Transmission interference and full-field optical coherence tomography combined imaging system and method

Abstract

The present disclosure provides a kind of transmission interference and full-field optical coherence tomography combined imaging system and method, it is related to medical imaging technical field.The system includes: illumination emission light path, for generating linearly polarized light, and linearly polarized light is incident to the eye of the person to be examined, wherein the part of linearly polarized light is generated back reflection or backscattering at the corneal anterior and posterior surface and corneal internal microstructure of the eye of the person to be examined, forms corneal back reflection light, another part occurs multiple scattering via posterior ocular tissue and returns to the eye front direction, forms secondary illumination light from the eye back to the eye front irradiation, secondary illumination light passes through cornea again, generates transmission interference light;Corneal transmission interference imaging light path is used for collecting the interference information of transmission interference light, obtains large field of view corneal transmission interference image;Full-field optical coherence tomography imaging light path is used for carrying out corneal axial tomography based on corneal back reflection light, obtains corneal tomogram.

Description

Technical Field

[0001] This disclosure relates to the field of medical optical imaging technology, specifically to a combined imaging system and method of transmission interferometry and full-field optical coherence tomography. Background Technology

[0002] The cornea is a highly transparent tissue with weak scattering. Early-stage corneal lesions often manifest as subtle changes in cell density, nerve fiber morphology, stromal scattering, and the arrangement of local microstructures. Because these changes do not necessarily present as significant increased reflectance, current single imaging modalities are usually insufficient to clearly visualize the corneal microstructure. Summary of the Invention

[0003] This disclosure provides a combined imaging system and method of transmission interferometry and full-field optical coherence tomography for clearly presenting the microstructure of the cornea.

[0004] The first aspect of this disclosure provides a combined transmission interferometry and full-field optical coherence tomography imaging system, comprising: an illumination emission optical path for generating linearly polarized light and incident the linearly polarized light onto the eye of a subject, wherein a portion of the linearly polarized light is back-reflected or back-scattered at the anterior and posterior surfaces of the cornea and at the microstructures inside the cornea, forming corneal back-reflected light, and another portion is scattered multiple times by the posterior eye tissue and returns in the direction in front of the eye, forming secondary illumination light illuminating from behind the eye to the eye, the secondary illumination light passing through the cornea again and undergoing phase modulation, refraction modulation, and diffraction modulation to generate transmission interferometry light; a corneal transmission interferometry imaging optical path for collecting interference information of the transmission interferometry light to obtain a large field-of-view corneal transmission interferometry image; and a full-field optical coherence tomography imaging optical path for performing corneal axial tomography based on the corneal back-reflected light to obtain a corneal tomographic image.

[0005] A second aspect of this disclosure also provides a method for combined transmission interferometry and full-field optical coherence tomography imaging, comprising: generating linearly polarized light using an illumination emission optical path in a low-light environment, and incident the linearly polarized light onto the eye of a subject, such that a portion of the linearly polarized light is back-reflected or back-scattered at the anterior and posterior surfaces of the cornea and the internal microstructures of the cornea, forming corneal back-reflected light; and another portion is scattered multiple times by the posterior eye tissue and returns in the direction in front of the eye, forming secondary illumination light illuminating from behind the eye to the eye. The secondary illumination light passes through the cornea again and undergoes phase modulation, refraction modulation, and diffraction modulation to generate transmission interferometry light; collecting the interference information of the transmission interferometry light using a corneal transmission interferometry imaging optical path to obtain a large field-of-view corneal transmission interferometry image; and performing corneal axial tomography based on the corneal back-reflected light using a full-field optical coherence tomography imaging optical path to obtain a corneal tomographic image.

[0006] A third aspect of this disclosure also provides an electronic device, including: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors perform the method described above.

[0007] A fourth aspect of this disclosure also provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the methods described above.

[0008] A fifth aspect of this disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0009] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0010] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0011] Figure 1 The schematic diagram illustrates one of the structural block diagrams of a combined transmission interferometry and full-field optical coherence tomography imaging system according to an embodiment of the present disclosure.

[0012] Figure 2 A second block diagram of a combined transmission interferometry and full-field optical coherence tomography imaging system according to an embodiment of the present disclosure is shown schematically.

[0013] Figure 3 A flowchart illustrating a combined imaging method of transmission interferometry and full-field optical coherence tomography according to an embodiment of the present disclosure is shown.

[0014] Figure 4 A block diagram of an electronic device for a combined transmission interferometry and full-field optical coherence tomography imaging method according to an embodiment of the present disclosure is shown schematically. Detailed Implementation

[0015] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0016] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0017] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0018] The accompanying drawings show some block diagrams and / or flowcharts. It should be understood that some blocks or combinations thereof in the block diagrams and / or flowcharts can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when executed by the processor, these instructions can create means for implementing the functions / operations described in these block diagrams and / or flowcharts.

