CN113876295A - Multi-mode double-off-axis retina imaging device and method - Google Patents

Abstract

Translated fromChinese

本发明涉及一种多模式双离轴视网膜成像装置，其特征在于：包括成像光路、照明光路、对焦光路和固视光路；所述的成像光路用于形成视网膜图像，所述的照明光路用于在眼底形成均匀的照明；所述的对焦光路用于在形成视网膜图像时，进行屈光补偿，保证拍摄照片的清晰度；所述的固视光路用于稳定人眼。该装置可以省去成像光路和照明光路之间的分光元件，通过离轴的方法，使两个光路在空间上分开，两个光路在人眼角膜上都形成汇聚的圆形光斑，无需环形照明，大幅简化了照明光路的加工和装调难度。

The invention relates to a multi-mode dual off-axis retinal imaging device, which is characterized in that it comprises an imaging optical path, an illumination optical path, a focusing optical path and a fixation optical path; the imaging optical path is used for forming a retinal image, and the illumination optical path is used for forming a retinal image. A uniform illumination is formed in the fundus; the focusing optical path is used for performing refractive compensation when forming a retinal image, so as to ensure the clarity of the photograph; the fixation optical path is used for stabilizing the human eye. The device can save the light splitting element between the imaging light path and the illumination light path, and separate the two light paths in space by an off-axis method, and both light paths form a converging circular light spot on the human cornea, without the need for annular illumination , which greatly simplifies the processing and adjustment of the lighting light path.

Description

Multi-mode double-off-axis retina imaging device and method

Technical Field

The invention belongs to the technical field of ophthalmic imaging, and relates to an eyeground retina imaging device and method which take white light and near-infrared LEDs as illumination light sources and image through an optical lens and a digital camera, in particular to a multimode double-off-axis retina imaging device and method.

Background

Retinal imaging techniques have been widely used in the field of fundus disease detection. The medicine shows that the ophthalmology disease and the systemic disease of the body can generate pathological changes on the retina of the eye fundus at the early stage of the onset. The method can accurately and timely detect retinopathy, play an important role in early diagnosis of diseases, and provide a good platform for pathological research of serious diseases.

The most common diagnostic device for fundus diseases is a fundus camera, the optical system of which is composed of at least two modules of an imaging light path and an illumination light path, and some of which also comprise modules of an alignment light path, a focusing light path and the like. Through years of research and development, two optical structures are gradually formed: an exterior lighting structure and an interior lighting structure. The main difference between the two structures is that the spectroscope in the external illumination structure is used as a light splitting element of an illumination light path and an imaging light path, the two light paths do not share a lens group, the internal illumination mode is that a hollow reflector is used as the light splitting element of the two light paths, and the two light paths share an eye objective lens. Compared with the internal illumination structure, the fundus illumination structure has uniform energy and high energy utilization rate, thereby having wider scientific research value and market space. And the structure of external illumination is more suitable for a portable fundus camera and a contact type fundus camera. However, in both the external illumination structure and the internal illumination structure, the light splitting element is present and the coaxial optical system is adopted, namely, the visual axis of the human eye, the optical axis of the illumination light path and the optical axis of the imaging light path are coincident.

The light emitted by the illumination light path can be reflected in the central area of the cornea of the human eye to form stray light, and the imaging quality of the fundus retina is seriously affected. For stray light formed by reflection of human eyes, annular illumination is generally adopted to avoid the stray light. Namely, the illumination light path forms an illumination light ring at the cornea of the human eye. The area within the ring of light is free of illumination light, and fundus reflection light exits from the center of this area and enters the imaging optical path. Under the design, the illumination light path and the imaging light path are separated in space and do not interfere with each other. However, in practical situations, it is often necessary to have a high quality illumination path in order to form a high quality light ring. The optical path lenses have the advantages of multiple lenses, precise structure, high installation and adjustment difficulty, large volume and high cost.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a retina imaging device with a double-off-axis structure, which can omit a light splitting element between an imaging light path and an illumination light path, and can separate the two light paths in space by an off-axis method, wherein the two light paths form converged circular light spots on the cornea of human eyes, so that annular illumination is not needed, and the processing and adjusting difficulty of the illumination light path is greatly simplified. The device can shoot large-field color and near-infrared images of the eye fundus retina under the condition of no mydriasis, and can also realize fluorescence radiography imaging and autofluorescence imaging through the combination of different optical filters to form various examination modes.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

