An electrically adjustable focal length OCT scanning probe

Abstract

The present invention belongs to the technical field of industrial surface imaging, and provides an electrically tunable focus OCT scanning probe, which includes an outer shell large sleeve, a lens group sleeve and a lens group. The outer shell large sleeve is the outermost straight tube sleeve, and there is a small hole at the outer circle of the right end. The lens group sleeve is placed inside the outer shell large sleeve, and its length is less than that of the outer shell large sleeve. A lens group is placed inside it. The lens group includes, in the order of the optical fiber from the light incident to the sample to be measured: an optical fiber adapter flange, a collimating lens, a focusing lens, an electrically tunable focus liquid lens and a reflecting prism. The lenses are fastened by means of a threaded pressing piece. The present invention can improve the measurement ability of the probe for samples to be measured with different diameters. By directly changing the measurement focal length, the process of replacing the probe is avoided, and the measurement efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial surface imaging, and relates to an electrically tunable focus OCT scanning probe. Background Art

[0002] Optical Coherence Tomography (OCT) is based on the Michelson interference technique. The interference signal of light is converted into relative depth information through Fourier transform to obtain three-dimensional data of the shallow surface layer of the sample to be measured. An OCT system usually has a reference arm and a sample arm. The laser emitted from the light source is divided into two beams by a beam splitter. One beam is directed to the reference arm, which is equipped with a plane mirror. The beam is reflected by the mirror and returns along the original path. The other beam is directed to the sample arm, where the sample to be measured is placed. The beam is reflected by the sample and returns along the original path. The two returned beams interfere, and the relative depth information of each layer on the sample surface can be obtained through Fourier transform.

[0003] A mechanism is required at the sample arm end to collimate and converge the light beam diverging from the optical fiber and to obtain the optical signal reflected from the sample surface. It is usually called a probe. The housing is made of flexible materials such as silica gel or rigid materials such as metal, and contains an optical fiber for transmitting the optical signal and a lens for collimating and converging. Existing probes usually consist of a fixed-focus lens and a simple housing, and cannot adapt to measuring holes of different sizes. Measuring outside the focal length of the probe will greatly reduce the imaging quality.

[0004] Some endoscope measurement methods based on OCT technology have been proposed, such as:

[0005] In an OCT probe proposed in Chinese invention patent ZL 202111015041.4, a self-focusing lens is used to converge the light beam emitted from the optical fiber. Based on the characteristics of the self-focusing lens itself, this probe faces the problems of small working distance and limited depth of focus, and can only measure the lumen structure of a fixed size.

[0006] In an OCT probe proposed in Chinese invention patent ZL 201610678116.X, a self-focusing optical fiber is fused to the end of a single-mode optical fiber, and then the end of the self-focusing optical fiber is sintered into a spherical lens to converge the light beam. It also faces the problem of fixed working distance and can only measure the lumen structure of a fixed size.

[0007] In a large-depth-of-focus OCT probe proposed in Chinese invention patent ZL 202311065279.7, a double-lens structure is formed by a spherical lens at the end of the optical fiber and a cylindrical lens located at the imaging window. At a medium working distance, the lateral resolution and depth of focus of the probe are effectively improved. However, at a smaller or larger distance, the probe also needs to be replaced, which affects the measurement efficiency. Summary of the Invention

[0008] In order to overcome the deficiencies of the prior art, the present invention provides an electrically tunable focus OCT scanning probe. By controlling the voltage value applied to the electrically tunable focus liquid lens, its refractive power is changed, so as to control the distance between the focus of the emitted light beam and the axis of the probe to control the working distance, and holes of different diameter sizes are measured.

[0009] The technical solutions adopted to solve the technical problems proposed by the present invention are as follows:

[0010] An electrically tunable focus OCT scanning probe, the electrically tunable focus OCT scanning probe includes an outer shell large sleeve 17, a lens group sleeve 3 and a lens group. The outer shell large sleeve 17 is the outermost straight tube sleeve. There is a small hole at a certain distance from the right end of the wall surface of the outer shell large sleeve 17, and the diameter of the small hole is larger than the diameter of the light beam. The lens group sleeve 3 is placed inside the outer shell large sleeve 17, and its length is less than that of the outer shell large sleeve 17, and a lens group is placed inside it. The lens group includes, in order from the direction of light incident from the optical fiber 2 to the sample to be measured (from left to right): an optical fiber adapter flange 1, a collimating lens 6, a focusing lens 9, an electrically tunable focus liquid lens and a reflecting prism 16. All lenses are fastened by a threaded pressing piece. The electrically tunable focus liquid lens is composed of a liquid lens housing 18, a liquid unit 19 and a wire 20. By adjusting the voltage value applied to the liquid unit, the surface curvature of the liquid unit can be adjusted to control its refractive power.

