Abstract: A multiwavelength interferometer (200,300) includes a light beam splitter (8) that separates each of a plurality of light beams having wave lengths different from each other into measuring light and reference light, an interference signal generator (100) that generates an interference signal of interference light of the reference light and reflected light obtained by illuminating the measuring light on a surface (27) to be measured to be reflected on the surface for each wavelength, an illumination state changer (25) that changes an illumination state of the measuring light on the surface, a detector (222a, 222b) that detects the interference signal while the illumination state is changed, and a measurement unit (23) that measures a position of the surface using phases of a plurality of interference signals for each wavelength and intensity information of at least one interference signal of the plurality of interference signals.

Abstract: An exemplary device has a stationary portion and a movable portion. The stationary portion has a first corner-cube, an optical system including a beamsplitter, and a light detector. The movable portion comprises a second corner-cube mountable on an object that is displaceable in a principal direction relative to the stationary portion. The beamsplitter splits a beam of collimated broadband light into a reference beam and a measurement beam that are directed by the optical system to make multiple roundtrip passes from the optical system to the respective corner cubes and back. The reference beam and measurement beam interfere with each other to produce a coherence envelope sensed by the detector, wherein a detected displacement of the coherence envelope corresponds to a respective position of the object in the principal direction.

Abstract: In position-measuring devices and a systems having a plurality of position-measuring devices for determining the position of an object in several spatial degrees of freedom, the plurality of optical position-measuring devices scan the object from a single probing direction, and the probing direction coincides with one of the two main axes of motion.

Abstract: A laser beam irradiation apparatus includes a laser beam oscillation unit including a pulse laser beam oscillator for oscillating a pulse laser beam and a cycle frequency setting unit for setting the cycle frequency, an acousto-optic deflection unit for deflecting the optical axis of the pulse laser beam oscillated from the laser beam oscillation section, and a control unit for controlling the acousto-optic deflection unit. The control unit outputs a driving pulse signal having a predetermined time width including a pulse width of the pulse laser beam oscillated from the pulse laser beam oscillator to the acousto-optic deflection unit based on the cycle frequency setting signal from the cycle frequency setting section.

Abstract: In an interferometer system and a method for its operation, the interferometer system includes an interferometer having an interferometer light source whose emitted radiation is able to be split into a measuring arm and a reference arm, an object to be measured being disposed in the measuring arm, and the interferometer delivering interferometer signals as a function of the position of the object to be measured. In addition, a detecting device is provided for detecting fluctuations in the refractive index of the air in the measuring arm and/or reference arm. The detecting device includes a spectrometer unit; the spectrometer unit has at least one spectrometer light source, as well as at least one spectrometer detector unit.

Abstract: A position measuring arrangement that includes a retroreflector, a light source generating a lightbeam and a scanning unit that generates a partially-divergent lightbeam. The scanning unit includes a scanning mirror mounted so it is deflected in a reproducible manner so that a grid-like scanning of a two-dimensional spatial area by the partially-divergent lightbeam takes place over a plurality of scanning tracks. The position measuring arrangement including an interferometric distance measuring unit that includes a beam splitter element that splits the lightbeam generated by the light source so that split lightbeams pass through a reference arm and a measuring arm at least once in each direction. The interferometric distance measuring unit includes an opto-electronic detector unit, through which a detection of distance-dependent signals from superimposed lightbeams from the reference arm and the measuring arm takes place.

Abstract: A method of steering a laser beam from an instrument toward a point on a retroreflector, including: intercepting with the retroreflector a cone of light from the instrument; obtaining a first image of retroreflected light on a photosensitive array and transmitting an electrical data signal in response; determining a position on the photosensitive array of the first image; calculating first and second angular increments to steer the laser beam to the point; rotating the first and second motors to intercept with the position detector the retroreflected laser beam and to place the laser beam at a preferred location on the position detector; measuring fifth and sixth angles with first and second angle transducers; measuring a distance with a distance meter; and determining three-dimensional coordinates of the point based at least in part on the fifth angle, the sixth angle, and the distance.