a multi-mode dual off-axis retinal imaging device, characterized by: the device comprises an imaging light path, an illumination light path, a focusing light path and a fixation light path; the imaging optical path is used for forming a retina image, and the illumination optical path is used for forming uniform illumination on the fundus; the focusing light path is used for performing refraction compensation when a retina image is formed, so that the definition of a shot picture is ensured; the fixation optical path is used for stabilizing human eyes. When the eye fixation device works, after the vision fixation light path stabilizes human eyes, the infrared LEDs in the illumination light path and the focusing light path are simultaneously lightened, and the imaging light path forms an infrared eye fundus image. The alignment in the direction X, Y is completed based on the infrared fundus image. Meanwhile, focusing in the Z direction is completed according to a slit pattern formed by the focusing light path. Finally, the white light LED in the illumination light path flashes, and the imaging light path forms a color fundus image.

And the imaging light path comprises an eyepiece group, an imaging optical filter, an imaging lens group and an imaging camera, the imaging lens group is arranged at the upper end in front of the eyepiece group, and the imaging optical filter and the imaging camera are sequentially arranged right in front of the imaging lens group from near to far.

The ocular lens group comprises a retina objective lens, a relay lens and an aperture diaphragm which are sequentially arranged from back to front, wherein the retina objective lens is used for collecting return light of the fundus of the human eye and forming a clear intermediate image surface; the relay lens and the retina objective lens enable a pupil of a human eye and the aperture diaphragm sheet to form an object-image conjugate relation, and enable light rays emitted from the aperture diaphragm sheet to be approximate to parallel light;

the retina objective lens is an optical lens group, the number of the lenses is 1-3, the lens is an aspheric lens when in a single lens, the lenses are spherical lenses when in multiple lenses, and at least one cemented lens is included;

the relay lens is an optical lens group, the number of the lenses is 1-2, and at least one cemented lens is included;

the aperture diaphragm is a black sheet, round holes with different diameters are respectively arranged on the black sheet at intervals, the round holes arranged on the left and the right form an illumination light path aperture and an imaging light path hole respectively, a fixation light path hole is arranged between the illumination light path aperture and the imaging light path hole, and focusing light path holes are arranged at the upper end and the lower end of the fixation light path hole;

the imaging filter is a band-pass optical coating filter, the working angle is 0 degree, the cut-off depth is not lower than OD4, and the function of the imaging filter is to cut off light rays of other wave bands while passing through fluorescence excited by illumination light to form a fluorescence image with high contrast.

And the imaging lens group is an optical lens group, the number of the lenses is 1-5, the imaging lens group at least comprises 2 cemented lenses, and the imaging lens group is used for re-imaging a middle image plane formed by the retina objective lens, correcting residual aberration and forming a clear retina image on the digital camera.

Moreover, the imaging camera is a CCD or CMOS camera, the photosensitive area is not less than 1/3 inches, and the resolution is not less than 300 ten thousand pixels.

And the illumination light path comprises a white light LED, an infrared LED, an illumination light filter, a first condenser lens, a second condenser lens, an illumination beam splitter, an illumination lens group and an eyepiece group, the illumination lens group is arranged at the lower end of the front of the eyepiece group, the illumination beam splitter, the first condenser lens, the illumination light filter and the white light LED are sequentially arranged right in front of the illumination lens group from back to front, and the second condenser lens and the infrared LED are sequentially arranged right below the illumination beam splitter from top to bottom.

Moreover, the white light LED is a patch type LED, the color temperature range is 4000K-5500K, and the color rendering index is not lower than 80%;

the infrared LED is a near-infrared band patch type LED, has a central wavelength range of 830-980 nm, is an infrared monitoring light source and is used for performing infrared imaging on the eye fundus before photographing;

the illumination optical filter is a band-pass optical coating optical filter, the working angle is 0 degrees, the cut-off depth is not lower than OD4, and the function of the illumination optical filter is to separate the optical wave band required by fluorescence imaging from the white light LED and project the optical wave band on a condenser lens;

the first condenser lens and the second condenser lens are optical lens groups, the number of the lenses is 1-2, and the first condenser lens and the second condenser lens are used for collecting light rays emitted by the white light LED light source and the infrared LED light source and projecting the light rays onto the illuminating lens groups through the illuminating beam splitter.

