An adaptive optical scanning laser fundus imaging system based on transmission optical elements

Abstract

An adaptive optical scanning laser fundus imaging system based on a transmission optical element relates to a medical imaging diagnostic technology for high-resolution imaging of the retina, in order to solve the problem that the existing fundus imaging system adopts a reflective system, which causes the entire device to be bulky and easily introduces additional optical aberrations. The wavefront sensor of the present invention detects the aberrations of the human eye and the optical system in real time, and uses this as feedback to control the transmission wavefront corrector to perform real-time correction of the aberrations, thereby achieving retinal imaging close to the diffraction limit. The use of a transmission element as the main component of the adaptive optical scanning laser fundus imaging system of the present invention greatly reduces the size of the system and reduces the cost; in addition, the transmission system is easier to control the optical aberrations of the system, which is conducive to improving the imaging quality of the system.

Description

Technical Field

[0001] The present invention relates to a medical imaging diagnosis technology for performing high-resolution imaging of the retina. Background Art

[0002] The retina is the human visual receptor, and retinal diseases often lead to vision loss or even blindness. The retina is also an extension of the human deep tissue and brain. The eye is the only living organ that can directly observe microvessels and deep tissues under non-invasive conditions. Therefore, high-resolution imaging of the retina is an important scientific method for studying retinal diseases, visual mechanisms, and brain cognition. However, the real human eye is not a perfect optical system. As the pupil increases, the eye's aberrations also increase rapidly, and the resolution of the optical imaging system actually decreases. Existing optical designs (such as lens compensation) can only correct for aberrations that we are familiar with, such as myopia and astigmatism, but are powerless to address other aberrations (especially high-order and dynamic aberrations). Due to the influence of human eye aberrations, the resolution of existing retinal imaging systems is greatly limited.

[0003] Adaptive optics is a wavefront correction technology developed in recent decades. It corrects the distorted wavefront in the optical path by adjusting the surface shape of a deformable mirror, thereby improving imaging resolution. Applying adaptive optics technology to fundus retinal imaging technology can correct the human eye aberrations that vary randomly in time and space, thereby achieving high-resolution imaging of the retina of the living human eye close to the diffraction limit.

[0004] U.S. Patent No. 6890076 describes a scanning laser fundus imaging system based on adaptive optics. This system uses a Hartmann wavefront sensor to measure eye aberrations and a reflective deformable mirror as a wavefront corrector to correct these aberrations, thereby improving retinal imaging resolution. Chinese Patent No. ZL20100197028.0 describes a reflective scanning laser fundus imaging system based on adaptive optics, employing a reflective deformable mirror for aberration correction and longitudinal tomography. Chinese Patent No. ZL20120385660.7 describes a dual-wavefront corrector 3D retinal imaging device that uses two reflective deformable mirrors to correct low-order and high-order aberrations, respectively, to improve imaging resolution. However, these adaptive optics scanning fundus imaging systems all employ a reflective optical design, meaning the wavefront corrector is reflective and the primary optical components in the optical path are spherical mirrors, making them reflective systems. However, the use of reflective systems results in a bulky device, hindering miniaturization. Furthermore, reflective systems are more susceptible to introducing additional optical aberrations, which compromises imaging resolution. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that the existing fundus imaging system adopts a reflective system, which makes the entire device bulky and easily introduces additional optical aberrations. An adaptive optical scanning laser fundus imaging system based on a transmissive optical element is proposed.

[0006] The adaptive optical scanning laser fundus imaging system based on a transmissive optical element described in the present invention comprises a laser light source, a collimating lens, a first 4f optical system, a second 4f optical system, a third 4f optical system, a fourth 4f optical system, an aperture, a myopic astigmatism corrector, a transmissive wavefront corrector, a wavefront sensor, a first scanning galvanometer, a second scanning galvanometer, a first beam splitter, a second beam splitter, a dichroic mirror, and a photoelectric detection system;

[0007] The light emitted by the laser light source is collimated by a collimating lens and then passes through an aperture to obtain a parallel light beam of a limited diameter, wherein the aperture is located on the focal plane of the collimating lens; the parallel light beam enters the first 4f optical system and is split by a first beam splitter into a first reflected light and a first transmitted light, and the first reflected light output by the first beam splitter reaches a first scanning galvanometer mirror for further reflection, wherein the first scanning galvanometer mirror is arranged horizontally; the light beam reflected by the first scanning galvanometer mirror enters the second 4f optical system and is incident on a second scanning galvanometer mirror for reflection, wherein the second scanning galvanometer mirror is arranged vertically; the light beam reflected by the second scanning galvanometer mirror then passes through the third 4f optical system and then sequentially passes through a dichroic mirror, a myopic astigmatism corrector, and a transmissive wavefront corrector before entering the human eye and being focused on the retina;

