816 results about "Phase sensitive" patented technology

A method and apparatus for obtaining three-dimensional surface measurements using phase-sensitive spectrally encoded imaging is described. Both transverse and depth information is transmitted through a single-mode optical fiber, allowing this technique to be incorporated into a miniature probe.

An apparatus includes a single or dual output port, dual-drive Mach-Zehnder Interferometer configured to generate a first optical signal in one path, and to generate a second optical signal in a different path. The apparatus also includes an optical spectrum analyzer configured to receive output from at least one port of the dual-drive Mach-Zehnder Interferometer. A method includes causing radio frequency signals from two different antennae to modulate an optical carrier at a corresponding drive of a dual-drive Mach-Zehnder Interferometer, and causing output from at least one port of the Mach-Zehnder Interferometer to be directed to an optical spectrum analyzer. The method further comprises determining arrival angle at each of a plurality of frequencies in the radio frequency signals based on output from the optical spectrum analyzer.

A phase-sensitive interferometeric broadband reflectometer includes an illumination source for generating an optical beam. A beam splitter or other optical element splits the optical beam into probe beam and reference beam portions. The probe beam is reflected by a subject under test and then rejoined with the reference beam. The combination of the two beams creates an interference pattern that may be modulated by changing the length of the path traveled by the probe or reference beams. The combined beam is received and analyzed by a spectrometer.

Micron-scale displacement measurement devices having enhanced performance characteristics are disclosed. One embodiment of a micron-scale displacement measurement device includes a phase-sensitive reflective diffraction grating for reflecting a first portion of an incident light and transmitting a second portion of the incident light such that the second portion of the incident light is diffracted. The device can further include a mechanical structure having a first region and a second region, the mechanical structure positioned a distance d above the diffraction grating and forming a wall of a cavity, the second portion of the incident light is reflected off of the first region of the structure such that an interference pattern is formed by the reflected first portion and the reflected second portion of the incident light. The device can further include an orifice formed in the cavity to provide for the passage of air between the inside and outside of the cavity.

The invention discloses a double-shaft fluxgate current sensor of the invention, relating to a device for measuring the current, comprising a fluxgate detecting probe, a zero flux current transformer and a signal processing circuit, wherein the fluxgate detecting probe is composed of two inner annular magnetic cores a and b, an excitation winding and an induction winding, wherein the fluxgate detecting probe is composed of an outer annular magnetic core and a secondary side winding; two inner annular magnetic cores a and b and the outer annular magnetic core are wound via a feedback winding; the signal processing circuit includes an exciting circuit and a detecting circuit, wherein the exciting circuit includes an exciting signal generating circuit, a voltage comparer and a power amplifying circuit; the detecting circuit includes an RLC resonant circuit, a differential amplifier circuit, a bandpass filtering circuit, a phase sensitive detecting circuit, a differential smooth filteringcircuit, a feedback circuit, a voltage controlled current source and a sampling resistor. The invention eliminates the measurement error of the current fluxgate current sensor by means of a closed loop formed by the feedback winding.

Methods and systems for measuring mechanical property of a vascular wall and a method and system for determining health of a vascular structure are provided wherein local deformation of a vessel wall resulting from physiologic pressures with altered transmural forces is measured. A non-invasive free-hand ultrasound scanning-procedure was performed to apply external force, comparable to the force generated in measuring a subject's blood pressure, to achieve higher strains by equalizing the internal arterial baseline pressure. When the applied pressure matched the internal baseline diastolic pressure, strain and strain rate increased by a factor of 10 over a cardiac cycle. Radial arterial strain was assessed in the vessel wall over the entire deformation procedure using a phase-sensitive, two-dimensional speckle-tracking algorithm. An elastic modulus reconstruction procedure was developed to estimate the non-linear elastic properties of the vascular wall.

The invention discloses a fiber bragg grating array-based phase-sensitive optical time domain reflection device and method. The device includes a light source, a laser frequency adjustment module, a modulator, an optical fiber amplifier, a circulator, a sensing optical fiber, a light detector, a data acquisition module and a data processing module; the sensing optical fiber is provided with an optical fiber array formed by a plurality of FBGs (fiber bragg grating) which are arranged equidistantly; the laser frequency adjustment module is used for frequency adjustment of continuous light emitted by the light source; the continuous light is modulated by the modulator so as to form pulsed light; the optical fiber amplifier performs power amplification on the pulsed light; the sensing optical fiber is used for receiving and transmitting the pulsed light which has been subjected to power amplification; the light detector receives scattered light and reflected light; the scattered light and reflected light are acquired by the data acquisition module; and the data processing module generates interference signal frequency response spectrum and obtains the length variation quantity of the sensing optical fiber between two adjacent FBGs through processing. With the fiber bragg grating array-based phase-sensitive optical time domain reflection device and method of the invention adopted, strain quantitative detection can be realized, and high-spatial resolution measurement can be realized based on quantitative analysis.

