Ophthalmic diagnostic instrument

Abstract

The invention discloses an ophthalmological diagnostic instrument, and relates to the technical field of medical equipment.The ophthalmological diagnostic instrument comprises a topographic map structure, a crack projection structure, an off-axis imaging structure, a dichroic optical element and a rotating mechanism, opaque circular rings and semitransparent circular rings which are alternately distributed are arranged on the Praxiso disc, the red light source is configured to perform backlight illumination on the semitransparent circular rings, and the first camera is a color sensitive image sensor, is aligned along the visual axis of the eye and is used for capturing a Praxiso pattern reflected by the surface of the cornea and a color image of the anterior segment of the eye; the fissure projection structure comprises a visual axis along the topographic map structure and projects a blue fissure light beam to the anterior segment, the off-axis imaging structure comprises a second camera, the second camera is obliquely arranged relative to the visual axis and is used for capturing an anterior segment cross section image irradiated by the blue fissure light beam, and the dichroic optical element is arranged along the visual axis.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an ophthalmic diagnostic instrument. Background Technology

[0002] In ophthalmic diagnosis, corneal topography is a core tool for assessing corneal surface morphology and is widely used in disease diagnosis and postoperative monitoring. Current mainstream techniques are divided into two categories: Plascidoo disc topography and Saxophone imaging. Plascidoo technique analyzes reflective deformation by projecting concentric circular patterns to measure the curvature of the anterior corneal surface, offering high accuracy in the circumferential direction, but its radial resolution is insufficient due to the limited number of rings. Saxophone imaging uses a tilting camera to capture cross-sectional images illuminated by a slit beam, achieving three-dimensional reconstruction through rotational scanning. It has high radial resolution, but its accuracy in concentric regions is limited by mechanical motion and eye movement interference. To overcome the limitations of a single technique, modern equipment attempts to integrate both modes.

[0003] A key bottleneck is the limitations of traditional topographic cameras. Topographic cameras typically only support monochrome imaging, failing to meet the diagnostic needs that rely on color information, such as red-eye analysis, fluorescein staining assessment, and lipid interferometry. Furthermore, integrating slit-beam projection with color imaging presents significant spectral interference issues—in traditional designs, the plascidograph illumination and slit beam share the visual axis; using conventional wavelength configurations leads to optical crosstalk or compromises topographic map accuracy. Additionally, compact devices require coordinated spatial layout of the plascidograph disk, slit source, and off-axis camera to ensure optical path registration across subsystems; existing solutions struggle to expand ocular surface color diagnostic capabilities while maintaining corneal measurement accuracy. Summary of the Invention

[0004] The main objective of this invention is to propose an ophthalmic diagnostic instrument that aims to maintain the accuracy of corneal measurements while expanding the diagnostic function of ocular surface color.

[0005] To achieve the above objectives, the present invention provides an ophthalmic diagnostic instrument comprising: The topographic map structure includes a Placido disk, a red light source, and a first camera. The Placido disk has alternating opaque and semi-transparent rings. The red light source is configured to backlight the semi-transparent rings. The first camera is a color-sensitive image sensor and is aligned along the visual axis of the eye to capture the Placido pattern reflected from the corneal surface and the color image of the anterior segment. A slit projection structure, comprising projecting a blue slit beam of light onto the anterior segment of the anterior segment along the visual axis of the topographic map structure; An off-axis imaging structure includes a second camera, which is tilted relative to the visual axis to capture an image of the anterior segment cross-section illuminated by the blue slit beam; A dichroic optical element is arranged along the line of sight and configured to reflect the blue slit beam to the second camera and transmit the red light to the first camera, thereby achieving spectral separation. The rotating mechanism is centered on the line of sight. The topographic map structure, the slit projection structure, and the off-axis imaging structure are all mounted on the rotating mechanism and can rotate around the line of sight.

[0006] Preferably, the wavelength of the red light source is less than 650 nm, the wavelength of the blue slit beam is less than 430 nm, and the cutoff wavelength of the dichroic optical element is less than 450 nm.

[0007] Preferably, the red light source is a plurality of LEDs, which are evenly arranged behind the semi-transparent ring of the Placido disk to achieve uniform backlighting of the ring.

