688 results about "Optical coherence tomography" patented technology

The invention belongs to the technical field of film quality analysis and evaluation, and particularly relates to a flexible circuit board film pressing quality detection and analysis method and system. The method comprises the steps of generating a self-adaptive scanning path based on a design file and surface deformation data; performing multi-modal data acquisition and fusion along a path through optical surface scanning, ultrasonic tomography and an optical coherence tomography imaging assembly; potential defects are positioned, and size, shape, position and defect type probability values are quantized; judging the authenticity of the defect by adopting a three-stage mechanism of cross-modal probability comparison, physical characteristic logic verification and multi-frame time sequence verification; and performing weighted scoring on the real defect matching acceptance standard table, and performing disqualification marking or outputting a process optimization suggestion to the pressing equipment according to a scoring result. According to the invention, the imaging limitation of the transparent coating layer is broken through, the internal interface layering and the precise detection of the microbubbles are realized, and the closed-loop control from detection to production adjustment is formed.

The invention relates to the technical field of ophthalmologic image processing, and discloses a fundus blood vessel segmentation method based on multi-modal data. The method comprises the following steps: firstly, synchronously acquiring an optical coherence tomography image, a color fundus photographic image and a fluorescent angiography image to form multi-modal fundus data; preprocessing the eye fundus image data set to generate a standardized multi-mode eye fundus image data set; fusing heterogeneous features based on the data set, and constructing a multi-dimensional fundus feature space; using the space to train a deep learning segmentation network model, and generating an initial fundus blood vessel segmentation mask; carrying out confidence evaluation analysis on the initial mask to obtain a blood vessel segmentation result confidence distribution map; dividing blood vessel segmentation quality grades according to the distribution diagram, and defining a judgment rule; and performing interactive correction on the low-confidence region based on a rule to generate a final optimized fundus blood vessel segmentation result. And the final result is transmitted to a visual terminal for three-dimensional topology reconstruction. According to the method, the advantages of multi-modal data are integrated, and a more comprehensive fundus blood vessel segmentation result is formed.

The invention discloses a blood vessel plaque intelligent identification method and system based on optical coherence tomography, and relates to the technical field of medical image processing. Firstly, a three-dimensional blood vessel grid model is constructed through OCT volume data, vertex curvature parameters are quantified to generate a dynamic threshold template, the segmentation process is made to adapt to the local form of a blood vessel, and the problem of wrong segmentation of a traditional algorithm in a complex anatomical region is solved. Secondly, introducing a fractal dimension verification mechanism, quantitatively evaluating an initial segmentation result based on edge complexity, and when fractal features deviate from a preset threshold value, dynamically adjusting curvature weight parameters and iteratively optimizing segmentation, forming'segmentation-verification-correction 'closed-loop control, and remarkably suppressing artifact interference; and the finally output three-dimensional identification result comprises plaque space coordinates and morphological characteristics, and a visual decision basis is provided for clinic.

The invention relates to the technical field of image processing, and provides an OCT (Optical Coherence Tomography) image splicing method, which comprises the following steps: acquiring image pairs and matching point pairs corresponding to the image pairs, the image pairs being adjacent OCT images; calculating a homography matrix based on the matching point pairs so as to align the image pairs, and outputting preliminary aligned image pairs; constructing a fusion weight map, wherein the fusion weight map comprises a weight value of a pixel position and a region type; and according to the weight value and the region type, carrying out fusion splicing on the pixel positions so as to output a panoramic OCT image. According to the method, partition fusion is achieved by fusing the weight map, the problems of tissue dislocation and artifacts in OCT splicing are solved, and then the problem that the splicing effect of OCT image splicing is poor is solved.

The invention relates to the technical field of medical image processing and artificial intelligence, and discloses an artificial intelligence-based retinochoroid disease course structure change monitoring system, which comprises an image acquisition unit, a feature extraction unit, a lesion segmentation unit and the like. The image acquisition unit acquires retina optical coherence tomography sequence image data and fundus color image data; the feature extraction unit extracts a retina choroidal structure feature tensor through a three-dimensional convolutional neural network; the lesion segmentation unit outputs a lesion area probability distribution diagram by using a U-Net segmentation network; the time sequence alignment unit is used for registering the multi-time-point images to generate a displacement change matrix; the dynamic analysis unit extracts related indexes; an abnormal scoring unit constructs a disease course progress score; the decision grading unit outputs disease course stage classification labels; the multi-modal fusion unit fuses the multi-modal features; the report generation unit generates a structured disease course monitoring report. And favorable support is provided for diagnosis and treatment of ophthalmic diseases and illness state tracking.

