442 results about "Spectral domain" patented technology

A method for tomographic imaging comprises the steps of providing a source of at least partially coherent radiation and a frequency-swept laser source through an interferometer; phase modulating the radiation in the interferometer at a modulation frequency for elimination of DC and autocorrelation noises as well as the mirror image; detecting interference fringes of the radiation backscattered from the sample into the interferometer to obtain a spectral signal; transforming the spectral signal of the detected backscattered interference fringes to obtain a time and location dependent signal, including the Doppler shift and variance, at each pixel location in a data window; and generating a tomographic image of the fluid flow in the data window and of the structure of the scanned fluid flow sample in the data window from the time and location dependent signal. The apparatus comprises a system for tomographic imaging operating according to the above method.

The present invention discloses simple and yet highly efficient configurations of optical coherence domain reflectometry systems. The combined use of a polarizing beam splitter with one or two polarization manipulator(s) that rotate the returned light wave polarization to an orthogonal direction, enables one to achieve high optical power delivery efficiency as well as fixed or predetermined output polarization state of the interfering light waves reaching a detector or detector array, which is especially beneficial for spectral domain optical coherence tomography. In addition, the system can be made insensitive to polarization fading resulting from the birefringence change in the sample and reference arms. Dispersion matching can also be easily achieved between the sample and the reference arm for high resolution longitudinal scanning.

A system, method and apparatus for anatomical mapping utilizing optical coherence tomography. In the present invention, 3-dimensional fundus intensity imagery can be acquired from a scanning of light back-reflected from an eye. The scanning can include spectral domain scanning, as an example. A fundus intensity image can be acquired in real-time. The 3-dimensional data set can be reduced to generate an anatomical mapping, such as an edema mapping and a thickness mapping. Optionally, a partial fundus intensity image can be produced from the scanning of the eye to generate an en face view of the retinal structure of the eye without first requiring a full segmentation of the 3-D data set. Advantageously, the system, method and apparatus of the present invention can provide quantitative three-dimensional information about the spatial location and extent of macular edema and other pathologies. This three-dimensional information can be used to determine the need for treatment, monitor the effectiveness of treatment and identify the return of fluid that may signal the need for re-treatment.

A method, apparatus and system for providing clock and data recovery in a receiver for receiving a high speed coherent polarization division multiplexed optical signal using a digital signal processing block including a spectral domain spatial combiner are provided.

An audio signal synthesizer generates a synthesis audio signal having a first frequency band and a second synthesized frequency band derived from the first frequency band and comprises a patch generator, a spectral converter, a raw signal processor and a combiner. The patch generator performs at least two different patching algorithms, each patching algorithm generating a raw signal. The patch generator is adapted to select one of the at least two different patching algorithms in response to a control information. The spectral converter converts the raw signal into a raw signal spectral representation. The raw signal processor processes the raw signal spectral representation in response to spectral domain spectral band replication parameters to obtain an adjusted raw signal spectral representation.

An audio encoder has a common preprocessing stage, an information sink based encoding branch such as spectral domain encoding branch, a information source based encoding branch such as an LPC-domain encoding branch and a switch for switching between these branches at inputs into these branches or outputs of these branches controlled by a decision stage. An audio decoder has a spectral domain decoding branch, an LPC-domain decoding branch, one or more switches for switching between the branches and a common post-processing stage for post-processing a time-domain audio signal for obtaining a post-processed audio signal.

An audio encoder has a first information sink oriented encoding branch such as a spectral domain encoding branch, a second information source or SNR oriented encoding branch such as an LPC-domain encoding branch, and a switch for switching between the first encoding branch and the second encoding branch, wherein the second encoding branch has a converter into a specific domain different from the spectral domain such as an LPC analysis stage generating an excitation signal, and wherein the second encoding branch furthermore has a specific domain coding branch such as LPC domain processing branch, and a specific spectral domain coding branch such as LPC spectral domain processing branch, and an additional switch for switching between the specific domain coding branch and the specific spectral domain coding branch. An audio decoder has a first domain decoder such as a spectral domain decoding branch, a second domain decoder such as an LPC domain decoding branch for decoding a signal such as an excitation signal in the second domain, and a third domain decoder such as an LPC-spectral decoder branch and two cascaded switches for switching between the decoders.

A fully automated optic nerve head assessment system, based on spectral domain optical coherence tomography, provides essential disc parameters for clinical analysis, early detection, and monitoring of progression.