[0019] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In the technical solution disclosed herein, all data involved (including but not limited to data used for analysis, data stored, data displayed, etc.) are information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, storage, use, processing, transmission, provision, disclosure, and application of the relevant data comply with relevant laws, regulations, and standards, necessary confidentiality measures have been taken, and they do not violate public order and good morals. Corresponding operation entry points are provided for users to choose to authorize or refuse.

[0022] In related technologies, corneal imaging methods include corneal endothelial microscopy or reflective corneal microscopy, in vivo confocal microscopy, optical coherence tomography (OCT), high-resolution OCT imaging, and transmitted or reflected illumination imaging.

[0023] In the process of developing this disclosure, it was discovered that corneal endothelial microscopy or reflective corneal microscopy mainly relies on corneal interface reflection signals, which is suitable for observing corneal endothelial cells, but has a limited imaging scope and is insufficient for displaying transparent, weakly scattering structures such as epithelium, stroma, and nerve fibers. When there is corneal edema, localized opacity, or abnormal reflective interfaces, the image quality is prone to deterioration.

[0024] In vivo confocal microscopy offers strong axial selectivity and cellular-level resolution, but typically has a small field of view, requiring multi-point localization and repeated scanning during examination. Some systems require contact or near-contact with the ocular surface, demanding a high level of patient cooperation and operator experience.

[0025] Conventional anterior segment OCT has insufficient lateral resolution to stably display corneal cell-like structures and fine nerve fibers; although high-resolution OCT can improve resolution, if only reflected / backscattered signals are used, the contrast for some transparent, low-scattered structures is still limited.

[0026] Transmission interferometry or reverse-transmission illumination is better suited for displaying minute changes in phase and refractive index in transparent tissues, and can reveal corneal microstructural differences within a larger field of view. However, the axial tomographic selectivity of transmission interferometry alone is relatively limited, and it still falls short in confirming tissue layers in suspected abnormal areas, verifying local cell morphology, and providing high-confidence interpretations. In addition, strong reflected light from the corneal surface usually needs to be filtered out in transmission interferometry, resulting in low light energy utilization.

[0027] In view of this, this disclosure proposes a combined imaging system and method of transmission interferometry and full-field optical coherence tomography (FF-OCT) for the observation of transparent corneal tissues. It can be used for non-contact, label-free, multimodal observation of corneal epithelium, corneal stroma, corneal nerves, endothelial regions, refractive surgery interfaces, and early changes in corneal edema or opacity. It can also be used for ophthalmic clinical screening, preoperative evaluation, postoperative follow-up, and research imaging. A detailed description is provided below with reference to specific embodiments.

[0028] Figure 1 The schematic diagram illustrates one of the structural block diagrams of a combined transmission interferometry and full-field optical coherence tomography imaging system according to an embodiment of the present disclosure.

[0029] like Figure 1As shown, the combined imaging system of transmission interferometry and full-field optical coherence tomography in this embodiment may include, for example, an illumination emission optical path, a corneal transmission interferometry imaging optical path, and a full-field optical coherence tomography imaging optical path.

[0030] The illumination emission light path generates linearly polarized light and directs it into the subject's eye. A portion of this linearly polarized light undergoes back reflection or backscattering at the anterior and posterior surfaces of the cornea and at the corneal microstructures, forming corneal backreflection light. Another portion is scattered multiple times by the posterior corneal tissues and returns in the direction of vision, forming secondary illumination light that illuminates from behind the eye to the eye. This secondary illumination light passes through the cornea again, undergoing phase modulation, refraction modulation, and diffraction modulation to produce transmitted interference light.

[0031] The corneal transmission interferometry imaging optical path serves as a transmission interference channel, used to collect interference information of the transmitted interference light and obtain a large field-of-view corneal transmission interferometry image.

[0032] The full-field optical coherence tomography (FF-OCT) optical path is used as the FF-OCT channel to perform corneal axial tomography based on corneal back-reflected light to obtain corneal tomographic images.

[0033] According to embodiments of this disclosure, after the system introduces linearly polarized light into the examined eye, a portion of the light undergoes back reflection or backscattering at the anterior and posterior surfaces of the cornea and at the microstructures within the cornea. For simple transmission interferometry, the corneal back-reflected light does not carry effective transmission interferometry information formed by secondary illumination from the posterior eye and typically needs to be suppressed or discarded. Embodiments of this disclosure do not simply discard this portion of light; instead, they introduce it into the FF-OCT channel through polarization separation and a low-coherence interference structure, interfering with the return light from the reference arm for corneal axial tomography.

