Anterior segment imaging system and method

Abstract

According to the anterior segment imaging system and method, Bessel beam illumination and tilt-shift photography imaging modes are adopted, the contradiction between the imaging depth and the axial resolution is broken through, and the large imaging depth of 20 mm and the high axial resolution lt are achieved; therefore, the imaging precision is greatly improved, and the requirement of ophthalmologic operations on high-precision imaging is met; expensive equipment such as a complex spectrograph, a sweep-frequency light source and a high-speed acquisition card is not needed, and the system is simple in structure, convenient to operate and low in maintenance cost.

Description

Technical Field

[0001] The present invention relates to the field of laser imaging, and particularly to an anterior segment imaging system and method. Background Art

[0002] In ophthalmic surgery, anterior segment imaging is crucial for intraoperative trajectory planning, and the imaging accuracy directly determines the surgical accuracy. Currently, the anterior segment imaging of commercially available ophthalmic surgical devices mostly adopts the optical coherence tomography imaging scheme, which has some deficiencies. Its imaging depth is inversely proportional to the axial resolution, and the lateral resolution is inversely proportional to the scanning speed, that is, the greater the imaging depth, the lower the axial resolution; the higher the scanning speed, the lower the lateral resolution. Therefore, if a larger imaging depth is obtained through the prior art, the axial resolution will be lower, about 30 - 50 μm; if the scanning speed is increased, the lateral resolution will be greater than 20 μm. In addition, due to the high cost of spectrometers, swept-source lasers, and high-speed acquisition cards, etc., the cost of the prior art is relatively high. Summary of the Invention

[0003] The present invention provides an anterior segment imaging system and method, which can solve the problems existing in the prior scanning imaging scheme pointed out in the background art, that is, the imaging depth is inversely proportional to the axial resolution, and the lateral resolution is inversely proportional to the scanning speed.

[0004] An anterior segment imaging system includes a laser light source, a beam expander and collimator, a line scanner, a DOE diffractive device, a focusing lens, an imaging lens, and a camera;

[0005] Among them, the incident light beam generates a Bessel beam through the DOE diffractive device and the focusing lens, and through the beam scanning of the line scanner, a light sheet for illumination can be formed;

[0006] The imaging lens and the camera form a Scheimpflug imaging structure for obtaining anterior segment photos.

[0007] Preferably, the laser light source is used to generate near-infrared laser.

[0008] Preferably, the wavelength band of the near-infrared laser covers 800 nm - 1300 nm.

[0009] Preferably, the scanning frequency of the line scanner is greater than 100 Hz.

[0010] Preferably, the lens plane of the imaging lens, the imaging plane of the camera, and the extension plane of the plane where the anterior segment is located intersect at the same straight line.

[0011] An anterior segment imaging method includes the following steps:

[0012] S1, generating a Bessel beam through a DOE diffractor;

[0013] S2. Generate a light sheet by scanning a Bessel beam with a line scanner;

[0014] S3. Illuminate the eyeball with the light sheet;

[0015] S4. Take pictures of the illuminated anterior segment area inside the eyeball by means of shift lens photography to achieve anterior segment image acquisition.

[0016] Preferably, the step S1 is specifically as follows:

[0017] Generate a Bessel beam by using a DOE diffractive optical element, adjust the parameters of the Bessel beam through a beam shaping system to make it have a narrow and long shape, and expand the size of the Bessel beam through a beam expansion system.

[0018] Preferably, the step S2 is specifically as follows: Use a line scanner to perform line scanning on the Bessel beam, and adjust the thickness of the beam through a beam shaping system to form a light sheet.

[0019] Preferably, the step S4 is specifically as follows:

[0020] Image the illuminated area inside the eyeball with a high-speed camera, and adjust the imaging angle of the camera through a shift lens imaging system to achieve shift lens photography.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts the Bessel beam illumination and shift lens photography imaging method, breaks through the contradiction between imaging depth and axial resolution, realizes a large imaging depth of 20 mm and a high axial resolution of <10 μm, greatly improves the imaging accuracy, and meets the requirements of high-precision imaging for ophthalmic surgery;

[0022] There is no need for expensive equipment such as complex spectrometers, swept-source lasers, and high-speed acquisition cards. The system has a simple structure, convenient operation, and low maintenance cost. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the anterior segment imaging optical path;

[0024] Figure 2 It is a schematic diagram of the illumination structure;

[0025] Figure 3 It is a phase distribution diagram of the DOE diffractive device;

[0026] Figure 4 It is an anterior segment image taken by the anterior segment imaging system. Specific Embodiments

[0027] The following combines the drawings to describe in detail a specific embodiment of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

[0028] Example 1

[0029] As Figures 1 to 4 shown, an anterior segment imaging system provided by an embodiment of the present invention includes a laser light source, a beam expander collimator, a line scanner, a DOE diffraction device, a focusing lens, an imaging lens, and a camera;

[0030] Among them, the laser light source is used to generate near-infrared laser, and the laser band covers 800 - 1300 mm;

[0031] The beam expander collimator is used to shape and expand and collimate the laser;

[0032] The line scanner performs one-dimensional ultra-fast line scanning on the light beam, and the scanning frequency is greater than 100 hz;

