Abstract: When detecting an object structure, at least one portion of the object is initially illuminated with illumination light of an at least partly coherent light source from at least one preferred illumination direction. At least one diffraction image of the illuminated portion is recorded by spatially resolved detection of the diffraction intensity of the illumination light, diffracted by the illuminated portion, in a detection plane. At least one portion of the object structure is reconstructed from the at least one recorded diffraction image using an iterative method. Here, the iteration diffraction image of a raw object structure is calculated starting from an iteration start value and said raw object structure is compared to the recorded diffraction image in each iteration step.

Abstract: The present invention relates to a laser positioning apparatus and a laser positioning method, the laser positioning apparatus comprises a laser emitting module configured to generate a first laser; a laser direction adjusting module configured to adjust the first laser to a second laser in a first direction and a third laser in a second direction perpendicular to the first direction; a distance determining module configured to receive the laser reflected or diffused back by the second laser on a surface of a first object to be measured to determine a distance from the laser positioning apparatus to the first object to be measured, and/or receive the laser reflected or diffused back by the third laser on a surface of a second object to be measured to determine a distance from the laser positioning apparatus to the second object to be measured.

Abstract: A detection system for measuring one or more conditions within a predetermined area includes a fiber optic cable including a first core for transmitting light to the ambient atmosphere adjacent a node and a second core for receiving scattered light from the ambient atmosphere adjacent the node. A discrimination assembly operably coupled to the first and second cores includes at least one focusing element and at least one optical enhancement device. The at least one optical enhancement device separates the scattered light received from the ambient atmosphere into a plurality of wavelengths. A control system operably coupled to the fiber optic cable receives the scattered light received from the ambient atmosphere. The scattered light received from the ambient atmosphere has a higher frequency than the light transmitted to the ambient atmosphere and only the scattered light having a desired wavelength is transmitted to the control system.

Abstract: A LIDAR system for vehicle operation that can operate in degraded visual environments (DVE) is described. The LIDAR system may use a spatial light modulator to find the phase conjugate of the DVE being traversed by the laser beam and cancel out the backscatter from the DVE, which allows the detection of extremely small numbers of directly reflected photons reflected by a target surface. If the target is not detected, the LIDAR is iteratively scanned to its maximum available depth of focus until the target is acquired. The LIDAR system is especially useful for autonomous landing of VTOL aerial vehicles in locations where the target landing spot is approximately known but cannot be directly visualized due to DVE media, such as smoke, dust, fog, or the like.

Abstract: A radar sensor is mounted in the area of a parking space for a motor vehicle in such a way that if a motor vehicle is present in the parking space, signals that are emitted by the radar sensor are reflected back from the motor vehicle. A method for determining an occupancy state of the parking space includes the steps of emitting radar signals; receiving reflected radar signals; and determining whether a motor vehicle is present in the parking space, based on the reflected radar signals. The determination is based on noise components of the reflected radar signals.

Abstract: A condenser lens for collecting a laser beam (300) is disposed between the laser oscillator and the incident end surface of the optical fiber. The laser beam (300) is divided into a plurality of beams (303, 304). The power of the laser beam (304) is measured and maximized by adjusting the position of the condenser lens. The FFP of the laser beam (303) is measured and minimized by adjusting the position of the condenser lens. These adjusted positions are stored as the first and second lens positions. The FFP of the laser beam (303) is measured while the condenser lens is being moved between these positions so as to make the BPP not more than a predetermined value.

Abstract: Provided are instantaneous phase mapping deflectometry measurement systems and methods based on multiplexing phase shifted fringe patterns with color, and decomposing them in X and Y using Fourier techniques. The new methods and devices provide accurate measurements, and more robust tools with less uncertainty when reconstructing a surface (e.g., compared to prior art Fourier Transform Profilometry (FTP) methods). The systems and methods revolutionize the applications of deflectometry by enabling measuring dynamic events (e.g., in high vibration environments, and a host of other previously impossible scenarios), and including environmental changes to the bending modes of large optics. Methods of error correction applicable to the new methods and devices are also provided.

