Abstract: A method for fitting an odometry noise model of a vehicle is described. The method includes collecting multiple passes of sensor measurements from motion sensors of the vehicle to measure a motion sensor noise during a testing operation of the vehicle. The method also includes determining an estimated standard deviation of the motion sensor noise measured during the testing operation of the vehicle. The method further includes determining the odometry noise model of the vehicle according to the estimated standard deviation of the motion sensor noise measured during the testing operation of the vehicle. The method also includes compensating, using the odometry noise model, the motion sensor noise during normal operation of the vehicle.

Abstract: A container for an injectable medicament can include an elongated body having a tubular-shaped sidewall extending along a longitudinal axis and having a distal end and a proximal end. The container can include an outlet at the distal end. The container can include a bung arranged inside the elongated body, sealingly engaged with the sidewall and slidable along the longitudinal axis relative to the sidewall. The container can include an interior volume to receive the injectable medicament and being confined by the sidewall, the outlet, and the bung. The container can include a measuring arrangement arranged in or on the bung. The measuring arrangement can include a signal generator configured to emit an electromagnetic measurement signal into or through the interior volume and a signal receiver configured to detect a feedback signal being indicative of an interaction of the measurement signal with at least one of the sidewall, the outlet or the interior volume.

Abstract: A light detection and ranging (LIDAR) system includes a LIDAR measurement unit, a reference measurement unit, and a phase cancellation unit. The LIDAR measurement unit estimates a time for which a laser beam travels. The reference measurement unit determines a phase of a laser source. The phase cancellation unit identifies phase noise and cancels the phase noise from the laser beam, at least partially based on the phase of the laser source and the time for which the laser beam travels. The denoised signal is used to determine the range between a laser source and a target.

Abstract: Sensor system comprising a frame supporting a force-sensing tip arranged to generate a signal based upon a force applied by said force-sensing tip to a material to be tested, the system further comprising: an input drum mounted in said frame such that it can rotate about an input axis of rotation; an output lever supported by said frame by means of an output revolute joint defining an output axis of rotation; wherein said force-sensing tip is mounted on said output lever such that said force-sensing tip is arranged to be brought into contact with a material to be tested; and wherein said sensor system comprises a mechanical transmission arranged to kinematically link said input drum to said output lever such that a rotation of said input drum about said input axis of rotation causes said output lever to pivot in an oscillatory manner about said output axis of rotation.

Abstract: It is an object of the present invention to provide a measuring apparatus capable of easily grasping a tracking state of a target and performing an efficient measurement. One aspect of the present invention is a measuring apparatus that emits a light beam toward a target, captures and tracks the target, and measures the three-dimensional coordinates of the target. The measuring apparatus comprises: a light source for emitting light beam; an angle control unit for controlling the emission angle of the light beam emitted from the light source so as to track the moving target; a display unit that provided on a device that is wearable by a measurer; a calculation unit for calculating the three-dimensional coordinates of the target based on the emission angle of the light beam and the light returning from the target; and a display control unit that controls information displayed on the display unit based on the three-dimensional coordinates calculated by the calculation unit.

Abstract: Systems, apparatuses, and methods are described for a privacy blocking device configured to prevent receipt, by a listening device, of video and/or audio data until a trigger occurs. A blocker may be configured to prevent receipt of video and/or audio data by one or more microphones and/or one or more cameras of a listening device. The blocker may use the one or more microphones, the one or more cameras, and/or one or more second microphones and/or one or more second cameras to monitor for a trigger. The blocker may process the data. Upon detecting the trigger, the blocker may transmit data to the listening device. For example, the blocker may transmit all or a part of a spoken phrase to the listening device.

Abstract: An interferometer apparatus includes a beam splitter arranged for splitting an input beam into a first beam propagating along a first interferometer arm including a deflection mirror and a second beam propagating along a second interferometer arm including a deflection mirror. The first and second interferometer arms have an identical optical path length. A beam combiner is arranged for recombining the first and second beams into a constructive output and a destructive output. In the first interferometer arm compared with the second interferometer arm, one additional Fresnel reflection at an optically dense medium is provided and a propagation of the electromagnetic fields of the first and second beams, when recombined by the beam combiner, results in a wavelength-independent phase difference of ? between the contributions of the two interferometer arms to the destructive output. Furthermore, an interferometric measurement apparatus and an interferometric measurement method are described.

