Apparatus for confocal ocular examination
By adopting the confocal structure of DMD chip in laser scanning eye examination equipment, the shortcomings of traditional equipment in image quality and imaging frame rate are solved, high-quality imaging and stable optical performance are achieved, and noise and cost are reduced.
Patent Information
- Application Number
- CN202380074263.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-11-22
- Filing Date
- 2023-09-07
- Publication Date
- 2025-06-24
AI Technical Summary
Traditional laser scanning eye examination equipment has shortcomings in image quality and imaging frame rate, and the presence of large moving parts in the equipment leads to unstable optical performance and high noise.
Using a digital micromirror device (DMD) chip as the imaging system of the scanner, high frame rate and high resolution imaging is achieved through the confocal structure of the DMD chip. The device uses the mirror of the DMD chip to guide and receive light, achieving flexible adjustment of pinhole size and shape, avoiding the use of large moving parts.
It has achieved high-quality imaging, improved image quality, accelerated imaging frame rate, stable optical performance of the equipment, quiet and noise-free, and high cost-effectiveness.
Smart Images
Figure CN120201958A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a device according to the subject matter of claim 1. Background Art
[0002] In a Scanning Laser Ophthalmoscope (SLO), a laser is used as a light source. When examining the fundus of the eye, it is necessary to use the laser to pass through the eyeball and emit detection light towards the fundus. The fundus will reflect light, and then the reflected light is analyzed and used to create an image. Usually, a laser is used to scan the fundus to form a grating pattern. The grating pattern usually goes from left to right and then is arranged vertically. In this way, the fundus area to be examined can be clearly imaged.
[0003] The principle of a scanning laser ophthalmoscope is similar to that of a laser scanning microscope. The difference from a laser scanning microscope is that a scanning laser ophthalmoscope uses the human eye lens as an objective lens, while in a laser scanning microscope, an artificial objective lens is equipped in the microscope.
[0004] Traditional scanning techniques are commonly used in ophthalmic optical imaging. These techniques include line scanning systems or confocal scanning laser systems, in which two independent scanners are provided in the X direction and the Y direction.
[0005] Devices for laser scanning eye examinations using traditional scanners generally have relatively expensive components, such as line scanning cameras or oscillating scanners. The photosensitivity of a traditional line scanning camera is lower than that of a single detector, and the image is limited to single-axis confocal when in use. An oscillating resonant scanner can be adjusted and uses a sine wave motion, which may sometimes generate relatively high noise. Summary of the Invention
[0006] In view of the above, the object of the present invention is to provide a device that can achieve the best imaging quality.
[0007] To achieve the above object, the present invention provides the features described in claim 1.
[0008] Accordingly, the illumination device includes a DMD chip, and the DMD chip can guide light to the sample and guide the light reflected back from the sample to the DMD chip to the detector.
[0009] According to the present invention, it is first recognized that an imaging system using a so-called Digital Mirror Device (DMD) as a scanner is used. Subsequently, it is recognized that in the current concept, the DMD or DMD chip is only used as an illumination unit.
[0010] It is also recognized that in the prior art, the light returned from the human eye (i.e., reflected light or scattered light) no longer passes through the DMD chip, but is first guided by a beam splitter to a high-resolution 2D camera chip, and then the chip creates an image.
[0011] It will also be recognized that this structure cannot be confocal, thus reducing the image quality. The photosensitivity of conventional high-resolution CMOS and CCD camera chips is much lower than that of a single detector.
[0012] It will also be recognized that when scanning the entire DMD chip pixel by pixel, the imaging frame rate of a high-resolution image will be relatively slow.
[0013] According to the present invention, it is finally recognized that high frame rate and high resolution can be achieved by using a confocal structure of the DMD chip. Such a device has the advantage of high-quality imaging due to its confocal structure. This device is basically free of large moving parts, with absolutely stable optical performance and quiet operation without noise.
