700 results about "Wavenumber" patented technology

Methods, systems and computer program products for generating parameters for software dispersion compensation in optical coherence tomography (OCT) systems are provided. Raw spectral interferogram data is acquired for a given lateral position on a sample and a given reference reflection. A trial spectral phase corresponding to each wavenumber sample of the acquired spectral interferogram data is postulated. The acquired raw spectral data and the postulated trial spectral phase data are assembled into trial complex spectrum data. Trial A-scan data is computed by performing an inverse Fourier transform on the trial complex spectrum data and determining the magnitude of a result.

Beamforming method that allows a high speed and high accuracy beamforming with no approximate interpolations. This beamforming method includes step (a) that generates reception signals by receiving waves arrival from a measurement object; and step (b) that performs a beamforming with respect to the reception signals generated by step (a); and step (b) including without performing wavenumber matching including approximate interpolation processings with respect to the reception signals, and the reception signals are Fourier's transformed in the axial direction and the calculated Fourier's transform is multiplied to a complex exponential function expressed using a wavenumber of the wave and a carrier frequency to perform wavenumber matching in the lateral direction and further, the product is Fourier's transformed in the lateral direction and the calculated result is multiplied to a complex exponential function, from which an effect of the lateral wavenumber matching is removed, to perform wavenumber matching in the axial direction, by which an image signal is generated.

A method for detecting the presence of particles, such as sand, flowing within a fluid in a conduit is disclosed. At least two optical sensors measure pressure variations propagating through the fluid. These pressure variations are caused by acoustic noise generated by typical background noises of the well production environment and from sand particles flowing within the fluid. If the acoustics are sufficiently energetic with respect to other disturbances, the signals provided by the sensors will form an acoustic ridge on a kω plot, where each data point represents the power of the acoustic wave corresponding to that particular wave number and temporal frequency. A sand metric then compares the average power of the data points forming the acoustic ridge to the average power of the data points falling outside of the acoustic ridge. The result of this comparison allows one to determine whether particles are present within the fluid. Furthermore, the present invention can also determine whether the generated acoustic noise is occurring upstream or downstream of the sensors, thus giving an indication of the location of the particles in the fluid relative to the sensors.

The invention is related to the instrument for measuring a Raman signal of tissue, the instrument comprising a laser, a signal detection unit for measuring the Raman signal, and a fiber optic probe, wherein the fiber optic probe comprises one or more optical fibers for directing laser light onto the tissue and for collecting light that is scattered by the tissue and guiding the collected light away from the tissue towards the signal detection unit, wherein the fiber or fibers for collecting light have substantially no Raman signal in one or more parts of the 2500-3700 cm⁻¹ spectral region, and wherein the detection unit records the Raman signal scattered by the tissue in said spectral region. The invention enables ex vivo, in vitro and in vivo analysis and diagnosis of atherosclerotic plaque and detection of tumor tissue with great advantages over current state-of-the-art technology.

A diffraction grating having a transparent supporting substrate; and a cured resin layer which is stacked on the transparent supporting substrate and which has concavities and convexities formed on a surface thereof, wherein when a Fourier-transformed image is obtained by performing two-dimensional fast Fourier transform processing on a concavity and convexity analysis image obtained by analyzing a shape of the concavities and convexities formed on the surface of the cured resin layer by use of an atomic force microscope, the Fourier-transformed image shows a circular or annular pattern substantially centered at an origin at which an absolute value of wavenumber is 0 μm⁻¹, and the circular or annular pattern is present within a region where an absolute value of wavenumber is within a range of 10 μm⁻¹ or less.

A method of performing near- field acoustic holography comprises the following steps. Establishing (102) acoustic data representing a set of near-field acoustic holography measurements at a first set of positions. Extrapolating (204) acoustic data using a model-based extrapolation to obtain extrapolated acoustic data relating to a plurality of positions outside the aperture. Applying a spatial frequency transform to the padded acoustic data to obtain data in a spatial frequency domain. Propagating (110) the Fourier transformed acoustic data. Applying (112) a regularization in a wavenumber domain. Performing (114) an inverse spatial frequency transform.