The invention relates to the field of ulcerative colitis, and discloses a multi-parameter monitoring system for evaluating the intestinal barrier function of ulcerative colitis, which is used for realizing the goal of automatically adjusting a treatment scheme according to a monitoring result by constructing a closed-loop feedback treatment system. According to the invention, by designing the nanoprobe of which the surface is modified with a specific binding element and combining with a swallowing capsule endoscopy, real-time imaging and molecular level dynamic tracking of the intestinal barrier are realized, genetically engineered bacteria are constructed to quantify intestinal permeability abnormality and local inflammation level, and an intestinal barrier function damage score and a disease progress prediction result are output; individual monitoring is achieved through transfer learning, ultrasonic elastography, optical coherence tomography, wearable equipment for measuring intestinal electric field impedance spectroscopy and other technologies are adopted, an intestinal wall mechanics-electrophysiology composite parameter set is obtained, and the evaluation accuracy is improved.

The invention provides an eye fundus image intelligent enhancement method and system based on multi-modal image fusion. The method comprises the following steps of obtaining a color eye fundus photography CFP image and an optical coherence tomography OCT image and performing preprocessing; establishing an image space coordinate mapping relation for the preprocessed color fundus photography CFP image and the preprocessed optical coherence tomography OCT image, and performing feature space alignment; the first branch network structure and the second branch network structure of the multi-layer Transform feature fusion module are used for carrying out feature extraction and enhancement on the features of the processed color fundus photography CFP image and the features of the processed optical coherence tomography OCT image respectively, and the features of the color fundus photography CFP image and the features of the processed optical coherence tomography OCT image are fused; multi-modal fusion image features are obtained; according to the multi-modal fusion image features, a deep learning model is adopted to reconstruct an eye fundus image; and constructing an image enhancement model to obtain an enhanced fundus image.

The invention discloses an optical coherence tomography device for optimizing aberration digital compensation and an imaging method, the device comprises an optical coherence tomography device and an image processing module, and the optical coherence tomography device comprises an illumination module, an interference module, an area array detection module and a synchronous control module. The imaging method comprises the following steps: setting device light source parameters according to coherent gating, and determining a sampling matching relation of the area array detection module according to a sampling theorem; selecting a frequency sweeping mode or a time domain mode, electrifying to activate a corresponding light source and a synchronous time sequence, and adjusting the position of a reference mirror; collecting a full-field interference sequence of the area-array camera, performing digital aberration compensation, performing compensation and denoising on volume data of different depths, and exporting a three-dimensional diffraction limit image; and outputting a three-dimensional tomographic image with transverse diffraction limit and axial micron-level resolution. According to the invention, the imaging resolution and the imaging speed of optical coherence tomography are improved under the conditions that the camera specification is reduced, the GPU dependence is reduced and the system cost is reduced.

The invention discloses a parallel imaging OCT (Optical Coherence Tomography) system based on a metasurface area array, which relates to the technical field of medical instruments, is small in size and can realize intraocular single-shot area array imaging and a three-dimensional position depth perception function by using metasurface and optical coherence tomography imaging information in a sample tissue with a limited size. According to the technical scheme, a light beam emitted by a laser is divided into two paths through a beam splitter, and the two paths enter a sample arm module and a reference arm module respectively; the sample arm module is a probe and comprises a multi-core optical fiber and a first metasurface; the reference arm module comprises a collimator, a motor and a right-angle reflector; the probe enters a sample tissue, a light beam is focused on the sample tissue and then is backscattered, the backscattered light beam reversely passes through the first metasurface, the multi-core optical fiber, the beam splitter, the second metasurface, the third lens, the grating and the focusing lens and then forms a spectral line beam on the CCD sensor, and the computer reads a signal from the CCD sensor and performs three-dimensional reconstruction imaging on the sample tissue.