[0014] The use of a DMD chip ensures the durability and technical robustness of the device. Robust digital imaging can be advantageously achieved by using the device, avoiding similar problems such as scanning drift, sinusoidal trajectory distortion, and jitter.
[0015] The DMD chip is equipped with individual optical elements, namely extremely small mirrors or micromirrors. In order to direct or reflect the light incident on the mirror from one direction to another direction, each mirror can be moved independently, especially tilted.
[0016] In this context, light or a light beam can be guided from the DMD chip to the sample along the same optical path and then returned to the DMD chip as reflected light or a reflected light beam. Such that the same mirror of the DMD chip can both direct the incident light or light beam to irradiate the sample and receive the light or light beam reflected from the sample. By linking the individual mirrors of the DMD chip, the device can flexibly adjust the pinhole size and pinhole shape. Compared with other scanning systems, the device is cost-effective, has a compact structure, and is very affordable according to different resolutions.
[0017] The detector can be configured as a matrix detector and / or an MPPC array detector. In this way, a confocal structure can be achieved by using the DMD chip and digital scanning. Taking the human eye as the sample, the DMD chip is imaged onto the retina on the objective side, and the DMD chip is also imaged onto the detector array on the detector side.
[0018] The surface of the DMD chip can be divided into a certain number of partitions, and the surface of the detector can also be divided into a certain number of partitions. And the partitions of the DMD chip are optically corresponding to the partitions of the detector respectively to generate an image. In this way, the DMD chip can be optically imaged onto the detector array.
[0019] All partitions of the DMD chip can have the same size, and all partitions of the detector can also have the same size. Due to the large number of mirrors, the DMD chip can be configured to simulate each partition, especially the partition size, while the detector has truly spatially and physically defined partitions. Therefore, the DMD chip can be adjusted according to the detector. Alternatively or additionally, the partitions of the DMD chip can have the same size as the partitions of the detector. The DMD chip and the detector are divided into identical partitions to enable parallel scanning.
[0020] Each partition of the DMD chip can be precisely matched to a partition of the detector, enabling the DMD chip to image or project towards the sample side onto the surface to be measured of the sample and image or project towards the detector side onto the surface of the detector. In this way, the reflected light from the sample or the eyeball will pass through the DMD chip and be guided therefrom onto the partitioned detector or the partitioned detector array. In this regard, the DMD chip is not only used for illumination. The individual mirrors of the DMD chip act as pinholes, i.e., they exhibit a true confocal effect. Therefore, the pinhole size and pinhole shape can be flexibly varied.
[0021] The illumination device can include an illumination unit, and the light from the illumination unit can be guided onto the DMD chip. The DMD chip can then be used for illumination and become part of the illumination system. Alternatively, the light from the illumination unit can be guided onto the DMD chip through a TIR prism. The TIR prism generally consists of two mutually stacked prisms and can guide the incident light particularly compactly onto the DMD chip.
[0022] A beam splitter can be arranged between the illumination unit and the DMD chip and / or the TIR prism, and the light reflected from the sample can be deflected from this beam splitter onto the detector. In this way, the reflected light will reach the detector while maintaining the confocal principle.
[0023] The light emitted by the illumination unit can reach the TIR prism and / or the DMD chip after passing through the first lens and the second lens. In this way, a beam splitter can be arranged between the two axially spaced lenses mentioned above.
[0024] In this context, a beam splitter can be arranged between the first lens and the second lens. This beam splitter can guide the reflected light to the detector.
[0025] The light emitted from the DMD chip towards the sample can pass through the excitation lens or the third lens individually, or alternatively through the fourth lens and the fifth lens, and then reach the sample. Both of these lens configurations can achieve a confocal structure, in which the human eye lens becomes part of the optical arrangement. On the one hand, a simple structure can be made using only a single lens, and on the other hand, a simple expandable optical element can be made using, for example, three lenses.
