer combines a measurement wavefront reflected from the surface of interest with a reference wavefront reflected from areference surface to produce an interferogram. Fringes in the interferogram are indicative of spatial variations between the surface of interest and the reference surface.A scanning interferometer scans the optic
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    9. Scanning interferometry for thin film thickness and surface measurements

      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.
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    10. Triangulation methods and systems for profiling surfaces through a thin film coating

      An optical system includes a photolithography system, a low coherence interferometer, and a detector. The photolithography system is configured to illuminate a portion of an object with a light pattern and has a reference surface. The low coherence interferometer has a reference optical path and a measurement optical path. Light that passes along the reference optical path reflects at least once from the reference surface and light that passes along the measurement optical path reflects at least once from the object. The detector is configured to detect a low coherence interference signal including light that has passed along the reference ...
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    11. Low coherence grazing incidence interferometry for profiling and tilt sensing

      An optical system includes a photolithography system, a low coherence interferometer, and a detector. The photolithography system is configured to illuminate a portion of an object with a light pattern and has a reference surface. The low coherence interferometer has a reference optical path and a measurement optical path. Light that passes along the reference optical path reflects at least once from the reference surface and light that passes along the measurement optical path reflects at least once from the object. The detector is configured to detect a low coherence interference signal including light that has passed along the reference ...
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    12. Profiling complex surface structures using scanning interferometry

      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 information corresponding to the multiple models may include information about at least one amplitude component of a transform of a scanning interferometry signal corresponding to each of the models of the test object.
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    13. Profiling complex surface structures using height scanning interferometry

      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.
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    14. Interferometric microscopy using reflective optics for complex surface shapes

      An apparatus including: (i) an interferometer positioned to derive measurement and reference wavefronts from a source of electromagnetic radiation, wherein the interferometer is configured to direct the measurement wavefront to reflect from a measurement surface and the reference wavefront to reflect from a reference surface, and further directs reflected measurement and reflected reference wavefronts to overlap with one another and to form an interference pattern; (ii) an auxiliary optic having a curved reflective surface positioned to redirect the measurement wavefront between the interferometer and the measurement surface; and (iii) a translation stage, wherein paths for the measurement and reference wavefronts ...
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    15. Measurement of complex surface shapes using a spherical wavefront

      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.
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    16. Interferometer having a coupled cavity geometry for use with an extended source

      In certain aspects, the invention features an interferometry system that utilizes coupled cavities (e.g., at least one remote cavity and a main cavity) and an extended light source. The remote cavity and the main cavity can have similar optical properties (e.g., similar numerical apertures (NA's)), allowing them to introduce offsetting, and therefore compensating, non-zero optical path differences (OPD's) between the measurement and reference beams without degrading interference fringe contrast due to source spatial coherence. In other words, for each non-zero OPD in the main cavity there exists a configuration of the remote cavity such that the ...
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    17. Interferometric optical systems having simultaneously scanned optical path length and focus

      In certain aspects, the invention features scanning interferometry systems and methods that can scan an optical measurement surface over distances greater than a depth of focus of imaging optics in the interferometry system, while keeping an optical measurement surface in focus (i.e., maintaining an image of the optical measurement surface coincident with the detector). The optical measurement surface refers to a theoretical test surface in the path of test light in the interferometer that would reflect the test light to produce an optical path length difference (OPD) between it and reference light that is equal to a constant across ...
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    1-17 of 17
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