Abstract: The cost and power consumption of an imaging apparatus are reduced by facilitating detection of an incident angle of a light beam transmitted through a grating substrate. An image sensor converts an optical image captured by pixels arranged on an imaging surface and outputs the converted image signal. A modulator is configured to modulate intensity of light; and an image processing circuit performs image processing of the output image signal. The modulator has a grating substrate, a grating pattern formed on a back surface side of the grating substrate arranged in proximity to the light receiving surface of the image sensor; and a grating pattern formed on a front surface facing the back surface. Each of the grating patterns is constituted of a plurality of concentric circles. The modulator performs intensity modulation on the light transmitted through the grating pattern and outputs the modulated light to the image sensor.

Abstract: A biological tissue inspection apparatus is disclosed. The biological tissue inspection apparatus comprises a stage and a probe. The probe comprises an optical imaging device, an optical interference detector, and a light guide. The probe acquires data regarding optical images and optical interference, through the optical imaging device and the optical interference detector. The stage or the probe moves such that a selected area of the inspection object is positioned in the FOV of the optical imaging device and of the optical interference detector. The light guide is configured such that illumination light from the optical imaging device and measurement light from the optical interference detector are coaxially emitted to the inspection object.

Abstract: A reference laser beam locked to a femtosecond optical frequency comb is modulated through a high frequency electro-optic phase modulator, and laser sidebands with equal intervals are generated. Beat frequency is performed on the sixth-order sideband and the frequency sweeping laser beam, a beat signal and a frequency sweeping signal source are down-mixed to generate a difference frequency signal, and the difference frequency signal is locked to a reference clock through a digital phase detector and a PID controller. The frequency sweeping laser beam is locked to reference laser beam with a dynamic offset frequency under the closed loop control, and sinusoidal frequency sweeping is simultaneously performed together with the frequency sweeping signal source. The locked laser beam is used for absolute distance measurement, and a distance to be measured is obtained according to the synthetic wavelength transition theory.

Abstract: Optical measuring apparatus includes: a light source irradiating an object to be measured; a splitter splitting transmitted light or reflected light from the object to be measured; a phase changer changing a phase of a first light which is one of the lights split; a phase fixer maintaining a phase of a second light which is the other light split; a multiplexer multiplexing lights output from the phase changer and the phase fixer; a detector detecting the light (interference image) output from the multiplexer; and a controller that extracts a reference point from the interference image, when a displacement of the reference point is detected, corrects a luminance value for each pixel of the interference images in accordance with a displacement of the object to be measured indicated by a displacement of the reference point, constructs an interferogram based on the luminance value for each pixel of the interference images after the correction.

Abstract: A system for determining the absolute position of a first object with respect to a second object includes a scalar element attached to the first object and a measuring device attached to the second object. The scalar element comprises a series of coded regions. The coded region represents a number designating a position along an axis of the scalar element. The measuring device includes a two-dimensional optical sensor array configured to capture an image of a portion of the scalar element. The system also includes a processor configured to receive the image and determine an absolute position of the first object with respect to the second object based on at least one coded region of the series of coded regions.

Abstract: An optomechanical device for modulating an optical signal for reducing thermal noise and tracking mechanical resonance of a proof mass assembly comprises a circuit configured to receive, from a light-emitting device, the optical signal and modulate the optical signal to remove thermal noise and to drive a mechanical response frequency to the mechanical resonance of the proof mass assembly using a cooling feedback signal and a mechanical resonance feedback signal. The circuit is further configured to generate, using the modulated optical signal, the cooling feedback signal to correspond to a thermal noise signal of the modulated optical signal with a total loop gain of zero and a phase difference of 180 degrees and generate, using the modulated optical signal, the mechanical resonance feedback signal to drive the mechanical response frequency of the modulated optical signal to the mechanical resonance.