The invention relates to the technical field of laser cleaning processing, and particularly discloses a real-time monitoring method for laser cleaning of a carbon fiber composite material. An optical coherence tomography (OCT) detection unit and a sensor module are innovatively adopted to form a real-time monitoring system, and according to the surface treatment requirement of the carbon fiber composite material, a temperature sensor in the sensor module is used for collecting a heat radiation signal of a laser irradiation area in real time, and the surface layer temperature of a base material during machining is monitored in real time; the distance between a machining head and a base material is dynamically tracked through a laser ranging module in the sensor module, the OCT detection unit obtains micron-sized surface topography characteristics through frequency domain interference signal analysis, and surface roughness parameters are synchronously calculated. The data of the three channels are fused through the edge calculation module and then fed back in real time through the displayer, and the temperature field, the roughness and the focal length are effectively monitored in the cleaning process. According to the method, damage to the base material due to factors such as laser ablation can be avoided, the operation time is effectively shortened, and the operation efficiency is improved.

The invention provides an intraoperative real-time navigation system based on digital twinning, and relates to the technical field of digital twinning, and the system comprises a data collection module which is used for obtaining the three-dimensional form data of a liver and a biliary tract through an intraoperative ultrasonic imaging device, and collecting the elastic modulus distribution parameters of liver parenchyma and a bile duct wall; the construction registration module is used for constructing a real-time digital twin in the liver and gall area based on the three-dimensional form data and the elastic modulus distribution parameters, and carrying out multi-mode non-rigid registration on the digital twin and the liver surface topography and the vascular structure which are subjected to optical coherence tomography in the operation; therefore, a dynamic space mapping relation between the organ structure and the image data is established. According to the method, real-time navigation in the operation is realized through digital twinning, the obstacle avoidance path is updated, and the safety and efficiency in the operation are improved.

The invention discloses a 3D printing self-adaptive control system for bone defect, and relates to the technical field of 3D printing self-adaptive control, a miniaturized optical coherence tomography, a high-resolution camera, a force sense and temperature sensor and the like are installed on an operation site, and the whole process of material deposition and solidification is monitored; then, deviation is rapidly recognized through an anomaly detection and error prediction model, defect positions are output, and a closed-loop control unit is combined with model prediction control and self-adaptive path planning to achieve online adjustment of key variables such as the extrusion amount and the printing speed; when the defect cannot be made up automatically through parameter adjustment, the system can trigger local shutdown and secondary repair, the forming quality is evaluated through multi-modal scanning and a repair scoring function after repair, and the high matching degree and mechanical stability of the final bone scaffold and the bone defect part are ensured; the cooperation of multi-modal sensing and local path planning enables the system to have higher adaptability.

The invention relates to an OCT (Optical Coherence Tomography) navigation uterine cavity adhesion and dissection postoperative residual adhesion prediction method, which comprises the following steps of: acquiring an interference signal of an intraoperative uterine cavity wall area by utilizing OCT equipment, and identifying an adhesion fiber microstructure which is not completely broken so as to judge the existence of an optically invisible residual adhesion microbridge; applying low-frequency bioelectrical stimulation to the wounded area of the uterine cavity during the operation, and marking the wounded area as a tissue repair electrical activity silent area if no blood flow micro-reaction is continuously detected; oCT micro-deformation sequence analysis is carried out on the region after intraoperative dissection is completed, mutation breakpoints of tissue elastic distribution are identified, and the potential risk that traction after-tack occurs in the region is predicted; detecting whether a metabolic oxidation reaction residual zone exists in the operation area or not so as to judge local tissue repair activity decline and re-adhesion tendency; local micro-intervention stimulation is applied to the tissue area judged to be high in risk, OCT imaging is carried out again to detect the reversibility of tissue optical response, and if an image is still fractured and red shift is enhanced, it is judged that the area is the postoperative irreversible adhesion residual area.

Systems and methods for compensating for tilt of an intraocular lens (IOL) and systems and methods for adjusting an IOL are disclosed herein. For example, one of the methods may include capturing one or more optical coherence tomography (OCT) images of a subject's eye while implanting the IOL within the subject's eye. The method may further include generating a fixation target such that the fixation target is visible to an eye of the subject; and moving the fixation target until the lateral plane of the IOL is perpendicular or substantially perpendicular to the optical axis of the ophthalmic system. The method may also include directing a laser beam generated by a laser of the ophthalmic system at the IOL.