An endoscopic apparatus includes a light-generating mechanism for generating at least one modulated measuring beam, a light-transmitting mechanism for conducting the measuring beam onto an area to be observed, where the light-transmitting mechanism includes an illuminating lens, in addition to a light-imaging mechanism for imaging a signal beam from the area to be observed at least onto a phase-sensitive image sensor, which includes a number of pixels, where the light-imaging mechanism includes an imaging lens. At least one additional image sensor is provided and the light-imaging mechanism includes a beam-splitter and / or an optical switch, where at least one adaptive lens is provided for adapting the fields of vision of the image sensors. As a result, an apparatus is created for endoscopic 3D data collection that is suitable for various types of image sensors.

Systems and methods are described for phase-sensitive magnetic resonance imaging using an efficient and robust phase correction algorithm. A method includes obtaining a plurality of MRI data signals, such as two-point Dixon data, one-point Dixon data, or inversion recovery prepared data. The method further includes implementing a phase-correction algorithm, that may use phase gradients between the neighboring pixels of an image. At each step of the region growing, the method uses both the amplitude and phase of pixels surrounding a seed pixel to determine the correct orientation of the signal for the seed pixel. The method also includes using correlative information between images from different coils to ensure coil-to-coil consistency, and using correlative information between two neighboring slices to ensure slice-to-slice consistency. A system includes a MRI scanner to obtain the data signals, a controller to reconstruct the images from the data signals and implement the phase-correction algorithm, and an output device to display phase sensitive MR images such as fat-only images and / or water-only images.

The invention discloses an optical frequency division multiplexing phase-sensitive optical time domain reflectometer which comprises a narrow line width laser, an optical fiber coupler, a phase modulator, a scrambler, an erbium-doped optical fiber amplifier, an acoustic optical modulator, an optical fiber circulator, a signal generator module, a trigger source, a double balance detector, a low pass filter, a data acquisition card, a computer and a long-distance sensing optical fiber. According to the optical frequency division multiplexing phase-sensitive optical time domain reflectometer, the fundamental contradictions between the measuring distance and sampling rate in a distributed sensing system can be solved, and remoter or higher-frequency vibration is detected; and moreover, due to amplitude and phase information, the characteristics of a vibration source are judged at the first time, and the early warning can be provided immediately.

Micron-scale displacement measurement devices having enhanced performance characteristics are disclosed. One embodiment of a micron-scale displacement measurement device includes a phase-sensitive reflective diffraction grating for reflecting a first portion of an incident light and transmitting a second portion of the incident light such that the second portion of the incident light is diffracted. The device further includes a mechanical structure having a first region and a second region, the mechanical structure positioned a distance d above the diffraction grating, the second portion of the incident light is reflected off of the first region of the structure such that an interference pattern is formed by the reflected first portion and the reflected second portion of the incident light. The device can further include an electrode extending toward, but spaced a distance away from, the second region of the mechanical structure.

Phase-sensitive measurements are made by a resistivity imaging tool in a borehole having non-conductive mud in a conductive earth formation at a plurality of frequencies. From the phase sensitive measurements, the formation resistivity can be determined with higher sensitivity than is possible with the single frequency measurements. Tool standoff can also be determined from a knowledge of the mud resistivity and / or dielectric constant. Formation resistivity may also be determined when the effect of formation capacitance cannot be ignored.

Phase-sensitive measurements are made by a resistivity imaging tool in a borehole having non-conductive mud in a conductive earth formation at a plurality of frequencies. From the phase sensitive measurements, the formation resistivity can be determined with higher sensitivity than is possible with the single frequency measurements. Tool standoff can also be determined from a knowledge of the mud resistivity and / or dielectric constant. Formation resistivity may also be determined when the effect of formation capacitance cannot be ignored.

