The present invention relates to an arrangement and a method for single-shot interferometry which can be used for detecting distance, profile, shape, undulation, roughness or the optical path length in or on optically rough or smooth objects or else for optical coherence tomography (OCT). The arrangement comprises a light source, an interferometer, in which an end reflector is arranged in the reference beam path, and also a detector for detecting an interferogram. In the reference beam path of the interferometer, the end reflector can be embodied with three plane reflecting surfaces as a prism mirror or air mirror assembly in order to generate between reference and object beams a lateral shear of magnitude delta_q for obtaining a spatial interferogram. The embodiment of said assembly with regard to the angles and the arrangement of the reflecting surfaces makes possible a large aperture angle for a high numerical aperture. In the method, in the reference beam path it is possible to carry out a reduction of the aperture angle of the reference beam using beam-limiting means in order to achieve an optimum adaptation to the geometrically given aperture angle of the end reflector in the reference beam path, which is designed to be smaller than the aperture angle in the object beam path. The end reflector in the reference beam path can also be used as part of a second interferometer for high-resolution measurement of the displacement of the arrangement for single-shot interferometry, wherein said displacement serves for focusing. The end reflector is embodied as a triple reflection arrangement (e.g. a prism arrangement) having three reflecting surfaces. The triple reflection arrangement can have an M- or W-beam path, a non-intersecting zigzag beam path or an intersecting (zigzag) beam path.

The invention relates to a method for creating a two-dimensional interferogram with a Michelson-type free-beam interferometer, comprising an extended, partially spatially coherent light source and a two-dimensional light detector, wherein light from the light source is split by a beam splitter with a semitransparent beam splitter mirror into a sample light beam and a reference light beam and taken to a sample arm and a reference arm, wherein the sample light beam returning from a sample is directed by the beam splitter mirror onto the light detector, wherein the reference light beam emerging from the reference arm makes a predetermined angle greater than zero with the sample light beam on the light detector, and wherein the length of the reference arm is variable, where the reference light beam is directed by means of an odd number of reflections in each reflection plane in at least one reference arm section so that it is displaced laterally to itself and travels antiparallel through a light-deflecting element working by refraction or diffraction which is secured at the exit of the reference arm.

The present disclosure discloses a dual-channel optical three-dimensional interference method based on underdetermined blind source separation, which blindly separates out, through interference data collected by a CCD camera, interference signals between surfaces of a slide under test, to solve interference signal parameters, including an interference signal amplitude-frequency and an interference signal phase-frequency. Based on a dual-channel optical three-dimensional Michelson-type interference experiment, estimation of a mixed matrix is obtained by a K-means clustering algorithm, and recovery of a source signal is achieved by a L1 norm shortest path method. It is finally achieved that laser wavenumber scanning can accurately and blindly separate out the interference signals of the four surfaces based on light intensity values collected by the CCD camera, to achieve the blind separation of the interference signals of the four surfaces.

System and method for profiling of a surface with lateral scanning interferometer the optical axis of which is perpendicular to the surface. In-plane scanning of the surface is carried out with increments that correspond to integer number of pixels of an employed optical detector. Determination of height profile of a region-of-interest that is incomparably larger than a FOV of the interferometer objective is performed in time reduced by at least an order of magnitude as compared to time required for the same determination by a vertical scanning interferometer.

Systems and methods for improved interferometric imaging are presented. One embodiment is a partial field frequency-domain interferometric imaging system in which a light beam is scanned in two directions across a sample and the light scattered from the object is collected using a spatially resolved detector. The light beam could illuminate a spot, a line or a two-dimensional area on the sample. Additional embodiments with applicability to partial field as well as other types of interferometric systems are also presented.

An optical coherence tomography (OCT) system comprises an interferometer configured to generate interference light based on interference between a reference beam and a sample beam with which a sample has been irradiated. A detector operates to detect intensities of the interference light and/or one or more interference patterns; a processor is configured measure a signal falloff of the intensity of the interference light and/or the one or more interference patterns; and an optical delay line configured to adjust an optical path difference according to the signal falloff so as not substantially introduce artifacts to an image of the sample. In one embodiment, the optical delay line includes a main reflector consisting of a mirror and a Faraday rotator; the Faraday rotator is placed between the n and n+1 coherence revival modes of the interferometer, where n is greater than or equal to 1.

A holographic interferometer, comprising: at least one imaging device capturing an interference pattern created by at least two light beams; and at least one aperture located in an optical path of at least one light beam of the at least two light beams; wherein the at least one aperture is located away from an axis of the at least one light beam, thus transmitting a subset of the at least one light beam collected at an angle range.

The invention relates to an interferometric method, in which the light scattered by an object is imaged onto an electronic camera, wherein a sample light component is assigned to scattering sites on a sectional face in the interior of the object. This sample light component can be separated from the contributions of the other sample light components by processing of the camera image and leads to a sectional image. A particular advantage of the invention lies in the fact that multiple parallel sectional faces can be exposed sequentially at predetermined intervals from each other in the interior of the object. Such a sequence of sectional images can be used to calculate a solid model of the object.

An apparatus and method for die defect detection are disclosed. The apparatus includes: a light source unit (10) for emitting light of at least two wavelengths; a beam splitter (40) for receiving the light emitted by the light source unit (10) and splitting it into a first portion and a second portion, the first portion of the light reflected by a die (60) surface under inspection and thereby forming a detection beam; a reference unit (70) for receiving the second portion of the light and processing it into a reference beam; and a detection unit (90) for receiving the detection beam and the reference beam. The reference beam crosses the detection beam at an angle and thus produces interference fringes on a sensing surface of the detection unit (90), based on which a defect parameter of the die (60) surface under inspection is determined. This apparatus is capable of measuring a die with improved accuracy and efficiency and is suitable for the measurement of large dies.

A holographic interferometer, comprising: at least one imaging device capturing an interference pattern created by at least two light beams; and at least one aperture located in an optical path of at least one light beam of the at least two light beams; wherein the at least one aperture is located away from an axis of the at least one light beam, thus transmitting a subset of the at least one light beam collected at an angle range.