[0034] According to embodiments of this disclosure, another portion of the same linearly polarized light, after passing through the cornea and lens, is focused near the retina, choroid, or sclera. It then undergoes multiple scatterings by the posterior eye tissues and returns in the direction in front of the eye, forming secondary illumination light illuminating from behind the eye to the front. When this secondary illumination light passes through the transparent corneal tissue again, it is modulated by phase, refraction, and diffraction from cells, nerves, stromal texture, and interlaminar interfaces. The transmitted zero-order light and the sample (cornea) diffracted light form local interference near the sample, creating transmitted interference light, ultimately forming a large field-of-view corneal transmission interference image.

[0035] According to embodiments of this disclosure, the system separates two-mode detection optical paths by polarization separation: one polarization component is mainly introduced into the FF-OCT interferometric detection branch to make full use of corneal back-reflected light; the other polarization component, after being depolarized by back-eye scattering, can be selected by polarization to enter the transmission interferometric detection branch to obtain a transmission interferometric image of the transparent tissue of the cornea.

[0036] The system provided in this disclosure uses a corneal transmission interferometry imaging optical path as the transmission interferometry channel to perform imaging based on the transmission interferometry light, thereby obtaining a large field-of-view phase / diffraction enhanced image of transparent or weakly scattering corneal tissue. It also uses a full-field optical coherence tomography imaging optical path as the optical coherence tomography channel, utilizing the back-reflected light from the cornea, which is normally ineffective in transmission interferometry, and achieving axial scanning and tomographic imaging of the cornea through the axial displacement of the reference arm mirror. This emphasizes corneal back-reflection and tomographic structural information, making it suitable for axial positioning and layer confirmation. The combination of these two methods clearly presents the corneal microstructure, thereby improving the completeness of corneal microstructure interpretation.

[0037] Figure 2 The diagram illustrates a second structural block diagram of a combined transmission interferometry and full-field optical coherence tomography imaging system according to an embodiment of the present disclosure.

[0038] like Figure 2 As shown, in some embodiments, the illumination emission optical path includes: a light source 1, a collimating lens 2, a linear polarizer 3, a beam splitter 4, a first relay lens 5, a polarizing beam splitter 6, and a first objective lens 7.

[0039] Light source 1 is used to output near-infrared light.

[0040] The collimating lens 2 is placed in the output light path of the light source 1 to collimate the near-infrared light and obtain collimated infrared light.

[0041] Linear polarizer 3 is placed in the output light path of collimating lens 2 to convert collimated infrared light into linearly polarized light. The linearly polarized light is incident on beam splitter 4, reflected and enters first relay lens 5, and then transmitted to polarizing beam splitter 6.

[0042] The polarizing beam splitter 6 is used to totally reflect linearly polarized light to the first objective lens 7.

[0043] The first objective lens 7 is used to direct linearly polarized light into the subject's eye.

[0044] According to embodiments of this disclosure, the light source 1 can output near-infrared light with a center wavelength of 800nm ​​to 900nm, preferably 820nm to 880nm, more preferably 840nm to 860nm, for example 850nm. This wavelength range can balance the transmission efficiency of light propagating from the anterior segment of the eye to the posterior segment, the ability of the posterior segment of the eye to generate secondary illumination light, the detection efficiency of corneal backreflection or backscattering signals, and the response characteristics of optical elements and detectors in the full-field optical coherence tomography (OCT) path.

[0045] This wavelength band is eye-friendly, and LEDs, SLDs, or low-coherence lasers can be used as light sources. During this phase, the aperture size, relay lens focal length, and light source divergence angle can be adjusted to change the size of the illumination spot projected onto the fundus, the numerical aperture of the illumination, and the spatial coherence of the secondary light source.

[0046] According to embodiments of this disclosure, the linear polarizer 3 and the polarizing beam splitter 6 can constitute a transmission interferometric polarization beam splitting and reflection suppression unit. The linear polarizer 3 converts the illumination light into linearly polarized light; the linear polarizer 6 reflects this linearly polarized light to illuminate the examined eye, while simultaneously performing polarization selection on the returned light. The specular reflection light from the anterior corneal surface has high polarization retention and is reflected back to the linear polarizer 6 and directed towards the FF-OCT imaging direction. The polarization state of the secondary illumination light after multiple scatterings by the retina, choroid, or sclera is randomized, wherein the polarization component that can pass through element 6 can enter the transmission interferometric detection path.

[0047] According to embodiments of this disclosure, the illumination light entering the subject's eye is precisely focused near the retina, choroid, or sclera after passing through the refractive system of the cornea and lens. The strong scattering tissues in the posterior segment of the eye scatter the incident light multiple times, returning the light towards the anterior segment, forming an extended but numerically limited secondary illumination light. This secondary illumination light is transmitted back through the corneal target tissue 8, causing phase delay, diffraction, and local interference contrast in the transparent / weakly scattering microstructures within the cornea, providing a signal basis for subsequent transmission interferometry imaging. The light returning from the eye passes through the shared first objective lens 7 and returns to the polarizing beam splitter 6. The specular reflection light from the anterior surface of the cornea remains almost unchanged in polarization state and is directly reflected by the polarizing beam splitter 6, guiding it into the imaging detection direction of FF-OCT and avoiding stray light interference with the transmission interferometry imaging path. The polarization state of the secondary illumination light after multiple scattering by the retina and choroid is completely randomized, with the component conforming to the polarization requirements of the transmission path directly passing through the polarizing beam splitter 6.