[0008] The reflected light from the human eye returns along the original optical path and passes through the transmissive wavefront corrector, myopia astigmatism corrector, dichroic mirror, 4f optical system No. 3, second scanning galvanometer, 4f optical system No. 2, first scanning galvanometer, and first beam splitter in sequence. The first beam splitter further splits the light into a second reflected light and a second transmitted light. The second transmitted light enters the 4f optical system No. 4. The output light of the 4f optical system No. 4 reaches the second beam splitter, and the output light of the second beam splitter splits the light into a third reflected light and a third transmitted light. The third transmitted light enters the wavefront sensor, and the third reflected light enters the photoelectric detection system.

[0009] The photoelectric detection system reflects the information of the area scanned by the light spot on the retina to form a retinal image;

[0010] The laser light source, the light spot on the retina and the light spot of the photoelectric detection system are conjugate, and the aperture, the first scanning galvanometer, the second scanning galvanometer, the pupil of the human eye, the wavefront sensor and the photoelectric detection system are all on the conjugate plane;

[0011] The correction signal input end of the transmission type wavefront corrector is connected to the correction signal output end of the computer; the sensing signal output end of the wavefront sensor is connected to the sensing signal input end of the computer.

[0012] The present invention uses a wavefront sensor to detect the aberrations of the human eye and the aberrations in the optical path system in real time, and uses this as feedback to control the wavefront corrector to perform real-time correction of the aberrations, thereby achieving retinal imaging close to the diffraction limit.

[0013] The beneficial effect of the present invention is that a transmissive element is used as the main component of the adaptive optical scanning laser fundus imaging system, which greatly reduces the volume of the fundus imaging system and reduces the cost; in addition, the fundus imaging system performs real-time correction of the aberration of the wavefront corrector in the form of feedback, which makes it easier to control optical aberrations and is beneficial to improving the imaging quality of the fundus imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of a first embodiment of an adaptive optical scanning laser fundus imaging system based on a transmissive optical element. DETAILED DESCRIPTION

[0015] Specific implementation method 1: Combination Figure 1 This embodiment describes an adaptive optical scanning laser fundus imaging system based on a transmissive optical element, which includes a laser light source 1, a collimating lens 2, a first 4f optical system, a second 4f optical system, a third 4f optical system, a fourth 4f optical system, an aperture 3, a myopic astigmatism corrector 4, a transmissive wavefront corrector 5, a wavefront sensor 7, a first scanning galvanometer 21, a second scanning galvanometer 22, a first beam splitter 31, a second beam splitter 32, a dichroic mirror 33, and a photoelectric detection system.

[0016] The light emitted by the laser light source 1 is collimated by the collimating lens 2 and then passes through the aperture 3 to obtain a parallel light beam of a limited diameter, and the aperture 3 is located on the focal plane of the collimating lens; after entering the first 4f optical system, the parallel light beam is split into a first reflected light and a first transmitted light by the first beam splitter 31, and the first reflected light output by the first beam splitter 31 reaches the first scanning galvanometer 21 for further reflection, wherein the first scanning galvanometer 21 is arranged horizontally; after the light beam is reflected by the first scanning galvanometer 21, it enters the second 4f optical system and is incident on the second scanning galvanometer 22 for reflection, wherein the second scanning galvanometer 22 is arranged vertically; then, the light beam reflected by the second scanning galvanometer 22 passes through the third 4f optical system, and then passes through the dichroic mirror 33, the myopic astigmatism corrector 4 and the transmissive wavefront corrector 5 in sequence, and then enters the human eye 34 and is focused on the retina;

[0017] The reflected light from the human eye 34 returns along the original optical path and passes through the transmissive wavefront corrector 5, the myopia astigmatism corrector 4, the dichroic mirror 33, the third 4f optical system, the second scanning galvanometer 22, the second 4f optical system, the first scanning galvanometer 21, and the first beam splitter 31 in sequence. The first beam splitter 31 further splits the light into a second reflected light and a second transmitted light. The second transmitted light enters the fourth 4f optical system. The output light from the fourth 4f optical system reaches the second beam splitter 32, and the output light from the second beam splitter 32 is split into a third reflected light and a third transmitted light. The third transmitted light enters the wavefront sensor 7, and the third reflected light enters the photoelectric detection system.