[0011] Furthermore, the outer shell large sleeve 17 is in the shape of a thin-walled straight tube, and its inner and outer surfaces are smooth without grooves.

[0012] Furthermore, the lens group sleeve 3 is in the shape of a thin-walled straight tube, and its inner surface has two steps, and the inner diameter of the first step is smaller than that of the second step.

[0013] Furthermore, a reflecting prism fixing member 15 for fixing the reflecting prism 16 is provided on the right side of the lens group sleeve 3, and the right end face of the reflecting prism fixing member 15 is flush with the right end face of the outer shell large sleeve 17.

[0014] Furthermore, the reflecting prism fixing member 15 is in a boss structure. The right flange fits the inner surface of the outer shell large sleeve 17. There is a square hole in the center of the boss. The reflecting prism 16 is placed inside the square hole. There is a light passing hole on the side. The light passing hole on the side of the reflecting prism fixing member 15 is coaxially installed with the small hole on the outer circle on the right side of the outer shell large sleeve 17.

[0015] Further, the fiber optic adapter flange 1 is an FC (ferrule connection) adapter flange. A fiber optic cable 2 is also connected to the left side of the fiber optic adapter flange 1, and the fiber optic cable 2 receives the laser signal emitted from the light source. A flange is provided on the right side of the fiber optic adapter flange 1. A tapered hole is machined on the flange, and the right end face of the fiber optic cable 2 is installed at the tapered hole. The light beam starts to diverge from the fiber optic cable 2 when it breaks away from the tapered hole. The flange on the right side of the fiber optic adapter flange fits against the inner surface of the left side of the lens group sleeve 3, and the two are fixed by threaded connection.

[0016] Further, the tapered hole on the right side of the fiber optic adapter flange 1 is located at the focal position of the collimating lens 6. The light beam acts on the collimating lens 6 after diverging from the tapered hole on the right side of the fiber optic adapter flange 1, and the light beam passing through the collimating lens 6 is parallel.

[0017] Further, the collimating lens 6 is placed in a collimating lens fixing member 4. The collimating lens 6 is located inside the lens group sleeve 3 through the collimating lens fixing member 4, and the convex surface of the collimating lens 6 faces to the right and the concave surface faces to the left; the outer circular part of the collimating lens fixing member 4 is adapted to the middle inner diameter of the lens group sleeve 3, and an appropriate amount of optical glue is used for fixing when necessary.

[0018] Further, the collimating lens fixing member 4 has three steps from left to right, including a first step, a second step, and a third step. Specifically: the first step has threads for assembling a threaded pressing piece, the second step and the third step are smooth, the second step is used for assembling the collimating lens 6, and the third step is used to prevent the collimating lens from sliding out from the right side of the collimating lens fixing member 4. The collimating lens fixing member 4 is also equipped with a collimating lens threaded pressing piece 5, and the collimating lens threaded pressing piece 5 is adapted to the threads of the first step. The collimating lens 6 is pressed tightly through the collimating lens threaded pressing piece 5; the collimating lens 6 and the collimating lens fixing member 4 are coaxially installed, and the left end face of the collimating lens fixing member 4 fits against the left end face of the middle step of the lens group sleeve 3, and the two are coaxially installed.

[0019] Further, the focusing lens 9 is placed in a focusing lens fixing member 10. The focusing lens 9 is located inside the lens group sleeve 3 through the focusing lens fixing member 10. The convex surface of the focusing lens 9 faces to the left and the concave surface faces to the right, and it is pressed tightly by a focusing lens threaded pressing piece 8; the connection method and structure of the focusing lens fixing member 10 and the focusing lens threaded pressing piece 8 are the same as those of the collimating lens fixing member 4 and the collimating lens threaded pressing piece 5.