[0048] like Figure 2 As shown, in some embodiments, the corneal transmission interferometry imaging optical path may include: a transmission interferometry imaging lens 9 and a first detector 10.

[0049] The transmission interference imaging lens 9 and the first objective lens 7 form an imaging conjugate system, used to conjugate project the transmitted interference light passing through the polarizing beam splitter 6 onto the target surface of the first detector 10 without distortion, thus obtaining a large field-of-view corneal transmission interference image. This image can quickly display corneal nerve fibers, epithelial cell-like structures, stromal texture, wrinkles, postoperative interfaces, and local abnormal textures.

[0050] For example, the first detector 10 may be a two-dimensional detector.

[0051] In some embodiments, the optical path for full-field optical coherence tomography may include: a reference arm and an axial scanning unit, a beam combiner and a detector unit.

[0052] The reference arm and axial scanning unit are used to generate reference light corresponding to different depths of the cornea. The reference light corresponding to different depths is coherent with the back-reflected light of the cornea to realize axial scanning of optical coherence tomography.

[0053] The beam combining and detection unit is used to combine the back-reflected light from the cornea with the reference light and interfere to obtain the corneal tomographic image.

[0054] Furthermore, such as Figure 2 As shown, the reference arm and axial scanning unit include: a second relay lens 11, a first reflector 12, a second objective lens 13, a piezoelectric axial displacement platform 14, and a second reflector 15, with the second reflector 15 mounted on the piezoelectric axial displacement platform 14.

[0055] The second relay lens 11 and the second objective lens 13 form a conjugate system, projecting the collimated light transmitted from the beam splitter 4 onto the second reflecting mirror 15.

[0056] The first reflecting mirror 12 is placed between the second relay lens 11 and the second objective lens 13 to deflect the light path and direct the collimated light to the second reflecting mirror 15.

[0057] The piezoelectric axial displacement platform 14 drives the second reflecting mirror 15 to move axially along the optical axis to perform axial scanning of full-field optical coherence tomography and obtain reference light corresponding to different corneal depths.

[0058] The reference beam returns to beam splitter 4 via the same path.

[0059] According to the embodiments of this disclosure, the light generated by the light source 1 is split by the beam splitter and enters the reference arm and axial scanning unit. It then passes through the second relay lens 11, the first reflector 12, and the second objective lens 13 in sequence, and arrives at the second reflector 15. After being reflected by the second reflector 15, it is refracted back along the original light path to form the reference light.

[0060] The piezoelectric axial displacement platform 14 drives the second reflecting mirror 15 to translate along the optical axis, continuously changing the round-trip optical path of the reference light. By dynamically adjusting the optical path of the reference light, the reference light sequentially meets the coherence condition with the sample light returning from different depth positions of the human eye, thereby achieving axial scanning in the sample depth direction and acquiring interference signals from tissues at different depths to reconstruct tomographic images. According to the embodiments of this disclosure, the core function of the first reflecting mirror 12 is to fold the optical path of the reference arm by 90°, extending the transmission path of the reference light to the design value within the limited internal space of the device, thereby matching the optical path length of the sample arm and satisfying the equal optical path interference condition of the Michelson-type interferometer system.

[0061] Furthermore, such as Figure 2 As shown, the beam combining and detection unit includes: a beam splitter 4, a third relay lens 16, a fourth relay lens 17, and a second detector 18.

[0062] Beam splitter 4 is used to combine and interfere with the corneal back-reflected light and the reference light.

[0063] The third relay lens 16 and the fourth relay lens 17 are used to collimate the interference light so that the interference light is completely projected onto the target surface of the second detector 18.

[0064] The second detector 18 is used to collect interference light projected by the third relay lens 16 and the fourth relay lens 17 to obtain a corneal tomographic image.

[0065] According to the implementation of this disclosure, the third relay lens 16 and the fourth relay lens 17 can adopt a double Gaussian variant structure and be combined with an achromatic doublet lens design. This can simultaneously correct spherical aberration, chromatic aberration and polarization aberration introduced by the preceding optical path, achieve uniform image quality across the entire field of view in the 850nm near-infrared interference band, avoid blurring of fine structures such as nerve fibers and microvessels in the fundus edge area, and ensure that the fundus image from the center to the edge maintains high resolution.