Devices and analytical techniques are disclosed for measuring spatial profiles of complex permeability and conductivity of a material by multiple wavenumber interrogations. Coil array structures are disclosed which define a number of different fundamental wavelengths (or wavenumbers). Spatially periodic interrogation signals (of temporal frequency " omega ") from the coil array structures are attenuated by varying degrees in the material undergoing analysis, depending on the wavenumber ("k"), thereby permitting the derivation of composite complex permeability/conductivity profile.

The present invention provides apparatuses and methods for sample analysis, such as tissue analysis, that integrate high wavenumber (HW) Raman spectroscopy for chemical composition analysis and optical coherence tomography (OCT) to provide depth and morphological information. The invention also provides side-viewing optical probes that are based on a single double clad optical fiber for performing the combined HW Raman spectroscopy and OCT. Intravascular catheter embodiments and related vascular diagnostic methods are also provided.

A transmission/reception beamformer output provided with point spread functions having different wave number vector directions is used to obtain a compound image that is highly isochronous and sufficiently blurring-resistant.

A light control element includes a substrate, an optical coupling component formed on the substrate by a photonic crystal structure, and a variable refractive index part provided in a part of the photonic crystal structure so as to divide The optical coupling component into two regions, wherein a traveling direction of a light is changed at an interface of the regions by changing a refractive index at the variable refractive index part such that there is caused a reflection for at least one wavenumber of the light.

An estimated frequency-wavenumber spectrum is generated by applying a first Anti-leakage Fourier transform method to aliased frequency components in temporal-transformed seismic data and applying a second Anti-leakage Fourier transform method to unaliased frequency components in the temporal-transformed seismic data. The second Anti-leakage Fourier transform method applies an absolute frequency-wavenumber spectrum extrapolated from unaliased frequencies to aliased frequencies to weight frequency-wavenumber components of the aliased frequencies. An inverse temporal and spatial Fourier transform is applied to the estimated frequency-wavenumber spectrum, generating trace interpolation of the seismic data.

Generating a multispectral or hyperspectral image of an image source with an optical system having an adjustable, wavenumber-dependent point spread function, by collecting panchromatic images of the image source, each of which corresponds to a selected point spread function and includes a measured intensity data set corresponding to a range of wavelengths, transforming the panchromatic images into the spatial frequency domain by using a Fourier transform, solving a matrix equation at each spatial frequency, in which a vector of the transformed panchromatic images is equal to the product of a predetermined matrix of discrete weighting coefficients and a vector representing a wavenumber content of the image source at each spatial frequency, resulting in a determined wavenumber content of the image source in the spatial frequency domain, and inverse transforming the determined wavenumber content of the image source from the spatial frequency domain into the image domain, resulting in the multispectral or hyperspectral image.

The invention discloses a light-spectrum phase calibration system and a light-spectrum phase calibration method based on a cascade Mach-Zehnder interferometer. A first reference interference signal with optical path difference d1 close to maximum imaging depth of the system and a second reference interference signal with optical path difference d2 close to zero optical path are separated from a cascade MZI (Mach Zehnder Interferometer) interference spectrum signal through Fourier transform, filtering and inverse Fourier transform; the first reference interference signal is used for demarcating and calibrating a fractional part of a light spectrum phase jump at the maximum imaging depth part in real time during a wave-number sampling process; the second reference interference signal is used for determining 2pi integer multiples of the light spectrum phase jump at the maximum imaging depth part, wherein the phase jump caused by an initial wave-number jumping is in linear relation with the depth; and the practical phase jump at any depth can be calibrated by combining the two reference interference signals. According to the light-spectrum phase calibration system and the light-spectrum phase calibration method disclosed by the invention, not only is real-time linear calibration realized, but also calibration precision of the light-spectrum phase jump is ensured, so that a 2pi confusion problem of the light-spectrum phase jump calibration is solved, and the real-time high-flexibility phase detection and the reconstruction of phase images can be realized.