Abstract: A method of tracking the position of an object, comprising using reference interference data from first output beam, reference interference data from a second output beam, measurement interference data from the first output beam, measurement interference data from the second output beam, and knowledge of the difference between the absolute phase offset of the first output beam and the absolute phase offset of the second output beam for both a reference interferometer (15?) and a measurement interferometer (15) to calculate a parameter indicative of the absolute phase offset of the measurement interferometer (15) for the first output beam. The calculated parameter is used to calculate the ratio of the optical path differences of the measurement interferometer (15) and the reference interferometer (15?).

Abstract: A position measuring device includes a plurality of concave marks, a light source portion, a light receiving portion, and a concave portion measuring portion. The concave marks are formed on an external wall of an object to be a measuring target. Each of the plurality of the concave marks includes a plurality of concave portions disposed on a concentric circle with a preset concave mark central position to be a center of the concentric circle. The concave portions are provided so that densities of the concave portions become lower as distances from the concave mark central position become longer in each of the concave marks. The light source portion irradiates the object with an irradiating light. The light receiving portion receives a reflected light from the object, the refracted light being originated from the irradiating light. The concave portion measuring portion measures each three-dimensional position of the concave marks.

Abstract: There is provided a laser gauge interferometer with high measurement precision, which uses laser beam interference, includes: a measurement interferometer which generates a measurement output corresponding to a displacement of a moving member; and a correction interferometer which generates a measurement output corresponding to a change in refractive index of air at a constant reference interval. An arithmetic processing device computes a measurement target displacement amount for which the influence of the change in refractive index of air is corrected. A correction laser beam from the correction interferometer passes through the measurement interferometer and thus travels on the same optical path as an optical path of a correction laser beam from the measurement interferometer to become interference light corresponding to the change in refractive index of air through which a measurement laser beam passes, and then enters the arithmetic processing device.

Abstract: Disclosed is a method of determining geometric errors in a machine tool or measuring machine having a mobile unit for moving a target within a measuring volume. The method includes the steps of generating a succession of laser beams in different directions by means of an interferometer, and, for each direction, moving the target into a number of points along the beam; measuring, by means of the interferometer, the abscissa of each of the points from an origin located along the direction of the beam; acquiring the coordinates of each of the points by means of the machine; and determining error parameters of the machine on the basis of the abscissas measured by the interferometer, and the coordinates of the points acquired by the machine.

Abstract: The invention relates to an apparatus for measuring a distance. A self-mixing interference (SMI) unit (2) generates an SMI signal, wherein the SMI unit comprises a laser (3) emitting a first laser beam (4) for being directed to an object (5) and wherein the SMI signal depends on an interference of the first laser beam and a second laser beam (6) reflected by the object. A peak width determination unit (8) determines a peak width of the SMI signal, and a distance determination unit (9) determines a distance between the object and the SMI unit depending on the determined peak width of the SMI signal. Since the distance is determined depending on the peak width of the SMI signal, without requiring a laser driving current modulation, advanced electronics for modulating the driving current of the laser are not needed. This reduces the technical efforts needed for determining the distance.

Abstract: A method for determining information about changes in a position of an encoder scale includes separating, in a first interferometry cavity, a low coherence beam into a first beam propagating along a first path of the first interferometry cavity and a second beam propagating along a second path of the first interferometry cavity, combining the first beam and the second beam to form a first output beam, separating, in a second interferometry cavity, the first output beam into a measurement beam propagating along a measurement path of the second interferometry cavity and a reference beam propagating along a reference path of the second interferometry cavity, combining the measurement beam and the reference beam to form a second output beam, detecting an interference signal based on the second output beam, and determining the information about changes in the position of the encoder scale based on phase information from the interference signal.

Abstract: An encoder head includes one or more components arranged to: i) direct a first incident beam to the diffractive encoder scale at a first incident angle with respect to the encoder scale; ii) receive a first return beam from the encoder scale at a first return angle, the first return angle being different from the first incident angle; iii) redirect the first return beam to the encoder scale as a second incident beam at a second incident angle; and iv) receive a second return beam back from the encoder scale at a second return angle, the second return angle being different from the second incident angle, in which a difference between the first incident angle and second incident angle is less than a difference between the first incident angle and the first return angle and less than a difference between the second incident angle and the second return angle.