[0008] Preferably, the imaging lens of the topographic map structure is an achromatic cemented doublet lens.

[0009] Preferably, the second camera is equipped with a bandpass filter to allow wavelengths of light from the blue slit beam to pass through.

[0010] Preferably, the second camera captures multiple cross-sectional images at discrete angular positions for the reconstruction of the three-dimensional geometry of the anterior segment.

[0011] Preferably, the optical path between the first camera and the imaging lens has no spectral obstruction structure.

[0012] Preferably, the second camera is arranged according to the Sabine principle.

[0013] Preferably, the system further includes an image post-processing module, which is electrically connected to the first camera and is used to perform blue channel enhancement processing on the image acquired by the first camera.

[0014] Preferably, it also includes an auxiliary lighting subsystem, which is mounted on the rotating mechanism and uniformly arranged around the Plassey disk in the circumference, for emitting white light or multispectral light.

[0015] In the technical solution provided by this invention, the topographic map structure includes a Placido disk, a red light source, and a first camera. The Placido disk has alternating opaque and semi-transparent rings. The red light source is configured to backlight the semi-transparent rings. The first camera is a color-sensitive image sensor and is aligned along the visual axis of the eye to capture the Placido pattern reflected from the corneal surface and the anterior segment color image. The slit projection structure includes a blue slit beam projected onto the anterior segment along the visual axis of the topographic map structure. The off-axis imaging structure includes a second camera, which is tilted relative to the visual axis to capture the image illuminated by the blue slit beam. The image shows a cross-sectional image of the anterior segment. The dichroic optical element is arranged along the visual axis and configured to reflect the blue slit beam to the second camera and transmit the red light to the first camera, achieving spectral separation. The rotating mechanism is centered on the visual axis, and the topographic map structure, slit projection structure, and off-axis imaging structure are all mounted on the rotating mechanism and can rotate around the visual axis. This enables simultaneous assessment of corneal geometry and ocular surface condition in a single compact platform, solving the problem of limited diagnostic function caused by monochromatic imaging of topographic cameras in traditional devices. At the same time, it avoids optical interference between subsystems and ensures the independence and reliability of each imaging mode. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a three-dimensional schematic diagram of an embodiment of the ophthalmic diagnostic instrument provided by the present invention.

[0018] Explanation of icon numbers: 100. Ophthalmic diagnostic instruments; 1. Slit projection structure; 2. Dichroic optical element; 3. Topographic map structure; 4. Off-axis imaging structure.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] This invention provides an ophthalmic diagnostic instrument. Figure 1 This is an embodiment of the ophthalmic diagnostic instrument provided by the present invention.

[0024] In traditional ophthalmic diagnostic equipment, the Plassey multi-disc topography subsystem and the slit-beam projection subsystem share the same visual axis optical path. This inherent conflict in their illumination wavelength selection and optical component transmission characteristics results in monochromatic imaging along the visual axis. Specifically, Plassey multi-disc topography analysis requires the use of red light to ensure accurate corneal curvature measurement, while slit-beam projection requires blue light to achieve anterior segment cross-sectional imaging. This creates optical crosstalk in the spectral overlap region. This spectral interference forces a compromise between color fidelity and topography accuracy in the system design, preventing the topography / pupil camera from acquiring full-color images. Consequently, the system loses the ability to perform multi-dimensional assessments of ocular surface conditions, including the degree of conjunctival hyperemia, fluorescein staining patterns, and the identification of lipid layer interference fringes. This limits the scalability of diagnostic functions and affects the integrity of both anterior segment structural and functional assessments.

