CN116942077A

CN116942077A - Fundus self-adaptive optical imaging system with high universality

Info

Publication number: CN116942077A
Application number: CN202310910724.9A
Authority: CN
Inventors: 胡立发; 杨燕燕; 姜律; 华晟骁; 冯佳濠; 胡鸣; 王红燕; 张琪; 徐星宇; 吴晶晶; 俞琳
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2023-07-24
Filing date: 2023-07-24
Publication date: 2023-10-27

Abstract

The application discloses a fundus self-adaptive optical imaging system with high universality, and belongs to the field of self-adaptive optics. The system matches eyes with different diopters by adopting a four-reflector system with adjustable spacing, so that high-resolution imaging can be carried out on fundus with diopters between-8D and 8D; the annular light inner diameter is adjusted by controlling the distance between the positive axicon lens and the negative axicon lens so as to adapt to corneas of different human eyes, so that the universality of an imaging system is improved, and stray light reflected by the corneas is avoided; the voice coil deformable mirror with large phase modulation amount is adopted to correct the ocular fundus aberration, so that the imaging precision is improved.

Description

Fundus self-adaptive optical imaging system with high universality

Technical Field

The application relates to a fundus self-adaptive optical imaging system with high universality, and belongs to the field of self-adaptive optics.

Background

The retina is the only tissue in human body, the state of which can be observed by optical imaging technology under living and noninvasive conditions, and the high-resolution imaging of the retina is very important in the aspects of early diagnosis of cerebral arteriosclerosis, diabetes and other diseases (Yang Jie. Related factor analysis of diabetic retinopathy [ D ]. Xinjiang medical university, 2015.) the early symptoms of the diseases can be affected by ocular cone cells and micro-blood vessels of the fundus. The size of cone cells is 2-5 μm and the diameter of retinal microvasculature is about 5-8 μm, which exceeds the resolution of conventional fundus cameras (Gill J S, mooseajee M, dubis a m.celluar imaging of inherited retinal diseases using adaptive optics [ J ]. Eye,2019,33 (5)). The Adaptive Optics (AO) technology is used to compensate the aberration of human eye, and is an important means for obtaining high resolution images of ocular fundus retina cells and microvasculature.

At present, a great deal of researches are carried out on fundus imaging technology based on adaptive optics at home and abroad, and different types of systems are developed, mainly as follows: 1) An adaptive optics system (Cheng Shaoyuan, hu Lifa, cao Zhaoliang, etc.) based on a liquid crystal wavefront corrector, the application of liquid crystal adaptive optics in high resolution imaging of the ocular fundus [ J ]. Chinese laser, 2019,46 (7): 0704009.), the system being implemented based on a liquid crystal wavefront corrector, the liquid crystal having the advantages of high pixel density, low voltage, programmable control, etc.; 2) The self-adaptive optical system based on the double piezoelectric deformable mirrors is characterized in that the system corrects the high-order aberration and the low-order aberration of the fundus respectively by utilizing the two piezoelectric deformable mirrors, the energy utilization rate is high, but the driving voltage is high, the size of the deformable mirrors is larger, the overall structure is larger (the overall size of the system is about 1400mm multiplied by 800 mm), and the cost is high; 3) The AO-OCT-SLO technology combining the self-adaptive optical system with the imaging modes such as optical coherence tomography, laser scanning ophthalmoscope and the like has high-resolution imaging capability in the large view field and depth direction, the systems usually adopt the most advanced hardware and technology, the resolution or the individual performances such as the view field are outstanding, but the cost is high, the cost performance of the system is not outstanding, and the clinical application of the self-adaptive optical fundus imaging system is limited. In clinical application, the imaging system is required to detect not only the crowd with healthy vision, but also the crowd with different myopia degrees, so that the universality of the adaptive optical imaging system is required to be improved, and the system cost is reduced.

Considerable research has also been conducted in developing low cost fundus imaging systems. Betul Sahin et al propose real-time estimation of aberrations of the human eye based on pupil tracking measurements to control deformable mirrors for distortion compensation without the need for wavefront sensors (BETUL, SAHIN, BARBARA, et al Adaptive optics with pupil tracking for high resolution retinal imaging [ J ]. Biomedical optics express,2012,3 (2): 225-239). Marwan Suheimat performs wavefront compensation (suheiat M, DAINTY c.poster session.high resolution flood illumination retinal imaging system with adaptive optics C// 8th International Workshop on Adaptive Optics for Industry and Medicine.2020) based on MEMS (Micro Electro Mechanical System), but the adjustment range for different human eye diopters is smaller, the wavefront correction range of MEMS is also smaller, and the universality will be poor when applied. Fundus imaging adaptive optics designed by Fuensanta et al (Fuensanta A. Vera-Di az and Nathan Doble, the Human Eye and Adaptive Optics, topics in Adaptive Optics, edition by Dr. Bob Tyson, public InTech, public online 20, january, 2012) can only perform high resolution imaging for ocular fundus of normal vision or small diopter.

