875 results about "Phase coding" patented technology

Improved apparatus and methods for utilizing holographic waveforms for a variety of purposes including communication. In one exemplary embodiment, the holographic waveforms are wideband in nature and transmitted over an RF bearer medium to provide, inter alia, highly covert and robust communications. A multi-stage (e.g., dual) phase-coding approach is used in conjunction with a mathematical transform to further enhance robustness and security of the radiated waveforms.

The invention discloses a super-resolution fluorescence microscopy method based on tangential polarization, comprising the following steps: carrying out 0-2pi vortex phase coding focus on tangential polarization exciting light, and obtaining an exciting spot below a diffraction limit on a fluorescence sample; adjusting tangential polarization STED laser and the phase coding tangential polarization exciting light to realize confluence and co-axis, focusing on the fluorescence sample to form a circle bread-shaped focusing spot the central point of which coincides with the central point of the exciting spot; adjusting the operating power of the STED laser to cause the area of a luminous point in the exciting spot to reach the super-resolution ratio; and collecting fluorescence emitted from the luminous point and carrying out detection processing to obtain a microimage with the super-resolution ratio. The invention also discloses a device for realizing the super-resolution fluorescence microscopy method based on tangential polarization. In the invention, on the premise of ensuring the super-resolution ratio, the working power of the STED is reduced greatly, thereby lowering bleaching of the sample and avoiding damage for the sample.

A 3-D depth camera system, such as in a motion capture system, tracks an object such as a human in a field of view using an illuminator, where the field of view is illuminated using multiple diffracted beams. An image sensing component obtains an image of the object using a phase mask according to a double-helix point spread function, and determines a depth of each portion of the image based on a relative rotation of dots of light of the double-helix point spread function. In another aspect, dual image sensors are used to obtain a reference image and a phase-encoded image. A relative rotation of features in the images can be correlated with a depth. Depth information can be obtained using an optical transfer function of a point spread function of the reference image.

A computer implemented method for magnetic resonance imaging is provided. A 3D Fourier Transform acquisition is performed with two phase encode directions, wherein phase code locations are chosen so that a total number of phase encodes is less than a Nyquist rate, and closest distances between phase encode locations takes on a multiplicity of values. Readout signals are received through a multi-channel array of a plurality of receivers. An autocalibrating parallel imaging interpolation is performed and a noise correlation is generated. The noise correlation is used to weight a data consistency term of a compressed sensing iterative reconstruction. An image is created from the autocalibration parallel imaging using the weighted data consistency term. The image is displayed.

The invention provides a laser imaging radar device and a distance measurement method thereof. The laser imaging radar device and the distance measurement method thereof aims at the problem that an existing distance range gate laser imaging radar is low in distance resolution. The laser imaging radar device comprises a laser device, a laser modulation unit, an optical antenna unit, a detecting unit, a data processing unit and an image processing unit, wherein the detecting unit is composed of a counter, a gate controller and an array detector, and the data processing unit is composed of an accumulator and a correlator. According to the distance measurement method, an information loading process is carried out on laser signals with constant amplitude by using a phase code pulse amplitude modulation mode. The laser imaging radar device and the distance measurement method thereof have the advantages that the equipment and the method combine the advantages of long detecting distances of the distance ranging gate layer imaging radar and the advantage of high distance measurement resolution of the pulse phase coding mode, and meanwhile the detect of low distance measurement resolution of the distance ranging gate layer imaging radar and the detect of low imaging speed of the pulse phase coding mode are avoided.

Improved apparatus and methods for utilizing holographic waveforms for a variety of purposes including communication, ranging, and detection. In one exemplary embodiment, the holographic waveforms are transmitted over an RF bearer medium to provide, inter alia, highly covert communications, radar systems, and microwave data links. The bearer (i.e., carrier) is optionally frequency-hopped, and various pulse modulation techniques (including variation of the phase-coding clock epoch) applied in order to further increase communications efficiency and covertness. Methods of providing multiple access and high bandwidth data transmission are also disclosed. Improved apparatus utilizing these features; e.g., a wireless miniature covert transceiver/locator, are also disclosed.

In accordance with the present invention, there is provided a method of determining whether a particular high fidelity vibratory seismic survey phase encoding is likely to be a good one based on an analysis of the eigenvalue structure (i.e., eigenvalues, eigenvalue separation, condition number, and model resolution matrix) of a matrix formed from the Fourier transforms of the sweep signals. Preferably, a singular value decomposition will be used to calculate the eigenvalues. Using this same approach, the condition number and eigenvalues of matrices that are associated with multiple proposed designs can be compared with each other to determine which is likely to be yield the best seismic data. This approach is preferably used either as a component of the advanced planning for a survey or in the field during pre-survey testing. The use of the instant approach to determine an optimal phase encoding scheme is also taught.