A method of complex frequency-domain optical coherence tomography using differential sinusoidal phase modulation includes: based on complex frequency-domain optical coherence tomography using differential sinusoidal phase modulation, introducing sinusoidal phase modulation to transverse scan interference signals, subjecting acquired interference spectral signals to inverse Fourier transform along the wave-number direction, using a phase difference of adjacent complex tomographic signals to replace phases of complex tomographic signals obtained in conversion so that new differential complex tomographic signals are formed, respectively subjecting a real part and an imagery part of each differential complex tomographic signal to phase demodulation prior to addition so as to obtain mirror-removed complex tomographic signals, and removing amplitude to obtain a full-depth structural tomographic map of a tested sample. By the method, complex conjugate mirror images, direct current background and autocorrelation noise in the frequency-domain optical coherence tomographic images are eliminated, sensitivity does not decrease with increase of transverse scanning distance, the affection of internal high-speed movement of a sample on mirror image elimination is reduced, and the method is applicable to in vivo imaging of biological samples.

The invention provides optical switching-based systems and methods for catheter-based optical diagnosis which are particularly well suited to determining the condition of blood vessels, including the state of the vessels with respect to atherosclerosis and its development. Various embodiments provide catheter-based spectroscopic systems that are configured to cycle between different optical interrogation techniques such as Raman spectroscopy, optical coherence tomography and time-resolved laser-induced fluorescence spectroscopy. One embodiment of the invention provides an intravascular catheter-based diagnostic system that cycles between fingerprint region (200-2,500 cm⁻¹) Raman spectroscopy and high-wavenumber region (2,500-4,000 cm⁻¹) Raman spectroscopy.

A full wave inversion (FWI) may utilize an Amplitude-Frequency-Differentiation (AFD) or a Phase-Frequency-Differentiation (PFD) operation to form a velocity model of a subterranean formation utilizing recovered low wavenumber data. Received seismic data is processes to isolate two data signals at different frequencies. In an AFD operation, the two data signals are summed and the data of the envelope of the summed function is used for the FWI. In a PFD operation, the phase data of the quotient of the two data signals is used for the FWI. The FWI proceeds iteratively utilizing either the AFD or PFD data or with single frequency data until the cost function of the AFD or PFD is satisfied.

The invention relates to a spectral-domain optical coherence tomography imaging system based on a Fresnel spectrometer, which is characterized by comprising a Michelson interferometer, the Fresnel spectrometer and a Fourier transformation module. The Michelson interferometer sends coherent light which is formed by superposing sample light returned from various layers of a sample with reference light into the Fresnel spectrometer, the coherent light is emitted onto a Fresnel zone plate parallelly through a collimating lens and an expanded beam lens respectively, and is expanded at the same interval according to the wave number and then projected to a linear array CCDs (charge coupled devices) by the Fresnel zone plate, frequency spectrum data of the coherent light are read by the linear array CCDs and sent to the Fourier transformation module, and then recovered into information of spatial position of the sample by means of discrete Fourier transformation through the Fourier transformation module. The spectral-domain optical coherence tomography imaging system based on the Fresnel spectrometer can be applied to not only spectral-domain optical coherence tomography imaging but also spectral analysis having requirements for wavelength-wave number conversion and resampling for imaging or detecting and required to be expanded uniformly according to the wave number, and especially can be applied to the biomedical imaging process.

A microencapsulated hardener for epoxy resins which comprises cores comprising an epoxy-resin hardener and shells covering the cores, characterized in that the epoxy-resin hardener comprises as a major component an amine adduct obtained by the reaction of an epoxy resin (e1) with an amine compound, the epoxy-resin hardener has an overall amine value of 370 to 1,000, the epoxy-resin hardener has an average particle diameter of 0.3-12 [mu]m, excluding 0.3 [mu]m, and the shells have, on at least the surface thereof, a combined group (x) that absorbs infrared rays having a wavenumber of 1,630-1,680 cm-1, a combined group (y) that absorbs infrared rays having a wavenumber of 1,680-1,725 cm-1, and a combined group (z) that absorbs infrared rays having a wavenumber of 1,730-1,755 cm-1.