A compact conical diffraction Littrow spectrometer is disclosed. The distortion of the conically diffracted spectral component beams is compensated and as a result, the diffracted spectral beams can still be focused into a substantially straight line to shine onto a detector array. A spectral domain optical coherence tomography (SD-OCT) system incorporating a Littrow spectrometer or a spectrometer having one or more shared focusing element(s) and an SD-OCT system incorporating a spectrometer that is substantially polarization independent are also disclosed.

Systems and methods for enhancing spectral domain optical coherence tomography (OCT] are provided. In particular, a system and method for calibration of spectral interference signals using an acquired calibration signal are provided. The calibration signal may be logarithmically amplified to further improve the accuracy of the calibration. From the calibration signal, a series of more accurate calibration data are calculated. An acquired spectral interference signal is calibrated using these calibration data. Moreover, systems that include logarithmic amplification of the spectral interference signal and variable band-pass filtering of the spectral interference signal are provided. Such systems increase the dynamic range and visualization capabilities relative to conventional spectral domain OCT systems.

An apparatus according to an embodiment of the present invention for mixing a first frame of a first input data stream and a second frame of a second input data stream has a processing unit adapted to generate an output frame, wherein the output frame has output spectral data describing a lower part of an output spectrum up to an output cross-over frequency, and wherein the output frame further has output SBR-data describing a higher part of the output spectrum above the output cross-over frequency by way of energy-related values in an output time/frequency grid resolution. The processing unit is further adapted such that the output spectral data corresponding to frequencies below a minimum value of cross-over frequencies of the first frame, the second frame and the output cross-over frequency is generated in a spectral domain and the output SBR-data corresponding to frequencies above a maximum value of cross-over frequencies of the first and second frames and the output cross-over frequency is processed in a SBR-domain.

A system for imaging of the central and peripheral retina, includes one of a concave mirror and an elliptical mirror having an axis and being configured to rotate around the axis and a scanner configured to using a spectral domain optical coherence tomography system to obtain a non-contact wide angle OCT-image of a large portion of the central and peripheral retina.

The present invention discloses one kind of spectral-domain optical coherent tomography endoscopic image system for in vivo optical biopsy, and the system includes one fiber optical interferometer, one imaging probe, one detection unit, one image acquiring card and one computer. The detection unit has grating spectrograph for high imaging speed, and the imaging probe has axial axicon lens and inside rotating right angle prism or circularly symmetric beam splitter combined to ensure high transverse resolution in the whole depth range, so as to realize circularly scanning endoscopic imaging. The present invention proposes two embodiments of circularly scanning probe and their corresponding system structures. The present invention may be applied in the optical endoscopic biopsy and analytic study of oral cavity, respiratory tract, gastrointestinal tract, etc.

An information extraction unit extracts spectral envelope information of L-dimension from each frame of speech data. The spectral envelope information does not have a spectral fine structure. A basis storage unit stores N bases (L>N>1). Each basis is differently a frequency band having a maximum as a peak frequency in a spectral domain having L-dimension. A value corresponding to a frequency outside the frequency band along a frequency axis of the spectral domain is zero. Two frequency bands of which two peak frequencies are adjacent along the frequency axis partially overlap. A parameter calculation unit minimizes a distortion between the spectral envelope information and a linear combination of each basis with a coefficient by changing the coefficient, and sets the coefficient of each basis from which the distortion is minimized to a spectral envelope parameter of the spectral envelope information.

Methods and apparatus are presented for obtaining high-resolution 3-D images of a sample over a range of wavelengths, optionally with polarisation-sensitive detection. In preferred embodiments a spectral domain OCT apparatus is used to sample the complex field of light reflected or scattered from a sample, providing full range imaging. In certain embodiments structured illumination is utilised to provide enhanced lateral resolution. In certain embodiments the resolution or depth of field of images is enhanced by digital refocusing or digital correction of aberrations in the sample. Individual sample volumes are imaged using single shot techniques, and larger volumes can be imaged by stitching together images of adjacent volumes. In preferred embodiments a 2-D lenslet array is used to sample the reflected or scattered light in the Fourier plane or the image plane, with the lenslet array suitably angled with respect to the dispersive axis of a wavelength dispersive element such that the resulting beamlets are dispersed onto unique sets of pixels of a 2-D sensor array.