[0020] Further, there is also a collimating-focusing lens sleeve 7 between the focusing lens fixing member 10 and the collimating lens fixing member 4. The collimating-focusing lens sleeve 7 is in the shape of a thin-walled straight cylinder, and its outer wall surface fits against the inner wall surface of the middle part of the lens group sleeve 3.

[0021] Further, there is also a focusing-liquid lens sleeve 11 on the right side of the focusing lens fixing member 10. The focusing-liquid lens sleeve 11 is a thin-walled straight tube, and its outer wall surface fits against the inner wall surface of the middle part of the lens group sleeve 3.

[0022] Further, there are two electro-tunable focus liquid lenses, namely the first electro-tunable focus liquid lens 12 (left) and the second electro-tunable focus liquid lens 14 (right). The two electro-tunable focus liquid lenses have exactly the same properties and functions, and there is a liquid lens sleeve 13 between them.

[0023] Further, the first and second electro-tunable focus liquid lenses 12 and 14 are composed of a liquid lens housing 18, a liquid unit 19, and a wire 20.

[0024] Further, the left end face of the first electro-tunable focus liquid lens 12 (left) is closely aligned with the left end face of the third step of the lens group sleeve 3, and the right end face of the second electro-tunable focus liquid lens 14 (right) is closely aligned with the left end face of the reflection prism fixing member 15.

[0025] Further, the surface curvature of the two electro-tunable focus liquid lenses can change from positive to negative, that is, under suitable voltage control, the light beam can be converged and diverged.

[0026] Further, the reflection prism 16 is an external reflection prism, and its reflection surface forms a 45° angle with both right-angled sides. After the light beam is reflected by the reflection prism 16, it can smoothly pass through the light passing hole on the side of the reflection prism fixing member 15 and the light passing hole on the right side surface of the outer housing sleeve 17.

[0027] Further, antireflection films are provided on the surfaces of the collimating lens 6, the focusing lens 9, and the electro-tunable focus lens surfaces; an antireflection film is provided on the reflection surface of the reflection prism 16; the collimating lens and the focusing lens are doublet lenses.

[0028] A method for using an electro-tunable focus OCT scanning probe includes the following steps:

[0029] The system light source inputs the optical fiber 2. After the light beam diverges from the right side of the optical fiber 2, it irradiates the collimating lens 6 at a certain angle. The light beam emergence point is located at the left focal point of the collimating lens 6. Therefore, after being converged by the collimating lens 6, the light beam emitted from its right side is parallel. The parallel light beam is converged by the focusing lens 9 to form a light beam with a certain focal length. This light beam is further converged or diverged by two electrically tunable liquid lenses, and finally the light beam is vertically reflected by the reflection prism 16 and irradiates the sample surface through the small hole of the reflection prism fixing part 15 and the small hole on the right side of the outer shell large sleeve 17, realizing lateral scanning. In actual measurement, the scanning probe is placed at the center of the round hole, square hole or cavity, and the voltages applied to the first and second electrically tunable liquid lenses 12 and 14 are adjusted to change their surface curvature and further change the focal point position of the scanning probe, so that the focal point position falls on the sample surface. At this time, the returned optical signal that can be obtained reaches the maximum value, realizing effective measurement.

[0030] The beneficial effects of the present invention are as follows:

[0031] The electrically tunable liquid lens mentioned in the present invention is an electrowetting liquid lens. By changing the applied voltage, the curvature of the liquid lens can be precisely controlled, thereby adjusting the focal length of the lens. When the voltage is low, the curvature of the liquid lens decreases and the converging ability weakens. When the voltage is high, the curvature of the liquid lens increases and the converging ability enhances. The focal length change realized by the electrically tunable liquid lens is as follows: when the diopters of the two electrically tunable liquid lenses are at the negative limit, the light beam further diverges and the focal length increases. At this time, holes with larger diameter sizes can be measured; when the diopters of the two electrically tunable liquid lenses are at the positive limit, the light beam further converges and the focal length decreases. At this time, holes with smaller diameter sizes can be measured.

