Imaging method based on paraxial light path correction

Abstract

The invention provides an imaging method based on paraxial light path correction. According to the imaging method, accurate correspondence between an OCT (Optical Coherence Tomography) tomographic image and a microscopic observation image in an operation can be ensured; comprising the following steps: S1, emitting visible red light to a sample through a light path formed by a paraxial light path correction end, and forming a red light scanning point on a sample plane; s2, the imaging control end obtains the coordinate position of the red light scanning point in the microscope view field image, and compares the coordinate position with the center of the microscope view field image to obtain a deviation value; s3, acquiring a mapping relation between a light path deflection angle and a displacement error of the paraxial light path correction end according to the deviation value, and then adjusting the light path of the paraxial light path correction end until the red light scanning point coincides with the center of the microscope view field image; s4, focusing the light path along the optical axis direction, and feeding back to an imaging control end in real time to realize real-time focus tracking and image quality optimization; and S5, carrying out image fusion on the real-time image obtained by the imaging control end and the view field image captured by the microscope camera, and carrying out synchronous display.

Description

Technical Field

[0001] This invention relates to the field of medical optical imaging technology, specifically to an imaging method based on paraxial optical path correction. Background Technology

[0002] Existing ophthalmic surgical microscopes are often used for tissue observation and operation positioning during surgery, but they cannot provide information on the internal structure of tissues. Optical coherence tomography (OCT) technology, with its high-resolution and non-invasive tomographic imaging capabilities, is widely used in ophthalmic surgical navigation. However, when integrating OCT into a microscope system, traditional solutions often use a coaxial incident method, which requires significant modifications to the microscope's optical path, making it unsuitable for system compatibility and modular design. In contrast, a paraxial structure can couple the OCT beam into the microscope's optical path at a smaller angle, but it has the following problems: (1) there is an angular deviation between the OCT beam and the microscope's optical axis, resulting in incomplete overlap of the imaging area; (2) there is a geometric error between the reflection position of the sample surface and the interference reference position; (3) intraoperative equipment vibration or focal point changes can easily cause imaging drift.

[0003] Therefore, there is an urgent need for a system design that can automatically correct the optical path deviation of the off-axis OCT and achieve optical registration and imaging overlap, so as to improve the imaging accuracy and stability of the OCT microscope system. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an imaging method based on paraxial optical path correction, which can achieve spatial overlap and real-time correction between the OCT imaging optical path and the microscope optical axis, thereby ensuring accurate correspondence between intraoperative OCT tomographic images and microscopic observation images.

[0005] This invention adopts the following technical solution: an imaging method based on paraxial optical path correction, comprising the following steps: S1. Visible red light is incident on the sample through the optical path correction end of the off-axis optical path and forms a red light scanning point on the sample plane. The microscope camera captures the red light scanning point in real time. S2. The imaging control terminal obtains the coordinate position of the red light scanning point in the microscope field of view image and compares it with the center of the microscope field of view image to obtain the deviation value. S3. Obtain the mapping relationship between the optical path deflection angle of the off-axis optical path correction end and the displacement error based on the deviation value. Then adjust the optical path of the off-axis optical path correction end according to the mapping relationship until the red light scanning point coincides with the center of the microscope field of view image. S4. Focus the optical path formed by the off-axis optical path correction end along the optical axis direction and feed it back to the imaging control end in real time to achieve real-time focus tracking and image quality optimization. S5. The real-time image obtained by the imaging control terminal is fused with the field-of-view image captured by the microscope camera and displayed synchronously.