Abstract: A distance-measuring pixel apparatus includes a photonic integrated circuit disposed on a common substrate that further includes a photonic integrated circuit substrate having disposed thereon two 3 dB directional couplers, a GRIN lens, and a partially reflecting Faraday mirror having a first side that is optomechanically coupled to a second side of the GRIN lens; and a source laser, a first photodetector, and a second photodetector. A related distance measuring method includes, using the distance-measuring pixel apparatus, generating a local oscillator (LO) beam, generating an echo, combining the LO beam and the echo beam, splitting the combined LO beam and the echo beam, and producing a modulation of the photodetector assembly photocurrent at a frequency that encodes the distance of a remote object.

Abstract: A method is provided of determining three-dimensional coordinates of an object surface with a laser tracker and structured light scanner. The method includes providing the scanner having a body, a pair of cameras, a projector, a retroreflector and a processor. The projector and cameras are positioned in a non-collinear arrangement. The projector is configured to project a pattern onto the surface. The method also includes providing the tracker which emits a beam of light onto the retroreflector and receives a reflected beam of light. The first location and orientation is measured with the tracker. The first surface pattern is projected onto the surface. A pair of images of the surface pattern is acquired with cameras. The processor determines the 3D coordinates of a first plurality of points in the tracker frame of reference.

Abstract: A portable spectrometer, including a smart phone case storing a portable spectrometer, wherein the portable spectrometer includes a cavity; a source for emitting electromagnetic radiation that is directed on a sample in the cavity, wherein the electromagnetic radiation is reflected within the cavity to form multiple passes of the electromagnetic radiation through the sample; a detector for detecting the electromagnetic radiation after the electromagnetic radiation has made the multiple passes through the sample in the cavity, the detector outputting a signal in response to the detecting; and a device for communicating the signal to a smart phone, wherein the smart phone executes an application that performs a spectral analysis of the signal.

Abstract: A method and a device for determining a fill level of a medium using the radar principle that has a high degree of accuracy and reliability. In accordance with the method, an electromagnetic signal is transmitted from a transmitting device and an electromagnetic signal is received for determining the fill level. Thereby, a slope of the transmitting device relative to the force of gravity and an evaluation value dependent on the determined slope are identified for determining the fill level.

Abstract: A method is provided of determining three-dimensional coordinates of an object surface with a laser tracker and structured light scanner. The method includes providing the scanner having a body, a pair of cameras, a projector, and a processor. The projector and cameras are positioned in a non-collinear arrangement. The projector is configured to project a first pattern onto the surface. The method also includes providing the tracker which emits a beam of light onto the retroreflector. The tracker receives a reflected beam of light. The first location is measured with the tracker. The first orientation is measured with the tracker. The first surface pattern is projected onto the surface. A pair of images of the surface pattern is acquired with cameras. The processor determines the 3D coordinates of a first plurality of points in the tracker frame of reference based in part on epipolar constraints of the cameras and projector.

Abstract: A method for measuring a distance includes modulating the light beam at a first frequency, receiving a second beam by the optical detector to produce a first electrical signal having the first frequency and a first phase; modulating the light beam at a second frequency different than the first frequency; receiving the second beam by the optical detector to produce a second electrical signal having the second frequency and a second. After these steps, the retroreflector is moved while modulating the light beam continuously at the second frequency; and a first distance to the retroreflector is determined based at least in part on a the first and second frequencies and phases.

Abstract: Satellite data is used to determine water depth by accounting for the changing turbidity of the water over time and without requiring calibration using SONAR measurements. Radiance values at multiple wavelengths sensed at both a first time and a second time are stored in a database. Modeled reflectance values are calculated for a defined surface area on the water based on an assumed depth, assumed water constituents and assumed bottom cover. A plurality of differences between the modeled reflectance values and the reflectances sensed at the two times are calculated. A bathymetry application module minimizes the sum of the differences between the modeled and sensed subsurface reflectances by varying the assumed depth, bottom cover and water constituents. The differences are weighted based on wavelength before being summed. The depth that results in the minimized sum of the differences is the estimated depth, which is displayed on a graphical user interface.

