Handheld ophthalmic optical coherence tomography system

Abstract

The utility model relates to technical fields provides a kind of handheld ophthalmic optical coherence tomography scanning system, and the scanning system includes optical mainframe and image acquisition system;Optical mainframe includes swept-frequency light source, interferometer module and detector. Interferometer module contains detection module, built-in handheld probe, reference module, fiber coupler one, fiber coupler two. The detection module includes polarization controller one, handheld probe and connecting line;The handheld probe includes OCT scanning optical path and imaging module, realizes color imaging, FFA contrast imaging, FAF autofluorescence imaging, IR infrared imaging and multispectral imaging. The utility model is aimed at the OCT scanning imaging of passive measurement object, realizes fast high-resolution fundus tomogram, and retinal imaging, improves the resolution of handheld swept-frequency OCT equipment, simultaneously realizes fundus precision measurement under large field scanning.

Description

Technical Field

[0001] This utility model relates to the field of medical imaging equipment technology, and more specifically to a handheld ophthalmic optical coherence tomography scanning system. Background Technology

[0002] Optical coherence tomography (OCT) is a non-invasive, non-destructive optical imaging technique that can acquire depth-resolution information inside a sample and is now widely used in ophthalmic diagnosis.

[0003] In OCT, a tomographic image of the object being measured can be obtained by interfering the light reflected from the object with the light reflected from a reference mirror and analyzing the intensity of the interference light. Time-domain OCT (TD-OCT) is a type of OCT where depth information of the object is obtained by continuously changing the position of the reference mirror. Other types include Fourier-domain OCT (FD-OCT), which includes SD-OCT and SS-OCT.

[0004] Spectral domain OCT (SD-OCT) obtains frequency information by dividing the interference light obtained through optical interference induced by low-coherence light and replacing depth information with frequency information. SD-OCT uses a broadband light source to illuminate the eye and a spectrometer to collect the interference signal; however, the acquisition speed of the spectrometer camera limits the imaging speed of SD-OCT. SS-OCT, on the other hand, uses light whose wavelengths have been pre-divided using a wavelength-scanning light source to obtain the interference light. SS-OCT achieves faster imaging speeds by utilizing a high-speed sweeping light source and a photodetector.

[0005] Traditional desktop OCT devices dominate the market, but these devices require the patient to actively look at the scanner and cooperate with the operator's instructions to complete the test, a process that takes at least three to five minutes. Desktop OCT devices are non-contact, and the system includes multiple subsystems, such as a processing unit and a scanning subsystem. Traditional desktop OCT devices typically have a fixed interface through which the patient aligns with the system's optical path. This interface includes a support for the patient's jaw and a structure for aligning the patient with the OCT optical path. To obtain effective OCT images, desktop OCT devices usually require the patient's active cooperation.

[0006] Contact OCT imaging probes have been proposed in several patents. Portable imaging probes can be used for ophthalmic OCT imaging in infants, young children, adults who cannot actively cooperate, and animals. These contact imaging probes establish direct contact between the probe and the patient, and alignment is relatively simple because the tip of the probe can be intuitively placed at the intended location on the sample for imaging. However, the field of view (FOV) of these proposed contact OCT imaging probes is limited. The illumination and imaging paths share a common optical path, resulting in much stronger reflected light from the cornea than from the retina. This problem is exacerbated over a wider angle, thus limiting the actual FOV achievable by these proposed contact OCT imaging probes. Furthermore, in addition to the limited FOV, these proposed contact OCT imaging probes also suffer from severe aberrations across the entire field of view, leading to resolution loss.

[0007] Currently, commercially available OCT scanners have a lateral resolution of 12µm and an axial resolution of 5µm, capable of resolving biological tissues larger than 24µm laterally and larger than 10µm axially. However, they cannot resolve capillaries and cells at the 5-20µm scale, and their resolution does not meet clinical needs. Furthermore, due to aberrations, they cannot meet the requirements for quantitative fundus measurements. In addition, the published handheld OCT scanners can only acquire tomographic images or simultaneously acquire SLO images, but cannot acquire color fundus images. Utility Model Content

[0008] The purpose of this invention is to provide a handheld ophthalmic optical coherence tomography (OCT) scanning system for passively measured objects, enabling rapid and high-resolution fundus tomographic images and retinal imaging, improving the resolution of handheld frequency-scanning OCT devices, and simultaneously achieving precise fundus measurements under a large field of view.

