OCT imaging system and imaging method thereof

Abstract

The invention relates to an OCT (Optical Coherence Tomography) imaging system and an imaging method thereof. The OCT imaging system comprises a light source module for emitting a light signal; the optical fiber coupler is used for splitting light, transmitting the first sub-optical signal to the reference arm optical path and transmitting the second sub-optical signal to the sample arm optical path, and the first sub-optical signal forms return light through the reference arm optical path; the sample arm light path comprises a dynamic zoom module, a focal depth expansion element and a galvanometer scanner, and is used for adjusting the focal length and focal depth of a second sub-light signal according to a target detection requirement and scanning a target sample by using the adjusted second sub-light signal to form backscattered light, and the return light and the backscattered light interfere in an optical fiber coupler to form interference light; the detection module detects the interference light to form a detection signal; and the signal processing module processes the detection signal to obtain an imaging image of the target sample. Therefore, the problem of tradeoff between the transverse resolution and the focal depth is solved, and the focal depth can be changed to meet different detection requirements while the transverse resolution is achieved.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular to an OCT imaging system and an imaging method thereof. Background Art

[0002] OCT (Optical Coherence Tomography) is a non-invasive, high-resolution and high-speed interference imaging mode, and is another major technological breakthrough after X-CT and MRI technology.

[0003] OCT systems generally have an inherent limitation: the lateral resolution of the system is proportional to the numerical aperture, while the depth of focus is inversely proportional to the square of the numerical aperture. In other words, when a lens with a larger numerical aperture is used to improve the lateral resolution of the system, the depth of focus will also be shortened, thus affecting the overall imaging quality of the system. Therefore, current OCT systems are generally limited by low numerical aperture, which makes it impossible to distinguish fine details in the sample during the imaging process. In order to further broaden the application of OCT, the trade-off between lateral resolution and depth of focus must be resolved. In addition, conventional OCT systems adjust the spatial position of clear imaging by changing the relative position of the sample to be measured and the system. The adjustment process has poor controllability and a limited adjustment range. Therefore, unique optical paths need to be designed for different application scenarios, and the system has poor versatility. Summary of the Invention

[0004] The present application provides an OCT imaging system and imaging method thereof to address the trade-off between lateral resolution and depth of focus. A depth-of-focus extension element is used to generate a long-depth-of-focus beam, and a dynamic zoom module is used to change the working distance of the OCT system. While maintaining a high lateral resolution of the system, the imaging position can be flexibly changed to meet different detection requirements.

[0005] A first embodiment of the present application provides an OCT imaging system, comprising:

[0006] Light source module, fiber coupler, reference arm optical path, sample arm optical path, detection module and signal processing module, wherein,

[0007] The light source module is used to emit a light signal;

[0008] The optical fiber coupler is used to split the optical signal into a first sub-optical signal and a second sub-optical signal, and transmit the first sub-optical signal to the reference arm optical path, and transmit the second sub-optical signal to the sample arm optical path, and the first sub-optical signal passes through the reference arm optical path to form a return light;

[0009] The sample arm optical path includes a dynamic zoom module, a focal depth extension element, and a galvanometer scanner, wherein the dynamic zoom module is used to adjust the focal length of the second sub-light signal according to target detection requirements, the focal depth extension element is used to adjust the focal depth of the second sub-light signal according to the target detection requirements, and the galvanometer scanner is used to scan the target sample using the adjusted second sub-light signal and form backscattered light at the target sample, wherein the return light interferes with the backscattered light in the fiber coupler to form interference light;

[0010] The detection module detects the interference light to form a detection signal, and transmits the detection signal to the signal processing module;

[0011] The signal processing module processes the detection signal to obtain an imaging image of the target sample.

[0012] Optionally, in some embodiments, the focal depth extension element is a conic lens or a super lens.

[0013] Optionally, in some embodiments, when the focal depth extension element is the axicon, the sample arm optical path further includes: a first collimator, a first achromatic lens, and a second achromatic lens, wherein:

[0014] The first collimator, the dynamic zoom module, the conical lens, the first achromatic lens and the galvanometer scanner are arranged in sequence along the optical axis of the first collimator, the second achromatic lens is arranged behind the galvanometer scanner in a direction perpendicular to the optical axis of the first collimator, and the galvanometer scanner forms a preset angle with the optical axis of the first collimator.