Disclosure of Invention

In order to solve the imaging problem of eyes with different diopters and improve universality of a high-resolution fundus adaptive optical imaging system, the application provides an optical path design, wherein the diameter of annular light is controlled by adopting positive and negative axicon lenses with adjustable intervals, eyes with different diopters are matched by adopting a four-reflector system with adjustable intervals, and the aberration of the fundus is corrected by adopting a voice coil deformable mirror with large phase modulation amount. The high-resolution imaging of eyes with normal vision can be met, and the high-resolution imaging and the adjustment can be performed for eyes with high refractive error. The purpose is to provide a high-resolution fundus imaging adaptive optical system with high universality.

A highly versatile fundus-adaptive optical imaging system, the system comprising five subsystems: a sighting target staring subsystem, an illumination subsystem, a detection subsystem, an imaging subsystem and a pupil monitoring subsystem; the sighting target staring subsystem is used for avoiding irregular disturbance of eyes due to no target staring, and guiding the changes of the staring direction of the eyes by moving the sighting target so as to change the fundus imaging area; the illumination subsystem is used for providing illumination for the fundus imaging area; the detection subsystem is used for measuring human eye aberration; the imaging subsystem is used for imaging the fundus retina; the pupil monitoring subsystem is used for auxiliary alignment in the imaging process;

the system adopts positive and negative axicon lenses with adjustable spacing to control the diameter of annular light, adopts a four-reflector system with adjustable spacing to match eyes with different diopters, adopts a voice coil deformable mirror with large phase modulation amount to correct the aberration of the bottom of the eye, and realizes imaging of eyes with different pupil sizes and different diopters.

Optionally, the system comprises a first light source 1, a second light source 2, a first lens 3 and a second lens 4, a first beam splitter prism 5, a negative axicon lens 6 and a positive axicon lens 7, a second beam splitter prism 8, a third beam splitter prism 9, a third lens 10, a beam splitter 11, a first mirror 12, a second mirror 13, a third mirror 14, a fourth mirror 15, a fourth lens 16, a human or simulated human eye 17, a fifth lens 18, a deformable mirror 19, a fifth mirror 20, a sixth lens 21, a dichroic 22, a shack hartmann wavefront sensor 23, a seventh lens 24, an imaging camera 25, a pupil camera 26, an eighth lens 27 and an LED optotype light source 28;

the first mirror 12, the second mirror 13, the third mirror 14 and the fourth mirror 15 form a four-mirror system with adjustable space, the second mirror 13 and the third mirror 14 are perpendicular to each other, the first mirror 12 and the fourth mirror 15 are perpendicular to each other, and the pupils of different eyes are matched by adjusting the distance between the two groups of perpendicular mirrors.

Optionally, the first light source 1 is located on the focal plane of the first lens 3, and the second light source 2 is located on the focal plane of the second lens 4; the parallel light generated by the light emitted by the first light source 1 after passing through the first lens 3, or the parallel light generated by the light emitted by the second light source 2 after passing through the second lens 4, passes through the negative axicon lens 6 and the positive axicon lens 7 in sequence, and is parallel annular light; the cone angles of the negative axicon lens 6 and the positive axicon lens 7 are the same;

the inner diameter r of the annular light ₂ The method comprises the following steps:

wherein r is ₁ Is the radius of the incident beam, d is the distance between the positive and negative axicon, α is the cone angle of the positive and negative axicon, and n is the refractive index of the axicon.

Optionally, when the pupils of different eyes are matched, the moving distance Δd between the two groups of mutually perpendicular reflectors is as follows:

wherein D is the diopter of the human eye, f ₁₆ Is the focal length of the fourth lens 16.

Optionally, the splitting ratio of the first splitting prism 5, the second splitting prism 8 and the third splitting prism 9 is 50:50.

Optionally, the first light source 1 is a 808nm light source, and is used for wavefront detection; the second light source 2 is a 635nm light source and is used for imaging; the focal length of the first lens 3, the second lens 4 and the eighth lens 27 is 50mm, and the caliber is 25.4mm; the focal length of the third lens 10 is 300mm, and the caliber is 50mm; the focal length of the fourth lens 16 is 125mm, and the caliber is 25.4mm; the focal length of the fifth lens 18 is 200mm, and the caliber is 50mm; the focal length of the sixth lens 21 is 75mm, and the caliber is 25.4mm; the focal length of the seventh lens 24 is 125mm, and the caliber is 25.4mm; all lenses were double cemented achromats and the surface was coated with an anti-reflection film.

