Abstract: Shadows caused by opacities and obstructions (such as blood vessels) can block detection of structural information of objects below the shadow-causing structure, affecting visualization and analysis of those deeper structures. An image processing method for removing these shadows includes applying a low pass filter to an energy profile of an image to remove high frequency fluctuations in energy, thereby effectively recovering lower energy inside shadow regions and removing high frequency speckle. The image is then adjusted, for example by linear scaling, based on the filtered energy profile. Two dimensional filters may also be applied for volumes.

Abstract: A method for measuring layer thicknesses of a multi-layer structure includes generating first and second 2D images of the structure, each image being generated by measuring an intensity of a reflection of incident lights, from different discrete narrow spectral bands, on the structure. Thicknesses for at least one layer of the structure are then determined based on the measured reflection intensities at those locations.

Abstract: A method for thickness measurement of a multi-layer object combines frequency analysis and a theoretical model. The frequency analysis is used to determine the thickness of a thicker layer of the object. The theoretical model is used to determine the thickness of the thinner layer of the object.

Abstract: A machine learning model is trained to identify the texture difference between the different layers of a multilayer object. By training with data in full 3D space, the resulting model is capable of predicting the probability that each pixel in a 3D image belongs to a certain layer. With the resulting probability map, comparing probabilities allows one to determine boundaries between layers, and/or other properties and useful information such as volume data.

Abstract: An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

Abstract: A method for determining thickness of layers of the tear film includes reconstructing a full- or hyper-spectral interference pattern from an imaged multi-spectral pattern. Tear film thickness can then be estimated from the full- or hyper-spectral interference pattern. Using a full- or hyper-spectral interference pattern provides a greater number of frequency sampling points for increased tear film thickness estimation accuracy, without traditional time consuming techniques.

Abstract: An interferometric method of identifying the thickness of an object that is too thin to be resolved by a Fourier transform of the interference signal includes applying a harmonic frequency modulation to an envelope of the interference signal. Where the object is a tear film, this method may be utilized to determine a thickness of the lipid layer of the tear film.

Abstract: An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

Abstract: Ophthalmological mages generated by coherent imaging modalities have multiple types of noise, including random noise caused by the imaging system and speckle noise caused by turbid objects such as living tissues. These noises can occur at different levels in different locations. A noise-reduction method and system of the present disclosure thus relates to applying different filters for different types of noise and/or different locations of images, sequentially or in parallel and combined, to produce a final noise-reduced image.

Abstract: A low coherence imaging method comprises acquiring image data of an object with an interferometric imaging system, where the image data is from a location of the object at first and second times; determining a first depth profile from the image data from the location at the first time and a second depth profile from the image data of the location at the second time; determining a change with respect to depth between the first and second depth profiles; and determining a property, or identifying a location, of at least one dynamic particle in the object based on the change between the first and second depth profiles. The method is able to identify, analyze, and/or visualize dynamic particles with features comparable to at least fluorescein angiography, indocyanine green angiography, confocal scanning laser fluorescein angiography, confocal scanning laser indocyanine green angiography, and fluorescence microscopy images, without the use of a dye.

Abstract: A reference signal having a known induced optical delay is used for phase stabilization of optical coherence tomography (OCT) interferograms, and for correcting sampling differences within OCT interferograms, in single mode and multimodal OCT systems. The reference signal can then be used to the measure time shift or sample clock period shifts induced in the interferogram signal by the OCT system. A corresponding OCT interferogram signal can then be corrected to remove the shift induced by the system based on the determination.

Abstract: An interferometric imaging apparatus utilizes a split spectrum and/or frequency filtering process for generating fundus images. According to the split spectrum process, a bandwidth of a light source is divided into sub-spectrums of light, each used to generate pixel data for the fundus image. Data capture can thus be increased by a factor corresponding to the number of sub-spectrums. According to the frequency filtering process, a frequency filter associated with a depth of interest selectively retains data corresponding to that depth.

Abstract: A machine learning model is trained to identify the texture difference between the different layers of a multilayer object. By training with data in full 3D space, the resulting model is capable of predicting the probability that each pixel in a 3D image belongs to a certain layer. With the resulting probability map, comparing probabilities allows one to determine boundaries between layers, and/or other properties and useful information such as volume data.

Abstract: A method for measuring layer thicknesses of a multi-layer structure includes generating first and second 2D images of the structure, each image being generated by measuring an intensity of a reflection of incident lights, from different discrete narrow spectral bands, on the structure. Thicknesses for at least one layer of the structure are then determined based on the measured reflection intensities at those locations.

Abstract: A multimodal imaging system and method is capable of taking fundus images, automatically identifying regions of interest (ROIs) of the eye from the fundus images, and performing OCT imaging in the identified ROIs, where the OCT images can provide clinically relevant information for screening purposes. By automatically identifying the ROIs, expert intervention is not required to perform specialized OCT imaging and thus, such imaging and analysis can be provided at more facilities and for more subjects for a lower cost.

Abstract: Optical coherence tomography light sources can be non-linear and attempts to linearize them can lead to asynchrony between the light source and A-line scans and missampling in the scans causing signal noise. Accordingly, a system and methods are provided herein to detect missampling by obtaining a plurality of interferograms; providing at least two wavenumber reference signals at different wavenumbers, wherein the wavenumber reference signals comprise attenuated or enhanced portions of each of the plurality of interferograms; aligning each of the plurality of interferograms according to one of the at least two wavenumber reference signals; and for each of the plurality of interferograms, identifying an interferogram as missampled if another of the at least two reference signals does not align with a corresponding reference signal in a statistically significant number of the plurality of interferograms. An optical element, for example, an optical notch, may be used to generate the reference signals.

Abstract: A reference signal having a known induced optical delay is used for phase stabilization of optical coherence tomography (OCT) interferograms, and for correcting sampling differences within OCT interferograms, in single mode and multimodal OCT systems. The reference signal can then be used to the measure time shift or sample clock period shifts induced in the interferogram signal by the OCT system. A corresponding OCT interferogram signal can then be corrected to remove the shift induced by the system based on the determination.

Abstract: An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

Abstract: An embodiment provides a method for setting the characteristics of the light to be output from a light source unit for optical coherence tomography, using a computer. This method is performed by using relation information in which a representative wavelength, a wavelength range including said representative wavelength, and the light loss amount due to absorption by a medium are related to each other. This method includes the following steps: setting each value of a first parameter and a second parameter among the representative wavelength, the wavelength range, and the light loss amount; acquiring a value of a third parameter among the representative wavelength, the wavelength range, and the light loss amount other than said first parameter and said second parameter based on the set two values and said relation information; and outputting a value of said acquired third parameter.

Abstract: An image measuring method according to an embodiment comprises a clock generating step, a noise reducing step, a data acquisition step, a digital data generating step and an image data generating step. In the clock generating step, clock signals are generated. In the noise reducing step, the noise of the generated clock signals is reduced to a predetermined threshold or lower. In the data acquisition step, analog data indicating the inner morphology of an object is acquired. In the digital data generating step, digital data is generated by sampling the analog data based on the clock signals with reduced noise. In the image data generating step, image data of the object is generated by performing data processing including Fourier transform on the generated digital data.