Device for measuring eye length
By designing optical channels of different diameters and lengths, and using lenses to form focal planes and reference planes, the existing OCT technology has solved the problems of hardware modification and eye movement distortion in eye length measurement, achieving accurate and robust eye length measurement, suitable for existing OCT equipment.
Patent Information
- Application Number
- CN202380083805.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-19
- Filing Date
- 2023-09-21
- Publication Date
- 2025-07-11
AI Technical Summary
Existing OCT technologies require wider spectral or additional optical components when measuring eye length, and are prone to distortion due to eye movements and require hardware modification of the camera.
Two optical channels with different diameters and lengths are designed to form two focal planes and reference planes through lenses, using these planes for eye length measurement without the need for beam splitters and broadband OCT spectra, suitable for existing OCT devices, the lens group can adjust the beam refractive behavior, and the central beam and the outer edge beam are focused on the cornea and retina respectively.
It realizes accurate and robust eye length measurement without hardware modification, and enables clear imaging of the retina and cornea simultaneously, suitable for a variety of existing OCT devices.
Smart Images
Figure CN120303528A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an optical device according to the preamble of claim 1. Background Art
[0002] The term "Optical Coherence Tomography" (OCT for short) refers to an imaging method. Through this method, two-dimensional and three-dimensional images of light-scattering structures can be obtained. In this method, light with a certain bandwidth is usually split into two partial beams in a beam splitter. The first partial beam falls on the sample or object to be examined, and the second partial beam passes through a reference path. The light reflected from the sample or object interferes with the reference beam. Through the interference signal, with the help of a so-called A-scan, the sample can be analyzed for depth resolution, that is, along the depth of the optical axis of the first partial beam. In addition, the first partial beam can also be used to scan the sample in a plane or transversely to obtain an OCT image. A B-scan consists of multiple A-scans.
[0003] Currently, methods for measuring or estimating the eye length by means of the above-mentioned OCT technology are known.
[0004] Some of these methods require a relatively wide OCT spectrum, some other methods require additional optical components, and certain methods are time-consuming or prone to distortion due to eye movement. Summary of the Invention
[0005] In view of this, the object of the present invention is to propose a device that can simply and robustly measure the eye length, especially without hardware modification of the camera.
[0006] To achieve the above object, the present invention provides the features described in claim 1.
[0007] It is recognized according to the present invention that creating two optical channels with different diameters and lengths can not only generate two focal planes, but also generate two OCT reference planes with the same optical path length. Using these planes, eye length measurement can be selectively performed without using a beam splitter, especially a conventional beam splitter, in the optical device or the equipment equipped with the device. The device does not require a broadband OCT spectrum and can be used in many existing OCT devices. Without any hardware modification of the camera of the existing OCT device, the device can be used to perform eye length measurement. In addition, the optical device and the eye length measurement performed with it are very robust and accurate. Using the optical device or the eye length measurement performed with it can simultaneously and clearly image the retina and the cornea.
[0008] Two optical channels can be formed by lenses which are successively arranged collinearly and concentrically with respect to their respective optical axes, where at least one lens has a larger diameter than the other lens and the material part protruding from the other lens in a ring shape contributes to the second channel, thus forming an annular channel. These lenses are robust and can be easily connected to each other in a mechanical or material fit manner or in series optically. In addition, the optical properties of these lenses are clearly defined by their refractive behavior and are substantially unaffected by facilities such as heating or cooling. In such an optical device, the central beam will pass through all the lenses, while the outer edge beam will only pass through the lens with the larger diameter.
[0009] A plurality of lenses having the same second diameter can be placed as a lens group between at least two lenses having the same first diameter, where the first diameter is smaller than the second diameter. By using a plurality of lenses as a lens group, the refractive behavior of the entire light beam can be adjusted.
[0010] The optical device can have two focal planes, namely the first focal plane of the light rays passing through the internal first channel and the second focal plane of the light rays passing only through the annular second channel. The central beam and the outer edge beam converge on their respective focal planes. The optical device can be designed such that the focal plane of the central beam is located on the Cornea and the focal plane of the outer edge beam is located on the Retina.
[0011] The optical device can have two reference planes preferably having the same total optical path length, namely the first reference plane of the light rays passing through the internal first channel (constituting a longer optical path for the light rays) and the second reference plane of the light rays passing only through the annular second channel (constituting a shorter optical path for the light rays). Finally, the optical path lengths of the light rays reaching the two reference planes are the same, and only a part of the optical path (i.e., the first length) will be significantly extended for the central beam, depending on the glass refractive index. The optical path length of the central beam is significantly extended to obtain different reference planes. The optical device can be designed such that the reference plane of the central beam is located on the Cornea and the reference plane of the outer edge beam is located on the Retina.
[0012] Preferably, it is split into two focal regions or reference regions via concentric optical devices with different diameters. The central beam of the scanning field will pass through all the optical devices, while the edge rays will not pass through all the optical devices.
