71 results about "Frequency domain optical coherence tomography" patented technology

One embodiment of the present invention is a method for suppressing artifacts in frequency-domain OCT images, which method includes (a) providing sample and reference paths with a significant difference in their chromatic dispersion (b) correcting for the effects of the mismatch in chromatic dispersion, for the purpose of making artifacts in the OCT image readily distinguishable from the desired image.

In part, the invention relates to frequency-domain optical coherence tomography system. The system includes a tunable laser comprising a laser output for transmitting laser light and a laser cavity having a length L, a gain element disposed within the laser cavity; a tunable wavelength selective element disposed within the laser cavity; a reference reflector disposed outside of the laser cavity; an interferometer in optical communication with the laser output and the reference reflector, wherein the interferometer is configured to transmit a portion of the laser light to a sample and combine light scattered from the sample with light scattered from the reference reflector; and a detector in optical communication with the interferometer that receives the combination of light scattered from the sample and the light scattered from the reference reflector and transforms the combination of light into an electronic signal comprising measurement data with respect to the sample.

The invention discloses an optical coherence tomography method and an optical coherence tomography system for a complex polarization frequency domain. The method comprises the following steps of: on the basis of optical coherence tomography of a polarization frequency domain, driving a reference plane mirror of a reference arm to vibrate by a phase modulation device, introducing sinusoidal phase modulation while transversely scanning a sample, performing processing such as Fourier transform on acquired interference signals of horizontal and vertical polarization channels to obtain chromatography signals of the horizontal and vertical polarization channels without parasitic images, extracting magnitudes and phases of the chromatography signals respectively, and calculating to obtain an intensity image, a fast axis image and a delay image of the sample with double refraction properties within a full-depth range. According to the method, the imaging speed is high, a complex conjugate mirror image, a direct-current background and the self-coherence noise in the coherent tomography of the polarization frequency domain are removed, the sensitivity cannot be reduced along with the prolonging of a transverse scanning distance, and the method is not sensitive to motion blur in the sample.

The invention discloses a choroid layer automatic partitioning method based on a high-definition frequency domain optical coherence tomography (HD-OCT) image, and belongs to the technical field of image processing. According to the method, input HD-OCT images are subjected to denoising preprocessing first, a high-reflectance zone near a retina nerve fiber layer is removed by locating an internal limiting membrane, then the lower boundary of a retinochrome epithelial layer, namely the upper boundary of a choroid layer is located through high-reflectance information, finally candidate CSI boundary points obtained through the image features of the lower boundary of the choroid layer are connected through a graph searching method, and the CSI boundary of choroid membranes is obtained. Test results show that choroid layer partitioning accuracy is high and is equal to that of manual partitioning results, the method can replace the complex time-consuming work that a clinician measures the thickness of the choroid membranes manually, and significance in improving of working efficiency of a doctor is achieved.

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.

The invention relates to all-eye frequency-domain optical coherence tomography system and method. The method includes: a, an electric double-reflector turnover device is set in a sample arm, double reflectors image the anterior segment when in an optical path and image the fundus retina when moved out of the optical path; b, an optical distance switching device is set in a reference arm, incoming light is divided into three optical distances, the optical path returns in the same way to interfere with light reflected by the sample arm so that interference spectrum is formed, one anterior segment image and one fundus image are obtained sequentially after the interference spectrum is output from a fiber-optic coupler to a spectrograph; and c, trigger signals of the electric double-reflector turnover device and the optical distance switching device are controlled under synchronous operation. The method has the advantages that the form of the anterior segment and the form of the fundus are measured accurately and simultaneous imaging of the anterior segment and the fundus is achieved.

The invention provides a full-depth Fourier-range Doppler optical coherence tomography method which adopts an optical-fiber frequency domain optical coherence tomography system. The method is as follows: a complex tomographic signal obtained by the sinusoidal phase-modulation complex frequency domain optical coherence tomography method is used to calculate a Doppler signal so as to obtain a full-range structural tomographic image and a full-range Doppler image. The invention adopts the mode of synchronization of phase modulation and lateral scanning, so as to reduce the time of data acquisition and is enabled to be relatively suitable for in vivo imaging of a biological sample. The impact of a mirror image is eliminated to allow a to-be-test sample to be always in a region with a relatively-high signal-to-noise ratio in the system, and the modulation amplitude of sinusoidal phase modulation is small and close to a position of zero optical path difference all the time, so that a relatively-high velocity detection sensitivity can be obtained within the whole image. A full-depth Doppler image with a relatively-high velocity detection sensitivity can be obtained while a full-depth tomographic structural image with a relatively-high signal-to-noise ratio is obtained.