[0015] Optionally, in some embodiments, the first collimator is used to collimate the second sub-light signal, and the dynamic zoom module is used to adjust the focal length of the collimated second sub-light signal according to target detection requirements to obtain a shaped second sub-light signal;

[0016] The conical lens is used to adjust the focal depth of the shaped second sub-light signal to form an annular light beam according to the target detection requirements. The first achromatic lens is used to focus the annular light beam to the galvanometer scanner. The galvanometer scanner is used to reflect the focused annular light beam to the second achromatic lens. The second achromatic lens is used to focus the reflected annular light beam to the target sample, forming the backscattered light at the target sample. The backscattered light returns to the fiber coupler along the original path.

[0017] Optionally, in some embodiments, when the focal depth extension element is the metalens, the sample arm optical path further comprises: a second collimator and a focusing lens, wherein the dynamic zoom module is composed of a first liquid lens, the galvanometer scanner and a second liquid lens.

[0018] The second collimator, the super lens, the focusing lens, the first liquid lens and the galvanometer scanner are arranged in sequence along the optical axis of the second collimator. The second liquid lens is arranged behind the scanning galvanometer along a direction perpendicular to the optical axis of the second collimator. The galvanometer scanner forms a preset angle with the optical axis of the second collimator.

[0019] Optionally, in some embodiments, the second collimator is used to collimate the second sub-light signal, the metalens and the focusing lens are used to adjust the focal depth of the collimated second sub-light signal according to the target detection requirements to obtain the shaped second sub-light signal, and the second dynamic zoom module is used to adjust the focal length of the shaped second sub-light signal according to the target detection requirements, and focus the adjusted second sub-light signal to the target sample, forming backscattered light at the target sample, and the backscattered light returns to the fiber coupler along the original path.

[0020] Optionally, in some embodiments, the preset angle is 45.

[0021] Optionally, in some embodiments, the signal processing module is further configured to:

[0022] A control instruction is generated according to the detection signal, so as to control the galvanometer scanner according to the control instruction.

[0023] Optionally, in some embodiments, the light source includes at least one of a broadband light source and a swept frequency light source.

[0024] A second aspect of the present application provides an OCT imaging method, including: using the above-mentioned OCT imaging system, wherein the method includes the following steps:

[0025] Sending a light signal through the light source module;

[0026] Splitting the optical signal into a first sub-optical signal and a second sub-optical signal through the optical fiber coupler, transmitting the first sub-optical signal to the reference arm optical path, transmitting the second sub-optical signal to the sample arm optical path, and the first sub-optical signal passing through the reference arm optical path to form return light;

[0027] adjusting the focal length of the second light sub-signal according to target detection requirements by the dynamic zoom module, adjusting the focal depth of the second light sub-signal according to the target detection requirements by the focus extension element, scanning a target sample with the adjusted second light sub-signal by the galvanometer scanner, and forming backscattered light at the target sample, wherein the return light interferes with the backscattered light in the fiber coupler to form interference light;

[0028] The detection module detects the interference light to form a detection signal, and transmits the detection signal to the signal processing module;

[0029] The detection signal is processed by the signal processing module to obtain an imaging image of the target sample.

[0030] Thus, a light signal is emitted by a light source module, which is then divided into a first sub-light signal and a second sub-light signal by a fiber coupler. The first sub-light signal is transmitted to a reference arm optical path, and the second sub-light signal is transmitted to a sample arm optical path. The first sub-light signal forms a return light through the reference arm optical path. The dynamic zoom module adjusts the focal length of the second sub-light signal according to target detection requirements. The depth of focus extension element adjusts the focal depth of the second sub-light signal according to target detection requirements. The galvanometer scanner uses the adjusted second sub-light signal to scan the target sample, and forms backscattered light at the target sample. The return light and the backscattered light interfere with each other in the fiber coupler to form interference light. The interference light is detected by the detection module to form a detection signal, which is transmitted to the signal processing module. The signal processing module processes the detection signal to obtain an imaging image of the target sample. Thus, the trade-off between lateral resolution and depth of focus is solved. The depth of focus extension element is used to generate a long focal depth beam, and the dynamic zoom module is used to change the working distance of the OCT system. While maintaining a high lateral resolution of the system, the imaging position can be flexibly changed to meet different detection requirements.