[0013] The optical device can be designed as an objective lens or a replaceable objective lens. The objective lens forms a prefabricated structural unit. The OCT device can be modified by replacing the objective lens. Such an objective lens can be used for measuring the eye length. In particular, such an objective lens can be designed as a multi-focal objective lens.
[0014] In a method for determining the distance between two structures, using an optical device of the type described herein, a first structure can be captured in a first focal plane and / or a first reference plane of the optical device, wherein a second structure can be captured in a second focal plane and / or a second reference plane of the optical device, wherein the distance between the structures is determined based on their captured data and / or image presentation of the two structures.
[0015] The first structure may be the cornea or a corneal region of the eyeball, and the second structure may be the retina or a retinal region of the eyeball.This provides a method for measuring eye length by means of OCT technology.
[0016] A device for performing optical coherence tomography (OCT) comprises an optical arrangement of the type described herein and can be equipped (in particular as hardware in combination with corresponding software) with electronics for performing the method described herein for determining the distance between two structures.
[0017] The electronic device controls the optical device of the device, in particular the interferometer, so as to capture the spacing of the structures by means of the optical device. Furthermore, the electronic device determines the spacing of the captured structures automatically or in a user-defined manner by means of an algorithm. The electronic device can present the captured structures as an image. In this way, the user can gain insights that help the diagnosis from the image. The image can be stored and / or processed in a memory of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 shows a schematic diagram of an optical arrangement in which an optical device for eye length measurement by means of OCT technology is used;
[0019] Figure 2 A cross-sectional image is shown, showing that the cornea is clearly imaged in the central region and the retina is clearly imaged in the peripheral region. DETAILED DESCRIPTION
[0020] Figure 1 An optical device used in an apparatus 13 for performing optical coherence tomography is shown. The optical device includes or forms a cylindrical optical channel 1 for guiding and refracting light, the optical channel 1 having a first diameter 1a and a first length 1b. The first channel 1 is segmentedly surrounded by a second optical channel 2 to guide and refract light in an annular concentric manner, wherein the second channel 2 has a larger diameter 2a than the first channel 1 but a smaller length 2b.
[0021] Both channels 1 and 2 are formed by lenses 3a, 3b, 3c, 3d, which are successively collinear and concentrically arranged with respect to their respective optical axes 4a, 4b, 4c, 4d. Specifically, a single optical axis is set up in this regard, and the optical axes 4a, 4b, 4c, 4d all coincide with this single optical axis. At least one of the lenses 3b, 3c has a larger diameter than the other lenses 3a, 3d, and the material part protruding from the other lens in a ring shape contributes to the second channel 2, thus forming an annular channel.
[0022] Specifically, two lenses 3b, 3c having the same second diameter 2a are placed as a lens group between two lenses 3a, 3d having the same first diameter 1a, where the first diameter 1a is smaller than the second diameter 2a.
[0023] The optical device can have two focal planes 5, 6, namely the first focal plane 5 of the light rays passing through the internal first channel 1 and the second focal plane 6 of the light rays passing only through the annular second channel 2.
[0024] The optical device has two reference planes 7, 8, namely the first reference plane 7 of the light rays passing through the internal first channel 1 (constituting a longer optical path for the light rays) and the second reference plane 8 of the light rays passing only through the annular second channel 2 (constituting a shorter optical path for the light rays). The device is designed as an objective lens or a replaceable objective lens.
[0025] Figure 1 A method for measuring the spacing 9 between two structures is also shown based on this arrangement, where an optical device of the above type is used, where the first structure is captured in the first focal plane 5 and the first reference plane 7 of the optical device, where the second structure is captured in the second focal plane 6 and the second reference plane 8 of the optical device, and where the spacing 9 between the structures is determined based on their capture data and / or the image representation of the two structures.
[0026] In a specific but non-limiting embodiment, the first structure is the cornea 10 or a corneal 10 region of the eyeball 11, and the second structure is the retina 12 or a retinal 12 region of the eyeball 11.
[0027] In this regard, Figure 1 The optical structure of the objective lens is shown, specifically an OCT objective lens for measuring the eye length of the human eye 11. The objective lens is composed of a plurality of lenses 3a, 3b, 3c, 3d, which are concentrically arranged in series and have different diameters. Therefore, as Figure 1As shown, the central beam passes through all the optical components, while the outer peripheral beam only passes through the optical components with a larger diameter. In this way, different focal planes 5 and 6 are generated for the central beam and the outer peripheral beam. In addition, the optical path length of the central beam is significantly extended, so that different reference planes 7 and 8 with the same total optical path length are also obtained. The objective lens is designed such that the focal plane 6 and the reference plane 8 of the outer peripheral beam are located on the retina 12 (Retina). The focal plane 5 and the reference plane 7 of the central beam are located on the cornea 10 (Cornea).
[0028] Figure 1 A device 13 for performing optical coherence tomography (OCT) is schematically shown, including the optical device and the electronics 14 for performing the above method.