Optionally, the center wavelength of the LED optotype light source 28 is 550nm; the transmission and reflection light splitting ratio of the light splitting sheet 11 is 1:9; the deformable mirror 19 is a 69-unit deformable mirror with a light transmission caliber of 10mm; the color separator 22 is configured to transmit 808nm probe light and reflect 550nm and 635nm light.

Optionally, the human eye 17 comprises a resolution plate and a lens with a caliber of 10mm and a focal length of 20mm, and the caliber is 10mm; the resolution board is placed at the focal plane position of the lens and is used for simulating the retina of the ocular fundus.

Optionally, when the simulated human eye is used for wavefront correction and imaging, the shack Hartmann wavefront detector 23 is used for measuring the wavefront slope, the measured slope and the control matrix are used for calculating the voltage which should be applied to the deformable mirror 19, and the integration control method is used for performing closed-loop correction to control the deformable mirror 19 to compensate the distorted wavefront;

when the human eye is used for wavefront correction and imaging, firstly, the LED sighting target light source 28 is turned on, the human eye stares at a sighting target through the sighting target subsystem until the sighting target is in a clear position, and the human eye is aligned in the light path at the moment; the previous steps are then repeated, i.e. closed loop correction with shack hartmann wavefront sensor 23 and deformable mirror 19.

The application also provides application of the system in wavefront correction and fundus adaptive optical imaging.

The application has the beneficial effects that:

the diameter of annular light is controlled by adopting positive and negative axicon lenses with adjustable spacing, human eyes with different diopters are matched by adopting a four-reflector system with adjustable spacing, and the aberration of the bottom of the eye is corrected by adopting a voice coil deformable mirror with large phase modulation amount. The high-resolution imaging of eyes with normal vision can be met, and the high-resolution imaging and the adjustment can be performed for eyes with high refractive error. The system can carry out high-resolution imaging on the fundus of the eyes with diopter between-8D and 8D, and improves the universality of the imaging system. The annular light inner diameter is adjusted by controlling the distance between the positive axicon lens and the negative axicon lens so as to adapt to corneas of different eyes, so that the universality of an imaging system is improved, and stray light reflected by the corneas is avoided.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a fundus imaging adaptive optics system.

Fig. 2 is a schematic view of the optical path in the presence of defocus.

Fig. 3 is a schematic view of the optical path after focusing.

FIG. 4a is a graph of the wavefront before correction, PV and RMS 16.845 μm and 8.135 μm, respectively;

FIG. 4b is a corrected wavefront plot with PV and RMS of 1.43 μm and 0.225 μm, respectively.

FIG. 5a is a diagram of an imaging camera prior to correction;

fig. 5b is a corrected image obtained by the imaging camera.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

Embodiment one:

the present embodiment provides a fundus adaptive optical imaging system with high universality, see fig. 1, which includes five subsystems: a gaze subsystem, an illumination subsystem, a detection subsystem, an imaging subsystem, and a pupil monitoring subsystem.

In fig. 1, the first light source 1 is a 808nm light source for wavefront detection; the second light source 2 is a 635nm light source and is used for imaging; the focal length of the first lens 3 and the second lens 4 is 50mm, and the caliber is 25.4mm; the splitting ratio of the first splitting prism 5 is 50:50;6 and 7 are axicon lenses respectively, wherein 6 is a negative axicon lens and 7 is a positive axicon lens; the splitting ratio of the second splitting prism 8 is 50:50; the focal length of the eighth lens 27 is 50mm, and the aperture is 25.4mm;28 is an LED optotype light source with a central wavelength of 550nm; the third beam splitter prism 9 has a splitting ratio of 50:50; a pupil camera 26 is used for shooting the pupil of the human eye and assisting the human eye to aim at the light path and adjust the imaging area; the focal length of the third lens 10 is 300mm, and the caliber is 50mm;11 is a light-splitting sheet, and the transmission and reflection light-splitting ratio is 1:9; the first reflecting mirror 12, the second reflecting mirror 13, the third reflecting mirror 14 and the fourth reflecting mirror 15 form a four-reflecting mirror system with adjustable space, wherein the second reflecting mirror 13 and the third reflecting mirror 14 are a group of reflecting mirrors which are mutually perpendicular, the first reflecting mirror 12 and the fourth reflecting mirror 15 are a group of reflecting mirrors which are mutually perpendicular, and the pupils of different eyes can be matched by adjusting the distance between the two groups of mutually perpendicular reflecting mirrors; the focal length of the fourth lens 16 is 125mm, and the caliber is 25.4mm;17 is a human eye or a simulated human eye, wherein the simulated human eye comprises a resolution plate and a lens with the focal length of 20mm, and the caliber is 10mm; the focal length of the fifth lens 18 is 200mm, and the caliber is 50mm;19 is 69 unit deformable mirror of ALPAO company, the aperture of light transmission is 10mm; the caliber of the fifth reflecting mirror 20 is 25.4mm; the focal length of the sixth lens 21 is 75mm, and the caliber is 25.4mm;22 is a color separator, the detection light of 808nm is transmitted, and the light of 550nm and 635nm is reflected; 23 is shack Hartmann wave front detector, the focal length of the seventh lens 24 is 125mm, and the caliber is 25.4mm. And 25 is an imaging camera positioned at the focal plane of the lens 24 for imaging the fundus. Wherein, all lenses are double-glued achromats, and the surfaces are plated with antireflection films.