Abstract: A device for the interferometric measuring of an object, including a light source to generate an emitted beam, a beam splitting device for splitting the emitted beam into a measuring beam and at least first and second reference beams, an optic interference device, and first and second detectors, with the interference device and the first detector being embodied cooperating such that the measuring beam, at least partially reflected by the object, and the first reference beam are interfered on at least one detector area of the first detector. The interference device and the second detector are embodied cooperating such that the measuring beam, at least partially scattered by the object, and the second reference beam are interfered on at least one detector area of the second detector. A method is also provided for the interferometric measuring of an object.

Abstract: Phase differences associated with a defocused wavefront can be determined from a single color image. The color image, which is a measurement of intensity as a function of wavelength, is used to calculate the change in intensity with respect to wavelength over the image plane. The change in intensity can then be used to estimate a phase difference associated with the defocused wavefront using two-dimensional fast Fourier transform solvers. The phase difference can be used to infer information about objects in the path of the defocused wavefront. For example, it can be used to determine an object's shape, surface profile, or refractive index profile. It can also be used to calculate path length differences for actuating adaptive optical systems. Compared to other techniques, deriving phase from defocused color images is faster, simpler, and can be implemented using standard color filters.

Abstract: The time delay (and therefore the OPD) between object and reference beams in an interferometer is manipulated by changing the spectral properties of the source. The spectral distribution is tuned to produce a modulation peak at a value of OPD equal to the optical distance between the object and reference arms of a Fizeau interferometer, thereby enabling the use of its common-axis configuration to carry out white-light measurements free of coherence noise. Unwanted interferences from other reflections in the optical path are also removed by illuminating the object with appropriate spectral characteristics. OPD scanning is implemented without mechanical means by altering the source spectrum over time so as to shift the peak location by a predetermined scanning step between acquisition frames. Finally, the spectrum is controlled on a pixel-by-pixel basis to create a virtual surface that matches the profile of a particular sample surface.

Abstract: Methods and systems are provided for suppressing speckle and/or diffraction artifacts in coherent structured illumination sensing systems. A coherent radiation pattern forms an interference pattern at an illumination image plane and illuminates an object. Radiation scattered or otherwise emitted by the object is detected to produce a signal, which is integrated in time. Coherent artifact suppression is attained by using a spatial modulator, such as an acousto-optic device, to vary a phase gradient at the illumination image plane during the signal integration time. Various embodiments are provided for purposes including without limitation: preserving the depth of field of the coherent illumination; using the same acousto-optic device for pattern generation and coherent artifact suppression; electronically controlling the effective spatial coherence of the illumination system; and reducing errors due to coherent artifacts in a laser-based three dimensional imaging system.

Abstract: A lightwave interference measurement apparatus includes a phase detector configured to detect a phase of a signal of an interference between light from a distance-measurement light source and reflected on a reference surface and light from the distance-measurement light source and reflected on a target surface, an intensity detector configured to detect an intensity of light from a non-distance-measurement light source having a wavelength different from that of the distance-measurement light source and reflected on the reference surface and an intensity of light from the non-distance-measurement light source and reflected on the target surface, and an analyzer configured to calculate a geometric distance based on an optical path length calculated from the phase and a wavelength of the distance-measurement light source, and an average value of a vapor pressure distribution between the target surface and the reference surface calculated from intensity information of the light from the non-distance-measurement l

Abstract: An accelerometer instrument is provided for measuring acceleration. The instrument includes a laser, a Mach-Zender interferometer (MZI), a mechanical spring, a detector, a camera, and an analyzer. The laser emits a coherent light beam of photons. The MZI includes first and second beam-splitters along with first and second mirrors. The first mirror has an established mass m and connects to the spring for vibrating substantially perpendicular to its reflection plane. The mechanical spring has an established spring constant k. The MZI has an established weak measurement Nw based on a known offset ? for the beam-splitters. The detector detects the beam beyond the second beam-splitter. The camera provides a pointer measurement shift ?q of the photons. The camera is disposed after the detector. The analyzer determines the acceleration ? based on a = ( k mN w ) ? ? ? ? q .