Abstract: Distributed fiber sensing system including a laser source, a circulator, a detector and an optical fiber, the circulator coupled with the laser source, the detector and the optical fiber, the laser source for generating at least two ultra-narrow linewidth interrogating pulses, the detector having a predetermined detection bandwidth for detecting back-scattered signals, the laser source including an ultra-narrow linewidth laser and a modulator, coupled with the ultra-narrow linewidth laser and the circulator, the modulator generating a plurality of pairs of interrogating pulses having a time delay, a frequency difference between two pulses of the same interrogating pair being less than the predetermined detection bandwidth and a frequency difference between two pulses not of the same interrogating pair being larger than the predetermined detection bandwidth, wherein the optical fiber can be characterized based on beat-notes between back-scattered signals originating from the pair of interrogating pulses detect

Abstract: A first area and a second area are set for a first two-dimensional tomographic image where the first area and the second area overlap each other in a partial area in a horizontal direction of the first two-dimensional tomographic image. A positional deviation amount between the first two-dimensional tomographic image and a second two-dimensional tomographic image is obtained in each of the first area and the second area. A moving amount of the second two-dimensional tomographic image is determined with respect to the first two-dimensional tomographic image in an area where the first area and the second area overlap based on the positional deviation amount in the first area and the positional deviation amount the second area. Alignments are performed on the first two-dimensional tomographic image and the second two-dimensional tomographic image in an area where the first area and the second area overlap based on the moving amount.

Abstract: A method for determining operating conditions of a particle detector that includes a multimode Vertical Cavity Surface Emitting Laser (VCSEL) includes providing an electrical drive current to the multimode VCSEL such that a laser beam is emitted by the multimode VCSEL and varying the electrical drive current within a predefined range of electrical drive currents. The method further includes determining, as a function of the electrical drive current, an intensity signal of an optical wave within a laser cavity of the multimode VCSEL, determining, as a function of the electrical drive current, a noise measure of the intensity signal, determining a range of electrical drive currents for which the noise measure is below a predefined threshold noise measure value, and determining operating conditions of the particle detector by choosing an electrical drive current for particle detection out of the determined low noise range of electrical drive currents.

Abstract: A light measurement device that maintains high measurement precision. The light measurement device includes: light source that irradiates light upon measurement object; branch part that splits transmitted light or reflected light from measurement object; phase-changing unit that changes the phase of one beam of the branched light beams; phase-fixing unit that maintains the phase of the other beam of the branched light beams; adjustment mechanism, which is provided in phase-changing unit or phase-fixing unit, for adjusting the propagation direction of light; multiplexer that causes the light emitted by each of phase-changing unit and phase-fixing unit to interfere with each other; detection unit that detects light that is interfered with by multiplexer; and control unit that controls the adjustment mechanism on the basis of the luminance values of an interference image that is detected by detection unit and adjusts the propagation direction of light in phase-changing unit or phase-fixing unit.

Abstract: In one aspect, a load cell includes an elastic body, first optical unit, second optical unit, detector, and computation unit. The first optical unit has a light source, a first diffraction grating on which light from the light source is incident, and a light-receiving unit. The first optical unit is fixed to a first end portion of the elastic body and arranged within a hollow portion of the elastic body. The second optical unit has a second diffraction grating on which diffracted light from the first diffraction grating is incident to generate interference light. The second optical unit is fixed to a second end portion of the elastic body and arranged within the hollow portion. The detector detects the interference light. The computation unit computes a relative displacement amount of the second diffraction grating relative to the first diffraction grating on the basis of a signal obtained by the detector.

Abstract: A sensor, optical system, and combination lens for use with an optical sensor are disclosed. An illustrative optical system is described to include a photodetector having a proximity sensor area and an ambient light sensor area that is physically separated from the proximity sensor area as well as a combination lens that includes a proximity sensor focusing portion and an ambient light sensor focusing portion that each separately direct incident light for the proximity sensor area and the ambient light sensor area, respectively.

Abstract: A device for optically detecting in transmission nanoparticles moving in a fluid sample includes a light source for emitting a spatially incoherent beam for illuminating the sample; an imaging optical system; and a two-dimensional optical detector. The imaging optical system includes a microscope objective. The two-dimensional optical detector includes a detection plane conjugated with an object focal plane of the microscope objective by said imaging optical system. The two-dimensional optical detector allows a sequence of images of an analysis volume of the sample to be acquired, each image resulting from optical interferences between the illuminating beam incident on the sample and the beams scattered by each of the nanoparticles present in the analysis volume during a preset duration shorter than one millisecond.