The vision target staring subsystem consists of an LED vision target light source 28, an eighth lens 27, a second beam splitter prism 8, a third beam splitter prism 9, a third lens 10, a beam splitter 11, a first reflecting mirror 12, a second reflecting mirror 13, a third reflecting mirror 14, a fourth reflecting mirror 15, a fourth lens 16 and a human eye 17.

The illumination subsystem is composed of a second light source 2, a second lens 4, a first light splitting prism 5, a negative axicon lens 6, a positive axicon lens 7, a second light splitting prism 8, a third light splitting prism 9, a third lens 10, a light splitting sheet 11, a first reflecting mirror 12, a second reflecting mirror 13, a third reflecting mirror 14, a fourth reflecting mirror 15, a fourth lens 16 and a human eye 17.

The detection subsystem consists of a first light source 1, a first lens 3, a first light splitting prism 5, a negative axicon lens 6, a positive axicon lens 7, a second light splitting prism 8, a third light splitting prism 9, a third lens 10, a light splitting sheet 11, a first reflecting mirror 12, a second reflecting mirror 13, a third reflecting mirror 14, a fourth reflecting mirror 15, a fourth lens 16, a human eye 17, a fifth lens 18, a deformable mirror 19, a fifth reflecting mirror 20, a sixth lens 21, a color splitting sheet 22 and a shack hartmann 23.

The imaging subsystem is composed of a human eye 17, a fourth lens 16, a fourth mirror 15, a third mirror 14, a second mirror 13, a first mirror 12, a light-splitting sheet 11, a fifth lens 18, a anamorphic lens 19, a fifth mirror 20, a sixth lens 21, a color-splitting sheet 22, a seventh lens 24, and an imaging camera 25.

The pupil monitoring subsystem is composed of a human eye 17, a fourth lens 16, a fourth reflecting mirror 15, a third reflecting mirror 14, a second reflecting mirror 13, a first reflecting mirror 12, a light splitting sheet 11, a third lens 10, a third light splitting prism 9, and a pupil camera 26.

In the illumination subsystem, the second light source 2 is an optical fiber with the size of 1mm diameter, the light-emitting end face of the optical fiber is positioned on the focal plane of the second lens 4, the light collimated by the second lens 4 passes through the first beam-splitting prism 5, and the reflected light enters the negative axicon lens 6, wherein the first beam-splitting prism 5 and the negative axicon lens 6 are both positioned in parallel light, the positions of the first beam-splitting prism 5 and the negative axicon lens 6 have no strict requirements, and the optical fiber can be conveniently placed according to the adjustment of an optical path; the hollow beam is split into a positive axicon 7 by the apex of the negative axicon 6, and the cone angles of the two axicon are the same to ensure that the light exiting the positive axicon 7 is parallel annular light. The positive and negative axicon lenses are used for generating annular light beams so as to avoid the influence of stray light on the front surface of the cornea of the human eye on imaging, and replace the traditional annular diaphragm. Compared with the traditional annular diaphragm, the application adopts the positive and negative axicon lenses, the distance of which can be adjusted, so that the diameter of the annular light beam can be controlled. The magnification M of the incident beam by the positive and negative axicon lenses is as follows:

wherein r is ₁ Is the radius of the incident beam, r ₂ Is the inner ring radius of the ring beam, d is the distance between the two positive and negative axicon lenses, the cone angles alpha of the positive and negative axicon lenses are the same, and n is the refractive index of the axicon lens. Thus, the inside diameter of the annular light is:

after the glass material and the cone angle of the positive and negative axicon lenses are fixed, the inner diameter r of the annular light ₂ Has a linear relation with d, and thus, the inner diameter r of the annular beam can be controlled by adjusting the value of the spacing d ₂ To match the pupils of different human eyes.

