340 results about "Complex amplitude" patented technology

Disclosed are a method and a system for in frequency domain optical coherent tomography imaging. The method employs sine phase modulation to recreate complex amplitude of the coherent frequency interference signal; and then performs inverse Fourier transform to the complex amplitude to get the tomographic images of the tested objects and eliminate the complex conjugate image, direct current background and self-coherent noise three spurious images, which enlarges the imaging depth of frequency domain optical coherent tomography imaging is two times larger than the original depth and realizes full depth finding of frequency domain optical coherent tomography imaging.

Disclosed is a method for wireless signal transmission of signals from an array of two or more antennas, in which each signal to be transmitted is selected from a constellation of unitary space-time signals. Each unitary space-time signal is a unitary matrix, in which each column represents a respective antenna, each row represents a respective time interval, and each element represents a complex amplitude to be transmitted by a given antenna during a given time interval. In specific embodiments of the invention, the matrices of the signal constellation form a non-Abelian group having a positive diversity product, or a coset of such a group. In other embodiments, the signal constellation is a subset of such a group, and its multiplicative closure forms a finite non-Abelian group having a positive diversity product. In still other embodiments, the signal constellation is an extension of any of the preceding types of constellations, formed by adding one or more further elements that do not belong to and are not derived from the group or group subset.

The invention relates to a three-dimensional display device based on constructive interferences. The device comprises a coherent source device, a lamp optical system, a complex amplitude spatial light modulator, and a lens array, wherein the coherent source device is used for producing laser beams; the lamp optical system is used for receiving the laser beams and expanding the laser beams; the complex amplitude spatial light modulator is used for receiving the expanded laser beams and performing pixel-by-pixel modulation on amplitudes and phases; and the lens array is used for receiving light waves modulated by the complex amplitude spatial light modulator; a clear aperture of each lens in the lens array is designed, so that each lens can cover more than two pixels of the complex amplitude spatial light modulator; the light waves modulated by the each pixel of the complex amplitude spatial light modulator are focused by the corresponding lenses in the lens array to enlighten a subspace of a three-dimensional imaging space; the light waves modulated by different pixels are focused by different lenses in the lens array to form subspaces which are overlapped mutually; and volume elements are formed based on a constructive interference principle and constitute a discrete three-dimensional image.

The invention relates to a method for calculating the focal stack associated with an object space from the plenoptic function thereof, using a sum transform along the length of constrained planes in discrete hypercubes, which allows the computing time to be considerably reduced. The invention also relates to a method for increasing the resolution of the focal stack obtained. In addition, the invention relates to two methods for the real-time recovery of the depths and moduli and phases of the complex amplitude of the wavefront respectively in each position of the surfaces of a three-dimensional scene and to a system adapted for carrying out the aforementioned methods.

A synthetic aperture radar hybrid-polarity method and architecture comprising transmitting circular polarization (by driving the orthogonal linear feeds simultaneously by two identical waveforms, 90° out of phase), and receiving horizontal (H) and vertical (V) linear polarizations, coherently. Once calibrated, the H and V single-look complex amplitude data are sufficient to form all four Stokes parameters, which fully characterize the observed backscattered field.

A low level wind shear velocity estimation method based on compressed sensing comprises the following steps: 1), utilizing Doppler vectors to establish a redundant dictionary so as to achieve sparse representation of an echo signal; 2), establishing a measurement matrix; 3), computing a measured value after the signal is compressed; 4), utilizing a regularization orthogonal matching pursuit algorithm to reconfigure a sparse signal; 5), utilizing a non-zero value in a complex amplitude estimation value to obtain Doppler frequency estimation of the radar echo signal; 6), computing a position of a maximum value in the complex amplitude estimation value after clutter rejection is performed, namely a velocity estimation result of a wind shear signal; and 7), repeating the step 3) to the step 6), judging whether the velocity estimation is accomplished according to the number of range units, and sequentially performing velocity estimation on echo data of all the range units within the scope. Aiming at the problem that velocity estimation precision is poor when the number of pulses is small and a signal to noise ratio (SNR) is low, the low level wind shear velocity estimation method based on the compressed sensing is provided. The low level wind shear velocity estimation method based on the compressed sensing can enable frequency spectrum resolution to be greatly improved while the accurate velocity estimation can be obtained, namely, the wind shear signal and the ground clutter signal can be well distinguished, wherein an interval between a frequency domain of the wind shear signal and a frequency domain of the ground clutter signal is very close.