[0018] The photoelectric detection system reflects the information of the area scanned by the light spot on the retina to form a retinal image;

[0019] The laser light source 1, the light spot on the retina and the light spot of the photoelectric detection system are conjugate, and the aperture 3, the first scanning galvanometer 21, the second scanning galvanometer 22, the pupil of the human eye, the wavefront sensor 7 and the photoelectric detection system are all on the conjugate plane;

[0020] The correction signal input end of the transmission wavefront corrector 5 is connected to the correction signal output end of the computer 35 ; the sensing signal output end of the wavefront sensor 7 is connected to the sensing signal input end of the computer 35 .

[0021] In this embodiment, the laser light source 1 is a point light source; the myopic astigmatism corrector 4 mainly corrects the myopic astigmatism of a person through a standard lens; the transmissive wavefront corrector 5 corrects the dynamic aberration of the human eye 34 in real time; the first scanning galvanometer 21 and the second scanning galvanometer 22 cooperate to produce a small angle of deflection of the light beam in the horizontal and vertical directions, so that the light spot formed by the light beam on the retina is scanned in the horizontal and vertical directions; and the photoelectric signal detected by the photoelectric detection system reflects the information of the light spot scanning area on the retina, forming a retinal image; one of the first scanning galvanometer 21 and the second scanning galvanometer 22 has a much higher operating frequency than the other, for example, the imaging rate is 30 frames per second, the second scanning galvanometer in the vertical direction is 30Hz, and the first scanning galvanometer in the horizontal direction is 16kHz, and the electrical detection system collects synchronously to obtain a 512 pixel × 512 pixel image.

[0022] In this embodiment, the No. 1 4f optical system includes the No. 3 lens 10 and the No. 4 lens 11; the No. 2 4f optical system includes the No. 5 lens 12 and the No. 6 lens 13; the No. 3 4f optical system includes the No. 7 lens 14 and the No. 8 lens 15; and the No. 4 4f optical system includes the No. 9 lens 17 and the No. 10 lens 18.

[0023] Specific embodiment 2: This embodiment further limits the adaptive optical scanning laser fundus imaging system based on a transmissive optical element described in specific embodiment 1. In this embodiment, the fundus imaging system further includes a sight mark system;

[0024] The sight mark system includes an electronic display screen 6 and a number one lens 16;

[0025] The electronic display screen 6 is used to display a mark. The light of the mark passes through the first lens 16, is reflected by the dichroic mirror 33, and finally passes through the myopia astigmatism corrector 4 and the transmissive wavefront corrector 5 in sequence, enters the human eye 34, and forms an image on the retina.

[0026] In this embodiment, the purpose of adding the sight mark system is to make the human eye focus on the mark displayed on the electronic display screen 6 to reduce the shaking of the human eye.

[0027] Specific embodiment three: This embodiment further limits the adaptive optical scanning laser fundus imaging system based on a transmission optical element described in specific embodiment one. In this embodiment, the display signal input end of the electronic display screen 6 is connected to the display signal output end of the computer 35.

[0028] In this embodiment, the marks displayed on the electronic display screen 6 are controlled by a computer.

[0029] Specific embodiment 4: This embodiment further defines the adaptive optical scanning laser fundus imaging system based on a transmission optical element described in specific embodiment 1. In this embodiment, the photoelectric detection system includes a second lens 19, a pinhole 8, and a photomultiplier tube 9;

[0030] Another portion of the light reflected by the second beam splitter 32 first passes through the second lens 19 to focus the light beam onto the pinhole 8, and then is received by the photomultiplier tube 9.

[0031] In this embodiment, the pinhole 8 is used to filter stray light on non-focal planes and non-focal locations.

[0032] Specific embodiment five: This embodiment further limits the adaptive optical scanning laser fundus imaging system based on a transmission optical element described in specific embodiment one. In this embodiment, the photoelectric signal output end of the photomultiplier tube 9 is connected to the photoelectric signal input end of the computer 35.

[0033] Specific embodiment six: This embodiment further limits the adaptive optical scanning laser fundus imaging system based on a transmissive optical element described in specific embodiment one. In this embodiment, the control signal input end of the first scanning galvanometer 21 is connected to the first control signal output end of the computer 35; the control signal input end of the second scanning galvanometer 22 is connected to the second control signal output end of the computer 35.

