Retina imaging system

Abstract

The invention provides a retina imaging system, and relates to the technical field of life science. The system comprises a luminous source, a dodging collimation system, a polarization system, a digital micromirror array DMD, a first relay lens group, a turning system, an objective lens system, a second relay lens group and a CMOS camera, the luminous source, the dodging collimation system and the polarization system are arranged in sequence, and the objective lens system, the turning system, the second relay lens group and the CMOS camera are arranged in sequence. The first relay lens group is located on a light path between the polarization system and the turning system, and the digital micromirror array DMD is located on the side, away from the first relay lens group, of the polarization system. The DMD can improve the light intensity uniformity of the illumination system by utilizing the consistency of the micromirror array of the DMD, and an annular light scanning mode is adopted, so that the lens surface reflection is effectively reduced, and the imaging quality is improved. According to the retina imaging system, the overall combined structure of the light path system is optimized, the number of elements of the light path system is reduced, the size is reduced, the installation and debugging difficulty is lowered, and the cost is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of life science technology, and in particular to a retinal imaging system. Background Technology

[0002] Traditional fundus imaging and SLO ophthalmoscopy retinal imaging technologies are relatively mature. Traditional fundus imaging uses a ring light to illuminate the fundus, and the reflected light is imaged on a CMOS camera via an imaging system. The main problem with this technology is the presence of stray light, which reduces image clarity and results in a low signal-to-noise ratio. Traditional SLO technology, to avoid this stray light problem, uses a laser point source for two-dimensional scanning. The receiver employs a pinhole confocal principle to block stray light from entering the detector, improving the signal-to-noise ratio. However, the high-speed scanning of the resonator places high demands on the system's confocal accuracy, leading to higher costs.

[0003] The applicant has discovered at least the following technical problems in the prior art: the number of illumination components in the existing imaging system is large, which leads to a decrease in light transmittance and relatively high cost, as well as large installation errors. In addition, the TIR prism used in the existing imaging system is difficult to install and adjust, and has a large angle error. Furthermore, the spatial layout of the existing imaging system makes it large in size. Summary of the Invention

[0004] The purpose of this invention is to provide a retinal imaging system to solve the technical problems existing in the prior art. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are described in detail below.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A retinal imaging system includes a light source, a homogenizing and collimating system, a polarization system, a digital micromirror array (DMD), a first relay lens group, a deflection system, an objective lens system, a second relay lens group, and a CMOS camera. The light source, the homogenizing and collimating system, and the polarization system are arranged sequentially. The objective lens system, the deflection system, the second relay lens group, and the CMOS camera are also arranged sequentially. The first relay lens group is located in the optical path between the polarization system and the deflection system. The digital micromirror array (DMD) is located on the side of the polarization system away from the first relay lens group.

[0007] Preferably, the light source is an infrared LED.

[0008] Preferably, the uniform light collimation system includes a light guide rod, a first Fresnel lens, and a second Fresnel lens arranged sequentially along the optical path from the light source to the polarization system.

[0009] Preferably, the polarization system includes a first polarizing beam splitter, a first quarter-wave plate, and a linear polarizer. The first polarizing beam splitter is disposed in the optical path between the digital micromirror array (DMD) and the first relay lens group. The first quarter-wave plate is disposed in the optical path between the first polarizing beam splitter and the DMD. The linear polarizer is disposed in the optical path between the first polarizing beam splitter and the first relay lens group.

[0010] Preferably, the first relay lens group includes a first lens, a second lens, an annular stop, a third lens, and a fourth lens arranged sequentially in the optical path from the polarization system to the deflection system.

[0011] Preferably, the deflection system is a second polarizing beam splitter.

[0012] Preferably, the objective lens system includes an eyepiece objective and a second quarter-wave plate arranged sequentially in the optical path from the deflection system to the human eye.

[0013] Preferably, the second relay lens group includes a fifth lens, a circular aperture, and a sixth lens arranged sequentially in the optical path from the deflection system to the CMOS camera.

[0014] Preferably, the diameter of the output end of the light guide rod is larger than the diameter of the incident end.

[0015] Preferably, the diameter of the exit end section of the light guide rod is twice the diameter of the incident end section.

[0016] The beneficial effects of this invention are: the retinal imaging system reduces the number of components by using Fresnel lenses with high transmittance and low cost.

[0017] The retinal imaging system effectively reduces system assembly and adjustment errors and manufacturing difficulty by using a polarizing beam splitter (PBS) instead of the existing TIR prism.

[0018] The retinal imaging system employs a digital micromirror array (DMD) to form a DMD ring scanning mode. The DMD utilizes the consistency of its own micromirror array to improve the light intensity uniformity of the illumination system and can be combined with the ring aperture of the traditional fundus mirror system. By using a ring light scanning mode and polarizing light elements, it effectively reduces lens surface reflection and improves image quality.