The invention discloses a super-surface color vector complex amplitude holographic element, which comprises a bimetallic nanorod unit structure with adjustable in-plane rotation angles and in-plane displacement, wherein an aluminum-silicon dioxide-aluminum super-structure grating structure generates a polarization-selective type diffraction efficiency enhancement effect in a visible light range; asum of in-plane displacement of two metal nanorods in the unit structure and diffraction phase information are in a linear modulation relationship, a difference between the rotation angles of the twometal nanorods and a diffraction light amplitude are in a sinusoidal modulation relationship, and a sum of the rotation angles of the two metal nanorods and a diffraction light polarization directionare in a linear modulation relationship; and a color holographic method is implemented on diffraction level by utilizing the phase displacement based on inherent dispersion of the super-structure grating. The super-surface color vector complex amplitude holographic element disclosed by the invention has the advantages of low requirements for preparation control precision, simple structure, high degree of control freedom and the like, and has powerful functions of simultaneously controlling four parameters of light wave phase, polarization, amplitude and frequency.

In a method of wireless transmission, space time matrices are used to spread the transmission of data over two or more transmit antennas and/or over two or more symbol intervals. Initially, blocks of data are encoded as symbols, each being a complex amplitude selected from a symbol constellation. A finite set of space-time matrices, referred to as "dispersion matrices," is predetermined. In transmission, a group of symbols are transmitted concurrently. Each of the symbols to be transmitted is multiplied by a respective dispersion matrix. Thus, a composite matrix, proportional to a sum of dispersion matrices multiplied by their corresponding symbols, is modulated onto a carrier and transmitted. In reception, knowledge of the dispersion matrices is used to recover the transmitted symbols from the received signals corresponding to the composite matrix that was transmitted.

The invention belongs to the seismic data processing and relates to a method by utilizing an equivalent N point smooth spectrum for the simulation of deconvolution. The implementation steps are that the seismic data is collected; the Fourier transform is made for the seismic data at a certain time window; a low pass filter operator of the time domain with an interception frequency of FE and a sampling rate of DT is calculated, which is taken as the equivalent N point smooth operator; FE and DT satisfy the equation that FE*DT is equal to X*DF*1.024; the estimate value of the amplitude spectrum of the seismic wavelet and the reverse wavelet are obtained, which are convoluted with the original seismic data; and the deconvolution seismic data of the time window is obtained. The single peak hypothesis is not applied for the amplitude spectrum of the seismic wavelet in the invention, which suits for complex amplitude spectrum of the seismic wavelet; compared with the least square polynomial fitting, the shape of the simulated amplitude spectrum curve of the seismic record is not affected by the global influence; the invention has the advantages of high calculation efficiency, better stability and improved resolution of seismic profiles.

The invention discloses wavefront measurement method and device based on a multiple-pinhole plate. The wavefront measurement method comprises the following steps of: irradiating a measured object wave to the multiple-pinhole plate containing one reference pinhole and multiple measurement pinholes; recording an intensity distribution pattern of a Fraunhofer diffraction light field of the object wave transmitting the multiple-pinhole plate by an image sensor, wherein the Fraunhofer diffraction light field is in direct proportion to the Fourier transform of the object wave transmitting the multiple-pinhole plate; carrying out inverse Fourier transform on the recorded intensity distribution pattern, and extracting the function values of points which correspond to the center positions of the measurement pinholes of the multiple-pinhole plate in the inverse Fourier transform pattern, wherein the function values is in direct proportion to the complex amplitude values of the measured object wave on the measurement pinholes; and reproducing an imaged object in a computer by utilizing the complex amplitude values. The invention increases the diffraction imaging speed, has simple structure, convenient regulation and low cost, is suitable for multiple different light sources and can realize the real-time wavefront sensing and the diffraction imaging of a pure-phase object and a plural object or a three-dimensional object.