[0031] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0033] Figure 1 A flowchart of an OCT imaging system provided according to an embodiment of the present application;

[0034] Figure 2 A schematic diagram of a spectral OCT system provided according to one embodiment of the present application;

[0035] Figure 3 A schematic diagram of a swept-frequency OCT system according to one embodiment of the present application;

[0036] Figure 4 A schematic diagram illustrating the focal depths of two lenses according to an embodiment of the present application;

[0037] Figure 5 A schematic diagram of a sample arm optical circuit according to one embodiment of the present application;

[0038] Figure 6 A schematic diagram of a multifocal metalens provided according to one embodiment of the present application;

[0039] Figure 7 A schematic diagram of light intensity distribution simulation at different focal points provided according to one embodiment of the present application;

[0040] Figure 8 A schematic diagram of a sample arm optical circuit according to another embodiment of the present application;

[0041] Figure 9 Flowchart of an OCT imaging method provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0043] The OCT imaging system and imaging method of the embodiment of the present application are described below with reference to the accompanying drawings. In response to the trade-off between lateral resolution and depth of focus mentioned in the above background technology, the present application provides an OCT imaging system, in which a light source module, a fiber optic coupler, a reference arm optical path, a sample arm optical path, a detection module and a signal processing module are provided, wherein the light source module is used to emit a light signal; the fiber optic coupler is used to divide the light signal into a first sub-light signal and a second sub-light signal, and transmit the first sub-light signal to the reference arm optical path, and transmit the second sub-light signal to the sample arm optical path, and the first sub-light signal passes through the reference arm optical path to form a return light; the sample arm optical path includes a dynamic zoom module, a focus module, a detection module and a signal processing module. The depth-extending element and galvanometer scanner, the dynamic zoom module is used to adjust the focal length of the second sub-light signal according to the target detection requirements, the depth-of-focus extending element is used to adjust the focal depth of the second sub-light signal according to the target detection requirements, the galvanometer scanner is used to use the adjusted second sub-light signal to scan the target sample and form backscattered light at the target sample, wherein the return light and the backscattered light interfere with each other in the fiber coupler to form interference light; the detection module detects the interference light to form a detection signal and transmits the detection signal to the signal processing module; the signal processing module processes the detection signal to obtain an image of the target sample. This solves the trade-off between lateral resolution and depth of focus. The depth-of-focus extending element is used to generate a long focal depth beam, and the dynamic zoom module is used to change the working distance of the OCT system. While maintaining the system's high lateral resolution, the imaging position can be flexibly changed to meet different detection requirements.

[0044] Specifically, Figure 1 An OCT imaging system provided in an embodiment of the present application includes: a light source module 100, a fiber coupler 200, a reference arm optical path 300, a sample arm optical path 400, a detection module 500 and a signal processing module 600.

[0045] Specifically, the light source module 100 is used to emit a light signal; the optical fiber coupler 200 is used to divide the light signal into a first sub-light signal and a second sub-light signal, transmit the first sub-light signal to the reference arm optical path 300, and transmit the second sub-light signal to the sample arm optical path 400, and the first sub-light signal passes through the reference arm optical path 300 to form a return light; the sample arm optical path 400 includes a dynamic zoom module, a depth of focus extension element and a galvanometer scanner, the dynamic zoom module is used to adjust the focal length of the second sub-light signal according to the target detection requirements, the depth of focus extension element is used to adjust the focal depth of the second sub-light signal according to the target detection requirements, and the galvanometer scanner is used to use the adjusted second sub-light signal to scan the target sample and form backscattered light at the target sample, wherein the return light and the backscattered light interfere in the optical fiber coupler 200 to form interference light; the detection module 500 detects the interference light to form a detection signal, and transmits the detection signal to the signal processing module 600; the signal processing module 600 processes the detection signal to obtain an imaging image of the target sample.

[0046] Optionally, in some embodiments, the signal processing module 600 is further configured to generate a control instruction according to the detection signal, so as to control the galvanometer scanner according to the control instruction.

[0047] The light source module 100 is at least one of a broadband light source and a swept-frequency light source, and the focal depth extension element is a conic lens or a super lens.