A frequency domain optical coherent tomography method with large detection depth and a system are provided. The system adopts a folding spectrum detection method to realize the spectrum detection of broadband with high resolution. The thought is that a broadband spectrum with the bandwidth of Delta Lambada is folded into a plurality of narrow wavelength windows of Delta Lambada 1, Delta Lambada 2-, delta Lambada n. High resolution detection is realized on every spectrum band. Then, all spectrum bands are synthesized into a broadband through splicing. The folding of the spectrum bands is realized through a combined diffraction grating. A rotating sub-grating regulates the incident angle im of the incident light to every grating, which leads to that the diffraction light direction of the relative wavelength window Delta Lambada m of every sub-grating is distributed within the same range. Then, the diffraction lights of all spectrum bands are focused on the detection surface of a spectrum detection array through a toroidal focusing mirror. Through the spectrum folding, the invention increases the effective detection pixel number N of the spectrum detection and improves the detection depth of the optical coherent tomography system and the signal-noise ratio of chromatogram.

The invention discloses a chromatic dispersion compensation method of an FD-OCT (Fourier-Domain Optical Coherence Tomography) system. According to the chromatic dispersion compensation method disclosed by the invention, the chromatic dispersion mismatch induced by an optical path and a sample in the system can be automatically compensated from thick to thin by adopting a window iteration method, thus a broadening effect of chromatic dispersion in the system can be removed, and the resolution of the system can be increased. The chromatic dispersion compensation method has the advantages that different depths of the inner part of the sample can be compensated by adopting corresponding chromatic dispersion coefficients, the influence on a depth resolution chromatic dispersion compensation effect when the window width which is determined by adopting a single threshold value is unsuitable can be avoided, and thus an optimal compensation effect on the chromatic dispersion in different depths induced by the sample can be achieved.

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 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.

The invention discloses a method for rectifying the position and the phase of a frequency-domain optical coherence tomography signal, which comprises the following steps that: a B scanning initial position is rectified by an amplitude normalized crosscorrelation method; a zero optical path different position of an A scanning signal along a Z direction is rectified by the amplitude normalized crosscorrelation method; the phase rectification of the A scanning signal is realized based on the matching of the phase difference distribution characteristic vectors of the A scanning signal; the relations of the amplitude normalized crosscorrelation values and the cross ranges of all the sub areas are obtained, and the lateral position of the A scanning signal is calibrated; and the A scanning signal which has the unevenly-distributed lateral positions is converted into the evenly-distributed A scanning signal through interpolation. The method eliminates the system scanning error and the influence of sample vibration on the signal stability when an in vivo biological tissue is imaged. The method does not need to increase the hardware, not influence the system scanning speed and is suitable to the tissue detection of a living body; the method realizes the phase rectification at high accuracy and fast speed; and the method has strong portability, and can be used for Doppler optical coherence tomography (OCT) and other fields.

Frequency domain optical coherence tomography (FD-OCT) systems and methods are provided. Thereby, a first measurement and a second measurement is performed, wherein in the first measurement an object region is illuminated by measuring light having a spectrum with a first spectral width and in the second measurement the object region is illuminated with measuring light having a spectrum with a second spectral width, wherein the first spectral width is at least 10% greater than the second spectral width. Further, during the first measurement intensities of spectral ranges of light having interacted with the object and being superimposed with reference light are detected, wherein a width of these spectral ranges is greater than a corresponding width during the second measurement. Thus, switching an axial field of view of structural information of the object across a depth direction is enabled upon minimizing radiation damage at the object.

The invention relates to a sinusoidal phase modulation parallel complex frequency domain optical coherence tomography imaging system and a method. The method and the system are characterized in that on the basis of the parallel frequency domain optical coherence tomography imaging system and method, a reflective space sinusoidal phase modulation device is used for replacing a reference plane reflecting mirror of an interference reference arm, two-dimensional frequency domain interference fringes obtained on a two-dimensional photoelectric detector array are introduced into a space to be subjected to sinusoidal phase modulation, i.e. spatial carriers are introduced into the two-dimensional frequency domain interference fringes; and then, the two-dimensional frequency domain interference fringes containing the spatial carriers are subjected to spatial Fourier transform analysis, two-dimensional complex frequency domain interference fringes are obtained, and finally, the chromatographic profile of samples to be measured is obtained through the inverse Fourier transform in the optical frequency direction. The system and the method have the characteristics that the structure is simple, the imaging speed is high, the sensitivity on the motion blur is low, and the samples to be measured are always in a region with higher sensitivity. The chromatographic profile of samples to be measured can be obtained only through once exposure.