[0026] A detector lens or a sixth lens can be arranged between the beam splitter and the detector. In this way, the light can be focused onto the detector. The sample or the human eye is imaged on the DMD chip and the detector.
[0027] A single mirror of the DMD chip can act as a pinhole. Each mirror of the DMD chip acts as a so-called pinhole. This is how the confocal principle is realized.
[0028] In an arrangement including a device of the type described herein, the light emitted by the illumination unit of the illumination device or the swept-source OCT illumination unit can be split into a sample arm and a reference arm. Wherein, the optical signals from the sample arm and the reference arm can be superimposed and interfered at the detector, and an OCT image is generated from the interference signal by the evaluation device. In this way, the DMD chip is used for OCT imaging. The characteristic of the device used is fixed imaging.
[0029] The light from the sample arm can be guided to the DMD chip via a feed-in mirror, wherein the light from the reference arm can be guided to the DMD chip via a polarizing mirror or a reference beam splitter. When a swept-source OCT illumination unit is adopted, the DMD chip is illuminated.
[0030] The device described herein can be used for confocal laser scanning of two-dimensional images and OCT imaging. The device described herein can also be used in combination with a swept-source OCT (Swept-Source-OCT, SS-OCT).
[0031] The term "Optical Coherence Tomography" (commonly abbreviated as OCT) refers to an imaging method. Through this method, two-dimensional and three-dimensional images of light-scattering structures can be obtained.
[0032] This specification describes imaging of the human eye retina, but the device can also be used for other applications. Brief Description of the Drawings
[0033] Figure 1 Shows a device for confocal eye examination, which is provided with a plurality of lenses between the DMD chip or the TIR prism and the human eye;
[0034] Figure 2 The left middle figure shows a schematic diagram of the detector, where the detector surface is divided into a plurality of partitions. The middle figure shows a schematic diagram of the DMD chip, where the DMD chip surface is divided into a plurality of analog partitions. The sizes and numbers of the DMD chip partitions and the detector partitions correspond to each other. The right figure shows an image collected by the DMD chip and the detector, and this image is composed of a plurality of partitions;
[0035] Figure 3 Shows a confocal eye examination device with only one lens provided between the DMD chip or the TIR prism and the human eye;
[0036] Figure 4 shows an OCT imaging arrangement. Detailed implementation
[0037] Figure 1 The confocal ophthalmic device shown includes: an illumination device for illuminating the sample 13; and a lens group having a plurality of lenses 6 - 11 for guiding light from the illumination device to the sample 13 and back from the sample 13 to the detector 3. The illumination device includes a DMD chip 2 that can guide light to the sample 13 and guide the light reflected back from the sample 13 to the detector 3.
[0038] Figure 1 Schematically shows the function of a confocal optical arrangement for imaging the fundus (especially the retina 12). The human eye serves as the sample 13. The arrangement includes a device having an illumination device with an illumination unit 1 and a DMD chip 2.
[0039] The device includes a detector 3 configured as an MPPC array detector, where MPPC (MultiPixelPhoton Counter) represents "Multi - Pixel Photon Counter". The device also includes various other optical elements for guiding light, namely a beam splitter 4, a TIR prism 5, and various optical lenses 6 to 11.
[0040] Light or a light beam is guided from the DMD chip 2 to the sample 13 along the same optical path and returns from the sample 13 as a reflected light or reflected beam to the DMD chip 2, such that the same mirror of the DMD chip 2 can both guide the incident light or beam to irradiate the sample 13 and receive the light or beam reflected back from the sample 13.
[0041] The detector 3 is configured as a matrix detector, namely an MPPC array detector.
[0042] Figure 2 The middle figure of... shows the surface of the DMD chip 2 divided into a certain number of analog partitions 2a. Figure 2 The left figure of... shows the surface of the detector 3 also divided into a certain number of partitions 3a. The partitions 2a of the DMD chip 2 are optically corresponding to the partitions 3a of the detector 3 respectively to generate an image 15 as shown in Figure 2 the right figure.