[0066] In some embodiments, the first relay lens 5 is matched with the second relay lens 11.

[0067] According to the embodiments of this disclosure, matching can be understood as follows: the first relay lens 5 and the second relay lens 11 have symmetrical dispersion and aberration characteristics, which can simultaneously cancel the axial chromatic aberration and spherical aberration in the near-infrared working band, avoiding additional phase difference between the reference light and the sample light after passing through different lenses, and allowing the two return beams from the low-coherence light source to fall precisely within the coherence length range, stably generating interference signals. The optical path contribution of the first relay lens 5 and the second relay lens 11 is completely equal, and the optical path length inside the lens is completely consistent, without introducing additional optical path difference, reducing the adjustment difficulty of the subsequent optical path adjustment module.

[0068] In some embodiments, the first objective lens 7 and the second objective lens 13 are matched.

[0069] According to embodiments of this disclosure, the meaning of matching the first objective lens 7 and the second objective lens 13 is consistent with the meaning of matching the first relay lens 5 and the second relay lens 11.

[0070] According to embodiments of this disclosure, the imaging principle of the imaging system described above can be as follows.

[0071] (1) Scleral scattering forms “secondary illumination light”.

[0072] After the illumination light enters the eye through the objective lens, the cornea and lens focus the beam onto the retina / sclera region. The sclera, located behind the retina, strongly scatters the incident light, and some of the scattered light returns forward, becoming secondary illumination light that shines from behind the eye to in front of the eye. This returned light then passes through the anterior segment structures such as the cornea / lens, forming transmitted interference light that is collected by the objective lens and imaged onto the detector.

[0073] Illumination NA is denoted as NA i It is obtained from the axial length of the eye and the radius of the illumination beam:

[0074]

[0075] The detection range (NA) is determined by the microscope objective and is denoted as NA. d The effective NAs are taken as their algebraic average:

[0076]

[0077] Lateral resolution and depth of field are defined by the effective NA:

[0078]

[0079] (2) Local interference between the transmitted zero-order light and the sample diffracted light near the sample.

[0080] Secondary illumination light can generate transmitted zero-order light (the component not scattered / diffracted by the sample) and diffracted / scattered light (generated by the microstructure) at the sample (e.g., corneal cells, nerve fibers, lens microstructures). The two interfere locally on the sample plane, and then the interference intensity distribution is projected onto the detector target surface by a relay lens system.

[0081] (3) Polarization-separated two-mode detection optical path

[0082] The system utilizes a linear polarizer and a polarization beam splitter to separate the illumination light, corneal back-reflected light, and back-eye scattered return light. Corneal specular reflection or interlaminar reflection is typically strong and has high polarization retention, allowing it to be incorporated into the FF-OCT imaging path. The return light, after passing through the cornea and undergoing multiple scatterings by the posterior eye tissue, is partially depolarized, containing a polarization component that can pass through the transmission interference detection path. This configuration allows the FF-OCT channel to primarily receive the polarization-retained corneal back-reflected signal, while the transmission interference channel primarily receives the secondary illumination transmission signal after back-eye scattering and depolarization. This approach reduces the contamination of the transmission interference image by strong anterior corneal surface reflections, while also minimizing background crosstalk caused by the transmission interference light entering the FF-OCT channel.

[0083] (4) FF-OCT axial scanning and tomography

[0084] The FF-OCT channel uses corneal back-reflected light as the sample arm light and the light returned by the reference arm mirror 15 as the reference arm light. Only when the optical path lengths of the sample arm and the reference arm are matched within the coherence length range of the light source will the corneal reflection / scattering structure at the corresponding depth form an effective interference signal on the two-dimensional detector 18. The reference arm mirror 15 is mounted on the axial displacement stage 14. By moving the reference arm mirror 15 along the optical axis, the optical path length of the reference arm can be changed, and layers at different axial depths of the cornea can be selected sequentially to achieve axial scanning of structures such as the corneal epithelium, stroma, interface, and endothelium.

[0085] (5) Trade-off design between light source bandwidth and retinal spot size

[0086] FF-OCT requires a large light source bandwidth to achieve a shorter coherence length (lower temporal coherence) and higher axial resolution. This bandwidth ensures axial resolution while avoiding system dispersion and decreased transmission interference contrast caused by excessive bandwidth.

[0087] Transmission interferometry (TIA) imaging requires improved spatial coherence of the secondary illumination light scattered by posterior ocular tissues. Reducing the size of the light spot projected onto the retina / sclera region can decrease the equivalent illumination NA of the secondary illumination, thereby improving spatial coherence and transmission interferometry contrast. However, if the light spot is too small and the spatial coherence is too high, significant crosstalk, stray interference, ghosting, or multiple reflection fringes may appear in FF-OCT images; simultaneously, a reduced illumination NA may also impair lateral resolution. Therefore, a suitable trade-off needs to be struck between the light source bandwidth and the size of the fundus light spot.