Abstract: The present disclosure provides a full-field OCT system using a wavelength-tunable laser, which can observe peaks of a short-time A-line profile corresponding to each time point at which interference images of an object to be measured are acquired, so as to measure a depth direction movement of the object to be measured, and can correct the phases of interference signals on the basis of the measured depth direction movement, so as to generate an OCT image which is compensated for the depth direction movement.

Abstract: A method and a system for the optical detection, with hyperacuity, of a contrasted target, allowing the detection of the relative position of said target in relation to said detection system and therefore the acquisition and the pursuit of such a target. One or more embodiments is applicable to the field of autonomous robotic systems, especially for the positioning of drones or robots on a target.

Abstract: An incoming laser source beam is projected to a glass disc having a frosted upper surface. A refracted beam and a reflected beam are produced from the laser source beam. The refracted beam is reflected back to and through the glass disc to combine with the reflected beam to form an interference pattern on the target.

Abstract: An object is to enable removal fixed pattern noise even if the intensity of interference light changes during measurement. An image capturing apparatus comprises a light splitting unit that splits light emitted from a light source into reference light and measurement light, an interference signal detection unit that acquires an interference signal from interference light resulting from interference of the reference light and return light generated by irradiating an object to be inspected with the measurement light, a noise signal acquisition unit that acquires a noise signal containing a noise component contained in the interference light, a correction unit that corrects the intensity of one of the interference signal and the noise signal, and a noise removal unit that removes the noise component contained in the interference signal using the interference signal and the noise signal one of which is corrected.

Abstract: A laser interferometer that includes a laser interferometer, an position sensitive detector detecting an offset of an optical axis of the laser interferometer, a biaxial rotator turning the laser interferometer toward an arbitrary direction, an angle sensor detecting a rotation angle of the biaxial rotator, a retro reflector reflecting reflected light in a direction parallel to incident light, and a controller performing feedback control of the biaxial rotator so as to track the retro reflector based on signals from the position sensitive detector and the angle sensor. The tracking-type laser interferometer starts tracking control when return light from the retro reflector is returned to a detection range of the position sensitive detector, and changes gain for the feedback control in accordance with a behavior for a position of the return light on the position sensitive detector due to the tracking control.

Abstract: A method and device for non-contact detection of a thin medium (5) is disclosed. The device comprises a light source (1), an optical splitter (2), a reference plane (3), a linearly arrayed photoelectric detector (6), a signal processing module (4) and the thin medium (5).

Abstract: An optical pen for an optical measurement system includes a probe body arranged to be adjustably mounted in a measuring machine for optically measuring a test object. A single mode fiber optically coupled within the pen body transmits a source beam having an instantaneous or sequentially established bandwidth spanning a range of wavelengths to the pen body and also transmits a measurement beam from the pen body toward a detector. A combination and configuration of optics within the pen body provides a more compact and efficient optical pen.

Abstract: Disclosed are apparatuses and methods for measuring a thickness. The apparatus for measuring a thickness including a light source that emits a femto-second laser, an optical coupler through which a portion of the femto-second laser is incident onto a target and other portion of the femto-second laser is incident onto a reference mirror, a detector configured to receive a reflection signal reflected on the reference mirror and a sample signal generated from the target and configured to measure a thickness of the target based on an interference signal between the reflection signal and the sample signal, and a plurality of optical fiber lines configured to connect the light source, the optical coupler, and the detector to each other may be provided.

Abstract: An encoder interferometry system includes an encoder scale arranged to receive and diffract a measurement beam. The system further includes one or more optical elements configured and arranged to receive a first diffracted measurement beam and a second diffracted measurement beam from the encoder scale and to redirect the first diffracted measurement beam and the second diffracted measurement beam toward the encoder scale such that the first diffracted measurement beam and the second diffracted measurement beam propagate along non-parallel beam paths having an angular separation ? following a second diffraction at the encoder scale. The system further includes a first detector arranged to receive the first diffracted measurement beam and a second detector arranged to receive the second diffracted measurement beam.