Abstract: Remote seismic surveying systems and methods are disclosed. At least some embodiments illuminate a water or ground surface with a beam from a coherent electromagnetic wave source. Reflected electromagnetic energy is focused onto an image plane where it combines with a reference beam to form an interference pattern. Electronics track the intensity versus time for multiple points in the image and derive displacement signals for various physical locations in the survey region. These displacement signals are associated with seismic source firing times and locations before being stored as seismic traces in a survey database. Some variations use the reflected electromagnetic energy to create multiple interference patterns that vary due to different path length differences, thereby eliminating signal phase ambiguities.

Abstract: A measuring apparatus includes a light source unit configured to continuously scan wavelengths of a plurality of types of beams at different speeds in a plurality of discrete wavelength scanning ranges, a beam synthesizer, an interferometer unit configured to detect as an interference signal an interference fringe formed by a reference beam reflected on a reference surface and a target beam reflected on a target surface, and a processor configured to determine the absolute distance based upon the interference signal detected by the interferometer unit. The interferometer unit includes a single optical detector. The processor obtains the absolute distance for each of the plurality of types of beams through a frequency analysis of a synthesized interference signal, and outputs one absolute distance by operating a plurality of absolute distances that have been obtained.

Abstract: A coordinate measuring device includes a carrier that can be rotated automatically about two axes and that can be directed toward a measuring aid. The following are arranged on the carrier so as to be able to move together: an optical distance measuring device for measuring the distance to the measuring aid; a light source for emitting light, directly or by means of optical elements, wherein said light is visible as a target point when reflected on the measuring aid; a target detecting unit for determining a position as the position of the imaging of the target point on a position detection sensor. The control apparatus is designed to direct the carrier at the measuring aid by rotating the carrier about the at least two axes of the carrier according to the fine position and the rough position; and the light source is a superluminescent diode (SLED).

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 interferometric displacement measuring system operable to measure displacements of a movable object of the lithographic apparatus in a first direction using a measurement beam of radiation and a reflector. The reflector being substantially planar and substantially perpendicular to the first direction. Calibration is obtained using a first set of measurements of the angular position movable object. A phase offset in the measurement beam is affected. A second set of measurements of the angular position of the movable object is obtained. The interferometric displacement measuring system is calibrated based on the first and second sets of measurements.

Abstract: An interferometer of the present invention includes a PBS2 which splits light into reference light and measurement light, a reference mirror 4a which reflects the reference light entering the reference mirror from a first direction, a measurement mirror 4b which reflects the measurement light entering the measurement mirror from a second direction, a lens system 6 which reflected lights from the reference mirror 4a and the measurement light 4b enter, a reflective device 5 which reflects light from the lens system 6, and a light receiving device 16 which receives multiplexed light, wherein the reference mirror 4a and the measurement mirror 4b are in a conjugate relation with respect to the reflective device 5, and at least one of the reference mirror 4a and the measurement mirror 4b is tilted so that its normal direction differs from the first and the second direction.

Abstract: A physical quantity sensor includes a semiconductor laser for irradiating an object with a laser beam, and a laser driver for operating the semiconductor laser in such a way that a first oscillation period for which the oscillation wavelength increases and/or a second oscillation period for which the oscillation wavelength decreases is repetitively present. The sensor further includes a photodiode and a current-voltage conversion amplifying unit both for detecting an MHP containing an interference waveform formed by the self-coupling effect between the laser beam and the returning light beam from the object, a MHP extracting unit for measuring the period of the interference waveform contained in the output signal from the current-voltage conversion amplifying unit each time the interference waveform is inputted, and a computing unit for computing the displacement and/or the speed of the object from the measured individual period MHP extracting unit.

