Abstract: The present invention provides a measuring apparatus and a measuring method in which a relative moving velocity of a target to be measured or a separation displacement of the target to be measured can be accurately measured even in a case where the target to be measured is moved. In a measuring apparatus, a relative moving velocity of a target to be measured and a separation displacement of the target to be measured can be measured in consideration of the influence of Doppler shift that occurs due to the movement of the target to be measured in an in-plane direction, and thus, even in a case where the target to be measured is moved in the in-plane direction, the relative moving velocity of the target to be measured and the separation displacement of the target to be measured can be accurately measured.

Abstract: A GePD having uniform sensitivity in C and L bands is provided and a photodetector in which deterioration of a common-mode rejection ratio is curbed is provided. A photodetector according to an embodiment includes one or a plurality of sets of two photodiodes to which a differential signal is input, a monitor connected to each of the two photodiodes and configured to measure a photocurrent, and a voltage supply configured to control a voltage applied to each of the two photodiodes, and the voltage supply controls the voltage applied to each of the two photodiodes so that the photocurrent measured by the monitor connected to one of the two photodiodes is equal to the photocurrent measured by the monitor connected to another one of the two photodiodes.

Abstract: A switchable fringe pattern illuminator includes an optical path switch configured to receive light and dynamically control an amount of light that is provided to a first waveguide and an amount of light that is provided to a second waveguide. A first projector configured to generate a first fringe pattern using light from the first waveguide. The first fringe pattern illuminates a first portion of a target area. A second projector configured to generate a second fringe pattern using light from the second waveguide. The second fringe pattern illuminates a second portion of a target area. The illuminator may be part of a depth camera assembly (DCA). The DCA is configured to capture images of a portion of the target area. The DCA is further configured to determine depth information for an object in the target area based in part on the captured images.

Abstract: A method for determining a residual retardance of an LCOS (Liquid Crystal on Silicon) panel includes transmitting a light beam to the LCOS panel at an angle of incidence and measuring an intensity of a reflected light beam. The method includes biasing the LCOS panel in a dark state and measuring a dark state intensity of the reflected light beam. The method also includes biasing the LCOS panel in a bright state, and measuring a bright state intensity of the reflected light beam. A residual retardance of the LCOS panel is determined based on a contrast ratio of the bright state intensity and the dark state intensity. The method can also include selecting a compensator for the LCOS panel based on the residual retardance.

Abstract: A three-dimensional reconstruction system includes an infrared light source array including a plurality of infrared sub-light sources, and each of the infrared sub-light sources emitting an infrared light, and different infrared sub-light sources being coherent light sources, an infrared detector configured to receive an infrared light reflected from a target object, the reflected infrared light being a reflected light of an interference beam emitted by the coherent light source, a calculation circuit, configured to calculate a reference distance between a reflection point on the target object and the infrared sub-light source according to the reflected infrared light and the infrared light emitted by the infrared sub-light source, and a three-dimensional reconstruction circuit, configured to perform reconstruction of a three-dimensional image on the target object according to the plurality of reference distances.

Abstract: A Fourier-transform hyperspectral imaging system may include an optical imaging system configured to produce an image of an object, and an adjustable birefringent common-path interferometer module comprising a movable birefringent element and configured to produce interfering replicas of an input radiation which are delayed from each other by a phase delay adjustable by the moving birefringent element. The interferometer module may be configured to produce collinear replicas for entering optical rays parallel to said optical axis. The hyperspectral imaging system further comprises a two-dimensional light detector configured to receive the replicas and provide digital images of the object depending on said adjustable phase delay. The system also includes an analysis device configured to perform a Fourier Transform of the digital images to obtain a hyperspectral representation of the object.

Abstract: A compact light projection system is described for use in artificial reality systems, and which outputs patterned interferometric illumination that may be dynamically adjustable. The light projection systems are Integrated Circuits (IC)s, which are compact and easily added to other electronic devices in an artificial reality device. The IC illumination sources described herein provide flexibility by incorporating dynamically adjustable components as well as static components, such as phase delay devices, coupling controllers, switch-able light sources, and output gratings, which may each be adjusted to control the resulting pattern of interferometric illumination.