[0029] In the OCT method, the light is usually split into two partial beams. The first partial beam falls on the sample to be examined (such as the cornea 10 or the retina 12), and the second partial beam passes through the reference optical path. The corresponding first partial beam is specifically guided to the corresponding focal planes 5 and 6. The corresponding second partial beam passes through a reference optical path with a finite length. The position of the reference plane presented in the OCT image is defined by the reference arm length. The "optical path lengths" of RE1 (reference plane 7) and RE2 (reference plane 8) are the same, so that these two regions can be presented simultaneously in the OCT image. Specifically, the corresponding reference planes 7 and 8 coincide with the corresponding focal planes 5 and 6. The beam reflected from the sample interferes with the reference beam. Through the interference signal, by means of the so-called A-scan, the sample can be analyzed for depth resolution, that is, along the depth of the optical axis of the first partial beam.
[0030] Figure 2 Shows the result of applying the method to be described Figure 1 to the human eye, where the first structure is the cornea 10 or the cornea 10 region of the eyeball 11, and the second structure is the retina 12 or the retina 12 region of the eyeball 11. Figure 2 Shows the structure presented by the electronics 14 in the image 15. Figure 2 Shows the image 15 as a sectional image. If a linear scan (OCT-B scan) is performed radially along the optical axes 4a, 4b, 4c, 4d of the objective lens or the optical device, the Figure 2 shown sectional image can be obtained. The cornea 10 is clearly imaged in the central region, and the retina 12 is clearly imaged in the peripheral region. Through the spacing 9 of the structures in the sectional image, the spacing between the cornea 10 and the retina 12 can be accurately calculated.
[0031] Determining the accurate eye length has multiple advantages: for example, when the eye length is known, the ratio can be calculated more accurately, and the eye structure can be presented more realistically.
[0032] Reference signs
[0033] 1 Cylindrical optical channel
[0034] 1a First diameter
[0035] 1b First length
[0036] 2 Second optical channel
[0037] 2a Smaller length
[0038] 2b Larger diameter
[0039] 3a, 3b, 3c, 3d Lenses
[0040] 4a, 4b, 4c, 4d Optical axes
[0041] 5 First focal plane
[0042] 6 Second focal plane
[0043] 7 First reference plane
[0044] 8 Second reference plane
[0045] 9 Spacing
[0046] 10 Cornea
[0047] 11 Eyeball
[0048] 12 Retina
[0049] 13 OCT device
[0050] 14 Electronic device
[0051] 15 Image
Claims
1. An optical device used in a device (13) for performing optical coherence tomography (OCT), comprising a cylindrical optical channel (1) for guiding refracted light, the optical channel (1) having a first diameter (1a) and a first length (1b). Characterized in that the first channel (1) is segmentally surrounded by a second optical channel (2) to concentrically guide refracted light in a ring shape, wherein the second channel (2) has a larger diameter (2a) but a smaller length (2b) than the first channel (1).
2. The device according to claim 1, characterized in that Both channels (1, 2) are formed by lenses (3a, 3b, 3c, 3d), and the lenses (3a, 3b, 3c, 3d) are successively arranged collinearly and concentrically with respect to their respective optical axes (4a, 4b, 4c, 4d). Among them, at least one of the lenses (3b, 3c) has a larger diameter than the other lens (3a, 3d), and the material part protruding from the other lens in a ring shape contributes to the second channel (2), thereby forming an annular channel.
3. The device according to claim 2, characterized in that, A plurality of lenses (3b, 3c) having the same second diameter (2a) are placed as a lens group between at least two lenses (3a, 3d) having the same first diameter (1a), wherein the first diameter (1a) is smaller than the second diameter (2a).
4. The device according to any one of the preceding claims, characterized in that, Two focal planes (5, 6), namely, the first focal plane (5) of the light passing through the internal first channel (1) and the second focal plane (6) of the light passing only through the annular second channel (2).
5. The device according to any one of the preceding claims, characterized in that, Two reference planes (7, 8), namely, the first reference plane (7) of the light passing through the internal first channel (1), which constitutes a longer optical path for the light, and the second reference plane (8) of the light passing only through the annular second channel (2), which constitutes a shorter optical path for the light.
6. The device according to any one of the preceding claims, characterized in that, The device is designed as an objective lens or a replaceable objective lens.
7. A method for determining the distance (9) between two structures, wherein an optical device according to any one of the preceding claims is used, wherein, A first structure is captured in the first focal plane (5) and / or the first reference plane (7) of the optical device, and a second structure is captured in the second focal plane (6) and / or the second reference plane (8) of the optical device. Moreover, the spacing (9) between the structures is measured according to the data captured by it and / or the image presentation of the two structures.
8. The method according to claim 7, wherein The first structure is the cornea (10) or a cornea (10) region of the eyeball (11); and the second structure is the retina (12) or a retina (12) region of the eyeball (11).
9. A device (13) for performing optical coherence tomography (OCT), comprising the optical device according to any one of claims 1 to 6 and an electronic device (14) for performing the method according to claim 7 or 8.
10. The device according to claim 9, characterized in that, The electronic device (14) presents the structures in an image (15).