[0088] For example, the light source has a center wavelength of 850 nm and a bandwidth of 50 nm, resulting in a spot diameter of approximately 0.5 mm projected onto the retina / sclera region. This combination of parameters balances FF-OCT axial resolution, transmission interference spatial coherence, imaging depth of field, lateral resolution, and eye safety. In practice, the spot diameter can be adjusted from 0.3 mm to 1.0 mm, preferably approximately 0.5 mm, depending on the objective lens NA, axial length, camera sensitivity, and eye safety limits.

[0089] It should be noted that this method differs from traditional slit-lamp reverse illumination or ordinary reverse illumination. This disclosure does not employ large-area, low-spatial-coherence macroscopic reverse illumination, but rather projects 850nm illumination onto a local area of ​​the posterior eye, utilizing retinal, choroidal, or scleral scattering to form a limited NA secondary illumination source, and obtains enhanced contrast of transparent tissue through local interference between the transmitted zero-order light and the sample diffracted light.

[0090] It should be noted that, unlike reflective interferometry or OCT, the transmission interferometry channel disclosed herein does not rely on the separation of the reference arm and the sample arm, nor does it use reflection / backscattering tomography as the main mechanism. Instead, it utilizes local interference near the sample or near the image plane under transmission geometry to form intensity contrast. The structure is closer to common-path imaging, and it has a lower dependence on vibration and reference arm stability.

[0091] It should be noted that, unlike simple transmission interferometry imaging, this disclosure does not simply filter out the back-reflected light from the cornea, but instead uses it as a tomographic signal for FF-OCT sample arm imaging, thereby achieving complementarity between reflection tomographic information and transmission interferometry information under the same light source.

[0092] It should be noted that, unlike conventional FF-OCT, this disclosure not only utilizes corneal back-reflected light for low-coherence tomography, but also simultaneously utilizes a secondary illumination source formed by the back-eye scattering of the same illumination light to obtain a large field-of-view corneal transmission interference image.

[0093] It should be noted that, unlike modular multimodal systems, this disclosure uses the same 850 nm illumination source, the same front-end objective lens, and the same eye-viewing optical path. The coordinate systems of the two modes are highly consistent, which facilitates joint optimization of aberrations, working distance, pupil coupling, and eye safety parameters.

[0094] It should be understood that the differences listed above do not mean that the system disclosed herein can solve all the problems existing in the above systems, but are comparisons made for each individual system.

[0095] The system provided in this disclosure has at least the following beneficial effects:

[0096] The corneal multimodal information is complementary. The transmission interferometry channel focuses on the phase / diffraction enhancement information of transparent or weakly scattering tissues, suitable for large field-of-view screening; the FF-OCT channel focuses on corneal back reflection and tomographic structure information, suitable for axial localization and slice confirmation. The combination of the two can improve the completeness of corneal microstructure interpretation.

[0097] Transmission interferometry has a strong ability to display transparent tissues. It utilizes a secondary illumination source formed by scattering from the posterior ocular tissue, which can produce high contrast for corneal nerves, epithelial cell-like textures, subtle changes in the stroma, and postoperative interfaces, thus compensating for the insensitivity of reflective imaging to transparent, low-scattering tissues.

[0098] The front-end optics are highly overlapping, facilitating synchronous optimization. Both modes share the same illumination source, the same objective lens, and the same anterior alignment reference. The system's working distance, aberration correction, fixation control, pupil coupling, and eye movement compensation can all be performed on the same front-end platform.

[0099] The back-reflected light is utilized efficiently, resulting in high light energy utilization. Corneal back-reflected light forms a useless background in transmission interference; this invention directs it into the FF-OCT channel as effective sample light, reducing ineffective light loss and improving the overall information acquisition efficiency of the system.

[0100] This is beneficial for meeting eye safety requirements. Since the same 850 nm light source serves two imaging modalities simultaneously and effectively utilizes both reflected and transmitted light, complementary information can be obtained with lower repetition requirements. At the same time, the 850 nm near-infrared band is more suitable for human eye examination and facilitates the integration of power monitoring and safety interlock control.

[0101] Figure 3 A flowchart illustrating a combined imaging method of transmission interferometry and full-field optical coherence tomography according to an embodiment of the present disclosure is shown.

[0102] like Figure 3 As shown, the combined imaging method of transmission interferometry and full-field optical coherence tomography in this embodiment may include operations S310 to S330.

[0103] When operating S310, in a dark environment, linearly polarized light is generated using the illumination emission optical path, and the linearly polarized light is incident on the eye of the subject.

[0104] When operating the S320, interference information of transmitted interference light is collected using the corneal transmission interference imaging optical path to obtain a large field-of-view corneal transmission interference image.