[0019] The retinal imaging system optimizes the overall structure of the optical path system, simplifies the number of components, reduces the size, lowers the difficulty of installation and debugging, and effectively reduces costs. Attached Figure Description

[0020] 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 these drawings without creative effort.

[0021] Figure 1 This is a system framework diagram of the present invention;

[0022] Figure 2 This is a system layout diagram of the present invention;

[0023] Figure 3 This is a diagram illustrating the conjugate relationships of the present invention;

[0024] 1. Light source in the diagram;

[0025] 2. Uniform collimation system; 21. Optical guide rod; 22. First Fresnel lens; 23. Second Fresnel lens;

[0026] 3. Polarization system; 31. First polarizing beam splitter; 32. First quarter-wave plate; 33. Linear polarizer;

[0027] 4. Digital Micromirror Array (DMD);

[0028] 5. First relay lens group; 51. First lens; 52. Second lens; 53. Annular aperture; 54. Third lens; 55. Fourth lens;

[0029] 6. Transition system;

[0030] 7. Objective lens system; 71. Eyepiece objective lens; 72. Second quarter-wave plate;

[0031] 8. Second relay lens group; 81. Fifth lens; 82. Circular aperture; 83. Sixth lens;

[0032] 9. CMOS camera;

[0033] 101. Cornea; 102. Fundus. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] In the description of this invention, it should be understood that the terms "center," "side," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicate the orientation or positional relationship based on the appendix. Figure 1 The orientations or positional relationships shown are for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0036] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Reference Figures 1 to 3 The present invention provides a retinal imaging system, including a light source 1, a uniform collimation system 2, a polarization system 3, a digital micromirror array (DMD) 4, a first relay lens group 5, a transition system 6, an objective lens system 7, a second relay lens group 8, and a CMOS camera 9. The light source 1, the uniform collimation system 2, and the polarization system 3 are arranged sequentially, as are the objective lens system 7, the transition system 6, the second relay lens group 8, and the CMOS camera 9. The first relay lens group 5 is located in the optical path between the polarization system 3 and the transition system 6, and the digital micromirror array (DMD) 4 is located on the side of the polarization system 3 away from the first relay lens group 5.

[0038] The light source 1 is an infrared LED, which can emit near-infrared light toward the uniform light collimation system 2.

[0039] The uniform light collimation system 2 includes a light guide rod 21, a first Fresnel lens 22, and a second Fresnel lens 23 arranged sequentially along the optical path from the light source 1 to the polarization system 3.

[0040] In this embodiment, firstly, the diameter of the output end cross-section of the light guide rod 21 is preferably larger than the diameter of the incident end cross-section. Furthermore, the diameter of the output end cross-section of the light guide rod 21 is twice the diameter of the incident end cross-section. With this setting, the cross-sectional area of ​​the output end of the light guide rod 21 is four times the cross-sectional area of ​​the incident end. According to the principle of optical invariants in the lighting system, the sine of the beam angle at the output end is one-quarter of the beam angle at the incident end, which is beneficial for further collimation of the beam and improves the performance.

[0041] Fresnel lenses have higher transmittance and lower cost. By setting a first Fresnel lens 22 and a second Fresnel lens 23 in the light homogenization and collimation system 2, the existing lens group can be replaced, the number of components can be reduced, and the light can be further collimated and homogenized. The first Fresnel lens 22 and the second Fresnel lens 23 are preferably made of PMMA, which has a lower cost.

[0042] The uniform light collimation system 2, by employing a combination structure of light guide rod 21, first Fresnel lens 22 and second Fresnel lens 23, can be optimized to further improve transmittance and uniform light collimation.

[0043] The polarization system 3 includes a first polarizing beam splitter 31, a first quarter-wave plate 32, and a linear polarizer 33. The first polarizing beam splitter 31 is disposed in the optical path between the digital micromirror array (DMD4) and the first relay lens group 5. The first quarter-wave plate 32 is disposed in the optical path between the first polarizing beam splitter 31 and the DMD4. The linear polarizer 33 is disposed in the optical path between the first polarizing beam splitter 31 and the first relay lens group 5.

[0044] The first polarizing beam splitter 31 is formed by bonding the bottom edges of two 45-degree isosceles right-angle prisms. The inclined surface is coated with a polarizing beam splitting medium film, and the right-angle surface is coated with an anti-reflection film to reduce reflection loss. Its working principle is based on the polarization state separation of linearly polarized light. In the incident light, S-polarized light (vertically polarized) is reflected, and P-polarized light (parallel polarized) is transmitted, realizing beam splitting in the 90-degree direction.