Phase sensitive X-ray imaging methods can provide substantially increased contrast over conventional absorption based imaging, and therefore new and otherwise inaccessible information. The use of gratings as optical elements in hard X-ray phase imaging overcomes some of the problems that have impaired the wider use of phase contrast in X-ray radiography and tomography. So far, to separate the phase information from other contributions detected with a grating interferometer, a phase-stepping approach has been considered, which implies the acquisition of multiple radiographic projections. Here,an innovative, highly sensitive X-ray tomographic phase contrast imaging approach is presented based on grating interferometry, which extracts the phase contrast signal without the need of phase stepping. Compared to the existing phase step approach, the main advantage of this new method dubbed 'reverse projection' is the significantly reduced delivered dose, without degradation of the image quality. The new technique sets the pre-requisites for future fast and low dose phase contrast imaging methods, fundamental for imaging biological specimens and in-vivo studies.

A phase-sensitive interferometric broadband reflectometer includes an illumination source for generating an optical beam. A beam splitter or other optical element splits the optical beam into probe beam and reference beam portions. The probe beam is reflected by a subject under test and then rejoined with the reference beam. The combination of the two beams creates an interference pattern that may be modulated by changing the length of the path traveled by the probe or reference beams. The combined beam is received and analyzed by a spectrometer.

A high spatial resolution phase-sensitive technique employs a scanning near field ultrasound holography (SNFUH) methodology for imaging elastic as well as viscoelastic variations across a sample surface. SNFUH uses a near-field approach to measure time-resolved variations in ultrasonic oscillations at a sample surface. As such, it overcomes the spatial resolution limitations of conventional phase-resolved acoustic microscopy (i.e. holography) by eliminating the need for far-field acoustic lenses.

The invention discloses an intelligent visual defect detection system based on an AC magnetic field. The system comprises a probe, an auxiliary circuit and system detection software and uses a defect quantification and shape reconstruction algorithm. An excitation part of the probe adopts a double-U-shaped structural design and consists of a mangan zinc ferrite iron core and two sets of orthogonal current-carrying coils, a detection part adopts a two-dimensional array structure, and the array probe adopts a lifting-releasing type traveling mode. The hardware processing of detection signals comprises signal conditionings such as amplification, filtering, and the like and also introduces an original excitation signal as a reference signal to carry out phase sensitive detection and low-pass filtering on the detection signals. The signals are sent into a computer through an A / D acquisition card, then the detection software is used for carrying out digital filtering and correlation analysis on the signals to draw a magnetic induction intensity curve and a butterfly diagram in real time, and size quantification and three-dimensional shape inversion are realized through the defect quantification and the shape reconstruction algorithm. The intelligent visual defect detection system gives a full play of the advantages of the computer and greatly improves the intellectualized and visual levels of AC magnetic field detection.

A method for determining weights (or coefficients) for synthesizing k-space data for autocalibrated parallel imaging (API) combines training data sets (including k-space data such as autocalibrating signals (ACS)) acquired at multiple successive time points. Combining training data sets from multiple successive time points together to determine a set of weights increases the accuracy of the calculated weights. The weights may be applied to k-space data from a single or multiple time points. The method retains the phase information of the individual time point images and may thus be applied, for example, to phase-sensitive multi-point imaging such as chemical species separation studies.

An optical IQ modulator with automatic bias control is disclosed. A dither signal is applied to the modulator bias and its signature detected in light tapped from an output of the modulator using a phase sensitive dither detector such as a lock-in amplifier. The detected signal is processed using pre-recorded information defining the direction of the detected signal change relative to a change in the modulator bias, and the bias is adjusted in the direction determined using the information. The IQ phase bias is controlled by dithering I and Q optical signals in quadrature to produce opposite-sign single subband modulation of output light at two different dither frequencies, and detecting an oscillation at a difference frequency using a lock-in detector.

An online traffic volume monitoring system based on a phase-sensitive optical time domain reflectometry and its monitoring method are related to a field of intelligent transportation and an application of distributed fiber sensing. A vehicle moving temporal-spatial response graph is generated by accumulating differentiated Optical Time-Domain Reflectometry tracks at different moments in one unit monitoring period for traffic volume statistics, and then converted into a vehicle moving trajectory image through binarization and image pre-processing. Parameters of the moving vehicles are detected by utilizing a search-match method. A traffic volume, moving speeds, moving directions and locations are obtained respectively from detected trajectory number, and a tilt angle and pixel positions. The monitoring method is helpful to solve traffic congestion problem and informing drivers of real-time traffic volume, and contributes to realize an intelligent city traffic regulation.