The illumination light splitting sheet is a dichroic optical transflective lens, the working angle is 45 degrees, the illumination light splitting sheet has the function of reflecting visible light and transmitting near infrared light at the same time, so that the visible light and the near infrared light which are incident into the illumination light splitting sheet from mutually perpendicular directions are transmitted along the same direction after passing through the lens, and the purpose of beam combination is achieved;

the illuminating lens group is an optical lens group, the number of the lenses is 1-2, and the illuminating lens group is used for projecting light collected by the condensing lens to human eyes through the ocular lens group to form uniform illumination on the eyeground.

The focusing light path comprises a focusing light source, a collimating lens, a slit diaphragm and an eyepiece group, and the slit diaphragm, the collimating lens and the focusing light source are sequentially arranged right in front of the eyepiece group from near to far;

the focusing light source is a direct-insert near-infrared point light source LED, the central wavelength range is 830-980 nm, and the function of the focusing light source is to illuminate a slit through a collimating lens;

the collimating lens is an optical lens, has a focal length range of 5-25 mm and a numerical aperture not greater than 0.5, and is used for collecting light rays emitted by the focusing light source and projecting the light rays onto the ocular lens group through the slit;

the width of the slit diaphragm is not more than 0.2mm, and the length-width ratio is not less than 3: the eye diopter compensation method comprises the following steps that 1, an image of a slit is formed on the fundus through an objective lens, the diopter state of human eyes is judged according to the relative position of two slit images, the distance between a retina objective lens and a relay lens is changed to perform diopter compensation, and the definition of a shot picture is guaranteed.

The fixation light path comprises a fixation light source, a collimating lens and an ocular lens group, the collimating lens is arranged right in front of the ocular lens group, and the fixation light source is arranged right in front of the collimating lens;

the fixation light source is a direct-insert visible light LED, the central wavelength range is 500 nm-650 nm, and the fixation light source is used for providing a fixation target for human eyes and stabilizing the human eyes.

The collimating lens is an optical lens, the focal length range is 5-25 mm, the numerical aperture is not more than 0.5, and the collimating lens is used for collecting light rays emitted by the fixation light source and projecting the light rays to the eyeground through the ocular lens group.

A method of multi-mode dual off-axis retinal imaging, characterized by: the method comprises the following steps:

step 1, a vision fixation light source emits light rays, the light rays are projected to the eyeground through a vision fixation light path, and after a human eye observes the vision fixation light source, the stability is kept;

step 2, infrared LED emits 850nm near infrared light, enters the ocular lens group from the aperture of the illumination light path in the aperture diaphragm after passing through the second condenser lens, the illumination beam splitter and the illumination lens group, forms a convergent light spot on the cornea of human eyes through the refraction of the relay lens and the retinal objective lens, the near infrared light continuously transmits forwards and is scattered at the same time, and uniform illumination is formed on the eyeground;

step 3, the fundus retina reflects the illumination light, and the illumination light can pass through the other side of the cornea and enter the imaging light path after being emitted from the pupil;

the channels of the illumination light path and the imaging light path on the cornea are separated from each other and do not interfere with each other;

step 4, after the light reflected by the eyeground enters an imaging light path, the light passes through an imaging aperture diaphragm and is converged on an imaging camera by an imaging lens group to form an image;

meanwhile, the focusing light source also emits light rays, images of 2 slits are projected on the eyeground, the slit images are captured by the imaging camera and are superposed on the eyeground images, refraction compensation is carried out on human eyes according to the relative positions of the slits, and the slits are aligned after the refraction compensation is finished;

and 5, closing the focusing light source and the infrared LED, and lightening the white light LED for flashing, wherein light rays emitted by the white light LED can follow the path of the light rays emitted by the infrared LED again, and finally a clear color fundus image is formed on the imaging CCD.

The invention has the advantages and positive effects that:

the multimode double off-axis retina imaging device omits a light splitting element shared by an illumination light path and an imaging light path. The imaging light path and the illumination light path are symmetrically distributed on two sides of the cornea of the eye by taking the visual axis of the eye as the center, and are not interfered with each other, so that the imaging quality of the retina of the eye ground is ensured. The invention adopts a brand-new optical design, and the traditional schemes of 'polarization imaging' and 'black spot plate' are not needed to be used for eliminating stray light. The system has compact and simple structure, and is convenient for production, debugging and cost control.