The annular light beam is transmitted through the second beam splitting prism 8 and the third beam splitting prism 9, wherein the second beam splitting prism 8 and the third beam splitting prism 9 are positioned in parallel light paths, the positions of the second beam splitting prism 8 and the third beam splitting prism 9 are not strictly required, and the placement positions of the annular light beam can be conveniently determined through visual adjustment; the transmitted light is focused by the third lens 10, and the focuses of the second lens 4 and the third lens 10 are positioned at the same position; 10% of the light after passing through the light splitting sheet 11 is transmitted and reflected by the four-reflector system and enters the fourth lens 16, the positions of the light splitting sheet 11, the first reflector 12 and the fourth reflector 15 are not strictly required, and the light splitting sheet can be adjusted according to an actual light path; the annular light beam formed after the collimation of the fourth lens 16 enters the pupil of the human eye and finally forms an illumination spot on the fundus, wherein the focal positions of the third lens 10 and the fourth lens 16 are the same, and the distances from the second reflecting mirror 13 and the third reflecting mirror 14 to the first reflecting mirror 12 and the fourth reflecting mirror 15 can be adjusted; the pupil of the human eye is at the focal position of the fourth lens 16.

In the imaging subsystem, during imaging, a 808nm light source is adopted, light reflected by the fundus of the human eye 17 has the wavelength of 808nm, is focused after passing through the fourth lens 16, is reflected by the fourth reflecting mirror 15, the third reflecting mirror 14, the second reflecting mirror 13 and the first reflecting mirror 12, is reflected by the light splitting sheet 11 and 90 percent of light, is collimated by the fifth lens 18, and for the normal-vision human eye with diopter 0D, the focuses of the fourth lens 16 and the fifth lens 18 are overlapped; the light collimated by the fifth lens 18 is incident on the anamorphic lens 19, wherein the mirror surface of the anamorphic lens is located at the focal plane position of the fifth lens 18; the light modulated by the deformable mirror is reflected back to the fifth lens 18 and is reflected by the fifth reflector 20 to the sixth lens 21, and the fifth reflector 20 is obliquely placed at 45 degrees to play a role of light path folding axis; the light passing through the folding axis of the fifth reflecting mirror 20 is collimated by the sixth lens 21, and the focuses of the fifth lens 18 and the sixth lens 21 coincide, so that the fifth lens 18 and the sixth lens 21 play a role in conjugation, and the deformable mirror 19 is conjugated with the shack Hartmann wavefront detector 23; after being collimated by the sixth lens 21, the light with 808nm enters the seventh lens 24, and the focal positions of the sixth lens 21 and the seventh lens 24 coincide; finally, the light passing through the seventh lens 24 is imaged on a camera 25, the camera 25 being located on the focal plane of the seventh lens 24.

As shown in fig. 2, after the light is converged by the fourth lens 16, if the distance between the convergence point and the third lens 10 is greater (smaller) than the front focal length of the third lens 10, the light beam passes through the third lens 10 to be converged light (divergent light), so that the wavefront detected by the wavefront detector is greatly defocused. At this time, the first mirror 12 and the fifth mirror 15 are kept stationary, and by moving the second mirror 13 and the third mirror 14 up and down, the light beam is parallel light after passing through the third lens 10, as shown in fig. 3, and the wavefront detected by the wavefront detector is not defocused at this time, so that higher order aberrations can be corrected better. From the gaussian imaging formula, the moving distance Δd of the second mirror 13 and the third mirror 14 can be deduced as:

wherein Δd is in mm, Δd>0 indicates that the second mirror 13 and the third mirror 14 are moved upward, Δd<0 denotes that the second mirror 13 and the third mirror 14 move down; f (f) ₁₆ Is the focal length of the fourth lens 16 in mm; d is the diopter of the human eye.

In this system, the focal length f of the fourth lens 16 has been confirmed ₁₆ The adjustable maximum diopter is 8D, the second mirror 13 and the third mirror 14 have a certain range of movement: 62.5mm is less than or equal to delta D is less than or equal to 62.5mm, and the focusing range of the corresponding fundus self-adaptive imaging system is-8D.

In the detection subsystem, most of light paths coincide with imaging light paths, and a 635nm light source is adopted during wave front detection. Light reflected by the fundus of the human eye 17 has a wavelength of 635nm, is focused through the fourth lens 16, is reflected through the fourth mirror 15, the third mirror 14, the second mirror 13 and the first mirror 12, is reflected through the light splitting sheet 11, 90% of the light, is collimated by the fifth lens 18, and for a normal vision human eye with diopter 0D, the focuses of the fourth lens 16 and the fifth lens 18 coincide; the light collimated by the fifth lens 18 is incident on the anamorphic lens 19, wherein the mirror surface of the anamorphic lens is located at the focal plane position of the fifth lens 18; the light modulated by the deformable mirror 19 is reflected to the fifth lens 18 and is reflected by the fifth reflector 20 to the sixth lens 21, and the fifth reflector 20 is obliquely placed at 45 degrees to play a role of an optical path folding axis; the light passing through the folding axis of the fifth reflecting mirror 20 is collimated by the sixth lens 21, and the focuses of the fifth lens 18 and the sixth lens 21 coincide, so that the fifth lens 18 and the sixth lens 21 play a role in conjugation, and the deformable mirror 19 is conjugated with the shack Hartmann wavefront detector 23; after being collimated by the sixth lens 21, the 635nm light enters the shack Hartmann wavefront detector 23 through the color separation film, and the shack Hartmann wavefront detector 23 is located on the focal plane of the sixth lens 21.