[0025] Please refer to the following: Figure 1The ophthalmic diagnostic instrument includes a topographic mapping structure, a slit projection structure, an off-axis imaging structure, a dichroic optical element, and a rotating mechanism. The topographic mapping structure includes a Plascidoo disk, a red light source, and a first camera. The Plascidoo disk has alternating opaque and translucent rings. The red light source is configured to backlight the translucent rings. The first camera is a color-sensitive image sensor aligned along the visual axis of the eye, used to capture the Plascidoo pattern reflected from the corneal surface and the anterior segment color image. The slit projection structure includes components along the topographic mapping structure. The visual axis projects a blue slit beam onto the anterior segment. The off-axis imaging structure includes a second camera, which is tilted relative to the visual axis to capture a cross-sectional image of the anterior segment illuminated by the blue slit beam. The dichroic optical element is arranged along the visual axis and configured to reflect the blue slit beam to the second camera and transmit the red light to the first camera, thereby achieving spectral separation. The rotating mechanism is centered on the visual axis, and the topographic mapping structure, slit projection structure, and off-axis imaging structure are all mounted on the rotating mechanism and can rotate around the visual axis with it.

[0026] The topographic mapping structure comprises a Plascidoo disk, a red light source, and a first camera. The Plascidoo disk is an optical element with alternating opaque and transparent regions, which can be achieved by etching a metal coating onto a glass substrate, for example, by forming concentric ring patterns using photolithography. Its primary purpose is to project a ring pattern onto the cornea. The red light source provides backlighting and can be implemented using a halogen lamp with filters, such as a tungsten iodine lamp or an incandescent lamp, primarily to illuminate the translucent rings. The first camera is a color image capture device, which can be implemented using a complementary metal-oxide-semiconductor sensor or a charge-coupled device sensor, such as an image sensor with a Bayer color filter array. Its primary purpose is to capture the Plascidoo pattern reflected from the corneal surface and the anterior segment image. The slit projection structure is an optical component used to project a narrow beam along the visual axis. It can be implemented using a laser with a slit aperture, such as a helium-neon laser or a semiconductor laser, primarily to provide cross-sectional illumination to the anterior segment. The off-axis imaging structure includes a second camera, which is an imaging device tilted relative to the visual axis. This can be implemented using a camera module tilted at a fixed angle, for example, by adjusting the angle via a mechanical support. Its primary purpose is to capture cross-sectional images of the anterior segment. A dichroic optical element is a wavelength-selective optical element arranged along the visual axis. This can be implemented using a beam splitter with a multi-layer dielectric coating, such as a thin film formed by alternating deposition of silicon dioxide and titanium oxide. Its primary purpose is to reflect specific light beams to the second camera and transmit other light beams to the first camera. A rotation mechanism is a mechanical drive device centered on the visual axis. This can be implemented using a stepper motor in conjunction with gear transmission, such as a DC servo motor or a brushless motor. Its primary purpose is to rotate the topographic mapping structure, the slit projection structure, and the off-axis imaging structure around the visual axis. Therefore, this application, through the combination of spectral separation design and rotational scanning mechanism, achieves simultaneous color imaging and topographic map analysis on a single optical axis, avoiding optical crosstalk. This allows the topographic map channel to acquire images containing color information for ocular surface condition assessment, while maintaining the accuracy of corneal topographic data. This overcomes the limitation of traditional integrated ophthalmic instruments where topographic cameras can only perform monochrome imaging, thus failing to support color diagnostic functions. Specifically, this design, by rationally selecting the wavelength range of the light source and the characteristics of optical components, ensures effective spectral separation between red illumination and blue slit beams. This allows the first camera to receive some blue light information while capturing the plascidometry pattern, providing a basis for red-eye analysis and fluorescein staining assessment, without requiring additional hardware to expand diagnostic capabilities. As a preferred embodiment, the above structure is configured to capture multi-angle images during rotation for reconstructing the anterior segment geometry, thereby improving the comprehensiveness of diagnosis and spatial registration accuracy.