Abstract: Systems and methods are provided for a digital holography range Doppler receiver. The subject system transmits outgoing electromagnetic radiation to a target, and provides a first reference local oscillator (LO) beam to a first detector and a second reference LO beam to a second detector, based on the outgoing electromagnetic radiation. The system receives reflected electromagnetic radiation from the target through a first optical receiver and a second optical receiver having a smaller diameter, and determines range and velocity of the target simultaneously using an interference with the second reference LO beam. The system applies time and frequency offsets to the first reference LO beam based on the measured range and velocity to align the first reference LO beam with the reflected electromagnetic radiation, and produces an image of the target using the first reference LO beam having the applied time and frequency offsets.

Abstract: A switchable fringe pattern illuminator includes an optical path switch configured to receive light and dynamically control an amount of light that is provided to a first waveguide and an amount of light that is provided to a second waveguide. A first projector configured to generate a first fringe pattern using light from the first waveguide. The first fringe pattern illuminates a first portion of a target area. A second projector configured to generate a second fringe pattern using light from the second waveguide. The second fringe pattern illuminates a second portion of a target area. The illuminator may be part of a depth camera assembly (DCA). The DCA is configured to capture images of a portion of the target area. The DCA is further configured to determine depth information for an object in the target area based in part on the captured images.

Abstract: A method and system for identification of holographic tracking and identification of features of an object. A holograph is created from scattering off the object, intensity gradients are established for a plurality of pixels in the holograms, the direction of the intensity gradient is determined and those directions analyzed to identify features of the object and enables tracking of the object. Machine learning devices can be trained to estimate particle properties from holographic information.

Abstract: A method for monitoring a surface of an object via at least one optical camera including the steps: (i) image capture of a predetermined surface segment of the object by a camera at a first point in time, (ii) inspection of the predetermined surface segment of the object such that the surface of the object is acted on, and (iii) image capture of the predetermined surface segment of the object by a camera at a second point in time, which takes place after the first point in time, wherein the image data of the predetermined surface segment of the images of step (i) and step (iii) is sent to an evaluation means and then evaluated by this evaluation means and compared to each other, wherein, if a surface flaw detected in the image capture of step (iii), both in terms of its shape or its position on the surface of the object, coincides with a surface flaw detected in the image capture of step (i), then this surface flaw is classified as an actual surface flaw of the object.

Abstract: An image acquisition apparatus including a beam source, a beam expander, a beam splitter, an interferometer reference arm, a sample, a beam diffuser, a telecentric f-? lens, a beam scanner, and a beam detector uses a terahertz wave to acquire a surface image and a depth image of the sample.

Abstract: A shape measuring apparatus of the present invention measures a variation in a thickness of an object to be measured WA based on an A surface reference interference light and an A surface measuring interference light obtained by performing optical heterodyne interference on a first A surface measuring light and a second A surface measuring light and a B surface reference interference light and a B surface measuring interference light obtained by performing the optical heterodyne interference on a first B surface measuring light and a second B surface measuring light. When the optical heterodyne interference is performed, the shape measuring apparatus makes the first A surface measuring light and the second B surface measuring light equal in frequency and makes the first B surface measuring light and the second A surface measuring light equal in frequency.

Abstract: Methods and apparatuses for generating a model of a subject's teeth. Described herein are intraoral scanning methods and apparatuses for generating a three-dimensional model of a subject's intraoral region (e.g., teeth) including both surface features and internal features. These methods and apparatuses may be used for identifying and evaluating lesions, caries and cracks in the teeth. Any of these methods and apparatuses may use minimum scattering coefficients and/or segmentation to form a volumetric model of the teeth.

Abstract: The present invention relates to an arrangement for the generation of images of optical sections of a three-dimensional (3D) volume in space such as an object, scene, or target, comprising: an illumination unit, an optical arrangement for the imaging of the object onto at least one spatially resolving detector, a scanning mechanism for scanning the entire object and a signal processing unit for the implementation of a method for digital reconstruction of a three-dimensional representation of the object from images of said object as obtained by said detector (which may be in a form of a hologram), wherein the optical arrangement includes a diffractive optical element (herein a phase pinhole), realized using a Spatial Light Modulator (SLM) configured to mimic an actual physical pinhole, while allowing the formation of a three-dimensional representation for a specific point of interest in said object, such that for each scanning position a single hologram or an image is recorded.