[0034] In this embodiment, the first scanning galvanometer mirror 21 and the second scanning galvanometer mirror 22 are respectively controlled in real time by a computer, so that the light spot formed by the light beam on the retina can be scanned in the horizontal and vertical directions.

[0035] Obviously, the above embodiments are merely examples for illustrative purposes and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. However, any obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An adaptive optical scanning laser fundus imaging system based on a transmission optical element, characterized in that: It comprises a laser light source (1), a collimating lens (2), a No. 1 4f optical system, a No. 2 4f optical system, a No. 3 4f optical system, a No. 4 4f optical system, an aperture (3), a myopic astigmatism corrector (4), a transmission wavefront corrector (5), a wavefront sensor (7), a first scanning galvanometer (21), a second scanning galvanometer (22), a first beam splitter (31), a second beam splitter (32), a dichroic mirror (33), a sight mark system and a photoelectric detection system; The light emitted by the laser light source (1) is collimated by the collimating lens (2) and then passes through the aperture (3) to obtain a parallel light beam of a limited diameter, wherein the aperture (3) is located on the focal plane of the collimating lens; after the parallel light beam enters the first 4f optical system, it passes through the first beam splitter (31) to be split into a first reflected light and a first transmitted light, and the first reflected light output by the first beam splitter (31) reaches the first scanning galvanometer (21) for re-reflection, wherein the first scanning galvanometer (21) is arranged horizontally; after the light beam is reflected by the first scanning galvanometer (21), it enters the second 4f optical system and is incident on the second scanning galvanometer (22) for reflection, wherein the second scanning galvanometer (22) is arranged vertically; after that, the light beam reflected by the second scanning galvanometer (22) passes through the third 4f optical system and then passes through the dichroic mirror (33), the myopic astigmatism corrector (4) and the transmission wavefront corrector (5) in sequence before entering the human eye (34) and focusing on the retina; The reflected light of the human eye (34) returns along the original optical path and passes through the transmission wavefront corrector (5), the myopia astigmatism corrector (4), the dichroic mirror (33), the third 4f optical system, the second scanning galvanometer (22), the second 4f optical system, the first scanning galvanometer (21) and the first beam splitter (31) in sequence; wherein the first beam splitter (31) splits the light again into the second reflected light and the second transmitted light, the second transmitted light enters the fourth 4f optical system, the output light of the fourth 4f optical system reaches the second beam splitter (32), the output light of the second beam splitter (32) splits the light into the third reflected light and the third transmitted light; the third transmitted light enters the wavefront sensor (7); and the third reflected light enters the photoelectric detection system; The photoelectric detection system reflects the information of the area scanned by the light spot on the retina to form a retinal image; The laser light source (1), the light spot on the retina and the light spot of the photoelectric detection system are conjugate, and the aperture (3), the first scanning galvanometer (21), the second scanning galvanometer (22), the pupil of the human eye, the wavefront sensor (7) and the photoelectric detection system are all on the conjugate plane; The correction signal input end of the transmission wavefront corrector (5) is connected to the correction signal output end of the computer (35); the sensing signal output end of the wavefront sensor (7) is connected to the sensing signal input end of the computer (35); The sight mark system comprises an electronic display screen (6) and a first lens (16); The electronic display screen (6) is used to display a mark. The light of the mark passes through the first lens (16), is reflected by the dichroic mirror (33), and finally passes through the myopia astigmatism corrector (4) and the transmission wavefront corrector (5) in sequence, enters the human eye (34), and forms an image on the retina. The photoelectric detection system includes a second lens (19), a pinhole (8) and a photomultiplier tube (9); Another part of the light reflected by the second beam splitter (32) is first focused onto the pinhole (8) by the second lens (19), and then received by the photomultiplier tube (9).

2. The adaptive optical scanning laser fundus imaging system based on a transmission optical element according to claim 1, characterized in that: The display signal input terminal of the electronic display screen (6) is connected to the display signal output terminal of the computer (35).

3. The adaptive optical scanning laser fundus imaging system based on a transmission optical element according to claim 1, characterized in that: The photoelectric signal output end of the photomultiplier tube (9) is connected to the photoelectric signal input end of the computer (35).

4. The adaptive optical scanning laser fundus imaging system based on a transmission optical element according to claim 1, characterized in that: The control signal input end of the first scanning galvanometer (21) is connected to the first control signal output end of the computer (35); the control signal input end of the second scanning galvanometer (22) is connected to the second control signal output end of the computer (35).

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