Abstract: A method is provided of determining three-dimensional coordinates of an object surface with a laser tracker and structured light scanner. The method includes providing the scanner having a body, a pair of cameras, a projector, and a processor. The projector and cameras are positioned in a non-collinear arrangement. The projector is configured to project a first pattern onto the surface. The method also includes providing the tracker which emits a beam of light onto the retroreflector. The tracker receives a reflected beam of light. The first location is measured with the tracker. The first orientation is measured with the tracker. The first surface pattern is projected onto the surface. A pair of images of the surface pattern is acquired with cameras. The processor determines the 3D coordinates of a first plurality of points in the tracker frame of reference based in part on epipolar constraints of the cameras and projector.

Abstract: An assembly that includes a projector and camera is used with a processor to determine three-dimensional (3D) coordinates of an object surface. The processor fits collected 3D coordinates to a mathematical representation provided for a shape of a surface feature. The processor fits the measured 3D coordinates to the shape and, if the goodness of fit is not acceptable, selects and performs at least one of: changing a pose of the assembly, changing an illumination level of the light source, changing a pattern of the transmitted With the changes in place, another scan is made to obtain 3D coordinates.

Abstract: Disclosed is an autocorrelator for generating an autocorrelation signal for an ultrashort pulse to measure the ultrashort pulse. The autocorrelator comprises: a light source unit for generating an optical pulse; a double wedge interferometer in which a first wedge and a second wedge serving as a wedge-shaped optical medium are arranged such that facing surfaces of the first and second wedges are parallel to each other, so as to separate the optical pulse provided by the light source unit to generate two optical pulses; a harmonic light medium for receiving the generated two optical pulses to generate second harmonic light; and a measurement unit for detecting the second harmonic light to generate an autocorrelation signal. Thus, the time width of an ultrashort pulse can be measured by an interferometer using only two wedge-shaped optical components.

Abstract: A method and system are provided for controlling a laser tracker remotely from the laser tracker through gestures performed by a user. The method includes providing a rule of correspondence between each of a plurality of commands and each of a plurality of user gestures. A gesture is performed by the user with the user's body that corresponds to one of the plurality of user gestures. The gesture performed by the user is detected. The gesture recognition engine determines a first command from one of the plurality of commands that correspond with the detected gesture. Then the first command is executed with the laser tracker.

Abstract: A method of measuring surface sets on an object surface with a coordinate measurement device and a target scanner, includes providing the scanner having a body, a first retroreflector incorporating a pattern, a projector, a camera, and a processor, providing the device, selecting the source pattern of light; projecting the source pattern of light onto the object to produce the object pattern of light; imaging the object pattern of light onto the photosensitive array to obtain the image pattern of light; obtaining the pixel digital values for the image pattern of light; sending the first beam of light from the device to the first retroreflector; receiving the second beam of light from the first retroreflector; measuring the orientational and translational sets based at least in part on the second beam of light; determining the surface sets corresponding to the plurality of collinear pattern elements; and saving the surface sets.

Abstract: Measuring three surface sets on an object surface with a measurement device and scanner, each surface set being 3D coordinates of a point on the object surface. The method includes: the device sending a first light beam to the first retroreflector and receiving a second light beam from the first retroreflector, the second light beam being a portion of the first light beam, a scanner processor and a device processor jointly configured to determine the surface sets; selecting the source light pattern and projecting it onto the object to produce the object light pattern; imaging the object light pattern onto a photosensitive array to obtain the image light pattern; obtaining the pixel digital values for the image light pattern; measuring the translational and orientational sets with the device; determining the surface sets corresponding to three non-collinear pattern elements; and saving the surface sets.