[0105] When operating the S330, the corneal axial tomography is performed based on the back-reflected light from the cornea using the full-field optical coherence tomography path to obtain a corneal tomographic image.

[0106] For example, in a low-light environment, the subject remains stationary and undergoes pupil dilation. An 850nm near-infrared illumination source is activated, directing the beam towards the corneal tissue while simultaneously focusing it onto the sclera. The sclera scatters this light, creating secondary illumination that provides reverse transmission illumination to the cornea and lens. The system acquires wide-field-of-view transmission interferometry (FIT) images of the cornea. By appropriately adjusting the optical path of the reference arm, the control unit drives the axial movement of the reference arm mirror, enabling the acquisition of FF-OCT interferometry images at different corneal depths. The system then registers, suppresses background, reconstructs, and jointly displays the FIT and FF-OCT images.

[0107] It should be understood that in practice, either single-modal imaging (transmission interferometry or FF-OCT) or dual-modal imaging can be selected.

[0108] It should be noted that the method embodiment part of this disclosure is related to the system part of this disclosure, and their specific implementation details and technical effects are the same, so they will not be repeated here.

[0109] Any one or more of the modules, submodules, units, and subunits according to embodiments of the present disclosure, or at least part of the functions of any one or more of them, can be implemented in one module. Any one or more of the modules, submodules, units, and subunits according to embodiments of the present disclosure can be implemented by dividing them into multiple modules. Any one or more of the modules, submodules, units, and subunits according to embodiments of the present disclosure can be at least partially implemented as hardware circuitry, such as a Field-Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a System-on-Chip, a System-on-a-Substrate, a System-on-Package, an Application-Specific Integrated Circuit (ASIC), or implemented in hardware or firmware by any other reasonable means of integrating or packaging circuitry, or implemented in software, hardware, or firmware, or in any suitable combination of any of these three implementation methods. Alternatively, one or more of the modules, submodules, units, and subunits according to embodiments of the present disclosure can be at least partially implemented as computer program modules, which, when run, can perform corresponding functions.

[0110] Figure 4 A block diagram of an electronic device for a combined multi-transmission interferometry and full-field optical coherence tomography imaging method according to an embodiment of the present disclosure is shown schematically.

[0111] like Figure 4 As shown, an electronic device 400 according to an embodiment of the present disclosure includes a processor 401, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 402 or a program loaded from a storage portion 408 into a random access memory (RAM) 403. The processor 401 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 401 may also include onboard memory for caching purposes. The processor 401 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0112] RAM 403 stores various programs and data required for the operation of electronic device 400. Processor 401, ROM 402, and RAM 403 are interconnected via bus 404. Processor 401 performs various operations of the method flow according to embodiments of the present disclosure by executing programs in ROM 402 and / or RAM 403. It should be noted that the programs may also be stored in one or more memories other than ROM 402 and RAM 403. Processor 401 may also perform various operations of the method flow according to embodiments of the present disclosure by executing programs stored in said one or more memories.

[0113] According to embodiments of this disclosure, the electronic device 400 may further include an input / output (I / O) interface 405, which is also connected to a bus 404. The electronic device 400 may also include one or more of the following components connected to the I / O interface 405: an input section 406 including a keyboard, mouse, etc.; an output section 407 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 408 including a hard disk, etc.; and a communication section 409 including a network interface card such as a LAN card, modem, etc. The communication section 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to the I / O interface 405 as needed. A removable medium 411, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 410 as needed so that computer programs read from it can be installed into the storage section 408 as needed.

[0114] This disclosure also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs that, when executed, implement the method according to the embodiments of this disclosure.

[0115] According to embodiments of this disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium, such as including, but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this disclosure, the computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of this disclosure, the computer-readable storage medium may include ROM 402 and / or RAM 403 and / or one or more memories other than ROM 402 and RAM 403 described above.

[0116] Embodiments of this disclosure also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code is used to cause the computer system to implement the methods provided in the embodiments of this disclosure.

[0117] When the computer program is executed by the processor 401, it performs the functions defined in the system / apparatus of this disclosure embodiments. According to embodiments of this disclosure, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0118] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and downloaded and installed via communication section 409, and / or installed from removable medium 411. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0119] In such an embodiment, the computer program can be downloaded and installed from a network via communication section 409, and / or installed from removable medium 411. When the computer program is executed by processor 401, it performs the functions defined in the system of this disclosure embodiment. According to embodiments of this disclosure, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0120] According to embodiments of this disclosure, program code for executing the computer programs provided in embodiments of this disclosure can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can execute entirely on a user's computing device, partially on a user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0121] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0122] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0123] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A combined imaging system of transmission interferometry and full-field optical coherence tomography, characterized in that, include: An illumination emission light path is used to generate linearly polarized light and incident the linearly polarized light onto the eye of the examinee. A portion of the linearly polarized light is back-reflected or back-scattered at the anterior and posterior surfaces of the cornea and the internal microstructure of the cornea, forming corneal back-reflected light. Another portion is scattered multiple times by the posterior eye tissue and returns in the direction in front of the eye, forming secondary illumination light illuminating from behind the eye to in front of the eye. The secondary illumination light passes through the cornea again and undergoes phase modulation, refraction modulation, and diffraction modulation through the cornea to generate transmitted interference light. The corneal transmission interferometry imaging optical path is used to collect the interference information of the transmitted interference light to obtain a large field-of-view corneal transmission interferometry image; The full-field optical coherence tomography optical path is used to perform corneal axial tomography based on the back-reflected light from the cornea to obtain a corneal tomographic image.