The invention discloses a whole flow field 3D visualization velocity measuring method for a microflow field, which comprises the steps of establishing a microparticle tracking whole flow field visualization velocity measuring system based on a frequency-domain optical coherence tomography technique; conducing two-dimensional scanning on a fluid, and continuously acquiring interference spectral data of the fluid; obtaining a three-dimensional image of the fluid based on a Fourier transform method; using local gray-level thresholding and volume filtering methods to search for the microparticles in the flow field, and using a squared weighted centroid method to obtain three-dimensional coordinates of the microparticles to achieve visualization of the microparticles; matching the microparticles by defining a cost function; and using variations in the three-dimensional coordinates of the microparticles to obtain a kinematic velocity vector. The visualization of velocity in the flow field is achieved through imaging and tracking of the microparticles; the three-dimensional velocity vector of the whole flow field is measured through tracking of moving trajectories of the microparticles in the whole flow field; and with micron-level spatial resolution, the whole flow field 3D visualization velocity measuring method is especially suitable for three-dimensional velocity vector detection of complex micro-fluid fields.

The invention relates to the field of an optical coherence tomography system of a polarizing frequency domain and in particular relates to an optical coherence tomography system of a polarizing frequency domain of a single spectrograph based on a photoswitch. A high speed photoswitch which is divided into two paths is placed in a reference arm light path, time-shared detection of the single spectrograph for interference signals of two channels of horizontal polarization and vertical polarization is realized by means of channel selection of the photoswitch, and the detected two polarization signals are calculated to acquire an intensity image, a fast axis image and a delay image of a sample with double refraction properties. The system provided by the invention is simple in structure; the light path adjusting difficulty is greatly reduced without using a beam splitter prism, and inter-mode interference brought by a polarization beam splitter is also avoided; and meanwhile, polarization imaging can be realized without complicated phase modulation equipment and algorithms.

The invention provides a frequency domain optical coherence tomography continuous dispersion compensation imaging method and system. A broadband superradiant laser device (SLD) is adopted as a recording light source, three-step phase shift is adopted to obtain a complex interference intensity spectrum, a phase value of an interference spectrum intensity complex function is obtained, two-order dispersion coefficient values in several positions of depth layers are obtained through an iterative method, and a change curve of two-order dispersion coefficients with the positions of the depth layersis obtained through fitting. On this basis, the two-order dispersion coefficient values in all the depth layers are directly obtained, continuous dispersion compensation in the depth direction of a chromatogram is achieved, and the method and system have the advantages that phase distribution is extracted through the three-step phase shift, and continuous layered dispersion correction is achievedby directly obtaining the two-order dispersion coefficient values in all the layers through the fitting curve. Optical fiber and an optical fiber coupler are adopted by the optical system to split beams and combine the beams, the optical structure is simple and easy to apply, and a high-quality frequency domain OCT imaging result can be obtained in combination with a continuous dispersion compensation method.

The invention discloses a polarization frequency domain optical coherence tomography system based on a single detector. The polarization frequency domain optical coherence tomography system based on the single detector comprises a low-coherence optical source, a first collimator, a polarizer, a michelson interferometer, a polarization beam splitter, a second collimator, a first optical fiber, a third collimator, a fourth collimator, a second optical fiber, a fifth collimator, a grating, a cylindrical lens and a detector. According to the invention, the single detector is adopted, so that the system structure is simplified; the problem of time asynchronism when two detectors collect signals is prevented; meanwhile, two paths of light radiates the grating at the incident angle with highest diffraction efficiency; the improvement of the diffraction efficiency increases the signal to noise ratio of the system, and the image quality is improved.

The invention discloses a double-channel full-range complex-spectral-domain optical coherence tomographic system. A 3X3 fiber coupler splits light to form two reference arms and a sample arm. By using the spectral-domain optical coherence tomographic system composed of the two reference arms and the sample arm to detect samples at different depth, detection depth can be increased and imaging quality can be improved. The optical coherence tomographic system can be used for vividly imaging the deep samples by the aid of one light source and one spectrometer. The double-channel full-range complex-spectral-domain optical coherence tomographic system has potential application value for detecting high-scattering biological tissues and industrial samples.

The invention provides a three-dimensional structure functional imaging system which comprises a frequency domain optical coherence tomography subsystem, a fluorescence imaging and spectral analysis subsystem and a front-end scanning structure subsystem. According to the frequency domain optical coherence tomography subsystem, low coherence light is used as a light source, and the light source is input into a coupler after passing through a polarization controller, split to a reference arm and a sample arm and then returned back to the coupler to form a coherent light field. The fluorescence imaging and spectral analysis subsystem can be provided with multiple selectable light sources, a light way is adjusted at the light machine part, and a light source with the preset power is obtained and coupled to a sample light way of the frequency domain optical coherence tomography subsystem. The front-end scanning structure subsystem is used for coupling the light sources of the fluorescence imaging and spectral analysis subsystem and the sample light of the frequency domain optical coherence tomography subsystem into the same light way, a two-dimensional scanning galvanometer is used for scanning emergent light to form a dot matrix image of a two-dimensional structure, and therefore a three-dimensional image comprising surface fluorescence signals and a structure fault is obtained. The three-dimensional structure functional imaging system has the advantages of being high in resolution ratio, low in cost, good in stability and high in reliability and achieving noninvasive imaging.