[0006] Furthermore, the paraxial optical path correction end includes a linear motor, a microscope, and a collimating mirror, an X-ray galvanometer, a Y-ray galvanometer, a focusing mirror, an OCT lens, and a reflecting mirror arranged sequentially along the optical path. The microscope has a microscope objective and a microscope camera. The light reflected by the reflecting mirror is projected onto the sample after passing through the microscope objective. The X-ray galvanometer and the Y-ray galvanometer are on different optical axes, the collimating mirror is on the same optical axis as the X-ray galvanometer, and the Y-ray galvanometer, the focusing mirror, the OCT lens, and the reflecting mirror are arranged sequentially along the same optical axis. The linear motor is connected to the focusing mirror. Furthermore, the imaging control unit includes an OCT interferometer, a visible-red light source, a spectrometer, a delay line, a computer, a display, a linear motor controller, an XY galvanometer controller, and a mirror angle controller. The visible-red light source, spectrometer, and delay line are all connected to the OCT interferometer. The delay line, spectrometer, display, linear motor controller, XY galvanometer controller, and mirror angle controller are all connected to the computer. The light beam generated by the OCT interferometer is emitted to the collimating lens. The linear motor controller is connected to the linear motor. The XY galvanometer controller is connected to both the X-mirror and Y-mirror. The mirror angle controller is connected to the mirror. The microscope camera is connected to the computer. Furthermore, the visible red light source emits visible red light with a wavelength of 635 nm, and the light emitted from the microscope objective is incident on the sample at an angle of 8°. Furthermore, in step S3, the deflection angle and displacement error of the X-mirror and Y-mirror are adjusted according to the mapping relationship to make the red light scanning point coincide with the center of the microscope field of view image; Furthermore, the deflection angle is divided into the deflection angle θ1 of the X-mirror and the deflection angle θ2 of the Y-mirror; the displacement error is divided into the X-direction displacement error Δd1 of the X-mirror and the Y-direction displacement error Δd2 of the Y-mirror. Furthermore, the mapping relationship between the deflection angle θ1 of the X-mirror and the X-direction displacement error Δd1 of the X-mirror is: Δd1 = 2·θ1·f_eff; The mapping relationship between the deflection angle θ2 of the Y-mirror and the Y-direction displacement error Δd2 of the Y-mirror is: Δd2=2·θ2·f_eff; Where f_eff = f_3·(f_1 / f_2); f_1 is the focal length of the focusing lens; f_2 is the focal length of the OCT lens; f_3 is the focal length of the microscope objective lens; Furthermore, in step S4, the linear motor is driven by the linear motor controller to push the focusing lens to adjust its displacement and achieve focusing, and the displacement range is ±2mm; Furthermore, in step S4, the computer receives the focused image in real time, and then uses a closed-loop autofocus algorithm to obtain the image sharpness. When the image sharpness drops below a set threshold, the focusing lens is repositioned again until a clear image is obtained. Furthermore, in step S5, the computer displays the fused image in real time via a monitor at a refresh rate of not less than 30 frames per second.

[0007] The beneficial effects of this invention are that it has high stability and strong adaptability, which can significantly improve the intraoperative imaging quality and operational safety. The visible red light is projected onto the sample through the side-axis optical path correction end, which can avoid the modification of the main optical path of the microscope, improve compatibility, and realize the spatial overlap and real-time correction between the OCT imaging optical path and the microscope optical axis, thereby ensuring the accurate correspondence between the intraoperative OCT tomographic image and the microscopic observation image, and has broad clinical application prospects. Attached Figure Description

[0008] Figure 1 This is a connection diagram of the present invention. Detailed Implementation

[0009] like Figure 1 As shown, an imaging method based on paraxial optical path correction according to the present invention includes the following steps: S1. Visible red light (wavelength 635 nm) emitted by the visible red light source is incident on sample 10 through the optical path formed by the off-axis optical path correction end, and a red light scanning point is formed on the plane of sample 10. The microscope camera 8 captures the red light scanning point in real time. That is, the light output by the OCT interferometer is converted into parallel light by the collimating lens 1, and then passes through the X galvanometer 2, Y galvanometer 3, focusing lens 4, OCT lens 5, and reflecting mirror 6 in sequence, and then enters the sample 10 from the microscope objective lens 7 at an angle of 8°. S2. The imaging control terminal obtains the coordinate position of the red light scanning point in the microscope field of view image through existing image recognition algorithms (such as centroid positioning or Hough circle detection), and compares it with the center of the microscope field of view image to obtain the deviation value. S3. Obtain the mapping relationship between the optical path deflection angle of the off-axis optical path correction end and the displacement error based on the deviation value. Then adjust the optical path of the off-axis optical path correction end according to the mapping relationship until the red light scanning point coincides with the center of the microscope field of view image. Specifically, in step S3, the deflection angle and displacement error of X-mirror 2 and Y-mirror 3 are adjusted according to the mapping relationship to make the red light scanning point coincide with the center of the microscope field of view image; The deflection angle is divided into the deflection angle θ1 of X-mirror 2 and the deflection angle θ2 of Y-mirror 3; the displacement error is divided into the X-direction displacement error Δd1 of X-mirror 2 and the Y-direction displacement error Δd2 of Y-mirror 3; the X-direction displacement error Δd1 of X-mirror 2 is actually the deviation between the X-direction of the center point in the microscope image coordinate system and the actual position (X-direction) of the red light scanning point in the microscope image; the Y-direction displacement error Δd2 of Y-mirror 3 is actually the deviation between the Y-direction of the center point in the microscope image coordinate system and the actual position (Y-direction) of the red light scanning point in the microscope image. The mapping relationship between the deflection angle θ1 of X-mirror 2 and the X-direction displacement error Δd1 of X-mirror 2 is: Δd1=2·θ1·f_eff; The mapping relationship between the deflection angle θ2 of Y-mirror 3 and the Y-direction displacement error Δd2 of Y-mirror 3 is: Δd2=2·θ2·f_eff; Where f_eff = f_3·(f_1 / f_2); f_1 is the focal length of focusing lens 4; f_2 is the focal length of OCT lens 5; f_3 is the focal length of microscope objective lens 7; S4. Focus the optical path formed by the off-axis optical path correction end along the optical axis direction and feed it back to the imaging control end in real time to achieve real-time focus tracking and image quality optimization. Furthermore, in step S4, a linear motor is driven by a linear motor controller to push the focusing lens 4 to adjust its displacement and achieve focusing, and the displacement range is ±2mm. Furthermore, in step S4, the computer receives the focused image in real time, and then uses a closed-loop autofocus algorithm to obtain the image sharpness. When the image sharpness drops below a set threshold, the focusing lens 4 is repositioned until a clear image is obtained. S5. The real-time image obtained by the imaging control terminal is fused with the field-of-view image captured by the microscope camera 8 and displayed synchronously. Furthermore, in step S5, the computer displays the fused image in real time via a monitor at a refresh rate of not less than 30 frames per second.