The invention discloses a transmission type sample amplitude and phase imaging device and a transmission type sample amplitude and phase imaging method. A small-aperture diaphragm is moved for scanning, diffraction spots of the small-aperture diaphragm at certain distances are used as light for illuminating a sample, the diffraction spots of the small-aperture diaphragm at different positions are recorded by using a detector in an image plane of the small-aperture diaphragm in an imaging system, and a complex amplitude transmittance function of the sample is obtained through a computer in an iterative operation way, so that amplitude information can be obtained, and phase imaging can be realized. In addition, by each diffraction pattern, the light intensity distribution of the diffraction spots can be recorded, and the actual position, which corresponds to the light intensity distribution, of the small-aperture diaphragm can be obtained through relevancy operation to realize translation stage accuracy-independent reproductive image reconstruction, so that errors caused by the low accuracy of a translation stage are eliminated.

The invention discloses a sparse reconstruction-based broadband radar high-speed group-target resolving method, which comprises the following steps: 1, keystone transformation is carried out on broadband radar echo signals of a space high-speed group-target, keystone transformation is realized through chirp-z transformation, and a discrete spectrum SCZT (m, n) of the mth broadband radar echo signal of the space high-speed group-target in a Doppler ambiguity-existing range frequency domain is obtained; 2, a relationship between an observation data matrix XCZT and a range Doppler two-dimensional complex amplitude matrix GMN of the space high-speed group-target is deduced; 3, a relationship between the observation data matrix XCZT and a range Doppler two-dimensional complex amplitude matrix G'(M*L)N of the high-speed group-target between space and time with different Doppler ambiguity times is deduced; 4, a problem of detecting and resolving the high-speed group-target between space and time with different Doppler ambiguity times is converted into a sparse optimization problem, and the range Doppler two-dimensional complex amplitude matrix G'(M*L)N of the high-speed group-target between space and time with different Doppler ambiguity times is obtained; and a range Doppler plane of the space high-speed group-target is drawn, and coherent accumulation and resolution of the space high-speed group target can be realized.

Apparatus has a transmitting antenna for radiating transmitting signals over a scanning range in the shape of a fan for a forward direction of ones own vehicle at a constant transmitting cycle, receiving antennas for receiving reflected waves by a target and for outputting receiving signals, spectrum computing means for computing a frequency complex amplitude spectrum from the receiving and transmitting signals, advancing direction computing means for computing an advancing direction of ones own vehicle, advancing direction element extracting means for extracting directional elements corresponding to the advancing direction from the frequency complex amplitude spectrum on the basis of the obtained advancing direction, and for outputting computed result data, distance-azimuth spectrum computing means for computing a distance-azimuth spectrum of ones own vehicle, and target detecting means for detecting the target which exists in a forward direction of ones own vehicle on the basis of the computed distance-azimuth spectrum.

An apparatus for measuring an object's surface shape that obtains complex amplitude at a plurality of positions substantially in the directions of the optical axis of the light reflected by the object and calculates the first surface shape of the object by the depth-from-focus principle. On the other hand, using the phase data of the complex amplitude, the apparatus can measure a micro shape in the sub-fringe order by ordinary laser interference measurement. The first surface shape data are applied to a region including a step of a height greater than ½ of the light's wavelength and second surface shape data are applied to the other region.