[0032] In summary, the electrically tunable OCT scanning probe provided by the present invention improves the measurement ability of the probe for samples to be measured with different diameters. By directly changing the measurement focal length, the process of replacing the probe is avoided, and the measurement efficiency is improved. Description of the Drawings

[0033] Figure 1 It is a basic structure diagram of an electrically tunable OCT scanning probe;

[0034] Figure 2 It is a basic structure diagram of an electrically tunable liquid lens;

[0035] Figure 3 It is an optical path diagram of an electrically tunable OCT scanning probe for measuring large holes;

[0036] Figure 4 It is an optical path diagram of an electrically tunable OCT scanning probe for measuring small holes;

[0037] In the figure: 1 optical fiber adapter flange; 2 optical fiber; 3 lens group sleeve; 4 collimating lens fixing member; 5 collimating lens threaded pressing piece; 6 collimating lens; 7 collimating-focusing lens sleeve; 8 focusing lens threaded pressing piece; 9 focusing lens; 10 focusing lens fixing member; 11 focusing-electro-tunable liquid lens sleeve; 12 first electro-tunable liquid lens; 13 liquid lens sleeve; 14 second electro-tunable liquid lens; 15 reflecting prism fixing member; 16 reflecting prism; 17 outer shell large sleeve; 18 liquid lens outer shell; 19 liquid unit; 20 wire. Detailed implementation manners

[0038] The structure of the invention will be further described below in conjunction with the accompanying drawings and the preferred specific embodiments of the present invention. It should be noted that, on the premise of no conflict, any combination can be formed between the following described embodiments or technical features to form a new embodiment.

[0039] As Figure 1 shown, the present invention provides an electro-tunable focus OCT scanning probe. The scanning probe includes an outer shell large sleeve 17, a lens group sleeve 3 and a lens group. The outer shell large sleeve 17 is the outermost straight tube sleeve, which is used to protect and support the lens group. There is a small hole at the outer circle of the barrel wall surface of the outer shell large sleeve 17 near the right end, and the diameter of the small hole is larger than the beam diameter. The lens group sleeve 3 is placed inside the outer shell large sleeve 17, and its length is less than that of the outer shell large sleeve 17. A lens group is placed inside it. The lens group includes, in the order of the optical fiber 2 from the light incident to the sample to be measured: an optical fiber adapter flange 1, a collimating lens 6, a focusing lens 9, first and second electro-tunable liquid lenses 12, 14, and a reflecting prism 16. All lenses are fastened by a threaded pressing piece.

[0040] Preferably, the outer shell large sleeve 17 is in the shape of a thin-walled straight tube, and the inner and outer surfaces are smooth without grooves.

[0041] Furthermore, the lens group sleeve 3 is in the shape of a thin-walled straight tube, and the inner surface is stepped. The inner diameter on the left side is smaller than that on the right side. There is a reflecting prism fixing member 15 for fixing the reflecting prism 16 on the right side. The right end face of the reflecting prism fixing member 15 is flush with the right end face of the outer shell large sleeve 17. The reflecting prism fixing member 15 is in a boss structure, the outer diameter of the bottom is the same as the inner diameter of the outer shell large sleeve 17, there is a square hole in the center of the boss, the reflecting prism 16 is placed inside the square hole, and there is a light passing hole on the side, and the light passing hole is coaxially installed with the small hole on the right outer circle of the outer shell large sleeve 17.

[0042] Preferably, the optical fiber adapter flange 1 is an FC adapter flange, and a fiber optic cable 2 of FC (ferrule connection) is also connected to its left side. The fiber optic cable 2 receives the laser signal emitted from the light source. A flange is provided on the right side of the optical fiber adapter flange 1, and a tapered hole is machined on the flange. The right end face of the fiber optic cable 2 is installed at the tapered hole. The light beam diverges from the fiber optic cable 2 at the tapered hole. The tapered hole is located at the focal position of the collimating lens 6. The light beam acts on the collimating lens 6 after diverging from the tapered hole on the right side of the optical fiber adapter flange 1, and the light beam passing through the collimating lens 6 is parallel. Further, the flange on the right side of the optical fiber adapter flange 1 is adapted to the inner diameter of the left side of the lens group sleeve 3 and is fixed by threaded connection.