[0048] Specifically, the OCT system of the embodiment of the present application may be a spectral OCT system or a swept frequency OCT system.

[0049] like Figure 2 As shown in the figure, the spectral OCT system mainly includes a broadband light source, a fiber coupler, a reference arm optical path, a sample arm optical path, a grating, a linear array camera, a signal generator module, a lower computer, a computer, etc.

[0050] The light source parameters of the broadband light source used in the embodiment of the present application can be pre-set by relevant personnel. Preferably, the embodiment of the present application can use a broadband light source with a wavelength of 850nm and a bandwidth of 50nm.

[0051] The light emitted by the broadband light source is split after passing through a coupler, allowing part of the light to enter the reference arm optical path and part of the light to enter the sample arm optical path. The galvanometer scanner in the sample arm optical path performs lateral scanning of the sample. The return light from the reference arm optical path and the backscattered light from the sample arm optical path interfere with each other in the fiber coupler. Because the broadband light source simultaneously emits beams of different wavelengths, the interference light has different wavelengths. In the spectrometer module, the interference light of different wavelengths is spatially separated by a grating and projected to different positions of the linear array camera, thereby achieving simultaneous detection of the intensity of the interference light of different wavelengths. During the imaging process, the length of the reference arm optical path does not need to be temporally modulated, and the reference arm optical path length remains unchanged. The lower computer and a signal generator module are responsible for the timing control between the galvanometer scanner and the linear array camera. The lateral scanning of the galvanometer scanner is controlled by a custom driver board, eliminating the need for an image acquisition card.

[0052] like Figure 3 As shown in FIG, the swept frequency OCT system mainly includes: fiber coupler, reference arm optical path, sample arm optical path, photodetector, image acquisition card, computer, etc.

[0053] The light source parameters of the swept-frequency light source used in the embodiment of the present application can be pre-set by relevant personnel. Preferably, the embodiment of the present application can use a swept-frequency light source with a wavelength of 1300nm.

[0054] The fiber coupler realizes the splitting effect, so that part of the light enters the reference arm optical path and part of the light enters the sample arm optical path. At the same time, the light beam from the reference arm optical path and the light beam scattered by the sample arm optical path interfere with each other in the fiber coupler. The interference light is detected by the photodetector. The swept light source outputs a single wavelength (or narrowband) laser at each moment, and the photodetector detects the intensity of the single wavelength (or narrowband) interference light at each moment. During the imaging process, the length of the reference optical path does not need to be temporally modulated, and the length of the reference optical path remains unchanged.

[0055] Optionally, in some embodiments, when the depth of focus extension element is a conical lens, the sample arm optical path 400 further includes: a first collimator, a first achromatic lens and a second achromatic lens, wherein the first collimator, the dynamic zoom module, the conical lens, the first achromatic lens and the galvanometer scanner are arranged in sequence along the optical axis of the first collimator, the second achromatic lens is arranged behind the galvanometer scanner along a direction perpendicular to the optical axis of the first collimator, and the galvanometer scanner and the optical axis of the first collimator are at a preset angle.

[0056] Furthermore, in some embodiments, a first collimator is used to collimate the second sub-light signal; a dynamic zoom module is used to adjust the focal length of the collimated second sub-light signal according to target detection requirements to obtain a shaped second sub-light signal; an aconic lens is used to adjust the focal depth of the shaped second sub-light signal according to target detection requirements to form an annular beam; a first achromatic lens is used to focus the annular beam onto a galvanometer scanner; the galvanometer scanner is used to reflect the focused annular beam to a second achromatic lens; the second achromatic lens is used to focus the reflected annular beam onto a target sample, forming backscattered light at the target sample, and the backscattered light returns along the original path to the fiber coupler 200. The preset angle is 45°.

[0057] It is understandable that in the traditional Gaussian imaging mode OCT system, the beam waist radius and focal position of the collimated Gaussian beam will change after being focused by the objective lens, and its DOF is defined as twice the Rayleigh range, such as Figure 4 (a). For wavelength λ, 1 / e 2 A Gaussian beam with a radius of ω0 is collimated and incident on a lens with a focal length of f. Its DOF is given by:

[0058]

[0059] The beam waist radius at the focus is given by:

[0060]

[0061] From the above formula, we can see that when the numerical aperture increases, the lateral resolution of the system will be improved, but this will also quickly reduce the DOF.