[0043] All the partitions 2a of the DMD chip 2 have the same size, and all the partitions 3a of the detector 3 also have the same size. The partitions 2a of the DMD chip 2 are optically corresponding to the partitions 3a of the detector 3.
[0044] Each partition 2a of the DMD chip 2 precisely matches one partition 3a of the detector 3, such that the DMD chip 2 can image towards the sample side or project onto the surface 12 to be measured of the retina of the sample 13, and can image towards the detector side or project onto the surface of the detector 3. As a result, the retina 12 is imaged onto the DMD chip 2 and the detector 3.
[0045] The illumination device includes an illumination unit 1, and the light from the illumination unit 1 can be guided onto the DMD chip 2. The DMD chip 2 is used to illuminate the sample 13. Figure 1 Specifically, it shows that the light from the illumination unit 1 is guided onto the DMD chip 2 through the TIR prism 5 and then turns towards the direction of the sample 13 from here.
[0046] A beam splitter 4 is arranged between the illumination unit 1 and the TIR prism 5, and the light reflected from the sample 13 can be deflected from this beam splitter 4 onto the detector 3. The light emitted by the illumination unit 1 can pass through the first lens 6 and the second lens 7, and then the light beam hits the TIR prism 5 and then hits the DMD chip 2 from here. The beam splitter 4 is arranged between the first lens 6 and the second lens 7.
[0047] The light emitted from the DMD chip 2 towards the sample 13 hits the sample 13 after passing through the third lens 8, the fourth lens 9, and the fifth lens 10. Here, the sample 13 is a human eye, and the human eye lens 20 is used to deflect or focus the light or light beam onto the retina 12.
[0048] A detector lens 11 or a sixth lens 11 is arranged between the beam splitter 4 and the detector 3. A single mirror of the DMD chip 2 acts as a pinhole for limiting the amount of light.
[0049] Figure 3 Another device is shown, whose structure is similar to Figure 1 the device shown, except that two lenses in the lens group are omitted.
[0050] Figure 1 and Figure 3 In the two devices shown, the detector 3, the DMD chip 2, and the retina 12 of the eyeball 13 are all optically imaged with each other.
[0051] The DMD chip 2 is composed of a number of individually controllable mirrors, and is imaged onto the retina 12 through the above-mentioned optical elements.
[0052] Each mirror can correspond to a pixel of the generated image 15. The surface of each mirror is very small. The diagonal of this surface is about 10 μm.
[0053] These mirrors can be controlled and moved at an extremely high speed, and the typical moving frequency can reach above 30 kHz.
[0054] Detection is performed by coupling the photosensitive detector 3 into the illumination optical path 14 via the beam splitter 4, so as to detect the reflected light from the sample 13 (i.e., the eyeball). The DMD chip 2 is imaged onto the surface of the detector 3 via the optical elements.
[0055] To generate the image 15, each mirror is switched at high speed one by one, scanning the fundus point by point, which is similar to a conventional laser scanning system.
[0056] In this way, light is guided from the mirror through the optical path to the fundus. The light reflected or scattered at the fundus returns along the same optical path and is guided to the detector 3 through the current active mirrors and the beam splitter 4.
[0057] When the light is reflected pointwise from the focal plane, the light intensity at the detector 3 reaches the maximum, and most of the light outside the focal plane will not be reflected by the active mirror. This is how the confocal principle is realized. Each single point is associated with a measurement value at the detector 3, and thus a two-dimensional image 15 can be formed.
[0058] Figure 2 The shown detector 3 uses an area array detector with multiple individually readable partitions or channels 3a instead of a single photosensitive detector. Correspondingly, the DMD chip 2 is also divided into partitions 2a in the same way.
[0059] By means of the partitions working in parallel, the so-called pixel clock or image generation speed can be significantly increased.