The invention relates to the technical field of oral medicine, in particular to an intelligent navigation system and method for alveolar bone finishing based on image data fusion, and the system comprises a real-time bone mineral density sensing module which obtains a bone mineral density value through laser scanning and adjusts the temperature; the personalized bone mineral density self-adaptive control module is used for adjusting a bone trimming tool and temperature compensation according to the bone mineral density value; the multi-sensor data fusion module is used for dynamically monitoring the bleeding amount and compensating mechanical vibration of equipment; and the bone cutting path space sensing module is used for acquiring a bone cutting path by combining laser scanning data, CT data and optical coherence tomography data, and determining a real-time path of the tool according to temperature and bleeding amount change. According to the system, through an anti-penetration protection mechanism combining real-time bone mineral density perception, multi-scale tactile feedback and visual enhancement, the penetration risk is remarkably reduced, the operation safety is improved, and the penetration risk is reduced by 93% through the anti-penetration mechanism.

The invention discloses a glass-based circuit board defect detection method and system, and relates to the technical field of glass substrate defect detection.The method comprises the steps that an optical coherence tomography system with the fixed scanning resolution of 320 * 320 is used for collecting a tomographic image of a target area, three-dimensional reconstruction is conducted on the tomographic image, and a three-dimensional body data model is obtained; extracting a plurality of three-dimensional morphological characteristics such as defect depth, transverse distribution profile and defect internal refractive index unevenness from the model; and inputting the features into a defect classifier constructed based on a three-dimensional convolutional neural network for identification, and performing spatial position verification in combination with a known design layout to generate a final detection report. According to the method, the standardization of the detection process is realized through the fixed scanning resolution, and the efficiency and the result consistency are improved; by quantifying the refractive index non-uniformity in the defect, the optical property variation type defect in the material is effectively identified, and the detection depth and accuracy are enhanced.

The present invention relates to an optical system and a method for chromatic confocal spectral-domain optical coherence tomography or for chromatic confocal two-beam interferometry. The optical system comprises a multispectral light source unit configured to generate a plurality of spatially coherent multispectral light beams with spectra having a respective centroid wavenumbers, an achromatic focusing unit configured such that in at least a paraxial region around a common point located on an optical axis at the output of the achromatic focusing unit, the wavefronts of the respective spatially coherent multispectral light beams have different radii of curvatures, a chromatic confocal dual-beam interferometer having an non-zero optical path difference arranged downstream of the multispectral light source unit and a detection unit for detecting light returned from the dual-beam interferometer. The reference arm of the double-beam interferometer is configured to be achromatic and the object arm to have chromatic depth slitting of foci. In the reference arm, a plurality of depth separated reference light spots are formed. In the object arm, a plurality of at least partially colinear and overlapping multispectral stretches of diffraction limited light spots extended in a depth direction of the object arm is formed. The light reflected by a current sharply focused diffraction limited object light spot of each of the multispectral stretches of diffraction limited light spots is combined with a respective reference light spot, is confocally discriminated by a confocal discrimination unit of the detection unit and subsequently detected by at least one spectrometer, evaluation dual-beam interferometer or fast detector detects the confocally discriminated light.

An OCT instrument comprising: an optical coupler which generates signal light and reference light from a swept narrowband light source; a detector which samples a time-varying interference signal based on the reference light and signal light returned from a sample; an adjustable optical frequency shifter which: generates a first sideband light by adjusting an optical frequency of the reference light, such that the detector unit samples a first time-varying interference signal resulting from an interference between the sideband light and the returned signal light; and maintains the optical frequency of the reference light such that the detector unit samples a second time-varying interference signal resulting from an interference between the reference light and the returned signal light. The OCT instrument generates a respective axial depth profile of the sample based on each of the sampled first time-varying interference signal and the sampled second time-varying interference signal.

The invention provides a silicon carbide crystal ingot defect detecting and cutting device based on optical coherence tomography, and belongs to the technical field of silicon carbide crystal ingot defect detecting and cutting. In order to solve the technical problems that after a traditional crystal ingot is cut, the detection efficiency is low, imaging is not timely, the imaging resolution is low, and the portability and the linkage performance are poor due to the fact that detection equipment and cutting equipment are separated, the adopted technical scheme is that the output end of an OCT module is connected with the input end of a sample arm module through a wire; the sample arm module is installed below the sample arm support through the sample arm lifting support, and supporting legs on the two sides of the sample arm support are installed on the base. A fixed seat is arranged right below the sample arm module, the fixed seat is mounted on the base through a lifting base, and a crystal ingot is placed on the fixed seat; rolling wheels are further arranged on the two sides of the fixing base and placed on the base, and a cutting line is further connected between the two rolling wheels; the method is applied to defect detection of the silicon carbide crystal ingot.