The invention relates to an optical fiber sensor. The invention discloses an optical fiber destabilization detecting method combining based on a phase sensitivity light time domain reflection and a polarization sensitivity light time domain reflection method and distributed optical fiber sensing system thereof to improve the detecting accuracy and reliability of the optical fiber destabilization. The method comprises: a. injecting an optical signal with determined polarization state into the optical fiber; b. receiving the back rayleigh scattering light in the optical fiber; c. diving the rayleigh scattering light into two bundles to perform the Phi-OTDR data acquisition and the POTDR data acquisition; d. determining the destabilization and position thereof based on the distortion points of the Phi-OTDR data and the POTDR data. The invention also discloses an optical fiber destabilization detecting device. The technical scheme of the invention is used for monitoring and protecting the optical cable lines, thereby greatly improving the precision and the sensitivity of the monitoring system and reducing the erroneous judgment rate and the missing report rate.

The invention discloses an eddy current testing recognition and evaluation method for defects of the inner wall and outer wall of a steel pipe under direct current magnetization. The method comprises the steps of: carrying out non-saturated magnetization on the steel pipe by adopting a traversing direct-current magnetizing coil, picking up electromagnetic disturbance information at the defects by utilizing an eddy current detection coil, and selecting a reasonable direct-current magnetizing range according to phase contrast, thus detecting the defects of the inner wall and the outer wall and recognizing through phase difference, and realizing consistency judgment on the inner and outer wall defects of equivalent damage through respectively setting alarming thresholds of the inner and outer wall defects. A detection device comprises a phase sensitive detection module which aims at eliminating the disturbance of the defects to leakage field. The method is fast in detection speed, easily realizes automation, and can be applicable to defect detection of various ferromagnetism pipelines, thus having wide application prospects.

The invention discloses a bidirectional magnetic saturated time difference fluxgate sensor, which is characterized in that two ends of a sensor magnetic core are wound with exciting coils, the middle section of the sensor magnetic core is wound with induction coils, output poles of the induction coils are connected with an amplifying circuit, and the amplifying circuit is connected with a counting display circuit through a band-pass filter circuit and a retardation shaping circuit. By detecting and calculating a positive negative pulse time difference value output by the fluxgate sensor in a time domain, the strength of the measured magnetic field is judged. Compared with the prior fluxgate sensor, the detection circuit is simple, the measurement stability of the system is ensured without a feedback structure, a complex subsequent circuit is not needed, the required excitation current is lower, the data processing is simple, the measured relative quantity is little, the integral volume and power consumption of the sensor are effectively reduced, and the measurement result is acquired quickly. The fluxgate sensor avoids a filter-phase-sensitive demodulation-smooth filter circuit of the prior fluxgate sensor, makes up the defect that the prior fluxgate sensor has harsh process requirement, and achieves the digitized magnetic measurement of the fluxgate sensor.

This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to an OCT system having a configuration that uses a phase sensitive B-scan registration method. In this disclosure, an OCT system may have a configuration that scans a physical object, acquires OCT signals to form B-scans, uses these B-scans to determine an optimal shift in an axial direction by using total phase error between B-scans, and align B-scans, thereby minimizing effects of motion that may occur during scanning of the physical object.

The invention concerns a current transducer for measuring a current flowing through a cable, comprising at least one magnetic field sensor and an electronic circuit. The current transducer comprises a head with a ferromagnetic core optimized to reduce the effects of external magnetic fields. The invention further concerns a magnetic transducer comprising a magnetic field sensor and an electronic circuit. The electronic circuit comprises at least one current source, a transformer, a fully differential preamplifier coupled to the transformer, a phase sensitive detector coupled to the preamplifier and a logic block configured to operate the magnetic field sensor(s) to provide an AC output voltage. The magnetic field sensor(s) is preferably either a Hall element or an AMR sensor or a flux-gate sensor.

A scanning tunable detection system and related method for analyzing samples includes a source of time varying excitation signals and a tunable optical filter for selectively transmitting time-varying optical signals emanated from a sample following irradiation with the time varying excitation signals. A detector is provided for converting the time-varying optical signals to electrical detection signals. The system can identify components in a sample using phase sensitive or time sensitive detection. A slew scan mode can be used to permit slow scanning through spectral regions rich in information but quickly in regions without such information.