Abstract: The proposed self-mixing interference device comprises a substrate (1) with an integrated optical wave guide structure (3), a semiconductor laser source (2) arranged on a surface of the substrate (1) and emitting laser radiation towards said surface, and a photodetector arranged to detect intensity variations of the laser radiation. The wave guide structure (3) is optically connected to the laser source (2) and designed to guide the laser radiation emitted by the laser source to an out-coupling area at the surface of the substrate (1) and to guide a portion of the laser radiation scattered back from a target object (4) outside of the substrate (1) to re-enter the laser source (2). This self-mixing interference device can be realized with a lower total height compared to the known self-mixing interference devices.

Abstract: An anomaly detection and cataloging system is described that includes a handheld probe having a probe tip, a user interface, and a communications interface. The system further includes a system controller and a probe locating device. The probe is operable, via the user interface, for transmitting, via the communications interface, a user selected anomaly type to the system controller, the anomaly type being associated with a manufactured part or airplane on the ground (AOG). The probe locating device is operable to provide to the system controller a location associated with the probe tip, and the system is programmed to associate the user selected anomaly type with the location associated with the probe tip.

Abstract: Measuring apparatus comprising a tunable laser diode for generating a mono mode measurement radiation, said laser diode being designed as a laser beam source in such a way that an emission wavelength of the measurement radiation is variable within a wavelength range by means of the variation of a tuning parameter, comprising an absorption medium defining absorption lines within the wavelength range, comprising a memory having a line atlas for the absorption medium, comprising a detector for determining an absorptivity and comprising a control and evaluation unit for regulating the emission wavelength by means of the at least one tuning parameter in a manner dependent on the absorptivity determined in such a way that the emission wavelength remains stable.

Abstract: Disclosed is an imaging apparatus for generating data of a phase image based on an interference pattern acquired by a shearing interferometer, including: a differential phase data calculating unit that calculates first differential phase data expressing a change of a phase in a first direction and second differential phase data expressing a change of a phase in a second direction, based on interference pattern data generated by an electromagnetic wave transmitted through a subject; a second-order differential phase data calculating unit that calculates first second-order differential phase data by differentiating the first differential phase data in the first direction, and calculates second second-order differential phase data by differentiating the second differential phase data in the second direction; and a phase data calculating unit that calculates the phase image by solving a second-order differential equation including the first and second second-order differential phase data as functions.

Abstract: An object of the present invention is to provide an optical remote airflow measurement apparatus with which even colored noise corresponding to an external environment of the apparatus can be reduced, thereby reducing measurement reliability deterioration and enabling long-distance measurement in a wide flying speed range. A colored noise reduction method according to the present invention includes: considering a signal strength of scattered light to be substantially non-existent in a remotest region and beyond; calculating a noise distribution by performing processing to average the signal strength in respective Doppler frequency components divided at intervals of a certain frequency in the remotest measurement region and beyond, and performing subtraction processing in each of the Doppler frequency components on all signal strength distributions of the measurement region, which are obtained by dividing the noise distribution at intervals of a certain distance.

Abstract: A process for producing an interface unit and also a group of such interface units are specified. The interface unit exhibits a first reference surface for beaming in radiation, a second reference surface for emitting the radiation, and an axis extending in the direction from the first to the second reference surface. The production process comprises the steps of setting an optical path length of the interface unit between the first and second reference surfaces along the axis and the fixing of the set optical path length of the interface unit. The optical path length of the interface unit is set in such a way that radiation of a defined numerical aperture beamed in at the first reference surface exhibits a focus location that is predetermined with respect to the second reference surface in the direction of the axis. A precise and uniform focus location with respect to the second reference surface is obtained.

Abstract: The present invention refers to a method of operating a self-mixing interference sensor and a corresponding self-mixing interference sensor device. In the method the laser (1) of the device is controlled to periodically emit a laser pulse followed by an emission period of laser radiation having a lower amplitude. The pulse width of the laser pulse is selected such that the pulse after reflection at the object (3) re-enters the laser (1) during the emission period of laser radiation with lower amplitude. The corresponding SMI signal has an increased signal to noise ratio.