[0010] The paraxial optical path correction end includes a linear motor 9, a microscope, and a collimating mirror 1, an X-ray mirror 2, a Y-ray mirror 3, a focusing mirror 4, an OCT lens 5, and a reflecting mirror 6 arranged sequentially along the optical path. The microscope has a microscope objective lens 7 and a microscope camera 8. The light reflected by the reflecting mirror 6 passes through the microscope objective lens 7 and is then projected onto the sample. The X-ray mirror 2 and the Y-ray mirror 3 are on different optical axes, while the collimating mirror 1 and the X-ray mirror 2 are on the same optical axis. The Y-ray mirror 3, the focusing mirror 4, the OCT lens 5, and the reflecting mirror 6 are arranged sequentially along the same optical axis. The linear motor is connected to the focusing mirror 4.

[0011] The imaging control unit includes an OCT interferometer, a visible-red light source, a spectrometer, a delay line, a computer, a monitor, a linear motor controller, an XY galvanometer controller, and a 6-angle reflector controller. The visible-red light source, spectrometer, and delay line are all connected to the OCT interferometer. The delay line, spectrometer, monitor, linear motor controller, XY galvanometer controller, and 6-angle reflector controller are all connected to the computer. The light beam generated by the OCT interferometer is emitted to collimating lens 1. The linear motor controller is connected to the linear motor. The XY galvanometer controller is connected to both the X-mirror 2 and Y-mirror 3. The 6-angle reflector controller is connected to reflector 6. The microscope camera 8 is connected to the computer. By driving the delay line, the optical path length can be adjusted, allowing the OCT imaging depth to gradually approach the preset ideal imaging position, thereby ensuring that the subsequent intraoperative retinal image can be stably formed at the optimal depth position to obtain the maximum signal intensity.

[0012] In step S3, the X-mirror 2 and Y-mirror 3 are adjusted to ensure that the red light scanning point coincides with the center of the microscope's field of view image. This ensures that the red light scanning point can be precisely spatially superimposed on the center of the microscope image in the X and Y directions, improving positioning accuracy. Subsequently, focusing is achieved by pushing the focusing mirror 4 to adjust its displacement, ensuring that the OCT imaging focus is precisely aligned with the sample depth. The existing closed-loop automatic focusing algorithm can dynamically compensate for focus drift, enabling OCT imaging to maintain stable and clear tomographic images in dynamic surgical scenarios, achieving real-time focus tracking and image quality optimization. Finally, image fusion is performed, allowing the OCT image to accurately cover the corresponding position in the microscope's field of view. This achieves high-precision fusion of OCT and ophthalmic surgical microscopes, with a simple structure, high stability, and strong adaptability. It can significantly improve intraoperative imaging quality and operational safety, and has broad clinical application prospects.