[0043] Further, the collimating lens 6 is placed in a collimating lens fixing member 4. The collimating lens 6 is located inside the lens group sleeve 3 through the collimating lens fixing member 4. The convex surface of the collimating lens 6 faces to the right and the concave surface faces to the left. The outer circular part of the collimating lens fixing member 4 is adapted to the inner diameter in the middle of the lens group sleeve 3 and is fixed with an appropriate amount of optical glue if necessary. The collimating lens fixing member 4 has three steps from left to right. The first step has a thread, and the second step and the third step are smooth. The second step is used to assemble the collimating lens 6, and the third step is used to prevent the collimating lens from sliding out from the right side of the collimating lens fixing member 4. The collimating lens fixing member 4 is also equipped with a collimating lens threaded retainer 5, and the collimating lens threaded retainer 5 is adapted to the thread of the first step. The collimating lens 6 is pressed tightly by using the collimating lens threaded retainer 5 so that the collimating lens 6 and the collimating lens fixing member 4 are coaxially installed. The left end face of the collimating lens fixing member 4 is in contact with the left end face of the middle step of the lens group sleeve 3, and the two are coaxially installed.

[0044] Further, the focusing lens 9 is placed in a focusing lens fixing member 10. The focusing lens 9 is located inside the lens group sleeve 3 through the focusing lens fixing member 10 and is pressed tightly by using a focusing lens threaded retainer 8. The connection method and structure of the focusing lens fixing member 10 and the focusing lens threaded retainer 8 are the same as those of the collimating lens fixing member 4 and the collimating lens threaded retainer 5. The convex surface of the focusing lens 9 faces to the left and the concave surface faces to the right. There is also a collimating-focusing lens sleeve 7 between the focusing lens fixing member 10 and the collimating lens fixing member 4. The collimating-focusing lens sleeve 7 is a thin-walled straight tube, and its outer wall surface fits with the inner wall surface in the middle of the lens group sleeve 3. There is also a focusing-liquid lens sleeve 11 on the right side of the focusing lens fixing member 10. The focusing-liquid lens sleeve 11 is a thin-walled straight tube, and its outer wall surface fits with the inner wall surface in the middle of the lens group sleeve 3.

[0045] Preferably, the focal length of the collimating lens 6 is 15 mm and the diameter is 8 mm; the focal length of the focusing lens 9 is 50 mm and the diameter is 12.7 mm.

[0046] AsFigure 2 As shown, the first and second electrically tunable focal length liquid lenses 12 and 14 are composed of a liquid lens housing 18, a liquid unit 19, and a wire 20. The external controller transmits a voltage signal through the wire 20. By adjusting the voltage value applied to the liquid unit 19, the surface curvature of the liquid unit can be adjusted to control its refractive power. There are two electrically tunable focal length liquid lenses, namely the first electrically tunable focal length liquid lens 12 (left) and the second electrically tunable focal length liquid lens 14 (right). The two electrically tunable focal length liquid lenses have exactly the same properties and functions, and there is a liquid lens sleeve 13 between them. The surface curvature of the two electrically tunable focal length liquid lenses can change from a positive value to a negative value, that is, under suitable voltage control, the light beam can be converged and diverged.

[0047] Furthermore, the left end face of the first electrically tunable focal length liquid lens 12 is closely aligned with the left end face of the third step of the lens group sleeve 3, and the right end face of the second electrically tunable focal length liquid lens 14 is closely aligned with the left end face of the reflection prism fixing member 15.

[0048] Preferably, the diopter of the electrically tunable focal length liquid lens is -5 to 10, and the clear aperture is 5.8 mm.

[0049] Preferably, the reflection prism 16 is an external reflection prism, and the reflection surface forms a 45° angle with both right-angled sides. The light beam can pass through the light passing hole on the side of the reflection prism fixing member 15 and the light passing hole on the right side of the outer sleeve 17 of the housing smoothly after being reflected by the reflection prism. Furthermore, antireflection films are provided on the surfaces of the collimating lens 6, the focusing lens 9, and the electrically tunable focal length lenses 12 and 14; an antireflection film is provided on the reflection surface of the reflection prism 16; the collimating lens 6 and the focusing lens 9 are doublet lenses.

[0050] Preferably, the distance between the right end face of the optical fiber adapter 1 and the axis of the left concave surface of the collimating lens 6 is 15 mm; the distance between the axis of the right convex surface of the collimating lens 6 and the axis of the left convex surface of the focusing lens 9 is 10 mm; the distance between the focusing lens 9 and the first electrically tunable focal length liquid lens 12 (left) is determined by the focusing-liquid lens sleeve, and its thickness is 1 mm; the distance between the first electrically tunable focal length liquid lens 12 (left) and the second electrically tunable focal length liquid lens 14 (right) is determined by the liquid lens sleeve 13, and its thickness is 3 mm.