The invention discloses a control method for robot-assisted laser in-situ windowing, which comprises the following steps: receiving an execution instruction sent by a main control end through a robot catheter system, sending a laser fiber into a target artery, and enabling the laser fiber to be in accurate contact with a stent covering film; a laser energy closed-loop control subsystem is combined to accurately ablate holes in a stent covering film through a photochemical effect and a photothermal effect, and laser windowing is achieved; in the laser windowing process, the thickness of the blood vessel wall is measured in real time based on optical coherence tomography, and the laser ablation process is detected based on photoacoustic monitoring, so that the laser power is dynamically adjusted, and it is ensured that the thermal damage range in the laser windowing process is smaller than 200 microns. Therefore, accurate creation of the channel between the aortic dissection false cavity and the true cavity is achieved, hemodynamic balance is recovered, the operation accuracy is improved, and the risk of complications in the perioperative period is reduced.

The invention relates to a double-side view field optical coherence tomography scanning system and an image reconstruction method. The system comprises a light source, an optical scanning module, a first acquisition light path, a second acquisition light path, a reference light path, an imaging module and a coupler. The coupler is connected with the light source, the reference light path, the imaging module and the optical scanning module through optical fibers; one end of the first acquisition light path is arranged opposite to a first light splitting side on the optical scanning module; the other end of the first acquisition light path extends to the first side of the target sample; one end of the second acquisition light path is arranged opposite to the second light splitting side of the optical scanning module; and the other end of the second acquisition light path extends to the second side of the target sample. Light emitted by the light source is divided into two paths at the scanning module, scanning is carried out on the two sides of the target sample, structural information of the two sides can be obtained without reversing and moving the target sample, and the quality and efficiency of scanning imaging are improved.

The invention discloses a retina OCT (Optical Coherence Tomography) image denoising method based on zero sample learning. The method comprises the following steps: generating a noise independent image pair for a single noisy image by adopting a CDIS (Coherent Discrete Identifier) The method comprises the following steps of: carrying out de-noising by using an MLFSnet network (AF-MSDSConv, Aap-LSM, SA, a reconstruction module); using RMSE symmetry and consistency joint loss zero sample training; in the reasoning stage, an original image is directly input, and a same-resolution de-noising result is output. The speckle noise can be significantly suppressed and the layered structure of the retina can be retained without noise-free true values or pairwise data, so that the retina can be used while being shot.

In accordance with one aspect of the present invention, an optical coherence tomography-based ophthalmic testing center system includes an optical coherence tomography instrument comprising an eyepiece for receiving at least one eye of a user or subject; a light source that outputs light that is directed through the eyepiece into the user's or subject's eye, an interferometer configured to produce optical interference using light reflected from the user's / subject's eye, an optical detector disposed so as to detect said optical interference; and a processing unit coupled to the detector. The ophthalmic testing center system can be configured to perform a multitude of self-administered functional and / or structural ophthalmic tests and output the test data.

Systems and relative method of monitoring the state of a subject's retinal disease employ remote based OCT imaging of a subject's retina. A method includes receiving optical coherence tomography (OCT) image data of a retina of a subject for each of a series of OCT imaging sessions of the retina. The OCT image data of the retina is processed to determine a series of measured extent values. Each of the one or more measured extent values is indicative of a respective extent of the retinal disease.

A needle is provided for subretinal injection. The needle may comprise a concentric assembly 100 forming a lumen 140 for a substance to be injected below a retinal surface layer, the concentric assembly comprising an outer tube 130, an intermediate tube 120, and an inner tube 110 comprising a tip 116 for piercing the retinal surface layer, wherein the tip is at a distal end of the inner tube, wherein the inner tube extends axially from a distal end of the intermediate tube, wherein the inner tube is at least partially translucent to optical coherence tomography (OCT), wherein the tip is beveled, wherein the inner tube has an inner tube outer diameter of 120µm or less at an onset of the bevel. Furthermore, a needle system is provided which comprises the needle and a flexible tubing to supply the substance to the needle.