Abstract: A multi-axis heterodyne interferometer is disclosed for observations of five degrees of dynamic freedom using a single illumination source. The sensor utilizes polarization and frequency multiplexing to simultaneously observe and separate the image and Fourier planes following scattering of coherent illumination from a dynamic surface. Multiple carrier frequencies and polarizations separate two segments of a Mach-Zehnder interferometer. Segments of this interferometer have unique optical configurations to generate the image and Fourier planes simultaneously on a focal plane array. The measured irradiance contains information pertaining to an object's in-plane translation, out-of-plane rotation, and out-of-plane displacement.

Abstract: An optical tomography apparatus comprises: a polychromatic light source, a one-dimensional optical sensor, an interferometric microscope, a one-dimensional confocal spatial filtering system, an actuation system making it possible to perform a one-way scan depthwise of an object to be observed and a processor for reconstructing a two-dimensional image of a section of the object from a plurality of one-dimensional interferential images acquired by the image sensor during the one-way scan. An optical tomography method based on use of such an apparatus is also provided.

Abstract: A method for analyzing a microscopic sample with a microscope includes illuminating at least a sub-region of the microscopic sample by illumination light. Detection light emanating from the microscopic sample is guided on a detection beam path, which includes at least one focusing optical element and which has a plurality of detection beam path branches, each with at least one detector element. The detector elements are parts of the same surface detector. By art adjusting element in at least a first one of the detection beam path branches, an optical path length of the first detection beam path branch is adjusted in such a way that the portion of the detection light guided on the first detection beam path branch is focused on the detector element of the first detection beam path branch.

Abstract: A wavefront analyzer is modified to simply determine the differences in amplitude and tilt which can exist between the different regions of an initial wavefront (S0). To achieve this, interference between two waves only is produced from beams (F1, F2) which come from neighboring regions on the initial wavefront. Such an analyzer can be used to coherently combine laser radiation produced by different sources arranged in parallel. Another use is for the determination of the differences in height and inclination which exist between the neighboring mirror segments of a Keck telescope.

Abstract: A technique for modular high-speed video vibration analysis of a structure. An embodiment of a device for high-speed video vibration analysis comprises a camera arrangement configured to generate at least two high-speed video streams of the structure and a data analyzer unit, connected to the camera arrangement. The data analyzer unit comprises a processing unit configured to extract vibrational data of at least a portion of the captured structure by considering estimated deformations of at least a portion of the captured structure along a first plane and determined depth information of at least a portion of the captured structure along a second plane different from the first plane or along an axis included in the second plane.

Abstract: The present invention provides a detection device and a detection method. The detection device comprises a light source module, a receiving module, an image generation module and a judgment module. The light source module is configured to emit light towards a film at a predetermined angle, the receiving module is configured to receive interference light formed by first reflected light reflected by an upper surface of the film and second reflected light reflected by a lower surface of the film, the image generation module is configured to generate an equal thickness interference fringe image according to the interference light, and the judgment module is configured to judge whether thickness of the film is uniform according to the equal thickness interference fringe image. The detection device can perform high accuracy detection on uniformity of the thickness of a film, thereby facilitating improving display quality of a display panel.

Abstract: An instantaneous phase-shift interferometer uses a light source having a coherence length shorter than a difference in optical path length between the light reflected from a reference surface and the light reflected from a measured surface. A beam from the light source is split and, using an adjustable delay optical path, a first beam is delayed to cause a difference in optical path length and is superimposed on the same optical axis as a second beam, after which the reference beam and the measurement beam are generated. The optical path length of the delay optical path is changed during adjustment, a plurality of interference fringe images are individually captured, and at least one of a bias, amplitude, and phase shift amount of the interference fringes obtained in each of the interference fringe images is calculated. A shape of a measured object is measured based on bias calculation results, amplitude calculation results, and phase shift amount calculation results.