Abstract: A device for interferometric vibration measurement, having a radiation source for generating an original beam, a first beam splitter for dividing it into measuring and reference beams, a detector and a focusing device. The measuring beam at least partly reflected by the object and the reference beam are superimposed on a detection area of the detector, and the focusing device in the beam path of the measuring beam between the image unit and object focuses it onto a measuring point. Here, a measuring beam having a wavelength greater than 1100 nm is generated and the device has an image unit for two-dimensional imaging of the object surrounding the measuring point. The measuring beam focus lies in the focal plane of the image unit and, by use of the focusing device, the focal point of the measuring beam and the focal plane of the imaging unit are displaceable simultaneously.

Abstract: A method distributing data in a network is provided. The method comprises measuring the path lengths between a reference clock and a plurality of remote destinations and sending a timing signal from the reference clock to the plurality of remote destinations. The method further comprises measuring the phase between the reference clock and a return signal from each of the plurality of remote destinations and adjusting the phase of the data such that each remote destination receives the data within a skew tolerance.

Abstract: A portion of a first portion of light (13, 90, 90?) from a source of light (11) is masked by a mask (138), and the resulting masked first portion of light (90?) is combined using a beam splitter optic (136) with at least one second portion of the light (30) that had been subject to scattering by a medium (20, 20?, 20?). The mask (138) is configured so that interference patterns (104, 47) generated from the first and at least one second portions of light are substantially mutually exclusive even though those interference patterns (104, 47) would otherwise overlap one another absent the mask (138).

Abstract: A localized dynamic light scattering measurement system includes a beam displacer for splitting an incident beam having two orthogonal linearly polarized beam components with slightly different frequencies into two orthogonal linearly polarized output beams focused onto an object to be measured. The beam displacer cooperates with an iris to collect and recombine scattering beams each reversely backscattered at 180 degrees from the object so as to form a signal beam, which is polarized by a polarizer to produce two polarization components, thereby generating a heterodyne interference signal associated with the polarization components. A signal processing unit obtains measurement data on the object based on power spectrum or autocorrelation data corresponding to the heterodyne interference signal.

Abstract: A process for producing an interface unit and also a group of such interface units are specified. The interface unit exhibits a first reference surface for beaming in radiation, a second reference surface for emitting the radiation, and an axis extending in the direction from the first to the second reference surface. The production process comprises the steps of setting an optical path length of the interface unit between the first and second reference surfaces along the axis and the fixing of the set optical path length of the interface unit. The optical path length of the interface unit is set in such a way that radiation of a defined numerical aperture beamed in at the first reference surface exhibits a focus location that is predetermined with respect to the second reference surface in the direction of the axis. A precise and uniform focus location with respect to the second reference surface is obtained.

Abstract: An imprint apparatus includes a detector and an adjusting device. A second mark formed on a substrate includes a grating pattern having grating pitches in first and second directions which are respectively parallel to first and second axes which are parallel to a pattern surface of a mold and orthogonal to each other. A first mark formed on the mold includes a grating pattern having a grating pitch in the first direction. The first and second marks have different grating pitches in the first direction. The detector includes an image sensor, and an optical system which forms a moire fringe on an image sensing surface of the image sensor. The adjusting device adjusts, in a plane including the second axis and a third axis that is perpendicular to the first and second axes, an angle between the optical axis of the detector and the third axis.