Abstract: The oscillation wavelength of a variable wavelength laser is measured by using an optical comb, and a feedback control is performed, whereby laser beams of plural predetermined wavelengths are obtained, or a variable wavelength laser is caused to oscillate at plural arbitrary wavelengths to obtain plural distance measurement values. The wavelengths (frequencies) of laser beams when the respective distance measurement values are obtained are measured by the optical comb, and used in calculation of the geometric distance. Plural lasers are used, and the geometric distance is obtained while the wavelengths of laser beams oscillated from the lasers are measured by the optical comb.

Abstract: The present invention provides a measurement apparatus which measures a wavefront of light traveling from a member to be measured, the apparatus including a first reference surface, a second reference surface configured to function as a reference surface for the first reference surface, an optical system configured to form a first interference pattern of light traveling from the member to be measured and light traveling from the first reference surface, and a second interference pattern of light traveling from the first reference surface and light traveling from the second reference surface, a detection unit configured to detect the first interference pattern and the second interference pattern, respectively, and a calculation unit configured to calculate a wavefront of light traveling from the member to be measured based on the first interference pattern and the second interference pattern detected by the detection unit.

Abstract: A measurement apparatus includes a beam splitter that splits light from a light source into measurement light to be directed to an object to be measured and reference light to be directed to a reference surface, a beam combiner that combines the measurement light reflected by the object and the reference light reflected by the reference surface to generate combined light, and obtains physical information of the object based on the combined light. The measurement apparatus further includes a coherence controller which changes spatial coherences of the measurement light and the reference light.

Abstract: A method for determining three-dimensional coordinates of an object point on a surface of an object, including steps of providing a transparent plate having a first region and a second region, the second region having a different wedge angle than the first region; splitting a first beam of light into a first light and a second light; sending the first light through the first region or the second region; combining the first light and the second light to produce a fringe pattern on the surface of the object, the pitch of the fringe pattern depending on the wedge angle through which the first light travels; imaging the object point onto an array point on a photosensitive array to obtain an electrical data value; determining the three-dimensional coordinates of the first object point based at least in part on the electrical data value.

Abstract: The stage apparatus includes a stage having a range of movement on a stage base, an interferometer and a fixed mirror that are installed outside the stage on the stage base, and a first movable mirror disposed on the stage to reflect light, which is introduced from the interferometer, toward the fixed mirror, and to reflect the light, which is received after being reflected by the fixed mirror, to the interferometer.

Abstract: A method of detecting a movement of a measuring probe provided between an objective lens adapted to image an object plane on a predetermined image plane and the object plane is disclosed. Additionally, a measuring instrument comprising an objective lens and a measuring probe is disclosed. An input beam of light is split into a measurement beam and a reference beam. The measurement beam is focused on a reverse focal plane of the objective lens such that the measurement beam is collimated by the objective lens. The collimated measurement beam is reflected at the measuring probe. The reflected measurement beam is directed towards the objective lens such that the objective lens focuses the reflected measurement beam on the reverse focal plane. The reflected measurement beam is collimated. The collimated reference beam and the reference beam are superimposed to form a superimposed beam and an interference between the reflected measurement beam and the reference beam is detected.

Abstract: The invention relates to a method and arrangement for determining structures and/or geometry of a workpiece in a coordinate measuring machine by means of a tactile-optical measuring method, wherein the position of a shaped probe element is determined in at least one direction by means of a first sensor using an optically lateral measuring method, and the position of the shaped probe element is determined in at least one second direction using at least one distance sensor. In order to allow the error-free detection of the shaped probe element using the sensors, the invention proposes that at least one flexible connector element is used in a mounting for fastening the shaped probe element, permeated by the beam path of the first sensor in the beam direction, wherein the connecting element is transparent and/or is disposed severely out of focus with respect to the first sensor.

Abstract: An interferometer of the present invention includes a PBS2 which splits light into reference light and measurement light, a reference mirror which reflects the reference light entering the reference mirror from a first direction, a measurement mirror which reflects the measurement light entering the measurement mirror from a second direction, a lens system which reflected lights from the reference mirror and the measurement light enter, a reflective device which reflects light from the lens system, and a light receiving device which receives multiplexed light, wherein the reference mirror and the measurement mirror are in a conjugate relation with respect to the reflective device, and at least one of the reference mirror and the measurement mirror is tilted so that its normal direction differs from the first and the second direction.