[0027] By integrating a topographic mapping structure, a slit projection structure, an off-axis imaging structure, dichroic optical elements, and a rotating mechanism, the system achieves coordinated operation of full-color imaging along the visual axis and anterior segment cross-sectional imaging. Specifically, the red light source in the topographic mapping structure provides backlight illumination for the translucent rings of the Plassiddo disk. The alternating ring patterns of the Plassiddo disk are reflected from the corneal surface and captured by a first camera aligned along the visual axis of the eye. This first camera acts as a color-sensitive image sensor, simultaneously acquiring Plassiddo pattern deformation data from the corneal surface and an anterior segment color image. The selection of the red light wavelength ensures the accuracy of topographic map analysis while allowing the sensor to receive some blue light information to support color imaging. The slit projection structure projects a blue slit beam along the same visual axis to the anterior segment, providing the basis for cross-sectional illumination. The dichroic optical elements are arranged along the visual axis, and their spectral characteristics are designed to reflect the blue slit beam to the off-axis imaging structure while transmitting red light to the first camera, thereby achieving spectral isolation between the two imaging channels and effectively avoiding optical crosstalk. The second camera in the off-axis imaging structure is tilted relative to the visual axis and positioned according to the Schaperone principle. It is used to capture cross-sectional images of the anterior segment illuminated by a blue slit beam. Its tilt angle ensures that the entire cross-section is in sharp focus, thereby achieving accurate depth measurement and geometric reconstruction. The rotation mechanism is centered on the visual axis, on which the topographic mapping structure, slit projection structure, and off-axis imaging structure are all mounted. It can rotate around the visual axis with the mechanism, thereby capturing multiple images at discrete angular positions, providing data support for the reconstruction of the three-dimensional geometry of the anterior segment.

[0028] Therefore, in the technical solution provided by the present invention, the topographic map structure includes a Placido disk, a red light source, and a first camera. The Placido disk has alternating opaque and semi-transparent rings. The red light source is configured to backlight the semi-transparent rings. The first camera is a color-sensitive image sensor and is aligned along the visual axis of the eye to capture the Placido pattern reflected from the corneal surface and the color image of the anterior segment. The slit projection structure includes a blue slit beam projected onto the anterior segment along the visual axis of the topographic map structure. The off-axis imaging structure includes a second camera, which is tilted relative to the visual axis to capture the image under the illumination of the blue slit beam. The image is a cross-sectional image of the anterior segment. The dichroic optical element is arranged along the visual axis and configured to reflect the blue slit beam to the second camera and transmit the red light to the first camera, thereby achieving spectral separation. The rotating mechanism is centered on the visual axis, and the topographic map structure, slit projection structure, and off-axis imaging structure are all mounted on the rotating mechanism and can rotate around the visual axis with it. This enables simultaneous assessment of corneal geometry and ocular surface condition in a single compact platform, solving the problem of limited diagnostic function caused by the monochromatic imaging limitation of topographic cameras in traditional devices. At the same time, it avoids optical interference between subsystems and ensures the independence and reliability of each imaging mode.

[0029] The lack of precise definition of the light source wavelength and optical element parameters can lead to spectral overlap between Pracido red light and slit blue light, causing the dichroic optical element to be unable to effectively distinguish between the two light signals. This can result in slit blue light potentially leaking into the first camera channel and interfering with the quality of color imaging. At the same time, red light components may mix into the off-axis imaging path, reducing the clarity of the cross-sectional image. Ultimately, this affects the accuracy of corneal topography analysis and the reliability of ocular surface diagnosis. A spectral separation mechanism is proposed to avoid optical interference between the topographic structure and the slit projection structure.

[0030] Specifically, in the embodiments of the present invention, the wavelength of the red light source is less than 650 nm, the wavelength of the blue slit beam is less than 430 nm, and the cutoff wavelength of the dichroic optical element is less than 450 nm.

[0031] A red light source with a wavelength less than 650nm means that the emission spectrum of the light source used for Plassey multi-disc backlighting is mainly distributed in the visible red light region. This can be achieved using a halogen lamp with a long-pass filter or a tungsten filament lamp system. The purpose is to ensure that the red light component can efficiently transmit through the dichroic optical element, avoiding interference with slit imaging caused by some light being reflected off-axis due to excessively long wavelengths. A blue slit beam with a wavelength less than 430nm can be understood as the center wavelength of the beam emitted by the slit projection structure being located in the short-wavelength blue light region. This can be achieved using a mercury lamp with a narrow... This can be achieved using filters or gas discharge light sources. The purpose is to lock the light source within the high-reflectivity band of the dichroic optical element, preventing blue light from transmitting to the first camera channel and causing noise in the color image. The cutoff wavelength of the dichroic optical element is less than 450nm, specifically referring to the inflection point wavelength between the reflection and transmission characteristics of the dichroic mirror. This can be achieved using a coated glass substrate or a multilayer dielectric film interference filter. The purpose is to define the critical boundary of spectral separation, forcing short-wavelength light to be reflected while long-wavelength light is transmitted, thereby establishing a steep transition between the red and blue light bands.