The invention relates to an optical three-dimensional measuring method based on a phase coding technology, belonging to the technical field of three-dimensional measurement. The method comprises the following steps of: (1) producing a grating coding stripe image by a computer; (2) projecting the grating coding stripe image by using digital projection equipment; and (3) acquiring the grating coding stripe image and performing coding solution and three-dimensional measurement by adopting a phase-shift algorithm. The method is characterized in that: the number of pixels in each grating period of the grating coding stripe image equals to the step number of the adopted phase-shift algorithm; the gray scale of the pixels in each grating period of the grating coding stripe image meets sine or cosine curve distribution, and the gray-scale value of the pixels are extreme points of the corresponding sine or cosine function. Compared with the traditional sine phase-shift coding method, the method has strong interference resistance to the nonlinear influence of gamma rays of the digital projection equipment, the coding has higher stability, reliability and correctness, and the method is important in the aspect of accurate measurement of an optical three-dimensional outline on the external surface of an object.

An authentication system using a correlator that correlates an input with a reference wherein at least one of the input and reference comprises a phase volume mask having structures, preferably points, that are each less than about six microns in size and can have an aspect ratio (AR) greater than 1:1 so as to produce a phase encoded random pattern having millions of combinations in a mask that is as small as one square millimeter. The random pattern can be convolved with a second pattern, such as a biometric pattern, to produce a phase convolved mask. The correlator preferably is a nonlinear joint transform correlator that can use “chirp” encoding to permit the input to be located in a different plane than the reference. The correlator optically Fourier transforms images of the reference and input that are thereafter nonlinearly transformed and inverse Fourier transformed by a processor to determine the presence or absence of a correlation spike indicative of authenticity. A spatial light modulator (SLM) can be used as an input or reference and preferably is a liquid crystal panel having pixels or elements whose phase or grey scale intensity can be selectively controlled by a processor. The SLM can be used to display a biometric pattern, preferably scanned in real time from a person, that is correlated against an input or reference that can comprise a label on a card, a tag, or another object.

The invention discloses an apparatus of generating microwave phase coding signals in an optical manner, and relates to the microwave technology field and the optical communication technology field. The apparatus is mainly applied to generating pulse compression signals in pulse compression radar. By means of the frequency shift characteristics of two parallel Mach-Zehnder modulators, the optical wavelength modulated by coding signals and the optical wavelength after a frequency shift are coupled to each other and then are detected through a photoelectric detector, in this way, phase coding microwave signals can be generated. The apparatus can produce binary, quaternary or multi-nary phase coding microwave signals. The generated phase coding microwave signals are wide in frequency adjustable scope, and have a great time-bandwidth product. A conventional phase coding microwave signal generation mode in the electric field is restricted by the bottleneck of the rate and the bandwidth of an electronic device, and the cost of generation of high frequency signals is extremely high or high frequency signals cannot be produced, the time-bandwidth product is limited, the reconstructiblity and the frequency adjustability of a system are poor, etc. The apparatus of the invention helps to overcome the above problems.

Methods and systems for designing electromagnetic wave filters and electromagnetic wave filters designed using the methods and systems are disclosed. In one method, functions are selected whose linear combination define the surface of a filter for producing a desired phase-encoded image. Free parameter values are selected for the function and are varied. The values of the free parameters are observed with regard to an optimization function. Final values of the free parameters are selected based on the optimization function having a specific value or range of values.

A system and method for reducing the scan time of an MR imaging system using a data acquisition technique that combines partial Fourier acquisition and compressed sensing includes a computer programmed to acquire a partial MR data set in k-space along a phase encoding direction, the data set having missing data in the phase encoding direction due to the omission of phase encoding steps. The computer is further programmed to generate an estimate of a reconstructed image, compensate the partial MR data set for the missing data, and reconstruct an MR image by iteratively minimizing the total squared difference between the k-space data of the estimate of the reconstructed image and the measured k-space data of the compensated partial MR data set.

Method for rapid inversion of data from a controlled-source electromagnetic survey of a subterranean region. Selected (51) common-receiver or common-source gathers of the data are reformed into composite gathers (52) by summing their data. Each composite gather is forward modeled (in the inversion process) with multiple active source locations (53). Computer time is reduced in proportion to the ratio of the total number of composite gathers to the total number of original common-receiver or common-source gathers. The data may be phase encoded to prevent data cancellation. Methods for mitigating loss of far offset information by data overlap in the summing process are disclosed.