In the gaze subsystem, most of the light paths coincide with the illumination subsystem. The LED optotype light source 28 is an LED light source with a central wavelength of 550nm; the LED optotype light source 28 is located on the focal plane of the eighth lens 27 and is capable of two-dimensional movement in a direction perpendicular to the optical axis to guide the human eye to stare at the target and change the imaging area. Then, the light passes through the second beam splitter prism 8, a part of the reflected light passes through the third beam splitter prism 9, and a part of the reflected light is transmitted, wherein the positions of the second beam splitter prism 8 and the third beam splitter prism 9 are as described above; the transmitted light is focused by the third lens 10, and the eighth lens 27 and the third lens 10 are at the same position; 10% of the light passing through the light splitting sheet 11 is transmitted and reflected by the first reflecting mirror 12, the second reflecting mirror 13, the third reflecting mirror 14 and the fourth reflecting mirror 15 and enters the fourth lens 16, and the positions of the light splitting sheet 11, the first reflecting mirror 12 and the fifth reflecting mirror 15 are not strictly required and can be adjusted according to an actual light path; the annular light beam formed after the collimation of the fourth lens 16 enters the pupil of the human eye and finally forms an illumination spot on the fundus, wherein the focal positions of the third lens 10 and the fourth lens 16 are the same, and the distances from the second reflecting mirror 13 and the third reflecting mirror 14 to the first reflecting mirror 12 and the fourth reflecting mirror 15 can be adjusted; the pupil of the human eye is at the focal position of the fourth lens 16. The sighting mark staring subsystem plays a role in stabilizing eyes and avoids irregular disturbance of the eyes due to no target staring; meanwhile, when the optotype is moved, the staring direction of eyes can be guided to change, so that the fundus imaging area is changed.

In the pupil monitoring subsystem, part of the optical path coincides with the detection subsystem. The light reflected by the pupil of the human eye 17 passes through the fourth lens 16, then passes through the fourth mirror 15, the third mirror 14, the second mirror 13 and the first mirror 12, then passes through the light splitting sheet 11, and 10% of the light is transmitted, passes through the third lens 10 and the third splitting prism 9, and then is imaged by the pupil camera 26. Pupil camera 26 is at the focal plane position of third lens 10 and the positions of the remaining optical elements are the same as described in the detection subsystem. The pupil monitoring subsystem serves to assist in alignment.

Before the wavefront correction, the human eye 17 is replaced by a simulated human eye, wherein the simulated human eye comprises a lens with the caliber of 10mm and the focal length of 20mm and ground glass, the ground glass is placed at the focal plane position of the lens, and the fundus retina of the human eye is simulated; the 635nm imaging light was turned off, the 808nm probe light was turned on, and the response function of the deformable mirror 19 was measured with the shack Hartmann wavefront sensor 23, and then a control matrix was calculated.

When the simulated human eye is used for wavefront correction and imaging, the shack Hartmann wavefront detector 23 can be used for measuring the wavefront slope, the voltage which is required to be applied to the deformable mirror 19 is calculated by using the measured slope and a control matrix, closed loop correction is performed by using an integral control method, the deformable mirror is controlled to compensate for the distorted wavefront, the compensated wavefront is smoother, and the obtained aberration is smaller. In the correction process, 635nm imaging light is collected on the imaging CCD, and an imaging result with high resolution and large field of view can be obtained on the CCD. When the human eyes are used for wavefront correction and imaging, firstly, a sighting target light source is turned on, the human eyes stare at a sighting target through a sighting target subsystem until the sighting target is in a clear position, and at the moment, the human eyes are aligned in a light path; then, the previous steps, namely, the closed loop correction by using the shack Hartmann wavefront sensor 23 and the deformable mirror 19 are repeated; in the correction process, 635nm imaging light is collected on the imaging CCD, and an imaging result with high resolution and large field of view can be obtained on the CCD.

Example two

The present embodiment provides a method for performing wavefront correction and fundus adaptive imaging by the above system, in this embodiment, a process of wavefront detection is simulated, and first, a light lattice is generated; secondly, calculating a slope according to the light spot array; then, the slope is thinned to simulate the sparse acquisition process of the light spots, meanwhile, in the compression detection algorithm, the slope with sparsity is satisfied, and the slope recovery can be completed through a nonlinear reconstruction algorithm; fourth, recovering the sparse slope; finally, the wavefront can be reconstructed from the slope according to conventional wavefront reconstruction algorithms.