[0032] Traditional single light source or non-uniform arrangement methods can easily lead to uneven distribution of illumination intensity, causing differences in brightness or shadow areas in the Plassey multi-disc ring reflection image, which in turn interferes with the accurate capture and deformation analysis of the corneal surface reflection pattern and affects the reliability of topographic map data.

[0033] Specifically, in an embodiment of the present invention, the red light source is a plurality of LEDs, which are evenly arranged behind the semi-transparent ring of the Placido disk to achieve uniform backlighting of the ring.

[0034] In practical applications, multiple LEDs refer to the design of using a distributed light source array to replace the traditional single light source. This can be achieved using a ring array, a linear array, or an irregularly distributed LED array to avoid the lighting gradient problem caused by the fixed position of the light source. Among them, uniform arrangement can be understood as the LEDs being distributed at equal intervals in space according to a specific geometric law. Specifically, it can be arranged at equal angular intervals along the circumference or at equal distances along the radial direction. The purpose is to ensure that each area of ​​the semi-transparent ring receives a consistent lighting intensity and eliminate differences in brightness.

[0035] Ordinary optical lenses are prone to chromatic aberration when working over a wide spectral range, causing the focusing position of light of different wavelengths to shift, resulting in blurred edges or color distortion in color images. This, in turn, affects the accurate resolution of corneal surface reflection patterns and the accuracy of anterior segment color diagnostic information. Therefore, an imaging lens with a topographic map structure has been proposed to achieve high-quality imaging.

[0036] Specifically, in the technical solution of the present invention, the imaging lens of the topographic map structure is an achromatic cemented doublet lens.

[0037] In practical applications, achromatic cemented doublets refer to composite lens structures made of two optical materials with different refractive indices and Abbe numbers cemented together. They can be achieved by combining positive and negative lenses. For example, low-dispersion crown glass can be used as the positive lens material and high-dispersion flint glass as the negative lens material. The purpose is to use the complementary dispersive characteristics of the two materials to focus light within a specific wavelength range onto approximately the same image point, thereby effectively suppressing axial chromatic aberration.

[0038] The configuration of a bandpass filter in the off-axis imaging structure to achieve spectrally selective imaging is also a feature of this invention. Specifically, in an embodiment of this invention, the second camera is configured with a bandpass filter to allow the wavelength of the blue slit beam to pass through.

[0039] Among them, a bandpass filter is an optical filtering element that can be implemented using an interference filter or a multilayer dielectric film filter. Its purpose is to selectively transmit light within a specific wavelength range while blocking light of other wavelengths, thereby ensuring the spectral purity of the imaging system.

[0040] Specifically, the solution in this application constructs a precise filtering mechanism for the wavelength of the blue slit beam by integrating a bandpass filter at the front end of the second camera. The spectral transmission window of the bandpass filter is precisely limited to the operating wavelength range of the blue slit beam, effectively blocking stray light from ambient white illumination, red light source leakage, or other non-target wavelengths, thus ensuring that the second camera captures only the optical signal in the target wavelength band. This spectral separation mechanism, combined with the spectral characteristics of the dichroic optical element, enables the blue slit beam to be efficiently transmitted to the second camera while suppressing uncorrelated light interference, significantly improving the contrast of the cross-sectional image, and providing a reliable optical reference for subsequent 3D geometric reconstruction.

[0041] In some of the embodiments described above in this application, a rotating mechanism is proposed to acquire a sequence of anterior segment cross-sectional images for three-dimensional reconstruction. However, in its implementation, continuous rotation is susceptible to the effects of the patient's involuntary eye movements and mechanical system motion errors, resulting in inaccurate cross-sectional image registration and thus reducing the accuracy of three-dimensional geometric reconstruction.