The invention discloses an SLD circular polarization output device, a composite liquid crystal polarization grating and a preparation method thereof, belongs to the technical field of optical devices, and particularly relates to the technical field of gratings and preparation processes thereof. In order to solve the problems that series connection of multistage polarization optical elements causes significant optical power loss and wave plate devices are difficult to realize consistent polarization regulation and control in a wide spectral range covered by an SLD, the invention provides a composite liquid crystal polarization grating which is formed by bonding two layers of polarization gratings with different grating periods, wherein the period of one layer is half of that of the other layer; the invention further provides an SLD circular polarization output device. The composite liquid crystal polarization grating is used for converting an optical signal generated by the ridge-shaped inclined SLD into circular polarization light. The invention also provides a preparation method of the composite liquid crystal polarization grating. The preparation method comprises the following steps: cleaning the glass substrate, spin-coating the light-operated orientation material, performing polarization holographic exposure to form gratings with different periods, injecting liquid crystal and finally bonding. The method is suitable for the technical field of optical coherence tomography.

A gaze tracking circuit with an optical range finder is disclosed. An eyewear, such as a head-mounted device, may include an adjustable prescription lens and / or may include a display. The eyewear may include a gaze tracking circuit that tracks a gaze direction of a user. The gaze tracking circuit may include a range finder that determines an eye pitch using a phase-based optical coherence tomography. The rangefinder may include one or more emitters, such as lasers, that emit infrared light into a beam splitter that splits the light into signal light that travels to a free space path of the eye and reference light that travels toward a fixed reference path of a plurality of image sensors located around a perimeter of the eye. The signal light is specularly reflected away from the eye (thereby producing an eye flash), and the reflected signal light is combined with the reference light to produce an interference pattern that can be detected by the image sensors and analyzed to determine an eye distance.

Deep learning methods and systems for detecting biomarkers within optical coherence tomography volumes using such deep learning methods and systems are provided. Embodiments predict the presence or absence of clinically useful biomarkers in OCT images using deep neural networks. The lack of available training data for canonical deep learning approaches is overcome in embodiments by leveraging a large external dataset consisting of foveal scans using transfer learning. Embodiments represent the three-dimensional OCT volume by “tiling” each slice into a single two dimensional image, and adding an additional component to encourage the network to consider local spatial structure. Methods and systems, according to embodiments are able to identify the presence or absence of AMD-related biomarkers on par with clinicians. Beyond identifying biomarkers, additional models could be trained, according to embodiments, to predict the progression of these biomarkers over time.

The invention discloses a high-power super-radiation light-emitting diode based on three-section integration and a preparation method, belongs to the technical field of structures and processing of optoelectronic devices, and solves the technical problem of directional amplification of optical power output by a super-radiation light-emitting diode based on a three-section integration structure. The diode is of a three-section integrated structure, and the three-section integrated structure is of a cascade structure formed by sequentially connecting a DBR grating area, a J-shaped ridge waveguide super-radiation light-emitting diode area and a semiconductor optical amplifier area. The three-section integrated structure is provided with multiple layers of structures from bottom to top, and the multiple layers of structures are a lower electrode, a lower substrate, a lower limiting layer, an MQW multi-quantum well active layer, an upper limiting layer, an upper substrate and an upper electrode in sequence. And the DBR grating region comprises a waveguide layer and a transverse tapered waveguide structure of a cladding. The J-shaped ridge waveguide super-radiation light-emitting diode area is composed of a bent waveguide part and a straight waveguide part. The semiconductor optical amplifier area is of a conical traveling wave structure. The optical power amplifier is suitable for the fields of optical coherence tomography and optical fiber gyroscopes, and optical power amplification is achieved.

Eyewear such as a head-mounted device may include adjustable prescription lenses and / or may include displays. The eyewear may include gaze tracking circuitry that tracks a gaze direction of a user. The gaze tracking circuitry may include a range finder that uses phase-based optical coherence tomography to determine eye distance. The range finder may include one or more emitters such as lasers that emit infrared light into a beam splitter that splits the light into signal light that travels a free space path to the eye and reference light that travels a fixed reference path towards multiple image sensors located around the periphery of the eye. The signal light specularly reflects off of the eye (creating an eye glint) and the reflected signal light combines with the reference light, creating an interference pattern that can be detected by the image sensors and analyzed to determine eye distance.