Abstract: A velocity-compensated frequency sweeping interferometer has a single measurement light producing device that produces a coherent light source consisting of a single light beam. The light producing device produces a scanning wavelength light beam. A primary beam splitter produces a first reference beam and a first measurement beam from said single light beam. The first reference beam travels a fixed path length to a primary reference reflector and the first measurement beam travels to and from a moveable reflective target over an unknown path length. A distance measurement interferometer is created by interfering the first reference beam with the first measurement beam. A return frequency measurement interferometer provides a measure of frequency of the return beam from the target which, when compared with the frequency of the outgoing beam, allows for velocity compensation of the target.

Abstract: A method, apparatus, and system are provided to monitor and characterize the dynamics of a phase change region (PCR) created during laser welding, specifically keyhole welding, and other material modification processes, using low-coherence interferometry. By directing a measurement beam to multiple locations within and overlapping with the PCR, the system, apparatus, and method are used to determine, in real time, spatial and temporal characteristics of the weld such as keyhole depth, length, width, shape and whether the keyhole is unstable, closes or collapses. This information is important in determining the quality and material properties of a completed finished weld. It can also be used with feedback to modify the material modification process in real time.

Abstract: A multiple beam path laser optical system using a multiple beam reflector. The multiple beam path laser optical system includes a light source part to generate a laser beam to be irradiated to a specimen, the multiple beam reflector to split a laser beam incident thereto from the light source part and to provide a plurality of optical paths, a main beam splitter to irradiate the laser beam split by the multiple beam reflector to the specimen, a transducer to excite the specimen for signal detection of the laser beam irradiated to the specimen, and a control part to analyze an interference pattern of a laser beam reflected from the specimen and recombined in the main beam splitter.

Abstract: A fiber optic sensing system for determining the position of an object requires a light source, an optical fiber, a fiber optic splitter, a fiber tip lens, an optical detector and signal processing circuitry. Light emitted by the light source is conveyed via optical fiber and the splitter to the lens and onto an object, such that at least a portion of the light is reflected by the object and conveyed via fiber and the splitter to the detector. Signal processing circuitry coupled to the detector determines the position of the object with respect to the lens based on a characteristic of the reflected light. The system is suitably employed with a hydraulic accumulator having a piston, the position of which varies with the volume of fluid in the accumulator, with the system arranged to determine the position of the piston, from which the volume can be calculated.

Abstract: The invention relates to a lithography system comprising an optical column, a moveable target carrier for displacing a target such as a wafer, and a differential interferometer module, wherein the 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 an interferometer module and method for measuring such a displacement and rotations.

Abstract: An irradiation module for a measuring apparatus is provided. The irradiation module is light-conductive, is configured as a cohesive body and comprises a beam-splitting surface arranged within the irradiation module for splitting an incoming measuring beam into two partial beams. Furthermore, the irradiation module comprises an optical diffraction grating for interaction with a first of the two partial beams and a reflection surface for reflecting the second partial beam.

Abstract: An apparatus, method and computer program for measuring a distance using a self-mixing interference (SMI) unit that generates an SMI signal. The SMI unit comprises a laser emitting a first laser beam directed to an object and wherein the SMI signal depends on an interference of the first laser beam and a second laser beam reflected by the object. A peak width determination unit determines a peak width of the SMI signal, and a distance determination unit 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 decorative lighting apparatus including at least one light source and an attenuation assembly. The attenuation assembly including an attenuator, a first housing being configured to be coupled to a second housing, and a first base being configured to be coupled to a second base. When the first housing is coupled to the second housing, the first and second housings form a recess designed and dimensioned to receive and hold the attenuator in a substantially fixed position, and when the first base is coupled to the second base, the first and second bases form a further recess designed and dimensioned to receive and hold the coupled first housing and second housing in a substantially fixed position.

Abstract: A motion assembly for a decorative lighting apparatus. The motion assembly including an articulating element configured to secure an optical element in a path of a light being generated by the decorative lighting apparatus, and a motor coupled to the articulating element via a linkage such that a movement generated by the motor is imparted to the articulating element so that the light passing through the optical element is articulated when projected onto a surface.