1) The imaging camera 25 used was a CCD camera model pco.edge 4.2, a single pixel size of 6.5 μm, a resolution of 2048×2048, and a sensor size of 13.3mm×13.3mm;

2) The deformable mirror 19 used was a 69-unit voice coil deformable mirror from ALPAO, france, and had an effective aperture of 10.5mm and a phase modulation depth of 60. Mu.m.

3) The 808nm light source 1 is a laser light source, and is an MDL-E-808 type laser of vincrist industry company and is used for wave front detection; the second light source 2 is 635nm light source of Daheng company and is used for imaging;

4) The first beam splitter prism 5, the second beam splitter prism 8 and the third beam splitter prism 9 are all wide-band beam splitter prisms of Daheng corporation, 25.4mm multiplied by 25.4mm, and the beam splitting ratio is 50:50.

5) The positive and negative axicon lens materials are ultraviolet fused silica (UVFS), the refractive index n is 1.517, the cone angle is 20 DEG, and thus r is obtained by the formula (2) ₂ And approximately 0.214d. Thus, the annular beam inner diameter r ₂ The distance d between the positive axis cone lens and the negative axis cone lens has a linear relation, and the inner diameter of the annular light beam can be controlled by adjusting the value of the distance d so as to match the pupils of different eyes.

6) The LED optotype light source 28 is an LED light source of Thorlab company, and the center wavelength is 550nm;

7) Pupil camera 26 is a Thorlab CS165CU/M camera, 160 ten thousand pixels, for capturing the pupil of the human eye, assisting the human eye in aligning the optical path and adjusting the imaging area.

8) The light-splitting sheet 11 is a broadband light-splitting sheet of Daheng corporation, and the transmission and reflection light-splitting ratio is 1:9.

9) The first mirror 12, the second mirror 13, the third mirror 14, the fourth mirror 15 and the fifth mirror 20 are all large constant company mirrors with a diameter of 25.4mm and a thickness of 8mm. Wherein the second mirror 13 and the third mirror 14 are perpendicular to each other in the optical path, and the first mirror 12 and the fourth mirror 15 are perpendicular to each other.

10 The color separator 22 is a long-pass color separator, the detection light of 808nm is transmitted, and the light of 550nm and 635nm is reflected;

11 23 is a shack Hartmann wavefront sensor, the camera is an art cam-990SWIR camera from ARTRAY company, 1280 x 1024 pixels, a dynamic range of 12 bits, and a relative quantum efficiency of about 82%.

12 With the above elements, the light path is laid out according to fig. 1. Before the wavefront correction, the human eye 17 is replaced by a simulated human eye, wherein the simulated human eye comprises a lens with the caliber of 10mm and the focal length of 20mm and ground glass, the ground glass is placed at the focal plane position of the lens, and the fundus retina of the human eye is simulated; the 635nm imaging light was turned off, the 808nm probe light was turned on, and the response function of the deformable mirror 19 was measured with the shack Hartmann wavefront sensor 23, and then a control matrix was calculated.

13 When the simulated human eye is used for wavefront correction and imaging, the shack Hartmann wavefront detector 23 can be used for measuring the wavefront slope, the voltage which is required to be applied to the deformable mirror 19 is calculated by using the measured slope and the control matrix, closed loop correction is performed by using an integral control method, the deformable mirror is controlled to compensate for the distorted wavefront, the compensated wavefront is smoother, and the obtained aberration is smaller. In the correction process, 635nm imaging light is collected on the imaging CCD, and an imaging result with high resolution and large field of view can be obtained on the CCD.

14 Artificial introduction of a large defocus as shown in fig. 4a and 4b, the wavefront before correction as shown in fig. 4a, pv and RMS 16.845 μm and 8.135 μm respectively; the corrected wavefront is shown in FIG. 4b with PV and RMS of 1.43 μm and 0.225 μm, respectively. The images before and after correction obtained by the imaging camera 25 are shown in fig. 5a and 5b, fig. 5a being the image before correction and hardly resolved, fig. 5b being the resolution plate after correction, stripes and numerals being visible; the corrected definition is obviously improved, at this time, the spot diameter on the CCD panel occupies about 450 pixels, and the illumination area of 450 pixels corresponding to the fundus is about 293 μm.

Some steps in the embodiments of the present application may be implemented by using software, and the corresponding software program may be stored in a readable storage medium, such as an optical disc or a hard disk.

The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the application are intended to be included within the scope of the application.