The invention has a plurality of working modes, and can shoot fundus color images, infrared images, fluorescence contrast images and autofluorescence images through the combination of different optical filters.

Drawings

FIG. 1 is a schematic (top view) view of the imaging and illumination optical path configuration of the present invention;

FIG. 2 is a schematic diagram showing the distribution of the aperture of each optical path in the aperture diaphragm of the present invention;

FIG. 3 is a schematic structural diagram (front view) of a focusing light path and a fixation light path according to the present invention;

FIG. 4 is a schematic diagram of the position of the double slits of the focusing optical path under different diopters (fig. a is far vision, fig. b is near vision, and fig. c is front vision);

fig. 5 is a schematic diagram showing the comparison of the positions of the imaging channel and the illumination channel of the human eye on the cornea in the conventional annular illumination method and the illumination method of the present invention (fig. d is the conventional annular illumination method, and fig. e is the illumination method of the present invention).

Description of the reference numerals

The system comprises ahuman eye 1, aretina object 2, arelay lens 3, anaperture diaphragm 4, a cementedlens 5, animaging filter 6, animaging camera 7, anillumination beam splitter 8, afirst condenser 9, anillumination filter 10, a white light LED11, asecond condenser 12, an infrared LED13, a focusinglight path aperture 14, a fixationlight path aperture 15, an imaginglight path aperture 16, an illuminationlight path aperture 17, aslit diaphragm 18, acollimator 19, a focusinglight source 20 and afixation light source 21.

Detailed Description

The embodiments of the invention are described in further detail below with reference to the following figures:

the optical system of the present embodiment is composed of an imaging optical path, an illumination optical path, a focusing optical path, and a fixation optical path. The imaging optical path includes an eyepiece group, animaging filter 6, an imaging lens group, and animaging camera 7, as shown in fig. 1.

The ocular lens group comprises a retinaobjective lens 2, arelay lens 3 and anaperture diaphragm 4, and is a shared component of all light paths.

Wherein, the retina objective lens is a double-sided aspherical lens, the surface type is a double-convex lens, and the focal length is about 25 mm. Which serves as a collection of return light from the fundus of thehuman eye 1 and forms a good quality intermediate image plane. In consideration of cost control, the retina objective lens is made of low-melting-point glass and can be subjected to die pressing.

Wherein, the relay lens contains 2 optical lens, and wherein 1 is double cemented lens, and the combined focal length is about 150 mm. The function of the lens is to make the pupil of human eye and the aperture diaphragm form object-image conjugate relation together with the retina objective lens, and make the light emergent from the aperture diaphragm approximate to parallel light.

The aperture diaphragm is a black sheet, which comprises 5 round holes with different diameters and is used as aperture diaphragms of different light paths. As shown in FIG. 2, the diameter of theaperture 17 of the illumination light path is 10mm, the diameter of theaperture 16 of the imaging light path is 8mm, the two apertures are horizontally distributed at a distance of 16 mm. The diameters of 14 light diaphragms of focusing light path apertures are 4mm, the focusing light path apertures are 2, the focusing light path apertures are vertically distributed at intervals of 16mm, the fixed viewing light path apertures are 15mm, and the fixed viewing light path apertures are located at the center of aperture diaphragm sheets, namely on the optical axis of a system.

The imaging filter is a band-pass optical coating filter, the working angle is 0 degree, and the cut-off depth isOD 6. The function of the fluorescence imaging device is to cut off light rays in other wave bands while transmitting fluorescence excited by illumination light, and to form a high-contrast fluorescence image. The imaging filter used for fluorescence radiography can transmit green light of 510 nm-550 nm, and the imaging filter used for autofluorescence can transmit red light of 620 nm-670 nm.

The imaging lens group is an optical lens group and consists of 2 cementedtriplet lenses 5, and the combined focal length is 45 mm. The function of the digital image processing system is to re-image the intermediate image plane formed by the retina objective lens, correct residual aberration and form a clear retina image on the digital camera. The objective of using a tri-cemented lens is to better correct for secondary chromatic aberration.

The imaging camera is a CMOS camera, with a photosensitive area of 2/3 inches and a resolution of 500 ten thousand pixels.