The invention discloses a beam shaping method for simultaneously modulating amplitude and phase. The method includes the steps: adjusting the background of an object field by building the beam object field and a filter to obtain a simulated object field; simulating the propagation process and the back propagation process of beams by a computer; filtering a calculated light field of an output plane by a filter and reserving the phase outside an object region; multiplying the simulated object field with the reserved phase to serve as new light field complex amplitude for next circular calculation to obtain a single phase hologram; shaping the beams into beams with the amplitude and the phase distributed as needed in the object region of the output plane by the aid of the phase hologram. The method with the simple steps is convenient in operation and fine in convergence effect, the shapes of the beams are arbitrarily set without any constraint, and the beams in various shapes and phase distribution can be manufactured.

The invention discloses a coherent diffraction imaging method and processing device thereof. The object wave passes through a rotary multi-pinhole plate. The Fraunhofer diffraction intensity distribution pattern of the object wave passing through the multi-pinhole plate is recorded by an image sensor. The diffraction intensity distribution is subjected to inverse Fourier transformation to obtain the correlation function pattern of the recorded object wave, the amplitude and phase information of the object wave to be measured are directly extracted from the points corresponding with each measurement pinhole center position coordinate in the correlation function pattern and the diffraction imaging of the complex amplitude object is realized in the computer. The coherent diffraction imaging method has no need of any iterative process and greatly reduces the requirement of the scanning recording process and positioning accuracy and increases the diffraction imaging speed, with other features of simple processing device, convenient adjustment, lower cost, suitable of various different light source, and the imaging of the complex object or three-dimensional object can be realized without imaging lens, especially suitable for the situation that it is difficult to prepare high-quality X-ray using the imaging lens.

The invention discloses a near-field surface plasmon complex amplitude modulation method based on metasurface, and belongs to the field of micro and nano optics. According to the method, the Berry phase principle is utilized, by adjusting the nano rectangular hole lengths and the orientation angles in all isomeric nano rectangular hole arrays in every cycle simultaneously, the discretized amplitude of a target optical field and phase information are obtained, therefore a surface plasmon is activated, arbitrary complex amplitude regulation is conducted on the surface plasmon in the sub-wavelength, and complex optical field distribution and propagation in the surface are achieved. The invention mainly aims at achieving the technical purpose of providing the near-field complex amplitude modulation method based on the metasurface which can activate the surface plasmon, conduct arbitrary complex amplitude regulation on the surface plasmon in the sub-wavelength and achieve the complex optical field distribution and propagation. The near-field surface plasmon complex amplitude modulation method based on the metasurface can arbitrarily modulate the amplitude and phase of the near-field surface plasmon, and has extremely good application value in the fields of surface wave beam shaping, an integrated electron-optical system, surface wave holography and the like.

The invention discloses a multi-wavelength lamination imaging technology facing to three-dimensional information recovery. Samples to be tested are irradiated by various wavelengths and are translated successively in a lamination scanning way in a measurement plane, and corresponding series intensity images are recorded by an image sensor, the recorded series intensity images are processed, and a three-dimensional image of each sample to be tested can be obtained in a computer by an iterative reconstruction algorithm based on multi-wavelength lamination scanning. According to the selection of diffraction distance in a multi-wavelength lamination algorithm, the information of the surface layer, the bottom layer and each inner layer of each sample to be tested can be respectively recovered, i.e. the three-dimensional complex amplitude information of the sample to be tested can be recovered, and the problem that layers in the traditional lamination imaging are mutually overlapped and are difficult to distinguish can be effectively solved. According to the multi-wavelength lamination imaging technology, various wavelengths are adopted, so that the quality of the recovered image can be greatly improved, and meanwhile, the anti-noise capability of the system is better. The multi-wavelength lamination imaging technology has the advantages of high imaging efficiency and good transportability and is suitable for the three-dimensional imaging of the surface layer of a reflection-type object, the imaging of the surface layer and the bottom layer of a transmission-type thin object and the three-dimensional imaging of each layer of a transmission-type thick object.

The invention relates to a design method of an annular vortex array mask plate with controllable vortex number. By means of computer generated hologram principle, light beam complex amplitude computational simulation is carried out to superimpose two perfect vortex beam mask plates with different radii, so that an annular vortex array can be generated in a far field. Cone angles of two axicon lens are adjusted to control the light ring superposition degree of concentric perfect vortexes, thus achieving generation of an annular vortex array. The annular vortex array can achieve arbitrary control of the dark nuclear number of the ring, thus having very important application prospects in particle manipulation technology.