[0009] According to a first aspect of the present invention, a handheld ophthalmic optical coherence tomography scanning system is provided, comprising an optical host and an image acquisition system; The optical host includes a swept frequency light source, an interferometer module, a detector, and a synchronization signal generator; The synchronization signal generator is connected to the frequency sweep light source, the interferometer module, and the detector to send synchronization control signals; The interferometer module includes a detection module, a reference module, a fiber optic coupler 1, and a fiber optic coupler 2. The swept frequency light source is coupled to the detection module via the optical path of fiber optic coupler 1, and simultaneously coupled to fiber optic coupler 2 via fiber optics. The detection module includes a polarization controller 1, a handheld probe, and a connecting cable. Fiber optic coupler 1 is connected to the optical path of the handheld probe via the polarization controller 1. The handheld probe includes an OCT scanning optical path and an imaging module. The imaging module includes an illumination source, a second lens group, a second beam splitter, a third lens group, and an imaging camera; The OCT scanning optical path includes a fiber collimating lens one, a deformable mirror, a beam splitter one, a focusing lens, an XY galvanometer, a mirror group one, a beam splitter two, and a mirror group two. One beam splitter one is coupled to a wavefront sensor, and the other beam splitter one is coupled to the focusing lens, and then coupled to mirror group one and beam splitter two via the XY galvanometer. One beam splitter two is coupled to mirror group two, and the other beam splitter two is coupled to the imaging module via mirror group three. The OCT scanning module and the imaging module share the same lens group 2. The OCT scanning module and the imaging module achieve scanning and imaging through a configured real eye or eye model.

[0010] Before system use, wavefront correction can be used to achieve the target resolution and enable high-resolution synchronous imaging, such as high-resolution OCT scanning imaging and fundus synchronous imaging. During the debugging phase, a wavefront sensor between the deformable mirror and the focusing lens is used to apply voltage to the deformable mirror to adjust its surface shape. The applied voltage to the deformable mirror is adjusted by detecting the laser wavefront returning from the simulated eye's original path and using the feedback from the wavefront sensor to control the adjustment of the wavefront residual until it is below a preset level, thus achieving the target resolution.

[0011] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the utility model subject matter of this disclosure, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the utility model subject matter of this disclosure.

[0012] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0013] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the handheld ophthalmic optical coherence tomography scanning system according to an embodiment of the present invention.

[0015] Figure 2 This is a specific example diagram of the handheld ophthalmic optical coherence tomography scanning system according to the present invention.

[0016] Figure 3 This is a schematic diagram of the scanning optical path according to an embodiment of the present utility model.

[0017] Figure 4 This is a schematic diagram of the imaging optical path of the handheld probe according to an embodiment of the present invention. Detailed Implementation

[0018] To better understand the technical content of this utility model, specific embodiments are provided below in conjunction with the accompanying drawings.

[0019] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments disclosed herein are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the present invention can be used alone or in any suitable combination with other aspects disclosed herein.

[0020] Combination Figures 1-4 As shown, the handheld ophthalmic optical coherence tomography scanning system according to an embodiment of the present invention includes an optical host and an image acquisition system.

[0021] Combination Figure 1 , Figure 2 As shown, the optical host includes a swept frequency light source 1, an interferometer module, a detector 30, and a synchronization signal generator 26. The synchronization signal generator 26 is connected to the swept frequency light source 1, the interferometer module, and the detector 22 to send synchronization control signals.

[0022] The interferometer module includes a detection module 101, a reference module 102, a fiber optic coupler 1 21, and a fiber optic coupler 22; the swept frequency light source 1 is optically coupled to the detection module 101 via the fiber optic coupler 1 21, and simultaneously coupled to the fiber optic coupler 22 via an optical fiber.

[0023] The detection module includes a polarization controller 3, a handheld probe 100 and a connecting cable. The fiber optic coupler 21 is connected to the handheld probe 100 via the polarization controller 3. The handheld probe 100 includes an OCT scanning optical path and an imaging module.

[0024] The imaging module includes an illumination source, a second lens group 13, a second beam splitter 12, a third lens group 15, and an imaging camera 16.

[0025] Combination Figure 2 , 3As shown in example 4, the OCT scanning optical path includes a fiber collimating lens 4, a deformable mirror 7, a beam splitter 5, a focusing lens 8, an XY galvanometer, a mirror group 11, a beam splitter 12, and a mirror group 13. One beam splitter of beam splitter 5 is coupled to the wavefront sensor 6, and the other beam splitter is coupled to the focusing lens 8, and then coupled to mirror group 11 and beam splitter 12 via the XY galvanometer. One beam splitter of beam splitter 13 is coupled to mirror group 13, and the other beam splitter is coupled to the imaging module 16 via mirror group 13. Figure 2 As shown, the XY galvanometer typically consists of an X galvanometer 9 and a Y galvanometer 10.