[0060] Since the active mirrors or pixels of the DMD chip 2 are spatially separated (or divided into parallel scanning partitions), different from CCD or CMOS cameras, the confocal principle is still retained.
[0061] The illumination unit 1 is used to uniformly illuminate the optically active DMD chip 2 over a large area. The aperture stop is imaged onto the DMD chip 2. In Figure 1 and Figure 3 the light is guided by the TIR prism 5, but it can also be achieved without using the TIR prism. Since the light quantity is distributed over the entire area of the DMD chip 2 or the equivalent area of the retina 12, a relatively high illumination power is required. This can be achieved, for example, by infrared light-emitting diodes (IR-LEDs).
[0062] Figure 4 Shows the arrangement of the device basically including Figure 1 The light emitted by the illumination unit 1' of the illumination device or the swept-source OCT illumination unit 1' can be split into the sample arm 16 and the reference arm 17. Among them, the optical signals from the sample arm 16 and the reference arm 17 can be superimposed and interfered at the detector 3, and an OCT image is generated from the interference signal by the evaluation device.
[0063] Light from the sample arm 16 can be guided to the DMD chip 2 via the feed-in mirror 18, the first lens 6, and the illumination optical path 14, where light from the reference arm 17 can be guided to the DMD chip 2 via the polarizing beam splitter or reference beam splitter 19 and the excitation lens 8.
[0064] Light from the sample arm 16 propagates from the DMD chip 2 to the sample 13, and the light reflected from the sample 13 falls back onto the DMD chip 2 and then reaches the detector 3 via the TIR prism 5 and the beam splitter 4 from there.
[0065] Light from the reference arm 17 is guided to the reference beam splitter 19 via the coupling output mirror 21 and the coupling input mirror 22, passes through the excitation lens 8 and shoots in the direction of the DMD chip 2 from there, and then is guided to the detector 3 via the TIR prism 5 and the beam splitter 4 from there.
[0066] At the detector 3, the light rays from the sample arm 13 and the reference arm 17 interfere. By evaluating the interference, an OCT image can be generated.
[0067] Figure 4 An extended use of the device described herein for optical coherence tomography (OCT) is shown.
[0068] Figure 4 An optical setup for OCT image acquisition is shown. The illumination unit 1' is configured as a swept-source here and is divided into two arms, namely the sample arm 16 and the reference arm 17. At the detector 3, the optical signals from the sample arm 16 and the reference arm 17 are superimposed again and interfere. The lengths of the two arms 16, 17 must be coordinated with each other.
[0069] For example, the frequency of the swept-source can be 32 kHz. With 64 channels, an effective A-scan rate of 2 MHz can be achieved. This is equivalent to eight times faster than a frequency of 250 kHz. Two-dimensional laser scanning, OCT, and a patient display can be run through the same DMD chip. Due to its small and compact size, a binocular technical solution can also be envisioned.
[0070] Reference Signs
[0071] 1, 1' Illumination Unit
[0072] 2 DMD Chip
[0073] 3 Detector
[0074] 4 Beam Splitter
[0075] 5 TIR Prism
[0076] 6 First Lens
[0077] 7 Second Lens
[0078] 8 Third Lens
[0079] 9th Fourth Lens
[0080] 10th Fifth Lens
[0081] 11th Detector Lens
[0082] 12th Retina
[0083] 13th Sample
[0084] 14th Illumination Optical Path
[0085] 15th Image
[0086] 16th Sample Arm
[0087] 17th Reference Arm
[0088] 18th Feed-in Mirror
[0089] 19th Reference Beam Splitter
[0090] 20th Human Eye Lens
[0091] 21st Output Coupling Mirror
[0092] 22nd Input Coupling Mirror It should be noted that in the context of patent translation, it is very important to ensure accuracy and consistency. The above translation is for reference only, and it is recommended to further verify and adjust according to the specific patent content and relevant professional knowledge.