The illumination light path is kohler type illumination, and comprises a white light LED11, an infrared LED13, anillumination light filter 10, afirst condenser lens 9, asecond condenser lens 12, anillumination beam splitter 8, an illumination lens group and an eyepiece group, as shown in FIG. 1.

The white light LED is a patch LED. Color temperature 4200K, color rendering index 92%. The fluorescent imaging light source is a color imaging light source and is also an imaging light source with fluorescence contrast and autofluorescence functions.

Wherein, the infrared LED is a near-infrared band patch type LED. The central wavelength is 850 nm. The infrared monitoring light source is used for carrying out infrared imaging on the eye fundus before photographing, and is convenient to align and focus.

The lighting filter is a band-pass optical coating filter, the working angle is 0 degree, and the cut-off depth isOD 4. The function of the system is to separate the light wave band required by fluorescence imaging from the white light LED and project the light wave band on the condenser lens. Fluorescence imaging and autofluorescence use different illumination filters, respectively. The illumination filter used for the fluorescence radiography function can transmit 460-490 nm blue light. The illuminating filter with the autofluorescence function can transmit green light of 530-580 nm.

Wherein, the condensing lens is an optical lens group and consists of 2 plano-convex lenses, and the combined focal length is 25 mm. The LED light source module has the function of collecting light rays emitted by the LED light source and projecting the light rays to the illuminating lens group through the illuminating beam splitter.

Wherein, the illumination beam splitter is a dichroic optical transflective lens, and the working angle is 45 degrees. The function of the LED is to reflect the visible light emitted by the white light LED and transmit the near infrared light of 850nm emitted by the near infrared LED. Visible light and near infrared light which are incident into the lens from mutually vertical directions are transmitted along the same direction after passing through the lens, so that the purpose of beam combination is achieved.

The lighting lens group is an optical lens group and consists of 1 plano-convex lens and 1 meniscus lens, and the combined focal length is 50 mm. The function is to project the light collected by the condenser lens to human eyes through the ocular lens group, so as to form uniform illumination on the eyeground.

The focusing light path includes a focusinglight source 20, a collimatinglens 19, aslit diaphragm 18 and an eyepiece set, as shown in fig. 3.

The focusing light source is a direct-insert near-infrared point light source LED, and the central wavelength range is 850 nm. The effect of which is to illuminate the slit by means of a collimator lens.

Wherein, the collimating lens is an optical lens, the focal length is 15mm, and the numerical aperture is 0.2. The function of the focusing lens is to collect the light emitted by the focusing light source and project the light to the ocular lens group through the slit.

Wherein the slit width is 0.1mm, the aspect ratio is 5: 1. the objective lens is used for forming an image of a slit on the fundus of the eye. The diopter state of the human eyes can be judged according to the relative positions of the two slit images. As shown in fig. 4, the white rectangular blocks are slits, and the case of far vision is shown when the left slit is higher than the right slit in fig. a, and the case of near vision is shown when the left slit is lower than the right slit in fig. b. Refractive compensation is performed by varying the distance between the retinal objective lens and the relay lens. When the compensation is completed, the left and right slits are exactly aligned as shown in fig. c, which is the front view. In addition, since the reflectivity of the optic disc is high, when the optic disc is located in the fundus central region, the recognition of the double slit may be affected. Therefore, in order to avoid the interference that the optic disk may bring, the design position of the double slit is not at the fundus center position but at a position lower than the center.

The fixation light path comprises afixation light source 21, a collimating lens and an eyepiece group, as shown in fig. 3.

Wherein, the fixation light source is a direct-insert visible light LED with a central wavelength of 590 nm. The function of the eye-protecting device is to provide a fixed target for the human eye and stabilize the human eye.

Wherein, the collimating lens is an optical lens, the focal length is 15mm, and the numerical aperture is 0.2. The function of the device is to collect the light emitted by the fixation light source and project the light to the eyeground through the ocular lens group.

When the embodiment works, the fixation light source emits light and projects the light to the eyeground through the fixation light path. After the human eyes observe the fixation light source, the fixation light source is kept stable. The infrared LED emits near infrared light of 850nm, and the near infrared light passes through the condensing lens, the illumination beam splitter and the illumination lens group and then enters the ocular lens group from the aperture of the illumination light path in the aperture diaphragm. A convergent point is formed on the cornea of the human eye through refraction of the relay lens and the retinal objective lens. The light continues to spread forward while spreading out, allowing uniform illumination at the fundus.