[0026] The OCT scanning module and the imaging module share the same lens group 13. The OCT scanning module and the imaging module achieve scanning and imaging through a configured real eye or eye model 14.

[0027] During the system debugging phase, a voltage is applied to the deformable mirror 7 to adjust the surface shape of the deformable mirror. The wavefront sensor 6 between the deformable mirror 7 and the focusing lens 8 detects the laser wavefront returning from the original path of the simulated eye 14. The feedback result detected by the wavefront sensor 6 controls the adjustment of the applied voltage of the deformable mirror 7 until the wavefront residue is lower than the preset level, thereby achieving the target resolution.

[0028] When in use, the wavefront sensor 6 can be removed, and the control parameters of the deformable mirror 7 recorded when the target resolution is achieved can be used as the actual parameters during use, thereby achieving high-precision detection and imaging.

[0029] As an optional implementation, the swept frequency light source 1 is a broadband swept frequency light source with a wavelength of 1060nm ± 45nm. The frequency can be selected as 400KHz or 200KHz.

[0030] As an optional implementation, the connection includes fiber optic patch cords and cables. The fiber optic patch cords are connected to the fiber optic collimator 4 in the handheld probe 100, and the cables are used to supply power and drive signals to the XY galvanometer and imaging camera 16 in the handheld probe.

[0031] As an optional implementation, the deformable mirror 7 is a piezoelectric reflective deformable mirror, or a combination of a reflective mirror and a thin-film transmission deformable mirror.

[0032] As an optional implementation, the focusing lens 8 can be a liquid lens or an adjustable lens module with a single lens and motor focusing.

[0033] As an optional implementation, the X-mirror 9 and the Y-mirror 10 are scanning mirrors or MEMS mirrors.

[0034] As an optional implementation, beam splitter 5 and beam splitter 12 are dichroic mirrors.

[0035] As an optional implementation, beam splitter 5 and beam splitter 12 are respectively cubic beam splitters.

[0036] As an optional implementation, the second lens assembly 13 of the handheld probe 100 is a detachable lens assembly, used for imaging the retina by contact with the eyeball or imaging the anterior segment of the eye in a non-contact manner. For example, the second lens assembly 13 is designed with two specifications, a and b: lens assembly 13 specification a, which connects to the system to achieve imaging of the retina by contact with the eyeball; or, the second lens assembly 13 can be replaced with specification b to achieve imaging of the anterior segment of the eye in a non-contact manner.

[0037] As an optional implementation, the reference module 102 includes a polarization controller 2 17, a fiber collimating lens 2 18, a dispersion compensation module 19, and a fiber collimating lens 3 20, which are coupled in sequence.

[0038] As an optional implementation, the splitting ratio of the fiber optic coupler 21 is 10:90 or 20:80.

[0039] As an optional implementation, the splitting ratio of fiber coupler 22 is 50:50.

[0040] As an optional implementation, detector 30 is a balanced photodetector.

[0041] As an optional implementation, the imaging module is used to realize one of color imaging, FFA contrast imaging, FAF autofluorescence imaging, IR infrared imaging, and multispectral imaging.

[0042] In a specific embodiment, the imaging module is configured as follows: 1) When achieving fundus color imaging, the illumination source is a continuous spectrum white LED with a color temperature of 3000K-6500K; 2) When performing fundus FFA angiography, for the blue light excitation system, the illumination source is a monochromatic LED with a peak wavelength of 470nm and a bandwidth of 30-35nm, while the cutoff bandpass filter is 510-550nm; for the green light excitation system, the excitation source is a wavelength of 530-585nm, and the cutoff long-pass filter wavelength is >600nm; for the near-infrared excitation system, the excitation wavelength is a near-infrared source of 787nm, and the cutoff long-pass filter wavelength is >800nm. 3) When achieving FAF autofluorescence imaging, the illumination source is a 488nm argon-ion blue light source or a blue LED light source, and the cutoff filter is 510-630nm. 4) When realizing fundus IR, the illumination source is a single-wavelength 850nm LED; 5) When achieving multispectral imaging, the illumination source is a monochromatic LED with each discrete spectrum, and a filter wheel is set at the excitation end to filter the incident green light.

[0043] Combination Figure 2 As shown, as an optional implementation, the image acquisition system includes an image acquisition card 23, a computer system 24, and a display 25.

[0044] The electrical signals received and converted by the detector 30 are recorded in the computer system by the image acquisition card 23 for subsequent analysis and processing.