In a magnetic resonance tomography apparatus employing a FISP pulse sequence, the pulse sequence is repeated with a repetition time T_R with different phase-coding gradient directions and with an alternating operational sign of the flip angle α. The gradient pulse trains are thereby completely balanced. A phase increment ΔΦ=β is generated in addition to the alternating operational sign of the flip angle α between successive excitation pulses, so that the steady state signals for a first and a second spin ensemble optionally have either identical or reversed signal polarities. A first dataset on the basis of identical signal polarities and a second dataset on the basis of reversed signal polarities are obtained by means of the free selection of the mutual signal polarities. A pure image of the first and the second spin ensembles is thus obtained by the addition and/or subtraction of the first and second datasets.

The invention relates to a waveform design for a formation flying satellites SAR (synthetic aperture radar), and provides an orthogonal waveform designing method which is used for carrying out phase encoding for linear frequency modulation (LFM) signals. The orthogonal waveform designing method includes generating a linear frequency modulation signal at first, dividing the linear frequency modulation signal into N parts according to equal time intervals to form N sub-pulses, carrying out random phase encoding for each sub-pulse by M times according to the number M of the formation flying satellites, establishing an ambiguity function expression, calculating cluster tolerance xi meeting formation flying satellite synthetic aperture radar Doppler mismatch, finding out a critical N value meeting requirements by the aid of a searching comparison method, finally selecting energy and functions which are in autocorrelation and cross-correlation as cost functions, namely fitness functions in genetic algorithm, searching code values of phase encoding of the various sub-pulses by the aid of the genetic algorithm, and finding out orthogonal waveforms after optimization at last. The waveforms have low autocorrelation side lobes, cross-correlation peak values, bandwidth occupation ratio and Doppler mismatch, and excellently suppress echo signal interferences among different space-borne SARs.

The application discloses a magnetic resonance parallel imaging method. The method comprises: a target region is excited by using a radio-frequency pulse and a plurality of RF coils are used for collecting a magnetic resonance signal of the target region; phase coding is carried out on the magnetic resonance signal to obtain a plurality of data lines and K space is filled with the plurality of data lines, wherein the K space includes an all-sampling region and an under-sampling region; an intermediate image is obtained based on the data lines in the all-sampling region and pretreatment is carried out on the intermediate image; on the basis of the intermediate image after pretreatment, a correction data line in the all-sampling region is obtained; according to the correction data line in the all-sampling region, data lines of the under-sampling region are reconstructed and a synthesized K space data set is obtained; and according to the synthesized K space data set, a magnetic resonance image of a target region of a subject is obtained. With the method, the motion artifact can be suppressed; and the image quality can be improved. In addition, the application also provides a magnetic resonance imaging system.

A magnetic resonance imaging diagnostic apparatus includes a generating unit which generates a slice gradient magnetic field, a phase-encode gradient magnetic field and a read-out gradient magnetic field that extend in a slice axis, a phase-encode axis and a read-out axis, respectively, a setting unit which sets a dephase amount for weighting a signal-level decrease resulting from flows in the arteries and veins present in a region of interest of a subject, with respect to at least one axis selected form the slice axis, phase-encode axis and read-out axes, and a control unit which controls the generating unit by using a pulse sequence for a gradient echo system, which includes a dephase gradient-magnetic-field pulse that corresponds to the dephase amount set by the setting unit for the at least one axis.

This invenion discloses a distribution system for quantum ciphered keys testing polarization of phase coding, in which, a transmitting party is connected with a receiving party by a quantum channel and either of which includes a same polarized beam splitting and merging device with four ports, the reflection port of which is connected with a phase modulator and a 90deg. rotation Faraday mirror orderly to form a long circuit and a transmission port of which is conneted with the 90deg. rotation Faraday mirror to form a short circuit, the incident port of the beam splitting and merging device is connected with a single photon source and the exit port is connected to a common port of a lambda/2 wave plate and a three-port polarized splitting/merging device, the reflection and the transmission ports of which are connected with a single-photon detector.

A method of steady-state free precession MR imaging is provided that includes the steps of: (a) providing a balanced steady-state free precession imaging sequence that includes a plurality of phase encoding steps, wherein each phase encoding step comprises a phase encoding gradient and a slice selection gradient; and (b) acquiring imaging data by performing the plurality of phase encoding steps in sequence, wherein the imaging data is acquired is compensated for one or more effects due to eddy-currents, flow, or motion related artefacts due to the implementation of one or more artefact compensation strategies that consist of (i) “pairing” of consecutive phase encoding steps and of (ii) “through slice equilibration” of eddy-current and motion or flow related signal oscillations.