[0042] In response, this application further proposes a second camera that captures multiple cross-sectional images at discrete angular positions for the reconstruction of the three-dimensional geometry of the anterior segment.

[0043] In practical applications, discrete angular position refers to the rotating mechanism pausing its movement at a preset fixed angular point, rather than rotating continuously. This can be achieved using equal or non-equal angular intervals, such as dynamically adjusting the sampling point density based on eye anatomy features. The purpose is to avoid image blurring and misalignment caused by eye movement or mechanical vibration during rotation, ensuring that each capture position has a clear geometric correspondence.

[0044] The proposed solution involves controlling a rotating mechanism to stop moving at a specific angular position, allowing a second camera to capture cross-sectional images of the anterior segment under static conditions, ensuring that each image precisely corresponds to a fixed angular position. Subsequently, image processing algorithms are used to integrate multiple cross-sectional images from discrete angles to reconstruct the continuous three-dimensional geometry of the anterior segment. This approach effectively eliminates dynamic errors in continuous rotational scanning and improves the accuracy of image registration.

[0045] Specifically, in some embodiments of this application, a first camera is proposed to acquire color images of the anterior segment. However, in its implementation, if there is a spectral blocking structure in the optical path between the first camera and the imaging lens, some wavelengths of light, especially the blue spectral component, will be filtered out, resulting in insufficient blue channel signal in the color image, which cannot accurately present the color features of the ocular surface, thereby affecting the diagnosis and assessment of ocular surface diseases such as conjunctival hyperemia and fluorescein staining patterns.

[0046] In response, this application further proposes a spectral-blocking structure for the optical path between the first camera and the imaging lens.

[0047] The spectral-free structure can be understood as having no optical elements in the optical path between the first camera and the imaging lens that absorb or reflect a specific wavelength range. This can be achieved by omitting the spectral filtering components. The purpose is to ensure that the light reflected from the corneal surface can completely contain all wavelength components in the visible spectrum, thus avoiding the impact on the quality of the color image due to spectral selective attenuation.

[0048] Specifically, the solution in this application achieves spectral separation through a dichroic optical element, transmitting red light to the first camera and reflecting blue light to the second camera, while avoiding any spectral filtering elements in the optical path between the first camera and the imaging lens. This design allows the red light band and part of the blue light band transmitted from the dichroic optical element to be transmitted to the color image sensor of the first camera without attenuation, thus providing a complete spectral data foundation for the image post-processing module. Based on this, the system compensates for the blue channel signal intensity through digital enhancement technology, ultimately generating a full-color image suitable for ocular surface diagnosis, effectively solving the problem of limited diagnostic function caused by missing spectral information.

[0049] Traditional ophthalmic diagnostic instruments using a second camera to capture cross-sectional images of the anterior segment suffer from a problem where the tilt angle is not optimized according to specific optical principles, resulting in out-of-focus imaging of different depth regions of the anterior segment. This affects the geometric fidelity of the cross-sectional image and the accuracy of depth measurement, thereby weakening the reliability of 3D reconstruction.

[0050] In this regard, this application further proposes an ophthalmic diagnostic instrument as described in claim 1, characterized in that the second camera is arranged according to the Sabin principle.

[0051] The Schaperone principle refers to an optical imaging configuration that requires the camera's imaging plane to intersect with the illumination plane and the optical axis to be at a specific angle. This can be achieved by adjusting the camera's tilt angle and position. Its purpose is to ensure that objects on the illumination plane remain sharp throughout the imaging process, avoiding local defocusing caused by depth-of-field limitations.

[0052] Specifically, the solution in this application precisely arranges the second camera according to the Schaperone principle, ensuring that its imaging plane is strictly matched and intersected with the illumination plane of the blue slit beam generated by the slit projection structure. During operation, the slit projection structure projects a blue slit beam along the visual axis to the anterior segment, and the dichroic optical element reflects this beam to the second camera. Due to the coordinated configuration of the tilt angle of the second camera and the beam plane, the imaging focal plane intersects with the beam plane in the corneal region, allowing scattered light to be uniformly focused across the entire depth range from the anterior surface of the cornea to the lens. This structure avoids the localized radial blurring caused by angular deviations in ordinary tilted arrangements, ensuring the geometric continuity of the cross-sectional image and providing a high-fidelity data foundation for parallax-based distance calculations and 3D reconstruction.