[0062] A characteristic of a long-focus beam is that its lateral resolution remains constant within a limited focal depth, unchanged with depth. For example, using a long-focus Bessel beam generated by an axicon, if the central beam radius of the Bessel beam and the Gaussian beam are identical, the propagation distance of the central beam of the Bessel beam will be much greater than the Rayleigh length of the Gaussian beam. Due to the non-diffraction and self-healing properties of Bessel beams, their application in OCT can improve OCT imaging quality in scattering media.

[0063] In the embodiment of the present application, an axicon can be used to generate a long focal depth beam, such as Figure 5 As shown, Bessel beams can be generated by an axicon, as Figure 4 (b) shows an axicon with a cone angle of γ. The incident Gaussian beam has a 1 / e 2 The radius is ω0, then the light field intensity distribution behind the aconic lens is given by the following formula

[0064]

[0065] in, is the normalized cylindrical coordinate, ω0 is the incident Gaussian beam 1 / e 2 Radius, N = ω0β / λ is defined as the Fresnel number, β = sin -1 (n a sinγ)-γ,n a is the refractive index of the axicon, γ is the cone angle of the axicon, and J0 is the zero-order Bessel function of the first kind.

[0066] The characteristic of Bessel beam is that its lateral resolution remains constant within a limited focal depth range and does not change with depth. The lateral size R of the central beam of Bessel beam is B It is given by:

[0067] When the incident light has a finite radius, the Bessel beam will only be generated within a finite length behind the axicon. The full width at half maximum of the longitudinal intensity distribution of the Bessel beam is defined as DOF. DOF is given by the following formula:

[0068]

[0069] Among them, DOF B is the focal depth of the Bessel beam, β is a simplified formula, β=sin -1 (n a sinγ)-γ, k0 is the central wave number. The peak intensity of the central beam is given by:

[0070]

[0071] From the above formula, we can see that reducing γ or increasing ω0 can extend the depth of focus, but reducing γ will increase R B , which makes the lateral resolution of the system worse. Although increasing ω0 can extend the focal depth and keep the lateral resolution unchanged, this will cause the peak intensity of the central beam to decrease, thereby reducing the penetration depth of the beam and affecting the system signal-to-noise ratio.

[0072] The optical path of the sample arm is designed as follows: the light emitted from the single-mode optical fiber first passes through the first collimator to be collimated into a 2.4mm beam, and then enters a dynamic zoom module for beam shaping, wherein the dynamic zoom module can be a liquid lens or a lens group. The liquid lens can achieve dynamic adjustment of the focal length by changing the shape of the liquid interface or the refractive index distribution, thereby obtaining a Gaussian beam with a different beam radius (ω0); the same purpose can also be achieved through a lens group. For example, by adjusting the distance between the three lenses, a Gaussian beam with a different beam radius can be obtained. The principle is as follows: the distance between lens 1 and lens 2 is d1, the distance between lens 2 and lens 3 is d2, f1, f2 and f3 are the focal lengths of lens 1, lens 2 and lens 3 respectively, and M is the desired magnification. d1 and d2 can be determined by the following formula:

[0073]

[0074]

[0075] The shaped beam is incident on an axicon with a cone angle of γ, forming the first Bessel beam on its surface and an annular beam in the far field. However, the Bessel beam immediately adjacent to the axicon cannot meet the working distance and scanning requirements of OCT, and the beam needs to be transferred to the sample surface. A first achromatic lens is placed behind the axicon to focus the entire annular beam onto a galvanometer scanner. The galvanometer scanner is placed in the optical path at a 45° angle to the optical axis of the collimator and is controlled by a custom driver board to scan horizontally along the x-axis. The MEMS mirror reflects the annular beam to the second achromatic lens. After being focused by the lens, a second Bessel beam with an extended depth of focus is regenerated at the sample. The beam can be shaped into Gaussian beams with different radii using a dynamic focusing module. After passing through the axicon, the beam obtains Bessel beams with different focal depths, thereby achieving the purpose of flexible change of focal depth.