Abstract: A device for position determination includes a light source and a planar measurement reflector movable along a measurement direction oriented perpendicular to the measurement reflector. A detector device is disposed such that a beam emitted by the light source strikes the detector device after impinging on the measurement reflector so that, in an event of a movement of the measurement reflector along the measurement direction, a signal results which is dependent on a position of the measurement reflector and from which a reference signal is generatable at a defined reference position. A deflection unit is disposed so as to deflect the beam such that the beam strikes the measurement reflector twice and therebetween passes through the deflection unit. The deflection unit is arranged so that a deviation in beam direction, resulting after the first reflection from a tilt of the measurement reflector, is compensated after the second reflection.

Abstract: There are provided a method for obtaining a distance between a base portion of an electrostatic chuck and a back surface of a target object and a method for neutralizing the electrostatic chuck based on the obtained distance. The electrostatic chuck has an upper surface including the base portion and a plurality of convex portions projecting from the base portion. The target object is mounted on apexes of the convex portions of the electrostatic chuck such that the back surface is in contact with the apexes. By processing a first wavelength spectrum output from a spectroscope based on reflected light of light emitted from a light source, a distance between the back surface of the target object and the base portion of the electrostatic chuck is calculated. Based on the calculated distance, a voltage is applied to the electrostatic chuck to neutralize the electrostatic chuck.

Abstract: The invention relates to a differential interferometer module adapted for measuring a direction of displacement between a reference mirror and a measurement mirror. In an embodiment the differential interferometer module is adapted for emitting three reference beams towards a first mirror and three measurement beams towards a second mirror for determining a displacement between said first and second mirror. In a preferred embodiment the same module is adapted for measuring a relative rotation around two perpendicular axes as well. The present invention further relates to a lithography system comprising such a interferometer module and a method for measuring such a displacement and rotations.

Abstract: The invention relates to a method for the 3D measurement of the skin surface and near-surface skin layers by means of a confocal sensor with integrated color camera arranged in a handheld device, wherein said handheld device being moved by an operator via a sensor head to the location of the skin to be examined and a color image of the skin surface then being captured, whereupon the sensor being automatically changed over to confocal operation during which an image stack is generated by the simultaneous capturing of a multitude of all pixels necessary to create a complete image, said stack consisting of confocal images extending into the interior of the skin, with the entire area extending axially into the skin interior being scanned layer by layer in Z direction, wherein after capturing the measuring data an evaluation is performed resulting in a 3D image of the topography of the skin to be generated, and, moreover, from the image stack captured sectional images of the skin and skin volume are computed down

Abstract: A method for reducing interference from scattered light/reflected light of an interference path by generating carrier through phase. Phase modulation is applied on the terminal of a fiber path, and a target signal is separated from an interference signal by selecting a specific working point, to obtain a purer target signal, thereby lengthening the measurement distance. The signal demodulation manner used in this method is different from the traditional manner of modulation performed by generating a carrier through the phase, and does not need to use the modulation frequency as the reference signal during demodulation, so this manner is easily implemented. The method is applicable to long-distance pipeline monitoring and wide-range fiber perimeter security, and especially to an application environment in which the modulation end is far away from the signal demodulation end.

Abstract: A method for correcting a plurality of errors of a photolithographic mask is provided. First parameters of a imaging transformation of the photolithographic mask and second parameters of a laser beam locally directed onto the photolithographic mask are optimized, and the plurality of errors are corrected by applying an imaging transformation using optimized first parameters and locally directing the laser beam onto the photolithographic mask using optimized second parameters. The first and the second parameters are simultaneously optimized in a joint optimization process.

Abstract: The invention relates to an apparatus for determining a layer thickness on a tape moved along a feed direction, comprising: a movement unit for moving the tape along the feed direction, a light generating unit for generating illumination radiation, a beam shaping unit disposed downstream of the light generating unit for shaping at least one strip-shaped illumination beam for linear illumination of the tape transversely with respect to the feed direction, a detector unit for detecting illumination radiation reflected and/or transmitted at the tape, and an evaluation device for determining the layer thickness on the basis of the detected illumination radiation. The apparatus can also be used for determining a degree of contamination of a surface of the tape, the surface being contaminated by particles, by detecting illumination radiation scattered at the tape.