[0051] The system light source inputs into the optical fiber 2. After the light beam diverges from the right side of the optical fiber 2, it shoots towards the collimating lens 6 at a certain angle. The light beam exit point is located at the left focal point of the collimating lens 6. Therefore, after being converged by the collimating lens 6, the light beam emitted from its right side is parallel. The parallel light beam is converged by the focusing lens 9 to form a light beam with a certain focal length. This light beam is further converged or diverged by two electrically tunable liquid lenses. Finally, the light beam is vertically reflected by the reflecting prism 16 and shoots towards the sample from the small hole on the right side of the outer casing sleeve 17. The focus of the converged light beam falls on the sample surface, realizing lateral scanning. In actual measurement, the scanning probe is placed at the center of a round hole, a square hole or a deep cavity, and the voltage applied to the electrically tunable liquid lens is adjusted to change its surface curvature and further change the focal point position of the scanning probe, so that the focal point position falls on the sample surface.

[0052] The electrically tunable liquid lens mentioned in the present invention is an electrowetting liquid lens. By changing the applied voltage, the curvature of the liquid lens can be precisely controlled, thereby adjusting the focal length of the lens. When the voltage is low, the curvature of the liquid lens decreases and the converging ability weakens. When the voltage is high, the curvature of the liquid lens increases and the converging ability enhances. The focal length change achieved by the electrically tunable liquid lens is as follows: when the diopter of the two electrically tunable liquid lenses is at the negative limit, the light beam further diverges and the focal length increases. At this time, holes with a larger diameter size can be measured; when the diopter of the two electrically tunable liquid lenses is at the positive limit, the light beam further converges and the focal length decreases. At this time, holes with a smaller diameter size can be measured. In summary, an electrically tunable OCT scanning probe provided by the present invention improves the measurement ability of the probe for samples to be measured with different diameters. By directly changing the measurement focal length with the electrically tunable liquid lens, the process of replacing the probe is avoided, and the measurement efficiency is improved.