Abstract: The present invention provides a measurement apparatus which measures a distance between a reference surface fixed on a fiducial surface and a test surface located on a test object, the apparatus including an optical frequency comb generation unit configured to generate a light beam with a plurality of optical frequency components, which have equal optical frequency separations therebetween, a detection unit configured to, for at least two of the plurality of optical frequency components, detect an interference signal between a light beam reflected by the reference surface and a light beam reflected by the test surface to detect a phase corresponding to an optical path length between the reference surface and the test surface, and a calculation unit configured to calculate a geometric distance between the reference surface and the test surface based on the phases detected by the detection unit.

Abstract: An optical position-measuring device for detecting the relative position of two objects includes a measuring standard connected to one object, and a scanning unit connected to the other object and including a light source, one or more grating(s), and a detector system. The detector system includes a plurality of detector element groups arranged in a detection plane, via which a plurality of position-dependent, phase-shifted scanning signals is able to be generated by scanning a periodic fringe pattern that results in the detection plane, the detector elements that have in-phase scanning signals forming a group in each case. The sum of the areas and the centroid of the detector elements of a group is identical to the sum of the areas and the centroid, respectively, of the detector elements of each other group. Periodic diaphragm structures are arranged in front of the light-sensitive areas of the detector elements.

Abstract: Fourier domain a/LCI (faLCI) system and method which enables in vivo data acquisition at rapid rates using a single scan. Angle-resolved and depth resolved spectra information is obtained with one scan. The reference arm can remain fixed with respect to the sample due to only one scan required. A reference signal and a reflected sample signal are cross-correlated and dispersed at a multitude of reflected angles off of the sample, thereby representing reflections from a multitude of points on the sample at the same time in parallel. Information about all depths of the sample at each of the multitude of different points on the sample can be obtained with one scan on the order of approximately 40 milliseconds. From the spatial, cross-correlated reference signal, structural (size) information can also be obtained using techniques that allow size information of scatterers to be obtained from angle-resolved data.

Abstract: A microscopy system and method allow observing a fluorescent substance accumulated in a tissue. The tissue can be observed at a same time both with visible light and with fluorescent light. It is possible to observe a series of previously recorded fluorescent light images in superposition with the visible light images. An end of the series of images may be automatically determined. A thermal protective filter may be inserted into a beam path of an illuminating system at such automatically determined end of the series. Further, the fluorescent light image may be analyzed for identifying a coherent fluorescent portion thereof. A representation of a periphery line of the coherent portion may be generated, and depths profile data may be obtained only from the coherent portion. An illuminating light beam for exciting the fluorescence may be modulated for improving a contrast of fluorescent images.

Abstract: The present invention provides a displacement measurement method, an apparatus thereof, a probe microscope. which make it possible to stably measure an amount of displacement and a moving distance of an object under measurement with an accuracy of the sub-nanometer order or below without being affected by disturbances such as fluctuations of air, mechanical vibration. Specifically, with the present invention, a pulsed beam is split into two; one beam is reflected by an object under measurement and then inputted to a delay optical path equivalent to one pulse period; and the other beam is sent through the same delay optical path in the opposite direction up to the object under measurement with a delay of one pulse period, and then reflected by the object under measurement. Then, an optical phase variation caused by the movement of the object under measurement is obtained by subjecting the two pulsed beams to interference.

Abstract: The invention relates to alignment of an interferometer module for use in an exposure tool. An alignment method is provided for aligning an interferometer to the tool while outside of the too. Furthermore, the invention provides a dual interferometer module, an alignment frame use in the alignment method, and an exposure tool provided with first mounting surfaces for cooperative engagement with second mounting surfaces of an interferometer module.

Abstract: A touch panel is arranged to enable communication using infrared signals with nearby devices. The touch panel includes an array of infrared sensors, arranged parallel to the touchable surface of the panel and at least one of the sensors is capable of detecting an infrared signal received from a nearby device.