[0053] In some of the embodiments described above in this application, a color-sensitive image sensor is proposed to achieve full-color imaging. However, during its implementation, due to the cutoff wavelength limitation of the dichroic optical element, the intensity of the blue channel spectral transmission is attenuated, resulting in insufficient blue component in the anterior segment image captured by the first camera. This affects the reliability of diagnostic functions based on color features, such as ocular surface diagnostic tasks like conjunctival hyperemia assessment, fluorescein staining pattern recognition, and lipid layer interference fringe analysis, which cannot be performed accurately.

[0054] In this regard, this application further proposes to include an image post-processing module, which is electrically connected to the first camera and is used to perform blue channel enhancement processing on the image acquired by the first camera.

[0055] Specifically, the image post-processing module refers to an electronic component configured to perform digital image signal processing. It can be implemented as a dedicated image processing chip, a field-programmable gate array (FPGA), or a software algorithm running on a general-purpose processor. Its purpose is to compensate for the blue spectrum attenuation caused by the cutoff wavelength characteristics of dichroic optical elements in the optical system. The electrical connection with the first camera can be understood as establishing a direct electrical signal transmission path. Specifically, it can be implemented as a data cable connection, wireless data transmission, or integration on the same circuit board. Its purpose is to ensure that the image post-processing module can acquire the raw image data captured by the first camera in real time, avoiding delays or distortions during signal transmission. In practical applications, blue channel enhancement processing specifically refers to digital signal processing operations configured for the blue component in the image data. For example, it can be implemented as gain adjustment, histogram equalization, or a compensation algorithm based on a spectral response model. Its purpose is to improve the relative intensity and signal-to-noise ratio of the blue spectral band in the image and restore the accurate representation of the color characteristics of the ocular surface tissue.

[0056] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An ophthalmic diagnostic instrument, characterized in that, include: The topographic map structure includes a Placido disk, a red light source, and a first camera. The Placido disk has alternating opaque and semi-transparent rings. The red light source is configured to backlight the semi-transparent rings. The first camera is a color-sensitive image sensor and is aligned along the visual axis of the eye to capture the Placido pattern reflected from the corneal surface and the color image of the anterior segment. A slit projection structure, comprising projecting a blue slit beam of light onto the anterior segment of the anterior segment along the visual axis of the topographic map structure; An off-axis imaging structure includes a second camera, which is tilted relative to the visual axis to capture an image of the anterior segment cross-section illuminated by the blue slit beam; A dichroic optical element is arranged along the line of sight and configured to reflect the blue slit beam to the second camera and transmit the red light to the first camera, thereby achieving spectral separation. The rotating mechanism is centered on the line of sight. The topographic map structure, the slit projection structure, and the off-axis imaging structure are all mounted on the rotating mechanism and can rotate around the line of sight.

2. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The wavelength of the red light source is less than 650nm, the wavelength of the blue slit beam is less than 430nm, and the cutoff wavelength of the dichroic optical element is less than 450nm.

3. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The red light source consists of multiple LEDs, which are evenly arranged behind the semi-transparent ring of the Placido disk to achieve uniform backlighting of the ring.

4. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The imaging lens of the topographic map structure is an achromatic cemented doublet lens.

5. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The second camera is equipped with a bandpass filter to allow wavelengths of light from the blue slit beam to pass through.

6. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The second camera captures multiple cross-sectional images at discrete angular positions for the reconstruction of the three-dimensional geometry of the anterior segment.

7. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The optical path between the first camera and the imaging lens has no spectral obstruction structure.

8. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, The second camera is arranged according to the Schaperone principle.

9. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, It also includes an image post-processing module, which is electrically connected to the first camera and is used to perform blue channel enhancement processing on the image acquired by the first camera.

10. The ophthalmic diagnostic instrument as described in claim 1, characterized in that, It also includes an auxiliary lighting subsystem, which is mounted on the rotating mechanism and is evenly arranged around the Plassey disk for emitting white light or multispectral light.

Images