Abstract: A device for interferometrically determining the distance between two plates disposed substantially in parallel, includes a light source, beam-splitter element(s), reflector element(s), deflection elements, retroreflectors, and a detection unit. A beam of rays emitted by the light source falls on the first plate and splits into a reflected reference beam of rays and a transmitted measuring beam of rays. The measuring beam strikes a reflector on the second plate and undergoes a first reflection back toward the first plate. The reference beam traverses a first deflection element, and the measuring beam traverses a second deflection element. Both beams pass through a retroreflector. The reference beam is reflected at the first plate, and the measuring beam undergoes a second reflection at a reflector of the second plate, so that both beams propagate collinearly interferingly toward the detection unit, where a plurality of phase-shifted distance signals are generated.

Abstract: An optical measuring probe for measuring inner and/or outer diameters of objects, uses a first optical element for focusing or collimating an optical beam onto a surface of an object. A second optical element for splitting the optical beam into a first measuring beam and a second measuring beam is provided in the optical measuring probe in such a way that the second measuring beam is guided out of the measuring probe in a direction opposite the direction of the first measuring beam and that the first measuring beam forms a first scan point and the second measuring beam forms a second scan point. Also described is a corresponding method for measuring diameters using the optical measuring probe. The optical measuring probe and the associated method make it possible to optically measure inner and outer diameters of measuring probes objects in a simple manner.

Abstract: The present disclosure includes disclosure of devices, and methods to resolve microscopic structures. In at least one exemplary embodiment, a visualization apparatus comprises a source arm having a light source operable to emit a light beam, wherein the light beam defines a beam pathway, a reference arm comprising a reflecting surface positioned within the beam pathway, a sample arm comprising a wavefront sensor, an adaptive optics wavefront corrector, and a target, each of which are positioned within the beam pathway, wherein the adaptive optics wavefront corrector is operable to compensate for at least one aberration in the light beam, a detector arm comprising a beam detector positioned within the beam pathway, wherein the beam detector is operable to detect the reflected light beam from the reference arm and the target, and wherein the visualization apparatus is operable to minimize at least one aberration of the target.

Abstract: A white-light interferometric measuring device includes: a white light source that emits a white light beam; a beam splitter that reflects the white light beam; and an interference objective lens that collects the white light beam having reflected off the beam splitter in the direction of an optical axis and irradiates a measurement workpiece with the white light beam, the interference objective lens generating interference between a measurement light beam obtained by reflection of the white light beam off the measurement workpiece and a reference light beam obtained by branching of the white light beam to be converged on the measurement workpiece. Polarization correcting means that corrects the white light beam to enter the interference objective lens to circularly polarized light is arranged between the white light source and the interference objective lens.

Abstract: Four separately polarized beams are simultaneously measured upon diffraction from a substrate (W) to determine properties of the substrate. Linearly, circularly or elliptically polarized radiation is transmitted through a first beam splitter (N-PBS) and split into two polarized beams. These two beams are further split into two further beams using two further beam splitters, the further beam splitters (32,34) being rotated by 45° with respect to each other. The plurality of polarizing beam splitters enables the measurement of the intensity of all four beams and thus the measurement of the phase modulation and amplitude of the combined beams to give the features of the substrate. Algorithms are used to compare the four intensities of each of the polarized angles to give rise to the phase difference between the polarization directions and the ratio between the two main polarization direction amplitudes of the original polarized beam.

Abstract: The present invention provides an inexpensive range image sensor and etc. A range image sensor comprises diffractive optical elements and on which are formed diffractive gratings that change a traveling direction of incident parallel light so that in a coordinate space defined by a xyz-axis, the incident parallel light is split into split beams, and angles formed by the x-axis and line segments determined by projected light spots formed by the split beams on a predetermined projection plane intersecting the z-axis become predetermined angles. Furthermore, the range image sensor is provided with a distance determining unit for determining distances to the projected light spots on the basis of the tilting with respect to the x-axis of the line segments determined by the projected light spots formed on the object by the split beams.

Abstract: In a tool length measuring method measuring a length of a tool based on a movement amount of the tool from a predetermined position when the tool is moved from the predetermined position in a predetermined direction and interrupts a laser beam, the movement of the tool in a direction in which the tool approaches a main body of a laser device is stopped when a static signal indicating that the tool is interrupting the laser beam is detected.