[0033] The phase distribution of the DOE diffraction device is as Figure 3 shown;

[0034] As Figure 2 shown, the DOE diffraction device can shape the incident light beam, cooperate with the focusing lens to generate a slender Bessel beam, and cooperate with the beam scanning of the line scanner to form an ultra-thin light sheet for illuminating the eye;

[0035] The imaging lens and the camera are placed at a certain angle. Specifically, the lens plane of the imaging lens, the imaging plane of the camera, and the extension plane of the plane where the anterior segment is located intersect at the same straight line, thereby forming a Schlieren imaging structure to capture a photo of the anterior segment, as Figure 4 shown, its imaging depth can reach up to 20 mm at most, the transverse diameter can reach 20 mm, the axial resolution < 10 μm, and the transverse resolution < 10 μm;

[0036] By means of line-scanning the Bessel beam, the contradiction between the imaging speed and the transverse resolution is broken through, and a high-speed imaging frame rate of up to one hundred hertz and a high transverse resolution of < 10 μm are achieved, greatly improving the imaging speed and meeting the requirements of ophthalmic surgery for high-speed imaging;

[0037] This embodiment adopts an optical imaging method, without expensive devices such as complex spectrometers, swept-source lasers, and high-speed acquisition cards. The system has a simple structure, is easy to operate, and has low maintenance costs;

[0038] Embodiment 2

[0039] Based on the anterior segment imaging system of Embodiment 1, this embodiment proposes an anterior segment imaging method, which includes the following steps:

[0040] S1: Generate an elongated Bessel beam through a DOE diffractor, where (a) use a DOE diffractive optical element to generate a Bessel beam, (b) adjust the parameters of the Bessel beam through a beam shaping system to make it have a narrow / elongated shape, and (c) expand the size of the Bessel beam through a beam expansion system;

[0041] S2: Generate an ultra-thin light sheet by scanning the Bessel beam with a line scanner, where (a) use the line scanner to perform line scanning on the Bessel beam, and (b) adjust the thickness of the beam through a beam shaping system to form an ultra-thin light sheet;

[0042] S3: Illuminate the eyeball with the ultra-thin light sheet;

[0043] S4: Adopt the method of shift-axis photography to photograph the illuminated anterior segment area inside the eyeball to achieve anterior segment image acquisition, where (a) use a high-speed camera to image the illuminated area inside the eyeball, and (b) adjust the imaging angle of the camera through a shift-axis imaging system (imaging lens + camera, the imaging lens and the camera have a deflection angle) to achieve shift-axis photography;

[0044] Among them, the beam shaping system in step S2 adopts a beam expander and collimator;

[0045] In this embodiment, through the Bessel beam illumination and shift-axis photography imaging methods, the contradiction between imaging depth and axial resolution is broken through, and a large imaging depth of 20 mm and a high axial resolution of <10 μm are achieved, greatly improving the imaging accuracy and meeting the requirements of high-precision imaging for ophthalmic surgery.

[0046] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit and basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0047] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An anterior segment imaging system, comprising a laser light source and a beam expander and collimator, characterized in that, It also includes a line scanner, a DOE diffraction device, a focusing lens, an imaging lens, and a camera; Among them, the incident light beam passes through the DOE diffraction device and the focusing lens to generate a Bessel beam, and through the beam scanning of the line scanner, a light sheet for illumination can be formed; The imaging lens and the camera form a Scheimpflug imaging structure for obtaining anterior segment photographs.

2. The anterior segment imaging system according to claim 1, characterized in that, The laser light source is used to generate near-infrared laser.

3. The anterior segment imaging system according to claim 2, wherein, The wavelength band of the near-infrared laser covers 800mm - 1300mm.

4. The anterior segment imaging system according to claim 1, characterized in that, The scanning frequency of the line scanner is greater than 100hz.

5. The anterior segment imaging system according to claim 1, wherein The extension planes of the lens plane of the imaging lens, the imaging plane of the camera, and the plane where the anterior segment is located intersect at the same straight line.

6. An anterior segment imaging method, characterized in that, It includes the following steps: S1. Generate a Bessel beam through the DOE diffractor; S2. Scan the Bessel beam through the line scanner to generate a light sheet; S3. Illuminate the eyeball with the light sheet; S4. Adopt the shift photography method to photograph the illuminated anterior segment area in the eyeball to realize anterior segment image acquisition.

7. The anterior segment imaging method according to claim 6, wherein, The specific content of step S1 is: Use the DOE diffractive optical element to generate a Bessel beam, adjust the parameters of the Bessel beam through the beam shaping system to make it have a narrow and long shape, and expand the size of the Bessel beam through the beam expansion system.

8. The anterior segment imaging method according to claim 6, wherein The specific content of step S2 is: Use the line scanner to perform line scanning on the Bessel beam, and adjust the thickness of the beam through the beam shaping system to form a light sheet.

9. The anterior segment imaging method according to claim 6, wherein, The specific content of step S4 is: Use a high-speed camera to image the illuminated area in the eyeball, and adjust the imaging angle of the camera through the shift imaging system to realize shift photography.

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