[0045] The Digital Micromirror Array (DMD4) is an optical switching device based on microelectromechanical systems (MEMS) technology. It consists of a large number of deflectable micromirrors. This device can control the micromirrors to deflect at certain positive and negative angles through electrostatic drive to achieve the switching on and off of the optical path. The DMD4 can form a DMD ring scanning mode. The consistency of the DMD's own micromirror array can improve the light intensity uniformity of the illumination system. It can also be combined with the ring aperture of the traditional fundus lens system. By adopting a ring light scanning mode and polarizing light elements, it can effectively reduce lens surface reflection and improve image quality.

[0046] The first relay lens group 5 includes a first lens 51, a second lens 52, an annular aperture 53, a third lens 54, and a fourth lens 55 arranged sequentially in the optical path from the polarization system 3 to the deflection system 6. The first relay lens group 5 is capable of continuing to transmit optical information.

[0047] The transition system 6 is the second polarization beam splitter, which is formed by bonding the bottom edges of two 45-degree isosceles right-angle prisms. The inclined surface is coated with a polarization beam splitting medium film, and the right-angle surface is coated with an anti-reflection film to reduce reflection loss. Its working principle is based on the polarization state separation of linearly polarized light. In the incident light, S-polarized light (vertical polarization) is reflected, and P-polarized light (parallel polarization) is transmitted, realizing beam splitting in the 90-degree direction.

[0048] The objective system 7 includes an eyepiece objective 71 and a second quarter-wave plate 72 arranged sequentially in the optical path from the deflection system 6 to the human eye.

[0049] The second relay lens group 8 includes a fifth lens 81, a circular aperture 82, and a sixth lens 83 arranged sequentially in the optical path from the deflection system 6 to the CMOS camera 9. The second relay lens group 8 can continue to transmit light information, while the circular aperture 82 can pass through fundus reflected light, corneal reflection, and stray light.

[0050] The CMOS camera 9 is an imaging device that uses a CMOS image sensor, which converts light signals into electrical signals to achieve imaging.

[0051] Reference Figure 1 The diagram shows the system framework of this invention. Its optical path principle is as follows: Light is emitted from the light source 1, passes through the homogenizing and collimating system 2, and enters the first polarizing beam splitter 31 of the polarization system 3. The reflected light is S-polarized and is reflected by the first quarter-wave plate 32 into the digital micromirror array (DMD4). Each micromirror in the DMD4 is supported by a corresponding driving mechanism, allowing for programmable control of the number and position of each micromirror opening and closing. The light reflected from the DMD4 can be considered as individual image point sources, and then passes through the first quarter-wave plate 32 again. The light is transmitted upward through the first polarizing beam splitter 31, becoming P-polarized light. After passing through the linear polarizer 33, it becomes S-polarized light. It is then transmitted sequentially through the first relay lens group 5, reflected by the second polarizing beam splitter of the reversing system 6, and enters the eyepiece objective 71. After passing through the second quarter-wave plate 72, it finally enters the fundus 102. The light reflected from the fundus 102 passes through the second quarter-wave plate 72 again, this time becoming P-polarized light. After passing through the eyepiece objective 71, it is transmitted through the second polarizing beam splitter of the reversing system 6 and enters the second relay lens group 8, finally forming an image on the CMOS camera 9.

[0052] Reference Figure 2The diagram shows the system layout of this invention. Its optical path principle is as follows: Near-infrared light is emitted from an infrared LED, passes sequentially through the light guide rod 21 of the uniform collimation system 2, the first Fresnel lens 22, and the second Fresnel lens 23, and enters the first polarization beam splitter 31 of the polarization system 3. The reflected light is S-polarized and is reflected by the first quarter-wave plate 32 to the digital micromirror array (DMD4). Each micromirror in the DMD4 is supported by a corresponding driving mechanism, allowing for programmable control of the number and position of each micromirror opening and closing. The light reflected from the DMD4 can be considered as individual image point sources, passing again through the first quarter-wave plate 32 and upwards through the first polarization beam splitter 31. The polarized light is P-polarized. After passing through the linear polarizer 33, it becomes S-polarized. It is transmitted sequentially through the first lens 51, the second lens 52, the annular aperture 53, the third lens 54, and the fourth lens 55 of the first relay lens group 5. After being reflected by the second polarizing beam splitter of the reversing system 6, it enters the eyepiece objective 71. After passing through the second quarter-wave plate 72, it finally enters the fundus 102. The light reflected from the fundus 102 passes through the second quarter-wave plate 72 again. This time it is P-polarized. After passing through the eyepiece objective 71, it passes through the second polarizing beam splitter of the reversing system 6 and enters the second relay lens group 8. It is transmitted sequentially through the fifth lens 81, the circular aperture 82, and the sixth lens 83, and finally the image is formed on the CMOS camera 9.