[0076] Optionally, in some embodiments, when the depth of focus extension element is a metalens, the sample arm optical path 400 further includes: a second collimator, a focusing lens, wherein the dynamic zoom module is composed of a first liquid lens, a galvanometer scanner and a second liquid lens, the second collimator, the metalens, the focusing lens, the first liquid lens and the galvanometer scanner are arranged in sequence along the optical axis of the second collimator, the second liquid lens is arranged behind the scanning galvanometer along a direction perpendicular to the optical axis of the second collimator, and the galvanometer scanner and the optical axis of the second collimator are at a preset angle.

[0077] Furthermore, in some embodiments, a second collimator is used to collimate the second sub-light signal, the metalens and the focusing lens are used to adjust the focal depth of the collimated second sub-light signal according to the target detection requirements to obtain the shaped second sub-light signal, and the second dynamic zoom module is used to adjust the focal length of the shaped second sub-light signal according to the target detection requirements, and focus the adjusted second sub-light signal to the target sample, forming backscattered light at the target sample, and the backscattered light returns to the fiber coupler 200 along the original path.

[0078] Optionally, in some embodiments, the preset angle is 45.

[0079] It can be understood that the superlens is based on metasurface technology and is composed of sub-wavelength-scale nanostructures (such as silicon and silicon nitride columns). By regulating the geometric parameters of each nanostructure (such as height and diameter), the phase of the incident light can be precisely controlled, and a long focal depth beam can be generated while maintaining a high lateral resolution.

[0080] The performance of a metalens is primarily determined by the following parameters, including the wavelength of the incident light, the material, shape, height, and radius of the nanopillars, and the size of the lattice. The arrangement of the nanopillars on the surface of the metalens is achieved by matching the phases. Assuming the metalens surface is a two-dimensional plane with the coordinates of the center of each nanopillar at (x, y), the phase distribution of this two-dimensional plane is set based on the phase distribution of a traditional lens on the incident plane when focusing. The phase distribution of the metalens can be calculated using the following formula:

[0081]

[0082] Where x and y are the horizontal and vertical coordinates of the center of each nanorod, λ is the wavelength, and f is the focal length.

[0083] The long-depth-of-focus metalens designed in this embodiment can generate multiple focal points to achieve the goal of extending the depth of focus. The above formula shows that the phase shift of a single nanopillar is independent of its specific position, but only depends on its distance from the center. Therefore, it can be assumed that nanopillars at the same distance from the center of the entire metalens have the same phase shift. Dividing the entire two-dimensional surface of the metalens by radius into n parts will produce n circular rings. Setting each ring at a different focal length will produce n focal points, thereby increasing the focal depth of the entire focused beam. Figure 6 is a schematic diagram of a multifocal metalens. Figure 7 Simulation diagram of light intensity distribution at different focal points.

[0084] When the focal depth extension element is a metalens, the optical path of the sample arm is as follows: Figure 8 As shown, the light emitted from the single-mode fiber is collimated by the second collimator and then incident on the metalens and focusing lens to generate a long-focus beam. The dynamic zoom module composed of two liquid lenses and a galvanometer scanner can flexibly change the position of the long-focus beam in the sample to meet different detection requirements.

[0085] In summary, the embodiments of the present application combine a dynamic zoom module with an adjustable depth of focus element, enabling the system to maintain high lateral resolution while flexibly varying the depth of focus to accommodate different detection requirements. For example, when focusing on shallow-layer information in a sample, a Bessel beam with a short focal depth can be used to improve the system's signal-to-noise ratio and achieve better imaging quality. When focusing on deeper-layer information, a Bessel beam with a longer focal depth can be used to increase the imaging depth while maintaining high lateral resolution.

[0086] The present application can effectively expand the application of OCT. In the field of industrial inspection, for example, when performing defect detection on thicker lens groups, the OCT system using the embodiment of the present application can improve the detection depth while ensuring high lateral resolution, effectively reducing the factory's inspection costs; in the biomedical field, the OCT system using the embodiment of the present application can be used for skin disease examinations, and can obtain three-dimensional structural information of different layers of the skin epidermis, dermis and subcutaneous tissue, and through the dynamic zoom module, the depth of interest can be flexibly selected for imaging.