The fundus retina reflects the light rays, exits the pupil, passes through the other side of the cornea, and enters the imaging optical path. The illumination and imaging paths are separated from each other on the cornea, and do not interfere with each other, as shown in e of fig. 5, and d is a conventional ring illumination method. After entering the imaging light path, the light passes through the imaging aperture diaphragm and is converged on the imaging camera by the imaging lens group to form an image.

Meanwhile, the focusing light source also emits light rays, and images of 2 slits are projected on the fundus. The slit image is also captured by the imaging camera and superimposed on the fundus image. Refractive compensation is performed on the human eye based on the relative positions of the slits. The slits are aligned after completion.

And finally, closing the focusing light source and the infrared LED, and lightening the white light LED for flashing. The light emitted by the white light LED can follow the path of the light emitted by the infrared LED again, and finally a clear color fundus image is formed on the imaging CCD.

Although the embodiments of the present invention and the accompanying drawings are disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore the scope of the invention is not limited to the disclosure of the embodiments and the accompanying drawings.

Claims (10)

1. A multi-mode dual off-axis retinal imaging device, characterized by: the device comprises an imaging light path, an illumination light path, a focusing light path and a fixation light path; the imaging optical path is used for forming a retina image, and the illumination optical path is used for forming uniform illumination on the fundus; the focusing light path is used for performing refraction compensation when a retina image is formed, so that the definition of a shot picture is ensured; the fixation optical path is used for stabilizing human eyes.

2. A multi-mode dual off-axis retinal imaging device according to claim 1, wherein: the imaging light path comprises an eyepiece group, an imaging optical filter, an imaging lens group and an imaging camera, the imaging lens group is arranged at the upper end in front of the eyepiece group, and the imaging optical filter and the imaging camera are sequentially arranged right in front of the imaging lens group from near to far.

3. A multi-mode dual off-axis retinal imaging device according to claim 2, wherein: the eyepiece group comprises a retina objective lens, a relay lens and an aperture diaphragm, which are sequentially arranged from back to front, wherein the retina objective lens is used for collecting return light of the fundus of a human eye and forming a clear intermediate image surface; the relay lens and the retina objective lens enable a pupil of a human eye and the aperture diaphragm sheet to form an object-image conjugate relation, and enable light rays emitted from the aperture diaphragm sheet to be approximate to parallel light.

4. A multi-mode dual off-axis retinal imaging device according to claim 3, wherein: the aperture diaphragm sheet is a black sheet, round holes with different diameters are respectively arranged on the black sheet at intervals, the round holes arranged on the left and the right form an illumination light path aperture and an imaging light path hole respectively, a fixation light path hole is arranged between the illumination light path aperture and the imaging light path hole, and focusing light path holes are arranged at the upper end and the lower end of the fixation light path hole.

5. A multi-mode dual off-axis retinal imaging device according to claim 2, wherein: the imaging lens group is an optical lens group, the number of the lenses is 1-5, the imaging lens group at least comprises 2 cemented lenses, and the imaging lens group is used for re-imaging a middle image plane formed by the retinal objective lens, correcting residual aberration and forming a clear retinal image on the digital camera.

6. A multi-mode dual off-axis retinal imaging device according to claim 1, wherein: the illumination light path comprises a white light LED, an infrared LED, an illumination light filter, a first condenser lens, a second condenser lens, an illumination beam splitter, an illumination lens group and an eyepiece lens group, the illumination lens group is arranged at the lower end of the front of the eyepiece lens group, the illumination beam splitter, the first condenser lens, the illumination light filter and the white light LED are sequentially arranged in front of the illumination lens group from back to front, and the second condenser lens and the infrared LED are sequentially arranged under the illumination beam splitter from top to bottom.

7. A multi-mode dual off-axis retinal imaging device according to claim 6, wherein: the white light LED is a patch type LED, the color temperature range is 4000K-5500K, and the color rendering index is not lower than 80%;

the infrared LED is a near-infrared band patch type LED, has a central wavelength range of 830-980 nm, is an infrared monitoring light source and is used for performing infrared imaging on the eye fundus before photographing;

the illumination optical filter is a band-pass optical coating optical filter, the working angle is 0 degrees, the cut-off depth is not lower than OD4, and the function of the illumination optical filter is to separate the optical wave band required by fluorescence imaging from the white light LED and project the optical wave band on a condenser lens;

the first condenser lens and the second condenser lens are optical lens groups, the number of the lenses is 1-2, and the first condenser lens and the second condenser lens are used for collecting light rays emitted by the white light LED light source and the infrared LED light source and projecting the light rays onto the illuminating lens groups through the illuminating beam splitter.