Abstract: Position detector for determining the rotation angle position of a rotatably supported object, comprising a light source for producing a light beam, a diffraction grating, a mirror which is connected with the object in a co-rotating manner in such a way that the light beam is reflected therefrom onto the diffraction grating and passes over the diffraction grating during a rotation of the mirror, thereby producing diffraction light, an interference device which is configured such as to be able to bring different diffraction orders of the diffraction light to interference, thereby producing an interference pattern, a light detector by means of which a brightness course, caused by the passing over of the diffraction grating with the reflected light beam, of the interference pattern can be detected, and an evaluation unit by which the rotation angle position of the object can be determined based on the brightness course.

Abstract: A measurement system for measuring the position of a work piece (28) includes a stage grating (234) and an encoder head (236). A first measurement beam (38A) is directed at the stage grating (234) at a first angle, the first measurement beam (38A) being at a first wavelength. A second measurement beam (38B) is directed at the stage grating (234) at a second angle that is different than the first angle, the second measurement beam (38B) being at a second wavelength that is different than the first wavelength. At least a portion of the first measurement beam (38A) and at least a portion of the second measurement beam (38B) are interfered with one another to create a measurement signal along a signal axis.

Abstract: A shape determining device includes first and second homodyne interferometers respectively provided for front and back surfaces of an object to be measured and a thickness distribution calculator that calculates a thickness distribution of the object based on intensities of first and second interference light beams respectively detected by the first and second homodyne interferometers for the front and back surfaces of the object at a plurality of measurement sites. The thickness distribution calculator calculates, for each interference light beam for which the intensity is detected by the first and second homodyne interferometers, a phase difference between the polarization components of a corresponding reference light beam and a corresponding object light beam in a corresponding non-interference light beam based on the intensity of the interference light beam, and calculates the thickness distribution based on a distribution of the calculated phase differences.

Abstract: The present invention relates to a dual focusing optical coherence imaging system. The dual focusing optical coherence imaging system includes: a light source unit for generating broadband light; a main optical distributor for distributing the light generated from the light source to allow the light to be propagated; an interference unit including first and second interference parts for forming interference signals with respect to different focused areas of an object to be detected using the light distributed from the optical distributor, and a common sample arm commonly connected to the first and second interference parts; an optical switch connected to the first and second interference parts to select at least one of the interference signals transmitted from the first and second interference parts; and a detection unit for converting the interference signal selected by the optical switch according to a preset mode into an electrical signal.

Abstract: A white-light interferometric measuring device includes: a white light source that emits a white light beam; a beam splitter that reflects the white light beam; and an interference objective lens that collects the white light beam having reflected off the beam splitter in the direction of an optical axis and irradiates a measurement workpiece with the white light beam, the interference objective lens generating interference between a measurement light beam obtained by reflection of the white light beam off the measurement workpiece and a reference light beam obtained by branching of the white light beam to be converged on the measurement workpiece. Polarization correcting means that corrects the white light beam to enter the interference objective lens to circularly polarized light is arranged between the white light source and the interference objective lens.

Abstract: An optical coherence tomography (OCT) apparatus includes an optical source, an interferometer generating an object beam and a reference beam, a transverse scanner for scanning an object with said object beam, and a processor for generating an OCT image from an OCT signal returned by said interferometer. At least the optical source, the interferometer, and the scanner are mounted on a common translation stage displaceable towards and away from said object. A dynamic focus solution is provided when the scanner and a folded object path are placed on the translation stage.

Abstract: A compound common-path interferometer including first and second measurement arms for measuring a test object is arranged so that a reference optic of the first measurement arm is disconnected from a remainder of the first measurement arm and a coupling between the reference optics of the first and second measurement arms forms a monolithic measurement cavity for maintaining reference surfaces of the reference optics at a fixed spacing and orientation. Separate supports are provided for the monolithic measurement cavity and the remainder of the first measurement arm.

Abstract: The general field of the invention is that of optical systems for detection of the orientation of mobile objects in space. The main application is helmet posture detection inside of an aircraft cockpit. The system according to the invention operates by interferometry. It comprises a fixed electro-optical device comprising one or more collimated point-like emission sources and a detection assembly comprising one or more point-like photosensitive detectors. Two or more retro-reflecting devices referred to as “cube corner” are disposed on the mobile object. This system can be completed by optical means operating in polarized light mode allowing the direction of variation of the interference fringes to be determined and by other optical devices allowing an initial orientation to be measured.