Abstract: A system and method for determining a measured distance between a measuring device (20A) and an object (21), the system including a first laser source (13) for producing a first light beam (13A) having a first waveform (32) and a first frequency; a second laser source (11) for producing a second light beam (1 IA) having a second frequency, said second light beam (HA) having a second waveform (36), wherein said first frequency is chirped up at the first rate as said second frequency is chirped down at the first rate, and said second frequency is chirped up at the second rate as said first frequency is chirped down at the first rate; an optical element (15) for combining said first light beam (13A) with said second light beam (HA) into a combined light beam path (17), said optical element (15) splitting a returning portion of said combined light beam path (17) into a third light beam (24); and a single detector (23) for receiving said third light beam (24) including two different beat frequencies that are propo

Abstract: A unit pixel included in a photo-detection device, the unit pixel including a floating diffusion region in a semiconductor substrate, a ring-shaped collection gate over the semiconductor substrate, a ring-shaped drain gate over the semiconductor substrate, and a drain region in the semiconductor substrate, wherein the collection gate and the drain gate are respectively arranged between the floating diffusion region and the drain region.

Abstract: An all fiber optic laser based scanning system for real time terrain mapping under degraded visual conditions is disclosed. A laser output is modulated to achieve a desired pulse width and pulse repetition frequency (PRF) and the modulated signal is amplified. The amplified optical signals are split into N channels that correspond to N elements of an optically phased array that steers light by modulating the phase of light entering and exiting the optical system. By applying a linear phase shift across the beam's wave front, the light propagating along the system's optical axis is steered to an off-axis angle. A real time map of an underlying terrain is accomplished by sweeping the N channel array across the terrain while collecting range information from each scan grid.

Abstract: An optical position-measuring device includes a light source, a measuring reflector movable in space, a detection unit and a light-beam deflection unit that can align at least one beam of rays, emitted by the light source, in the direction of the measuring reflector. The light-beam deflection unit includes a cardan system having two cardan frames. A first cardan frame is adjustable by motor about a first axis of rotation, and a second cardan frame within the first cardan frame is adjustable by motor about a second axis of rotation oriented in a direction perpendicular to the first axis of rotation. The two axes of rotation intersect in a fixed reference point, at which a reference reflector is disposed. A plurality of mirrors are disposed rigidly on the cardan frames, so that the beam of rays can be pivoted about the fixed reference point via the mirrors during alignment.

Abstract: An image processing system includes an object illuminated by a pre-determined first spectrum of light and an array of fringe lines, an imaging device configured to capture an image of the object including the first spectrum of light and the fringe lines reflecting from a surface of the object, and a processor in signal communication with the imaging device to receive an input data representing the image of the object, wherein the processor: generates a first data model based on the input data; removes a DC-component from the first data model to create a second data model; and performs a two dimensional Fourier transform profilometry based on the second data model.

Abstract: An etching monitor device capable of high precision measurement in the presence of a mask region capable of producing interference. An interference optical system which acquires reflected interference light containing three interference component signals; a spectrometric measurement unit; an optical path difference analysis unit which computes optical path difference analysis data for the reflected interference spectrum; an uncorrected B-C interference distance computation unit; a correction table unit which computes and stores the relationship between mask thickness and amount of offset of optical path difference due to fusion of two interferences; a mask thickness measurement unit; a B-C interference distance true value computation unit; and an etching depth computation unit which computes the etching depth based on a corrected B-C interference distance and mask thickness.

Abstract: A laser radar system using collocated laser beams to unambiguously detects a range of a target and a range rate at which the target is moving relative to the laser radar system. Another aspect of various embodiments of the invention may relate to a laser radar system that uses multiple laser radar sections to obtain multiple simultaneous measurements (or substantially so), whereby both range and range rate can be determined without various temporal effects introduced by systems employing single laser sections taking sequential measurements. In addition, other aspects of various embodiments of the invention may enable faster determination of the range and rate of the target, a more accurate determination of the range and rate of the target, and/or may provide other advantages.

Abstract: The present invention provides a measurement apparatus including a phase detection unit configured to detect, from interfering light of light reflected by a reference surface and light reflected by a test surface, a phase corresponding to an optical path length between the reference surface and the test surface, a refractive index detection unit configured to detect a refractive index of a space between the reference surface and the test surface, and a processing unit configured to obtain the distance from a first phase and a first refractive index detected when the wavelength of light from the light source is a first wavelength, a second phase and a second refractive index detected when the wavelength of light from the light source is a second wavelength, and a third phase at a synthetic wavelength of the first wavelength and the second wavelength.