[0053] Reference Figure 3 The diagram below illustrates the conjugate relationship of this invention. The optical path principle is as follows: Light reflected from the digital micromirror array (DMD4) can be considered as individual image point sources. It passes through the first quarter-wave plate 32, then upwards through the first polarizing beam splitter 31. The polarized light is P-polarized. After passing through the linear polarizer 33, it becomes S-polarized. It is then transmitted through the first relay lens group 5 (a 4f lens group), reflected by the second polarizing beam splitter of the reversing system 6, and enters the eyepiece objective lens 71. After passing through the second quarter-wave plate 72, the exit pupil is at the cornea 101, where it intersects with the annular aperture of the first relay lens group 5. The light reflected from the fundus 102 is conjugated with the second quarter-wave plate 72, and is now P-polarized. It passes through the eyepiece objective lens 71 and is transmitted through the second polarizing beam splitter of the reversing system 6, entering the second relay lens group 8. The second relay lens group 8 is a 4f lens group, and finally the light is imaged on the CMOS camera 9. The circular aperture 82 in the second relay lens group 8 can pass through the fundus reflected light, corneal reflection, and stray light. The lens reflection will not pass through the second polarizing beam splitter of the reversing system 6.

[0054] Retinal imaging systems reduce the number of components by using Fresnel lenses, which have high transmittance and low cost.

[0055] The retinal imaging system effectively reduces system assembly and adjustment errors and manufacturing difficulty by using a polarizing beam splitter (PBS) instead of the existing TIR prism.

[0056] The retinal imaging system employs a digital micromirror array (DMD) to form a DMD ring scanning mode. The DMD utilizes the consistency of its own micromirror array to improve the light intensity uniformity of the illumination system and can be combined with the ring aperture of the traditional fundus mirror system. By using a ring light scanning mode and polarizing light elements, it effectively reduces lens surface reflection and improves image quality.

[0057] The retinal imaging system optimizes the overall structure of the optical path system, simplifies the number of components, reduces the size, lowers the difficulty of installation and debugging, and effectively reduces costs.

[0058] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A retinal imaging system, characterized in that, The system includes a light source (1), a uniform collimation system (2), a polarization system (3), a digital micromirror array (DMD) (4), a first relay lens group (5), a deflection system (6), an objective lens system (7), a second relay lens group (8), and a CMOS camera (9). The light source (1), the uniform collimation system (2), and the polarization system (3) are arranged in sequence. The objective lens system (7), the deflection system (6), the second relay lens group (8), and the CMOS camera (9) are arranged in sequence. The first relay lens group (5) is located on the optical path between the polarization system (3) and the deflection system (6). The digital micromirror array (DMD) (4) is located on the side of the polarization system (3) away from the first relay lens group (5).

2. The retinal imaging system according to claim 1, characterized in that, The light source (1) is an infrared LED.

3. The retinal imaging system according to claim 1, characterized in that, The uniform light collimation system (2) includes a light guide rod (21), a first Fresnel lens (22) and a second Fresnel lens (23) arranged sequentially on the optical path from the light source (1) to the polarization system (3).

4. The retinal imaging system according to claim 1, characterized in that, The polarization system (3) includes a first polarizing beam splitter (31), a first quarter-wave plate (32), and a linear polarizer (33). The first polarizing beam splitter (31) is disposed in the optical path between the digital micromirror array (DMD) (4) and the first relay lens group (5). The first quarter-wave plate (32) is disposed in the optical path between the first polarizing beam splitter (31) and the digital micromirror array (DMD) (4). The linear polarizer (33) is disposed in the optical path between the first polarizing beam splitter (31) and the first relay lens group (5).

5. The retinal imaging system according to claim 1, characterized in that, The first relay lens group (5) includes a first lens (51), a second lens (52), an annular aperture (53), a third lens (54) and a fourth lens (55) arranged sequentially in the optical path from the polarization system (3) to the deflection system (6).

6. The retinal imaging system according to claim 1, characterized in that, The turning system (6) is a second polarizing beam splitter.

7. The retinal imaging system according to claim 1, characterized in that, The objective system (7) includes an eyepiece objective (71) and a second quarter-wave plate (72) arranged sequentially in the optical path from the deflection system (6) to the human eye.

8. The retinal imaging system according to claim 1, characterized in that, The second relay lens group (8) includes a fifth lens (81), a circular aperture (82) and a sixth lens (83) arranged sequentially in the optical path from the deflection system (6) to the CMOS camera (9).

9. The retinal imaging system according to claim 3, characterized in that, The diameter of the output end of the optical guide rod (21) is larger than the diameter of the incident end.

10. The retinal imaging system according to claim 9, characterized in that, The diameter of the output end of the optical guide rod (21) is twice the diameter of the incident end.

Images