[0087] According to the OCT imaging system proposed in the embodiment of the present application, a light signal is emitted by a light source module, the light signal is divided into a first sub-light signal and a second sub-light signal by a fiber coupler, and the first sub-light signal is transmitted to the reference arm optical path, and the second sub-light signal is transmitted to the sample arm optical path. The first sub-light signal forms a return light through the reference arm optical path, the focal length of the second sub-light signal is adjusted according to the target detection requirements by a dynamic zoom module, the focal depth of the second sub-light signal is adjusted according to the target detection requirements by a depth of focus extension element, and the target sample is scanned by a galvanometer scanner using the adjusted second sub-light signal to form backscattered light at the target sample, wherein the return light and the backscattered light interfere with each other in the fiber coupler to form interference light; the interference light is detected by a detection module to form a detection signal, and the detection signal is transmitted to a signal processing module; the detection signal is processed by the signal processing module to obtain an imaging image of the target sample. Thus, the trade-off between lateral resolution and depth of focus is solved. The depth of focus extension element is used to generate a long focal depth beam, and the dynamic zoom module is used to change the working distance of the OCT system. While maintaining the high lateral resolution of the system, the imaging position can be flexibly changed to meet different detection requirements.

[0088] Next, the OCT imaging method proposed according to the embodiment of the present application is described with reference to the accompanying drawings.

[0089] like Figure 9 As shown, the OCT imaging method includes the following steps:

[0090] In step S101 , a light signal is emitted by a light source module.

[0091] In step S102, the optical signal is divided into a first sub-optical signal and a second sub-optical signal by an optical fiber coupler, and the first sub-optical signal is transmitted to the reference arm optical path, and the second sub-optical signal is transmitted to the sample arm optical path. The first sub-optical signal passes through the reference arm optical path to form a return light.

[0092] In step S103, the focal length of the second sub-light signal is adjusted according to the target detection requirements through the dynamic zoom module, the focal depth of the second sub-light signal is adjusted according to the target detection requirements through the depth of focus extension element, the adjusted second sub-light signal is used to scan the target sample through the galvanometer scanner, and backscattered light is formed at the target sample, wherein the return light and the backscattered light interfere with each other in the optical fiber coupler to form interference light.

[0093] In step S104 , the interference light is detected by the detection module to form a detection signal, and the detection signal is transmitted to the signal processing module.

[0094] In step S105 , the detection signal is processed by a signal processing module to obtain an imaging image of the target sample.

[0095] It should be noted that the aforementioned explanation of the OCT imaging system embodiment is also applicable to the OCT imaging method of this embodiment and will not be repeated here.

[0096] According to the OCT imaging method proposed in the embodiment of the present application, a light signal is emitted by a light source module, the light signal is divided into a first sub-light signal and a second sub-light signal by a fiber coupler, and the first sub-light signal is transmitted to the reference arm optical path, and the second sub-light signal is transmitted to the sample arm optical path. The first sub-light signal forms a return light through the reference arm optical path, the focal length of the second sub-light signal is adjusted according to the target detection requirements by a dynamic zoom module, the focal depth of the second sub-light signal is adjusted according to the target detection requirements by a depth of focus extension element, and the target sample is scanned by a galvanometer scanner using the adjusted second sub-light signal to form backscattered light at the target sample, wherein the return light and the backscattered light interfere with each other in the fiber coupler to form interference light; the interference light is detected by a detection module to form a detection signal, and the detection signal is transmitted to a signal processing module; the detection signal is processed by the signal processing module to obtain an imaging image of the target sample. Thus, the trade-off between lateral resolution and depth of focus is solved. The depth of focus extension element is used to generate a long focal depth beam, and the dynamic zoom module is used to change the working distance of the OCT system. While maintaining the high lateral resolution of the system, the imaging position can be flexibly changed to meet different detection requirements.

[0097] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0098] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0099] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0100] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0101] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0102] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An OCT imaging system, characterized in that: include: Light source module, fiber coupler, reference arm optical path, sample arm optical path, detection module and signal processing module, wherein, The light source module is used to emit a light signal; The optical fiber coupler is used to split the optical signal into a first sub-optical signal and a second sub-optical signal, and transmit the first sub-optical signal to the reference arm optical path, and transmit the second sub-optical signal to the sample arm optical path, and the first sub-optical signal passes through the reference arm optical path to form a return light; The sample arm optical path includes a dynamic zoom module, a focal depth extension element, and a galvanometer scanner, wherein the dynamic zoom module is used to adjust the focal length of the second sub-light signal according to target detection requirements, the focal depth extension element is used to adjust the focal depth of the second sub-light signal according to the target detection requirements, and the galvanometer scanner is used to scan the target sample using the adjusted second sub-light signal and form backscattered light at the target sample, wherein the return light interferes with the backscattered light in the fiber coupler to form interference light; The detection module detects the interference light to form a detection signal, and transmits the detection signal to the signal processing module; The signal processing module processes the detection signal to obtain an imaging image of the target sample.