Abstract: A method and system for forming a focused image on an image plane of a diffraction range finder with a variable pitch diffraction grating. Diffracted light is propagated through a lens and slit assembly and onto an image plane of a camera, the diffracted light having been diffracted by the variable pitch diffraction grating. The lens and slit assembly includes lens elements and a slit. The slit is surrounded by opaque material that is opaque to the diffracted light passing through the slit. The slit has a shape characterized by a long dimension and a short dimension that is shorter than the long dimension.

Abstract: The present invention provides a measurement apparatus which measures a distance between a reference surface and a test surface, including n (n=an integer of not smaller than 2) frequency scanning light sources, a splitting element configured to split beam from each of the n frequency scanning light sources to enter the reference surface and the test surface, a detector configured to detect n interference beams at once, formed by interference of beam reflected by the reference surface and beam reflected by the test surface, and output an interference signal, and a processing unit configured to perform processing of obtaining the distance.

Abstract: Light scattered by a portion of a fluid medium illuminated by a beam of substantially monochromatic light is received within a field-of-view nominally along an axis oriented in a different direction relative to the beam and processed by an interferometer to generate a corresponding fringe pattern that is detected and processed to generate at least one measure of the fluid medium at a plurality of different ranges.

Abstract: An all fiber optic laser based scanning system for real time terrain mapping under degraded visual conditions is disclosed. A laser output is modulated to achieve a desired pulse width and pulse repetition frequency (PRF) and the modulated signal is amplified. The amplified optical signals are split into N channels that correspond to N elements of an optically phased array that steers light by modulating the phase of light entering and exiting the optical system. By applying a linear phase shift across the beam's wave front, the light propagating along the system's optical axis is steered to an off-axis angle. A real time map of an underlying terrain is accomplished by sweeping the N channel array across the terrain while collecting range information from each scan grid.

Abstract: Systems and methods improve the accuracy of spatial coordinate measurements by optical digitizers by obtaining a separate distance measurement, which may be via direct ranging rather than triangulation, and combining the distance measurement with the spatial coordinate measurements to improve the accuracy of the three-dimensional spatial coordinate measurement.

Abstract: The present invention refers to a method of operating a self-mixing interference sensor and a corresponding self-mixing interference sensor device. In the method the laser (1) of the device is controlled to periodically emit a laser pulse followed by an emission period of laser radiation having a lower amplitude. The pulse width of the laser pulse is selected such that the pulse after reflection at the object (3) re-enters the laser (1) during the emission period of laser radiation with lower amplitude. The corresponding SMI signal has an increased signal to noise ratio.

Abstract: Methods are disclosed wherein the structural health of a civil structure, such as, but not limited to, a bridge or the like is measured by electronic distance measurement (EDM) from a plurality of stable locations to a plurality of cardinal points on the structure in a methodical manner. By measuring the coordinates of the cardinal points, the dynamic and long-term static behavior of the structure provide an indication of the health of the structure. Analysis includes: comparison to a Finite Element Model (FEM); comparison to historical data; and modeling based on linearity, hysteresis, symmetry, creep, damping coefficient, and harmonic analysis.

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.

Abstract: A super-resolution telescope. A target is illuminated with at least three laser beams, each beam having a slightly different frequency so as to produce an illumination pattern comprised of several sets of straight interference fringes which sweep across the target. The frequencies of the illumination beams are chosen so that each pair of beams has a unique beat frequency, and the corresponding fringe pattern for each pair sweeps over the target at a unique speed. By collecting a series of images, and demodulating them at the various beat frequencies, the downshifted spatial frequencies can be identified, correctly up-shifted, and fitted together with a set of special Fourier transform based algorithms to reconstruct high-resolution images. Applicants have performed laboratory experiments that this invention can provide resolution substantially better than diffraction limited resolution.