[0045] It should be understood that, in order to achieve the intended functionality, the system may also be configured with auxiliary components, including a simple robotic arm, a touch screen monitor, and control pedals, which can be implemented using existing designs.

[0046] Combination Figure 1 , Figure 2 As shown, the handheld ophthalmic optical coherence tomography system according to the foregoing embodiment, and the high-resolution ophthalmic optical coherence tomography method implemented therein, include the following steps: The light emitted from the sweep frequency light source 1 is first split by the fiber optic coupler 21 and then enters the detection module 101 and the reference module 102 respectively. The light entering the detection module 101 passes through the polarization controller 3 and the fiber optic jumper and then enters the handheld probe 100. The light emitted from the fiber passes through the fiber collimating lens 4 in the handheld probe for pre-collimation and then passes through the beam splitter 5 and enters the deformable mirror 7. After being reflected by the deformable mirror 7, it enters the focusing lens 8 and then passes through the XY galvanometer to achieve one-dimensional line scanning or two-dimensional area scanning. The emitted beam passes through the lens group 11, beam splitter 12, and lens group 2 13 in sequence to achieve scanning and convergence at the fundus. The light entering the reference module 102 passes through the polarization controller 17 and the fiber collimator 18 and then enters a free space optical path that matches the detection module 101. After passing through a set of dispersion compensation modules 19, it enters the pigtail of the fiber coupler 22 through the fiber collimator 20. The light scattered by the sample returns via the handheld probe 100, then enters another pigtail of the fiber coupler 21 via fiber coupler 1, where it interferes with the reference light. The interference light is then received by detector 30 and converted into an electrical signal, which is then recorded by acquisition card 23 in computer system 24. In the imaging module of the handheld probe 100, the illumination source illuminates the fundus, and the imaging light passes through the lens group 2 13 and then through the beam splitter 12. After passing through the lens group 3 15, it is received and imaged by the imaging camera 16, realizing high-resolution OCT scanning imaging and simultaneous fundus imaging.

[0047] The system can be adjusted for wavefront correction before use. The adjustment process includes: The laser emitted from the fiber collimating lens 4 is incident on the deformable mirror 7. A voltage is applied to the deformable mirror 7 to adjust its surface shape. At the same time, wavefront sensor 6 between the deformable mirror 7 and the focusing lens 8 provides wavefront feedback. By detecting the laser wavefront returning from the simulated eye 14, the wavefront sensor 6 controls the adjustment of the applied voltage to the deformable mirror 7 until the wavefront residue is lower than a preset level, achieving the target resolution, for example, λ / 20, where λ represents the wavelength.

[0048] In an optional embodiment, during the debugging process, the scanning galvanometer is placed at the zero position, and the zero-position wavefront value is adjusted according to the above method so that the wavefront residue is lower than the preset target resolution, such as λ / 20, to obtain the current target resolution, and the voltage value of the corresponding deformable mirror is recorded.

[0049] For the OCT unidirectional scan period Ta, consider the wavefront response data of n deformable mirrors distributed in a single sampling period. A single complete period is from zero position → far end → zero position → far end (reverse) → zero position. The response frequency of this data needs to be adapted to the maximum real-time response frequency ωmax of the deformable mirror. Otherwise, the system will exceed the response limit. It also needs to satisfy Ta / n≥1 / ωmax. This formula shows that the sampling data time interval when the deformable mirror is actually working needs to be greater than the minimum time interval that the deformable mirror can respond to (device limit).

[0050] In the actual debugging process, the position of each sampling point corresponds to a set of galvanometer states (XY galvanometers). At each sampling point position, the resolution needs to be adjusted using the above method, and the voltage value of the deformable mirror 7 at the corresponding position needs to be recorded. In actual use, the sampling point position information, i.e. the corresponding states of scanning galvanometers 9 and 10, is matched with the response voltage value of deformable mirror 7. In this way, open-loop AO-OCT optical resolution debugging can be achieved.

[0051] When the system is actually working, each time the scanning galvanometer group 9 and 10 reaches a sampling point, the deformable mirror 7 calls up the corresponding surface shape through the pre-recorded voltage value to achieve the target scanning resolution.

[0052] As an alternative, the operator can hold the probe manually for testing. Alternatively, the probe can be placed on a simple robotic arm to reduce the impact of operator hand tremors and facilitate precise adjustment.

[0053] In an alternative embodiment, the operator can adjust the imaging via a touchscreen monitor or by controlling a foot pedal, which can be implemented using existing designs.