2. The OCT imaging system according to claim 1, wherein: The focal depth extension element is an aconic lens or a super lens.

3. The OCT imaging system according to claim 2, wherein: When the focal depth extension element is the axicon, the sample arm optical path further includes: a first collimator, a first achromatic lens and a second achromatic lens, wherein: The first collimator, the dynamic zoom module, the conical lens, the first achromatic lens and the galvanometer scanner are arranged in sequence along the optical axis of the first collimator, the second achromatic lens is arranged behind the galvanometer scanner in a direction perpendicular to the optical axis of the first collimator, and the galvanometer scanner forms a preset angle with the optical axis of the first collimator.

4. The OCT imaging system according to claim 3, wherein: The first collimator is used to collimate the second sub-light signal, and the dynamic zoom module is used to adjust the focal length of the collimated second sub-light signal according to target detection requirements to obtain a shaped second sub-light signal; The conical lens is used to adjust the focal depth of the shaped second sub-light signal to form an annular light beam according to the target detection requirements. The first achromatic lens is used to focus the annular light beam to the galvanometer scanner. The galvanometer scanner is used to reflect the focused annular light beam to the second achromatic lens. The second achromatic lens is used to focus the reflected annular light beam to the target sample, forming the backscattered light at the target sample. The backscattered light returns to the fiber coupler along the original path.

5. The OCT imaging system according to claim 2, wherein: When the focal depth extension element is the metalens, the sample arm optical path further includes: a second collimator and a focusing lens, wherein the dynamic zoom module is composed of a first liquid lens, the galvanometer scanner and a second liquid lens. The second collimator, the super lens, the focusing lens, the first liquid lens and the galvanometer scanner are arranged in sequence along the optical axis of the second collimator. The second liquid lens is arranged behind the scanning galvanometer along a direction perpendicular to the optical axis of the second collimator. The galvanometer scanner forms a preset angle with the optical axis of the second collimator.

6. The OCT imaging system according to claim 5, wherein: The second collimator is used to collimate the second sub-light signal, the metalens and the focusing lens are used to adjust the focal depth of the collimated second sub-light signal according to the target detection requirements to obtain a shaped second sub-light signal, and the second dynamic zoom module is used to adjust the focal length of the shaped second sub-light signal according to the target detection requirements, and focus the adjusted second sub-light signal to the target sample, forming backscattered light at the target sample, and the backscattered light returns to the fiber coupler along the original path.

7. The OCT imaging system according to claim 3 or 5, characterized in that: The preset angle is 45.

8. The OCT imaging system according to claim 1, wherein: The signal processing module is further used to: A control instruction is generated according to the detection signal, so as to control the galvanometer scanner according to the control instruction.

9. The OCT imaging system according to claim 1, wherein: The light source includes at least one of a broadband light source and a swept frequency light source.

10. An OCT imaging method, characterized in that: The OCT imaging system according to any one of claims 1 to 9 is used, wherein the method comprises the following steps: Sending a light signal through the light source module; Splitting the optical signal into a first sub-optical signal and a second sub-optical signal through the optical fiber coupler, transmitting the first sub-optical signal to the reference arm optical path, transmitting the second sub-optical signal to the sample arm optical path, and the first sub-optical signal passing through the reference arm optical path to form return light; adjusting the focal length of the second light sub-signal according to target detection requirements by the dynamic zoom module, adjusting the focal depth of the second light sub-signal according to the target detection requirements by the focus extension element, scanning a target sample with the adjusted second light sub-signal by the galvanometer scanner, and forming backscattered light at the target sample, wherein the return light interferes with the backscattered light in the fiber coupler to form interference light; The detection module detects the interference light to form a detection signal, and transmits the detection signal to the signal processing module; The detection signal is processed by the signal processing module to obtain an imaging image of the target sample.

Images