Claims

1. A highly versatile fundus-adaptive optical imaging system, the system comprising five subsystems: a sighting target staring subsystem, an illumination subsystem, a detection subsystem, an imaging subsystem and a pupil monitoring subsystem; the sighting target staring subsystem is used for avoiding irregular disturbance of eyes due to no target staring, and guiding the changes of the staring direction of the eyes by moving the sighting target so as to change the fundus imaging area; the illumination subsystem is used for providing illumination for a fundus imaging area of a human eye; the detection subsystem is used for measuring human eye aberration; the imaging subsystem is used for imaging the fundus retina; the pupil monitoring subsystem is used for auxiliary alignment in the imaging process;

2. The system according to claim 1, characterized in that the system comprises a first light source (1), a second light source (2), a first lens (3) and a second lens (4), a first dichroic prism (5), a negative axicon lens (6) and a positive axicon lens (7), a second dichroic prism (8), a third dichroic prism (9), a third lens (10), a dichroic sheet (11), a first mirror (12), a second mirror (13), a third mirror (14), a fourth mirror (15), a fourth lens (16), a human eye or simulated human eye (17), a fifth lens (18), a deformable mirror (19), a fifth mirror (20), a sixth lens (21), a dichroic sheet (22), a shack hartmann wavefront detector (23), a seventh lens (24), an imaging camera (25), a pupil camera (26), an eighth lens (27) and an LED vision standard light source (28);

the first reflecting mirror (12), the second reflecting mirror (13), the third reflecting mirror (14) and the fourth reflecting mirror (15) form a four-reflecting mirror system with adjustable distance, the second reflecting mirror (13) and the third reflecting mirror (14) are mutually perpendicular, the first reflecting mirror (12) and the fourth reflecting mirror (15) are mutually perpendicular, and the pupils of different eyes are matched by adjusting the distance between two groups of mutually perpendicular reflecting mirrors.

3. The system according to claim 2, characterized in that the first light source (1) is located on the focal plane of the first lens (3) and the second light source (2) is located on the focal plane of the second lens (4); parallel light generated by light emitted by the first light source (1) after passing through the first lens (3) or parallel light generated by light emitted by the second light source (2) after passing through the second lens (4) sequentially passes through a negative axicon lens (6) and a positive axicon lens (7) and then is parallel annular light; the cone angles of the negative axicon (6) and the positive axicon (7) are the same;

4. A system according to claim 3, wherein the distance Δd of movement between the two sets of mutually perpendicular mirrors when matching the pupils of different eyes is:

wherein D is the diopter of the human eye, f ₁₆ Is the focal length of the fourth lens (16).

5. The system according to claim 4, characterized in that the splitting ratio of the first (5), second (8) and third (9) splitting prisms is 50:50.

6. The system according to claim 5, characterized in that the first light source (1) is a 808nm light source for wavefront detection; the second light source (2) is a 635nm light source and is used for imaging; the focal length of the first lens (3), the second lens (4) and the eighth lens (27) is 50mm, and the caliber is 25.4mm; the focal length of the third lens (10) is 300mm, and the caliber is 50mm; the focal length of the fourth lens (16) is 125mm, and the caliber is 25.4mm; the focal length of the fifth lens (18) is 200mm, and the caliber is 50mm; the focal length of the sixth lens (21) is 75mm, and the caliber is 25.4mm; the focal length of the seventh lens (24) is 125mm, and the caliber is 25.4mm; all lenses were double cemented achromats and the surface was coated with an anti-reflection film.

7. The system of claim 6, wherein the LED optotype light source (28) has a center wavelength of 550nm; the transmission and reflection light splitting ratio of the light splitting sheet (11) is 1:9; the deformable mirror (19) is a 69-unit deformable mirror with a light transmission caliber of 10mm; the color separation film (22) is used for transmitting 808nm detection light and reflecting 550nm and 635nm light.

8. The system according to claim 7, characterized in that the simulated human eye (17) comprises a resolution plate and a lens with a 10mm aperture and a focal length of 20mm, the aperture being 10mm; the resolution board is placed at the focal plane position of the lens and is used for simulating the retina of the ocular fundus.

9. The system according to claim 8, characterized in that, when performing wavefront correction and imaging with an analog human eye, the wavefront slope is measured with a shack hartmann wavefront sensor (23), the voltage that should be applied to the deformable mirror (19) is calculated with the measured slope and the control matrix, closed loop correction is performed with an integral control method, and the deformable mirror (19) is controlled to compensate for the distorted wavefront;

when the human eyes are used for wavefront correction and imaging, firstly, an LED sighting target light source (28) is turned on, the human eyes stare at a sighting target through a sighting target subsystem until the sighting target is in a clear position, and the human eyes are aligned in a light path at the moment; the preceding steps are then repeated, namely closed loop correction using the shack Hartmann wavefront sensor (23) and the deformable mirror (19).

10. Use of the system of any one of claims 1-9 for wavefront correction and fundus adaptive optical imaging.