[0013] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0014] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider 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 imaging method based on paraxial optical path correction, characterized in that: Includes the following steps: S1. Visible red light is incident on the sample through the optical path correction end of the off-axis optical path and forms a red light scanning point on the sample plane. The microscope camera captures the red light scanning point in real time. S2. The imaging control terminal obtains the coordinate position of the red light scanning point in the microscope field of view image and compares it with the center of the microscope field of view image to obtain the deviation value. S3. Obtain the mapping relationship between the optical path deflection angle of the off-axis optical path correction end and the displacement error based on the deviation value. Then adjust the optical path of the off-axis optical path correction end according to the mapping relationship until the red light scanning point coincides with the center of the microscope field of view image. S4. Focus the optical path formed by the off-axis optical path correction end along the optical axis direction and feed it back to the imaging control end in real time to achieve real-time focus tracking and image quality optimization. S5. The real-time image obtained by the imaging control terminal is fused with the field-of-view image captured by the microscope camera and displayed synchronously.

2. The imaging method based on paraxial optical path correction according to claim 1, characterized in that: The paraxial optical path correction end includes a linear motor, a microscope, and a collimating mirror, an X-ray galvanometer, a Y-ray galvanometer, a focusing mirror, an OCT lens, and a reflecting mirror arranged sequentially along the optical path. The microscope has a microscope objective and a microscope camera. The light reflected by the reflecting mirror passes through the microscope objective and is then projected onto the sample. The X-ray galvanometer and the Y-ray galvanometer are on different optical axes, the collimating mirror is on the same optical axis as the X-ray galvanometer, and the Y-ray galvanometer, the focusing mirror, the OCT lens, and the reflecting mirror are arranged sequentially along the same optical axis. The linear motor is connected to the focusing mirror.

3. The imaging method based on paraxial optical path correction according to claim 2, characterized in that: The imaging control unit includes an OCT interferometer, a visible-red light source, a spectrometer, a delay line, a computer, a display, a linear motor controller, an XY galvanometer controller, and a mirror angle controller. The visible-red light source, spectrometer, and delay line are all connected to the OCT interferometer. The delay line, spectrometer, display, linear motor controller, XY galvanometer controller, and mirror angle controller are all connected to the computer. The light beam generated by the OCT interferometer is emitted to the collimating lens. The linear motor controller is connected to the linear motor. The XY galvanometer controller is connected to both the X-mirror and Y-mirror. The mirror angle controller is connected to the mirror. The microscope camera is connected to the computer.

4. The imaging method based on paraxial optical path correction according to claim 3, characterized in that: The visible red light source emits visible red light with a wavelength of 635 nm, and the light emitted from the microscope objective is projected onto the sample at an angle of 8°.

5. The imaging method based on paraxial optical path correction according to claim 2, characterized in that: In step S3, the deflection angle and displacement error of the X-mirror and Y-mirror are adjusted according to the mapping relationship to make the red light scanning point coincide with the center of the microscope field of view image.

6. The imaging method based on paraxial optical path correction according to claim 2, characterized in that: The deflection angle is divided into the deflection angle θ1 of the X-mirror and the deflection angle θ2 of the Y-mirror; the displacement error is divided into the X-direction displacement error Δd1 of the X-mirror and the Y-direction displacement error Δd2 of the Y-mirror.

7. The imaging method based on paraxial optical path correction according to claim 6, characterized in that: The mapping relationship between the deflection angle θ1 of the X-mirror and the X-direction displacement error Δd1 of the X-mirror is: Δd1 = 2·θ1·f_eff; The mapping relationship between the deflection angle θ2 of the Y-mirror and the Y-direction displacement error Δd2 of the Y-mirror is: Δd2=2·θ2·f_eff; Where f_eff = f_3·(f_1 / f_2); f_1 is the focal length of the focusing lens; f_2 is the focal length of the OCT lens; f_3 is the focal length of the microscope objective.

8. The imaging method based on paraxial optical path correction according to claim 3, characterized in that: In step S4, the linear motor is driven by the linear motor controller to push the focusing lens to adjust its displacement and achieve focusing, and the displacement range is ±2mm.

9. The imaging method based on paraxial optical path correction according to claim 3, characterized in that: In step S4, the computer receives the focused image in real time, and then uses a closed-loop autofocus algorithm to obtain the image sharpness. When the image sharpness drops below a set threshold, the focusing lens is repositioned again until a clear image is obtained.

10. An imaging method based on paraxial optical path correction according to claim 3, characterized in that: In step S5, the computer displays the fused image in real time through the monitor at a refresh rate of not less than 30 frames per second.

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