Patent classifications
G01B9/02082
Speckle reduction in optical coherence tomography images
An optical coherence tomography (OCT) image composed of a plurality of A-scans of a structure is analyzed by defining, for each A-scan, a set of neighboring A-scans surrounding the A-slices scan. Following an optional de-noising step, the neighboring A-scans are aligned in the imaging direction, then a matrix X is formed from the aligned A-scans, and matrix completion is performed to obtain a reduced speckle noise image.
SPATIALLY OFFSET OPTICAL COHERENCE TOMOGRAPHY
An optical coherence tomography system for imaging a sample is configured so as to illuminate a region of interest of the sample with incident light from an optical source. The optical coherence tomography system is further configured so as to interfere, on an optical detector, reference light from the optical source with offset returning light emerging from the sample along an offset collection path which is spatially offset from the region of interest of the sample, thereby creating interference on the optical detector.
Speckle Mitigation
Described herein is a method and system for mitigating the effects of speckle in a laser Doppler system, and, in particular in a laser Doppler vibrometry/velocimetry system. A scan unit is provided in at least one of: a transmit path for scanning at least one beam from a transmitting antenna over a moving target surface and a receive path for scanning at least one reflected beam received from the moving target surface onto a receiving antenna. An averaging unit is provided prior to post-processing or demodulation to average electrical signals corresponding to the reflected beams. By averaging before demodulation, speckle in the output signal is mitigated.
MICRO-REFRACTIVE ELEMENT STABILIZED RESONATORS, LASERS AND MULTIPLE BEAM LASING
A resonator is provided that includes opposing mirrors arranged substantially parallel to each other and separated to confine reflections for gain. A gain medium is between the opposing mirrors. A pump pumps the gain medium. At least one microrefractive element, or tens, hundreds, thousands, millions or more, stabilizes the resonator. The refractive element is disposed between the opposing mirrors and is configured to support a laser beam at a position of the refractive element. A method for producing laser light directs pump light onto one or a plurality of microrefractive elements. Reflections from the one or a plurality of microrefractive elements are confined in a resonator volume. Gain is provided in the resonator volume. Laser energy is emitted from the resonator volume.
Noise reduction techniques, fractional bi-spectrum and fractional cross-correlation, and applications
A measurement method and system include illuminating an object to be measured with light at two different wavelengths and an incident angle; capturing an image of the object; detecting a frequency of an interference pattern from the image using Fractional Bi-Spectrum Analysis; and calculating a thickness of the object based on the Fractional Bi-Spectrum Analysis. The thickness is calculated based on a relationship between the thickness and the frequency of the interference pattern. The Fractional Bi-Spectrum Analysis is performed on a linear medium with the two different wavelengths being known.
Reducing speckle noise in optical coherence tomography images
A method and system are proposed to obtain a reduced speckle noise image of a subject from optical coherence tomography (OCT) image data of the subject. The cross sectional images each comprise a plurality of scan lines obtained by measuring the time delay of light reflected, in a depth direction, from optical interfaces within the subject. The method comprises two aligning steps. First the cross sectional images are aligned, then image patches of the aligned cross sectional images are aligned to form a set of aligned patches. An image matrix is then formed from the aligned patches; and matrix completion is applied to the image matrix to obtain a reduced speckle noise image of the subject.
METHODS AND APPARATUS FOR SPECKLE-FREE OPTICAL COHERENCE IMAGING
An apparatus includes a light splitter to receive a light beam and direct a first portion of the light beam to a reference arm and a second portion of the light beam to a sample arm. The sample arm includes a phase scrambler, in a path of the second portion of the light beam, to cause local-random-time varying phase modulation to the second portion of the light beam. The sample arm also includes a controller to change the local phase of the second portion of the light. The apparatus further includes a detector, in optical communication with the reference arm and the sample arm, to detect an interference pattern produced by the first portion of the light beam propagated through the reference arm and the second portion of the light beam scattered from the sample via the sample arm.
Method and apparatus for motility contrast imaging
A system for motility contrast imaging a biological target within tissue comprising a CCD array; an illumination source for generating an incoming beam; a first beam splitter for receiving the incoming beam and producing an object beam and a reference beam; a second beam splitter for illuminating a multitude of biological targets with the object beam and for directing backscattered object beams towards the CCD array; a computer-controlled delay stage for zero-path-matching the reference beam to the backscattered object beams; a reference beam that intersects the backscattered object beams at an angle to produce a series of interference fringes that modulate Fourier-domain information; and a computer for receiving a time series of Fourier-domain information. The interference fringes between the backscattered object beam and the reference beam are recorded by the CCD array and passed to the computer which constructs a digital hologram at successive times.
INTERFEROMETRIC SPECKLE VISIBILITY SPECTROSCOPY
Interferometric speckle visibility spectroscopy methods, systems, and non-transitory computer readable media for recovering sample speckle field data or a speckle field pattern from an off-axis interferogram recorded by one or more sensors over an exposure time and determining sample dynamics of a sample being analyzed from speckle statistics of the speckle field data or the speckle field pattern.
Optical speckle receiver
An optical speckle receiver for receiving a speckle signal from a sample, the optical speckle receiver comprising an optical detector and an aperture and/or lens array. The aperture and array respectively comprise a plurality of apertures or lenses and is located between the sample and the optical detector such that the received speckle pattern is obtained from multiple discrete sample locations.