The invention provides an intelligent imaging system for surgical operation. The intelligent imaging system comprises a frequency-domain optical coherence tomography subsystem for obtaining a depth image of a biological tissue, a fluorescence imaging and hyperspectral analysis subsystem for forming a hyperspectral image, a probe device for coupling optical paths of the frequency-domain optical coherence tomography subsystem and the fluorescence imaging and hyperspectral analysis subsystem, fusing the depth image of the biological tissue and the hyperspectral image to obtain a structural functional stereoscopic image of the biological tissue, determining an operative area according to the structural functional stereoscopic image of the biological tissue and performing scanning in the operative area to obtain a quasi-real-time image. The intelligent imaging system for the surgical operation has the advantages of being simple in structure, low in cost, simple in operation, high in imaging speed, high in image space resolution, small in size, light in weight and obvious in image effect.

The present application discloses methods and systems to track the anterior segment while establishing a position of the delay which will permit good control of the placement of anterior segment structures. This allows accurate dewarping by maximizing the amount of corneal surface that is imaged as well as reducing or eliminating overlap between real and complex conjugate images present in frequency-domain optical coherence tomography. A method to dewarp surfaces given partial corneal surface information is also disclosed.

The invention relates to a frequency domain optical coherence chromatography imaging method and a system thereof with adjustable detection depth range and depth resolution ratio; a variable cycle grating is used for frequency domain optical coherence chromatography imaging, and the light spectrum detection depth and the light spectrum detection resolution ratio of a frequency domain interference signal are changed by adjusting the grating period and the lateral position of the detector, so as to realize the frequency domain optical coherence chromatography imaging with adjustable frequency domain optical coherence chromatography imaging. The invention can be matched with the usage of a wide spectral width light source, the problem that the pixel array length of the detector is limited when the spectral width is wider, and different imaging requirements of uses for obtaining large detection depth range or / and deeper depth resolution ratio can be met.

The invention discloses an ophthalmologic frequency-domain optical coherence tomography (OCT) system based on a graphics processing unit (GPU) platform and a processing method. The system comprises a super luminescent diode (SLD) light source, a light circulator, an optical fiber beam splitter, a first polarization controller and a reference arm which are sequentially connected with each other, wherein the light circulator or the optical fiber beam splitter is also connected with a second polarization controller, the second polarization controller is also connected with a spectrometer, a high-speed camera data line, a high-speed image acquisition card and a computer sequentially, the optical fiber beam splitter is also connected with a third polarization controller and a sampling arm which is connected with a tested eye sequentially, and the computer is respectively connected with the sampling arm, an image display unit and a GPU image processor. The method is as follows: rules are firstly set: FrameNumber represents frame number, the size of a data block to be process is FrameNumber B-scan data sizes, and each B-scan consists of batch A-scans; and a sampling data f(lambda, y) is a function of wavelength which is acquired through the spectrometer and is subjected to analog (A) / digital (D) conversion, wherein a horizontal ordinate is the wavelength lambda, and a longitudinal ordinate is the numerical value y. The system meets requirements on clinical two-dimensional (2D) real-time imaging.

An optical coherence tomography (OCT) system comprising: a splitter configured to receive and split an optical source beam generating a reference beam and a sample beam, the sample beam directed at a sample and interacting with the sample to generate a return beam; a delay module configured to receive and introduce an optical delay in the reference beam, to generate a delayed reflected beam configured to interfere with the return beam to generate an interferogram; a spatial filter system capable of filtering randomly scattered light from at least one of the return beam or the interferogram; and a detector array to receive the interferogram for spatial and spectral analysis.

The invention relates to a shift multiplexing complex frequency domain optical coherence tomography scan detection method and a shift multiplexing complex frequency domain optical coherence tomography scan detection system. The shift multiplexing complex frequency domain optical coherence tomography scan detection system comprises an emitting light path system, a receiving light path system, a dispersion prism reflecting light path system and a dispersion prism transmitting light path system. The shift multiplexing complex frequency domain optical coherence tomography scan detection method comprises the following steps: through a mobile carrying translation stage, sequentially changing detection main point positions; for each detection main point position, performing phase shifting by using a piezoelectric ceramic translation stage, and acquiring a group of phase shift interferogram with a fixed step length till a required detection depth is achieved; for the acquired multiple groups of phase shift interferograms with the fixed step lengths, respectively performing phase shifting mirror image and direct current term removal to obtain m mirror image-free and direct current term-free sample chromatograms corresponding to the detection main point positions; and transversely intercepting front and back respective N / 2 pixels in a central position of each sample chromatogram respectively to obtain m intercepted images, and combining the m intercepted images which are arrayed in a detection direction into one chromatogram.