The invention discloses a non-iteration complex amplitude modulation holographic projection method which includes the steps of decomposing light vector of each pixel of a complex amplitude light field into two pure phase values to obtain two pure phase holograms with equal size of an original image, sampling and synthesizing the two pure phase holograms through chequer patterns, adding inclination plane wave factors on the synthesized pure phase hologram to obtain an encoded pure phase hologram, sequentially arranging a phase spatial light modulator, a light splitting prism, a first lens, a filtering diaphragm, a second lens and a screen, transmitting the encoded pure phase hologram to the phase spatial light modulator through a computer, and observing the complex amplitude light field on an output side screen through a 4f optical path system. Through the method, reconstruction image speckles can be eliminated, influence of device zero-order wave on a reconstructed image can be prevented, and the calculating speed of a hologram is increased.

The invention discloses a three-dimensional image optical reconstruction method and system based on phase shift compression Fresnel holography, and belongs to the technical field of data security, andthe method comprises the steps: carrying out the encryption of a three-dimensional object through a random phase mask, and obtaining three different holograms through the three different phase shiftsof reference light; calculating the complex amplitude of the object light field from the three different holograms by using a three-step phase shift method; and reconstructing the three-dimensional object from the complex amplitude of the object light field by using a compressed Fresnel holographic method and a secret key. According to the method, firstly, a complex object light field on a CCD imaging detector plane is calculated by using a three-step phase shift method for a hologram of a three-dimensional object obtained by encryption, and then a three-dimensional image is reconstructed byusing a compressed Fresnel holographic technology and a correct secret key, so that the interference of a square field term and a direct current term is effectively avoided, and the feasibility and superiority of image reconstruction are superior to those of the traditional method.

The invention relates to an ultrasound suspension field visible measuring method and a measuring system using the same. The technology is characterized in that: light beams emitted by a laser are divided into a first set of parallel beams and a second set of parallel beams; the first parallel beams run through an ultrasound suspension field to be measured, and are reflected and then run through the ultrasound suspension field to be measured along the original path, thereby forming measured object light; the second parallel beams are used as reference light, occur interference with the measured object light and form images on an area array CCD. The ultrasound suspension field visible measuring method has the advantages that: in the process of carrying out measurement, the method can avoid producing error, realize instantaneous record and detect the distribution of interference fringes caused by slight change of refractive index of the air due to sound field disturbance, so as to make a measuring result more intuitionistic and accurate. A digital hologram obtained by the measuring device CCD realizes various complex amplitude operations and manipulations in the real sense through digital reappearance so that a data process is simple, rapid and high precise. The measuring device can carry out real-time measurement to a large-size flow field and have great advantage for realizing undisturbed measurement of the ultrasound suspension field.

The invention provides an incoherent laminated diffraction imaging method achieving simultaneous multi-wavelength illumination.The imaging method comprises the following imaging processes that at least one kind of different lasers are adopted for illumination; emitted laser light is regulated to be horizontally emitted through double total reflection mirrors and then subjected to beam combination through double beam splitter prisms; the combined laser light is subjected to beam expansion through a spatial filter, collimated through an apochromatic lens and then reflected to probes; the probes perform laminated scanning on a sample to be measured; intensity information of diffraction images of the probe scanning positions is recorded through an imaging detector; the recorded diffraction image intensity information is substituted into a multiplexing iterative algorithm based on laminated scanning, and complex amplitude distribution of the sample to be measured, complex amplitude distribution of the probes and spectrum weights are recovered.According to the imaging scheme and the corresponding algorithm, not only can the complex amplitude sample to be measured corresponding to the different wave bands be recovered, but also the spectrum weights of the different wave bands and complex amplitude distribution of the illumination probes corresponding to the different wave bands can be recovered.