2. The system according to claim 1, characterized in that, The illumination emission optical path includes: a light source, a collimating lens, a linear polarizer, a beam splitter, a first relay lens, a polarizing beam splitter, and a first objective lens; The light source is used to output near-infrared light; The collimating lens is disposed in the output light path of the light source and is used to collimate the near-infrared light to obtain collimated infrared light; The linear polarizer is placed in the output light path of the collimating lens and is used to convert the collimated infrared light into the linearly polarized light. The linearly polarized light is incident on the beam splitter, reflected, enters the first relay lens, and is then transmitted to the polarizing beam splitter. The polarizing beam splitter is used to totally reflect the linearly polarized light back to the first objective lens; The first objective lens is used to direct the linearly polarized light into the eye of the subject.

3. The system according to claim 2, characterized in that, The corneal transmission interferometry imaging optical path includes: a transmission interferometry imaging lens and a first detector; The transmission interference imaging lens and the first objective lens constitute an imaging conjugate system, which is used to conjugate project the transmission interference light transmitted through the polarizing beam splitter, and project the target features of the cornea onto the target surface of the first detector without distortion, thereby obtaining the large field-of-view corneal transmission interference image.

4. The system according to claim 2, characterized in that, The full-field optical coherence tomography optical path includes: The reference arm and axial scanning unit are used to generate reference light corresponding to different depths of the cornea. The reference light corresponding to different depths is coherent with the back-reflected light of the cornea to realize axial scanning of optical coherence tomography. The beam combining and detection unit is used to combine the back-reflected light from the cornea with the reference light and interfere to obtain the corneal tomographic image.

5. The system according to claim 4, characterized in that, The reference arm and axial scanning unit include: a second relay lens, a first reflecting mirror, a second objective lens, a piezoelectric axial displacement platform, and a second reflecting mirror, wherein the second reflecting mirror is mounted on the piezoelectric axial displacement platform; The second relay lens and the second objective lens form a conjugate system, projecting the collimated light transmitted from the beam splitter onto the second reflecting mirror; The first reflecting mirror is placed between the second relay lens and the second objective lens to deflect the light path; The piezoelectric axial displacement platform drives the second reflector to move axially along the optical axis to perform axial scanning of full-field optical coherence tomography and obtain the reference light corresponding to different corneal depths; The reference light returns to the beam splitter via the original path.

6. The system according to claim 4 or 5, characterized in that, The beam combining and detection unit includes: the beam splitter, the third relay lens, the fourth relay lens, and the second detector; The beam splitter is used to combine and interfere with the back-reflected light from the cornea and the reference light; The third relay lens and the fourth relay lens are used to collimate the interference light so that the interference light is completely projected onto the target surface of the second detector; The second detector is used to collect interference light projected by the third relay lens and the fourth relay lens to obtain the corneal tomographic image.

7. The system according to claim 5, characterized in that, The first relay lens is matched with the second relay lens.

8. The system according to claim 5, characterized in that, The first objective lens and the second objective lens are matched.

9. The system according to claim 2, characterized in that, The center wavelength of the near-infrared light is 800nm~900nm.

10. A method for combined imaging of transmission interferometry and full-field optical coherence tomography, characterized in that, include: In low-light conditions, linearly polarized light is generated using an illumination emission light path and incident on the subject's eye. Part of the linearly polarized light is back-reflected or back-scattered at the anterior and posterior surfaces of the cornea and the internal microstructures of the cornea, forming corneal back-reflected light. Another part is scattered multiple times by the posterior eye tissues and returns in the direction in front of the eye, forming secondary illumination light that shines from behind the eye to the eye. The secondary illumination light passes through the cornea again and undergoes phase modulation, refraction modulation, and diffraction modulation to generate transmitted interference light. The interference information image of the transmitted interference light is collected using the corneal transmission interference imaging optical path to obtain a large field-of-view corneal transmission interference image; Axial tomography of the cornea is performed using the back-reflected light from the cornea through a full-field optical coherence tomography path to obtain a corneal tomographic image.

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