[0054] The handheld ophthalmic optical coherence tomography scanning system and method proposed in this invention can be applied to different ophthalmic diagnostic scenarios. It has a low learning cost for operators with different operating habits, avoids the alignment and vibration resistance requirements of passive measurement, and achieves high resolution by using wavefront correction method. Under the premise of meeting the requirements of large field of view scanning, it can achieve precise measurement after aberration correction.

[0055] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A handheld ophthalmic optical coherence tomography scanning system, characterized in that, Includes optical main unit and image acquisition system; The optical host includes a swept frequency light source (1), an interferometer module, a detector (30), and a synchronization signal generator (26); the synchronization signal generator (26) is signal-connected to the swept frequency light source (1), the interferometer module, and the detector (30) to send a synchronization control signal; The interferometer module includes a detection module (101), a reference module (102), a fiber coupler one (21), and a fiber coupler two (22); the swept frequency light source (1) is coupled to the detection module (101) via the optical path of the fiber coupler one (21), and is also coupled to the fiber coupler two (22) via optical fiber. The detection module includes a polarization controller (3), a handheld probe (100) and a connecting line. The fiber optic coupler (21) is connected to the handheld probe (100) via the polarization controller (3). The handheld probe (100) includes an OCT scanning optical path and an imaging module. The imaging module includes an illumination source, a second lens group (13), a second beam splitter (12), a third lens group (15), and an imaging camera (16). The OCT scanning optical path includes a fiber collimating lens (4), a deformable mirror (7), a beam splitter (5), a focusing lens (8), an XY galvanometer, a mirror group (11), a beam splitter (12), and a mirror group (13); one beam splitter of the beam splitter (5) is coupled to the wavefront sensor (6), and the other beam splitter is coupled to the focusing lens (8), and then coupled to the mirror group (11) and the beam splitter (12) via the XY galvanometer; one beam splitter of the beam splitter (12) is coupled to the mirror group (13), and the other beam splitter is coupled to the imaging module via the mirror group (3); The OCT scanning module and the imaging module share the same lens group two (13). The OCT scanning module and the imaging module achieve scanning and imaging through the configured real eye or eye model (14).

2. The handheld ophthalmic optical coherence tomography system according to claim 1, characterized in that, The swept frequency light source (1) is a 1060nm±45nm broadband swept frequency light source.

3. The handheld ophthalmic optical coherence tomography scanning system according to claim 1, characterized in that, The connection lines include fiber optic patch cords and cables. The fiber optic patch cords are connected to the fiber optic collimator (4) in the handheld probe (100), and the cables are used to supply power and drive signals to the XY galvanometer and imaging camera (16) in the handheld probe.

4. The handheld ophthalmic optical coherence tomography scanning system according to claim 1, characterized in that, The deformable mirror (7) is a piezoelectric reflective deformable mirror, or a combination of a reflective mirror and a thin-film transmission deformable mirror.

5. The handheld ophthalmic optical coherence tomography system according to claim 1, characterized in that, The focusing lens (8) is an adjustable lens module consisting of a liquid lens or a single lens with motor focusing.

6. The handheld ophthalmic optical coherence tomography scanning system according to claim 1, characterized in that, The galvanometers (9) and (10) are scanning galvanometers or MEMS galvanometers.

7. The handheld ophthalmic optical coherence tomography scanning system according to claim 1, characterized in that, The first beam splitter (5) and the second beam splitter (12) are dichroic mirrors.

8. The handheld ophthalmic optical coherence tomography system according to claim 1, characterized in that, The beam splitter one (5) and beam splitter two (12) are respectively cubic beam splitters.

9. The handheld ophthalmic optical coherence tomography system according to claim 1, characterized in that, The second lens group (13) of the handheld probe (100) is a detachable lens group, used for imaging the retina by contact with the eyeball or imaging the anterior segment of the eye by non-contact means.

10. The handheld ophthalmic optical coherence tomography system according to any one of claims 1-9, characterized in that, The reference module (102) includes a second polarization controller (17), a second fiber collimator (18), a dispersion compensation module (19), and a third fiber collimator (20) coupled in sequence.

11. The handheld ophthalmic optical coherence tomography system according to any one of claims 1-9, characterized in that, The splitting ratio of the fiber coupler (21) is 10:90 or 20:

80.

12. The handheld ophthalmic optical coherence tomography system according to any one of claims 1-9, characterized in that, The splitting ratio of the second fiber coupler (22) is 50:

50.

13. The handheld ophthalmic optical coherence tomography system according to any one of claims 1-9, characterized in that, The imaging module is used to realize one of the following: color imaging, FFA contrast imaging, FAF autofluorescence imaging, IR infrared imaging, and multispectral imaging.

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