Abstract: An optical device for characterizing a test surface combines a Fizeau interferometer with a polarization frequency-shifting element. Two substantially collinear, orthogonally polarized beams having respective frequencies differing by a predetermined frequency shift are generated by the polarization frequency-shifting element and projected into the Fizeau optical cavity to produce a pair of test beams and a pair of reference beams, wherein the beams in each pair have orthogonal polarization states and have frequencies differing by the predetermined frequency shift. A second, substantially equal frequency shift is introduced in the Fizeau cavity on either one of the pairs of test and reference beams, thereby generating a four-beam collinear output that produces an interferogram without tilt or short-coherence light. The invention may also be implemented by reversing the order of the Fizeau cavity and the polarization frequency-shifting element in the optical train.

Abstract: In one embodiment, the invention relates to an apparatus for increasing the repetition rate in a light source. The apparatus includes a first optical coupler comprising a first arm, a second arm and a third arm; a first mirror in optical communication with the second arm of the first optical coupler; and a first optical delay line having a first end in optical communication with the third arm of the first optical coupler and a second end in optical communication with a second mirror, wherein light entering the first arm of the first optical coupler leaves the first arm of the first optical coupler either delayed by an amount (?) or substantially undelayed.

Abstract: A correction algorithm may be applied for correcting misalignment of a radially-aligned array of sensors. Due to the tilt, signals from sensors that are further away from the media, may become slightly attenuated, while signals from sensors that are closer to the media are slightly increased. The error appears periodic and largely sinusoidal in nature around the array given the circular nature of the array of sensor elements. The algorithm determines the magnitude and phase of a sinusoidal function that best fits the wavelength data. In one embodiment, a discrete Fourier transform may be performed at the ‘frequency’ equivalent to one period around the array to determine the magnitude and phase estimate thereof. Then, a sinusoidal correction function may be generated using the magnitude and the phase in order to correct the reflectance data.

Abstract: A method for calibrating an apparatus for ellipsometric measurements performed on an arbitrarily large or continuously moving sample, using a visible sample reference frame, and one or more laser sources in order to calibrate the ellipsometer for variations in the distance between the ellipsometer apparatus and the sample of interest. Included are techniques for projecting a first laser beam spot from an incident laser source onto a sample, then analyzing the position of the first laser beam spot relative to the center of the sample reference frame using human-aided measurements and confirmations and/or computer vision techniques. Then adjusting pivot points and/or apparatus-to-sample distance to achieve a first beam spot being located about the center of the sample reference frame, and concurrently intersecting the plane of the sample. Other techniques include changing the incidence and reflectance angle using a semi-circular track arc design with a stepping motor activating each goniometer arm.

Abstract: The present disclosure includes disclosure of devices, and methods to resolve microscopic structures. In at least one exemplary embodiment, a visualization apparatus comprises a source arm having a light source operable to emit a light beam, wherein the light beam defines a beam pathway, a reference arm comprising a reflecting surface positioned within the beam pathway, a sample arm comprising a wavefront sensor, an adaptive optics wavefront corrector, and a target, each of which are positioned within the beam pathway, wherein the adaptive optics wavefront sensor is operable to compensate for at least one aberration in the light beam, a detector arm comprising a beam detector positioned within the beam pathway, wherein the beam detector is operable to detect the reflected light beam from the reference arm and the target, and wherein the visualization apparatus is operable to minimize at least one aberration of the target.

Abstract: An object of the present invention is to measure thickness distribution with precision by using a simple device configuration without being affected by vibrations of a to-be-measured object. In the present invention, for each of the front and the back surfaces of a to-be-measured object 1, each of light beams obtained by branching into two an emitted light beam from a laser light source 2 is further branched into two. Then, the light beams are reflected in reference surfaces and measurement points 1a and 1b mutually in a front and back relation, so that non-interference light beams Pax and Pbx each of which contains the reference light beam and the object light beam as mutually orthogonal polarization components are acquired. Then, each light beam is branched into a plurality. Onto one or more of the branched light beams, phase shift is performed in which a change is imparted to the phase difference between the orthogonal polarization components by using wavelength plates a261, a263, and a264 and the like.