The illumination light splitting sheet is a dichroic optical transflective lens, the working angle is 45 degrees, the illumination light splitting sheet has the function of reflecting visible light and transmitting near infrared light at the same time, so that the visible light and the near infrared light which are incident into the illumination light splitting sheet from mutually perpendicular directions are transmitted along the same direction after passing through the lens, and the purpose of beam combination is achieved;

the illuminating lens group is an optical lens group, the number of the lenses is 1-2, and the illuminating lens group is used for projecting light collected by the condensing lens to human eyes through the ocular lens group to form uniform illumination on the eyeground.

8. A multi-mode dual off-axis retinal imaging device according to claim 1, wherein: the focusing light path comprises a focusing light source, a collimating lens, a slit diaphragm and an eyepiece group, and the slit diaphragm, the collimating lens and the focusing light source are sequentially arranged right in front of the eyepiece group from near to far;

the focusing light source is a direct-insert near-infrared point light source LED, the central wavelength range is 830-980 nm, and the function of the focusing light source is to illuminate a slit through a collimating lens;

the collimating lens is an optical lens, has a focal length range of 5-25 mm and a numerical aperture not greater than 0.5, and is used for collecting light rays emitted by the focusing light source and projecting the light rays onto the ocular lens group through the slit;

the width of the slit diaphragm is not more than 0.2mm, and the length-width ratio is not less than 3: the eye diopter compensation method comprises the following steps that 1, an image of a slit is formed on the fundus through an objective lens, the diopter state of human eyes is judged according to the relative position of two slit images, the distance between a retina objective lens and a relay lens is changed to perform diopter compensation, and the definition of a shot picture is guaranteed.

9. A multi-mode dual off-axis retinal imaging device according to claim 1, wherein: the fixation light path comprises a fixation light source, a collimating lens and an eyepiece group, the collimating lens is arranged right in front of the eyepiece group, and the fixation light source is arranged right in front of the collimating lens;

the fixation light source is a direct-insert visible light LED, the central wavelength range is 500 nm-650 nm, and the fixation light source is used for providing a fixation target for human eyes and stabilizing the human eyes.

The collimating lens is an optical lens, the focal length range is 5-25 mm, the numerical aperture is not more than 0.5, and the collimating lens is used for collecting light rays emitted by the fixation light source and projecting the light rays to the eyeground through the ocular lens group.

10. A method of multi-mode dual off-axis retinal imaging, characterized by: the method comprises the following steps:

step 1, a vision fixation light source emits light rays, the light rays are projected to the eyeground through a vision fixation light path, and after a human eye observes the vision fixation light source, the stability is kept;

step 2, infrared LED emits 850nm near infrared light, enters the ocular lens group from the aperture of the illumination light path in the aperture diaphragm after passing through the second condenser lens, the illumination beam splitter and the illumination lens group, forms a convergent light spot on the cornea of human eyes through the refraction of the relay lens and the retinal objective lens, the near infrared light continuously transmits forwards and is scattered at the same time, and uniform illumination is formed on the eyeground;

step 3, the fundus retina reflects the illumination light, and the illumination light can pass through the other side of the cornea and enter the imaging light path after being emitted from the pupil;

the channels of the illumination light path and the imaging light path on the cornea are separated from each other and do not interfere with each other;

step 4, after the light reflected by the eyeground enters an imaging light path, the light passes through an imaging aperture diaphragm and is converged on an imaging camera by an imaging lens group to form an image;

meanwhile, the focusing light source also emits light rays, images of 2 slits are projected on the eyeground, the slit images are captured by the imaging camera and are superposed on the eyeground images, refraction compensation is carried out on human eyes according to the relative positions of the slits, and the slits are aligned after the refraction compensation is finished;

and 5, closing the focusing light source and the infrared LED, and lightening the white light LED for flashing, wherein light rays emitted by the white light LED can follow the path of the light rays emitted by the infrared LED again, and finally a clear color fundus image is formed on the imaging CCD.

Images