Claims
1. An apparatus for performing confocal eye examination, comprising: An illumination device for illuminating a sample (13); A lens group having a plurality of lenses (6-11) for guiding light from the illumination device to the sample (13) and guiding it back from the sample (13) to a detector (3), Characterized in that, The illumination device includes a DMD chip (2), and the DMD chip (2) can guide light to the sample (13) and can guide the light reflected back from the sample (13) to the DMD chip (2) to the detector (3).
2. The device according to claim 1, characterized in that, Light or a light beam can be guided from the DMD chip (2) to the sample (13) along the same optical path and then return to the DMD chip (2) as reflected light or a reflected light beam, such that the same mirror of the DMD chip (2) can both guide the incident light or light beam to irradiate the sample (13) and receive the light or light beam reflected back from the sample (13).
3. The device according to claim 1 or 2, characterized in that The detector (3) is configured as a area array detector and / or an MPPC array detector.
4. The device according to any one of the above claims, characterized in that, The surface of the DMD chip (2) is divided into a certain number of partitions (2a), wherein the surface of the detector (3) is also divided into a region of a certain number of partitions (3a), and wherein the partitions (2a) of the DMD chip (2) are respectively optically corresponding to the partitions (3a) of the detector (3) to generate an image (15).
5. The device according to claim 4, characterized in that, All the partitions (2a) of the DMD chip (2) have the same size, wherein all the partitions (3a) of the detector (3) have the same size; and / or the partitions (2a) of the DMD chip (2) have the same size as the partitions (3a) of the detector (3).
6. The device according to claim 4 or 5, characterized in that, Each partition (2a) of the DMD chip (2) precisely matches one partition (3a) of the detector (3), such that the DMD chip (2) can image or project towards the sample side onto the surface to be measured (12) of the sample (13) and image or project towards the detector side onto the surface of the detector (3).
7. The device according to any one of the preceding claims, characterized in that, The illumination device includes an illumination unit (1), wherein the light energy from the illumination unit (1) can be guided onto the DMD chip (2), or wherein the light energy from the illumination unit (1) can be guided onto the DMD chip (2) through a TIR prism (5).
8. The device according to any one of the preceding claims, characterized in that, A beam splitter (4) is arranged between the illumination unit (1) and the DMD chip (2) and / or the TIR prism (5), and the reflected light can be deflected from the beam splitter (4) onto the detector (3).
9. The device according to claim 7 or 8, characterized in that, The light emitted by the illumination unit (1) can pass through a first lens (6) and a second lens (7) and then irradiate onto the TIR prism (5) and / or the DMD chip (2).
10. The device according to claim 8 or 9, characterized in that, A beam splitter (4) is arranged between the first lens (6) and the second lens (7).
11. The device according to any one of the preceding claims, characterized in that, The light emitted from the DMD chip (2) towards the sample (13) can irradiate onto the sample (13) after passing through the third lens (8) alone or after passing through the third lens (8), the fourth lens (9), and the fifth lens (10).
12. The device according to any one of claims 8 to 11, characterized in that, A detector lens (11) or a sixth lens (11) is arranged between the beam splitter (4) and the detector (3).
13. The device according to any one of the preceding claims, characterized in that, A single mirror (2) of the DMD chip acts as a pinhole.
14. An arrangement comprising the device according to any one of the preceding claims, characterized in that, The light energy emitted by the illumination unit (1') of the illumination device or the swept-source OCT illumination unit (1') is split into a sample arm (16) and a reference arm (17), wherein the optical signals from the sample arm (16) and the reference arm (17) can interfere with each other at the detector (3), and wherein an OCT image is generated from the interference signal by an evaluation device.
15. The arrangement according to claim 14, characterized in that, The light energy from the sample arm (16) can be guided to the DMD chip (2) via a feed-in mirror (18), and the light energy from the reference arm (17) can be guided to the DMD chip (2) via a polarizing beam splitter or a reference beam splitter (19).