Abstract: The present invention provides an interferometer that measures a distance between a reference object and a measurement object, the interferometer including a light splitting element configured to split light from a light source into two light beams and cause one of the light beams to enter the reference object and the other light beam to enter the measurement object, a detection unit configured to detect interference light between light reflected by the reference object and light reflected by the measurement object and output a signal of the interference light, and a processing unit configured to perform processing for obtaining the distance.

Abstract: An apparatus and method for estimating a parameter of interest using values of a beam property from two or more electromagnetic beams that both pass through at least part of an optical displacement device. The apparatus may include a Fabry-Perot interferometer, a collimated light source, and a detection array. At least one mirror of the interferometer may be operably coupled to an element receiving an external stimulus, such as pressure, force, and/or acceleration. The method includes using the apparatus.

Abstract: To reduce the probability of incorrect determination to detect an object reliably. A reflective photoelectric sensor is provided with: a light projecting device for emitting light; a light receiving device for receiving the optical feedback of the light that is emitted from the light projecting device; a determining portion for determining whether or not an object exists in the direction in which the light is emitted from the light projecting device, based on the optical feedback; and a reflection preventing plate of a moth-eye structure, disposed at a position that is on the optical path of the light that is emitted from the light projecting device at a position that is more distant than the location wherein the object is anticipated to appear.

Abstract: Interferometric path length measurements using frequency-domain interferometry form the basis of several measurement techniques, including optical frequency domain reflectometry (OFDR), optical coherence tomography (OCT), and frequency-modulated continuous wave (FMCW) radar and lidar. A phase-sensitive and self-referenced approach to frequency-domain interferometry yields absolute and relative path length measurements with axial precision orders of magnitude better than the transform-limited axial resolution of the system.

Abstract: The invention relates to a position detection system for the contactless interferometric detection of the location of a target object. A target object unit comprises a reference light transmitter, which is configured such that it transmits a reference light beam having curved light wave fronts. The target object unit comprises at least one detector array having a plurality of detector pixels, which is fixed to the target object unit such that the reference light beam of the reference light transmitter impinges on the same.

Abstract: A reflective diffractometric hydrogel sensor includes an upper layer, including a microfluidic chamber formed from a substantially transparent material and configured to contain a solution, a reflective diffraction grating positioned within the microfluidic chamber, the diffraction grating including a plurality of hydrogel strips configured to change in dimension in response to a stimulus, each hydrogel strip having a top surface coated with a reflective material and a bottom surface in contact with the upper layer substrate, and a reflective surface below the reflective diffraction grating wherein when a coherent light is incident upon and reflected from the upper layer at an angle substantially normal to the upper layer an interference diffraction pattern results, including a first diffraction mode, a light intensity of which indicates the relative distance between the top surfaces of the plurality of hydrogel strips and the reflective surface.

Abstract: A fundamental limit to the sensitivity of optical interferometry is thermal noise that drives fluctuations in the positions of the surfaces of the interferometer's mirrors, and thereby in the phase of the intracavity field. A scheme for substantially reducing this thermally driven phase noise is provided in which the strain-induced phase shift from a mirror's optical coating cancels that due to the concomitant motion of the substrate's surface. As such, although the position of the physical surface may fluctuate, the optical phase upon reflection can be largely insensitive to this motion.

Abstract: A tracking-type laser interferometer in which a pattern emission control unit controls a changing mechanism such that light is emitted along a predetermined pattern when judged by a first judgment unit that at least one of received-light amounts at first and second light reception units is not greater than a first threshold value. A tracking control unit causes the changing mechanism to keep track of a retro reflector when judged by a second judgment unit that both of the received-light amounts at the first and second light reception units are greater than second threshold values during a time period in which the pattern emission control unit controls the changing mechanism for the emission of light along the pattern. The interferometer emits light along the pattern to search for the retro reflector upon losing sight thereof. Upon detection, the interferometer can keep track of the reflector again and resume measurement.