Abstract: Imaging systems are provided allowing examination of different object regions spaced apart in a depth direction by visual microscopy and by optical coherence tomography. An axial field of view and a lateral resolution is varied depending on which object region is examined by the imaging system. The proposed imaging systems are in particular applicable for thorough examination of the human eye.

Abstract: A motion detecting device and the method for dynamically adjusting image sensing area is disclosed. The motion detecting device includes a light source, an image capture unit and a processing unit. The image capture unit is used to capture reference image according to fixed sampling period. The processing unit is used to calculate exposure reference value of the light source and image characteristic value of reference image. The processing unit according to the exposure reference value and the image characteristic value to determine whether the surface is in first rough coefficient range or second rough coefficient range. If rough coefficient of the surface is in the first rough coefficient range, the processing unit defines first search radius or second search radius to increase or decrease the image sensing area. Otherwise, the processing unit defines third search radius or fourth search radius to increase or decrease the image sensing area.

Abstract: A laser tracking interferometer has a carriage provided with a first displacement gauge outputting a displacement signal associated with a relative displacement from a reference sphere; a second retroreflector provided to the carriage; a laser interferometer provided to the carriage and outputting a displacement signal associated with a relative displacement between the first retroreflector and the second retroreflector; and a data processor calculating a displacement of the first retroreflector with reference to the reference sphere based on the displacement signal output from the first displacement gauge and the displacement signal output from the laser interferometer.

Abstract: Method and systems for determining a change of distance to an object by interferometry with emitting measurement laser light from a laser diode are disclosed. The method may include receiving at least a part of the measurement laser light, superimposing the reflected measurement laser light with a reference laser light and thereby providing at an interferometric phase and determining the change of distance to the object depending on the superimposition. In some embodiments, the measurement laser light may be emitted with low coherence and broad spectral bandwidth. An emitting wavelength of the measurement laser light may be fluctuating hop-freely within the spectral bandwidth causing interferometric phase fluctuations.

Abstract: An apparatus for measuring the quantity and optical parameters of a liquid in a container using the principle of optical low coherence reflectometry is provided, the apparatus having: a source arm with a low coherence light source; a reference arm including a reference lens, a mirror, means for adjusting the distance between the reference lens and the mirror and means for measuring the distance between the reference lens and the mirror; a test arm with a test lens; means for dividing the output of the source arm between the test arm and the reference arm; means for combining light reflected back into the reference arm and the test arm to create an interference signal; and means for detecting and analyzing the interference signal.

Abstract: Scanning apparatus includes a transmitter, which is configured to emit a beam comprising pulses of light, and a scanning mirror, which is configured to scan the beam over a scene. A receiver is configured to receive the light reflected from the scene and to generate an output indicative of the pulses returned from the scene. A grating is formed on an optical surface in the apparatus and is configured to diffract a portion of the beam at a predetermined angle, so as to cause the diffracted portion to be returned from the scanning mirror to the receiver. A controller is coupled to process the output of the receiver so as to detect the diffracted portion and to monitor a scan of the mirror responsively thereto.

Abstract: An image correlation for images having speckle pattern is evaluated. Modulation transfer function (MTF) curves of speckle-pattern images captured at different times are figured out. Whether a correlation value between the MTF curves meets a threshold is checked. If the correlation value is smaller than the threshold, speckle-pattern images are re-selected for re-figuring out the MTF curves and the correlation value. Thus, error of strain and displacement for digital image correlation owing to blurring images of the on-moving target object is figured out; calculation time of the digital image correlation is reduced; and accuracy on measuring physical parameters of the target object before and after movement is improved for digital image correlation.

Abstract: The present invention relates to an optical coherence tomography device and an optical coherence tomography method using same for capturing the cornea and the retina of the eye by using light sources in respectively different wavelength ranges. According to the present invention, included are two light sources, a first interferometer and a second interferometer for generating respectively different interference patterns by the light outputted from each of the light sources, and interference pattern detection means for detecting an interference pattern occurring in each interferometer.

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: 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: 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: 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.