[0053] The above embodiments only represent the implementation manners of the present invention, but should not be construed as limiting the scope of the present invention patent. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. An electrically adjustable focus OCT scanning probe, characterized in that, The described electrically tunable focus OCT scanning probe includes an outer shell large sleeve (17), a lens group sleeve (3), and a lens group; the outer shell large sleeve (17) is the outermost straight tube sleeve, and there is a small hole on the right side of the wall surface of the outer shell large sleeve (17), and the diameter of the small hole is larger than the beam diameter; the lens group sleeve (3) is placed inside the outer shell large sleeve (17), and its length is less than that of the outer shell large sleeve (17), and a lens group is placed inside it; the lens group includes, in the direction from the incident light of the optical fiber (2) to the sample to be measured, arranged in sequence from left to right: an optical fiber adapter flange (1), a collimating lens fixing member (4), a collimating lens threaded pressing piece (5), a collimating lens (6), a focusing lens (9), an electrically tunable focus liquid lens, and a reflecting prism (16), and the reflecting prism (16) is fixed by a reflecting prism fixing member (15); all lenses are fastened by a threaded pressing piece; the electrically tunable focus liquid lens adjusts the surface curvature of the liquid unit by adjusting the voltage value applied to the liquid unit, and controls its refractive power; The focusing lens (9) is placed in a focusing lens fixing member (10), and the focusing lens (9) is fixed inside the lens group sleeve (3) through the focusing lens fixing member (10). The convex surface of the focusing lens (9) faces left and the concave surface faces right, and it is pressed tightly by a focusing lens threaded pressing piece (8); the connection method and structure of the focusing lens fixing member (10) and the focusing lens threaded pressing piece (8) are the same as those of the collimating lens fixing member (4) and the collimating lens threaded pressing piece (5); the lens group sleeve (3) is in the shape of a thin-walled straight tube, and there are two steps on the inner surface. The two steps divide the inside of the lens group sleeve (3) into three stepped cavities, and the inner diameters of the stepped cavities gradually increase from left to right, including a first stepped cavity, a second stepped cavity, and a third stepped cavity; there is a reflecting prism fixing member (15) on the right side of the lens group sleeve (3), and the right end face of the reflecting prism fixing member (15) is flush with the right end face of the outer shell large sleeve (17); There are two electrically tunable focus liquid lenses, namely the first electrically tunable focus liquid lens (12) on the left and the second electrically tunable focus liquid lens (14) on the right. The two electrically tunable focus liquid lenses have exactly the same properties and functions, and there is a liquid lens sleeve (13) between them; There is also a collimating-focusing lens sleeve (7) between the focusing lens fixing member (10) and the collimating lens fixing member (4). The collimating-focusing lens sleeve (7) is in the shape of a thin-walled straight tube, and its outer wall surface fits with the inner wall surface of the middle part of the lens group sleeve (3); there is also a focusing-liquid lens sleeve (11) on the right side of the focusing lens fixing member (10). The focusing-liquid lens sleeve (11) is in the shape of a thin-walled straight tube, and its outer wall surface fits with the inner wall surface of the middle part of the lens group sleeve (3); The first electrically tunable focus liquid lens (12) is composed of a liquid lens housing (18), a liquid unit (19), and a wire (20); the second electrically tunable focus liquid lens (14) is composed of a liquid lens housing (18), a liquid unit (19), and a wire (20); The left end face of the first electrically tunable focus liquid lens (12) is closely aligned with the left end face of the second step of the lens group sleeve (3), and the right end face of the second electrically tunable focus liquid lens is closely aligned with the left end face of the reflecting prism fixing member (15); The surface curvature of the electrically tunable focus liquid lens can change from a positive value to a negative value, converging and diverging light beams under suitable voltage control; The collimating lens (6) is located inside the lens group sleeve (3) through the collimating lens fixing member (4), and the convex surface of the collimating lens (6) faces to the right and the concave surface faces to the left; the outer circular part of the collimating lens fixing member (4) is adapted to the middle inner diameter of the lens group sleeve (3); The collimating lens fixing member (4) has three steps from left to right, including a first step, a second step, and a third step. Specifically: the first step has a thread for assembling a threaded pressing piece; the second step and the third step are smooth. The second step is used for assembling the collimating lens (6), and the third step is used to prevent the collimating lens from sliding out from the right side of the collimating lens fixing member (4); the collimating lens fixing member (4) is also equipped with a collimating lens threaded pressing piece (5), and the collimating lens threaded pressing piece (5) is adapted to the thread of the first step, and the collimating lens (6) is pressed tightly through the collimating lens threaded pressing piece (5); the collimating lens (6) is coaxially installed with the collimating lens fixing member (4), and the left end face of the collimating lens fixing member (4) fits the left end face of the middle step of the lens group sleeve (3), and the two are coaxially installed.

2. An electrically tunable focus OCT scanning probe according to claim 1, wherein: The outer shell large sleeve (17) is in the shape of a thin-walled straight cylinder, and its inner and outer surfaces are smooth without grooves.

3. An electro-adjustable focus OCT scanning probe according to claim 2, wherein The reflecting prism fixing member (15) is a boss structure, the right flange fits the inner surface of the outer shell large sleeve (17), and there is a square hole in the central part of the boss. A reflecting prism (16) is placed inside the square hole; a light passing hole is provided on the side of the reflecting prism fixing member (15), and it is coaxially installed with the small hole on the right side of the barrel wall surface of the outer shell large sleeve (17).

4. An electrically tunable focus OCT scanning probe according to claim 1, wherein: The fiber optic adapter flange (1) is a ferrule connection adapter flange, that is, an FC adapter flange; a FC optical fiber (2) is connected to the left side of the fiber optic adapter flange (1), and the FC optical fiber (2) receives the laser signal emitted from the light source; a flange is provided on the right side of the fiber optic adapter flange (1), and a tapered hole is machined on the flange. The right end face of the FC optical fiber (2) is installed at the tapered hole, and the light beam diverges from the tapered hole of the FC optical fiber (2); The right flange of the fiber optic adapter flange (1) fits the left inner surface of the lens group sleeve (3), and the two are fixedly connected; The right tapered hole of the fiber optic adapter flange (1) is located at the focal position of the collimating lens (6), and the light beam diverges from the right tapered hole of the fiber optic adapter flange (1) and acts on the collimating lens (6), and the light beam passing through the collimating lens (6) is parallel.

5. An electro-adjustable focus OCT scanning probe according to claim 1, characterized in that, The reflecting prism (16) is an external reflecting prism, and the angle between its reflecting surface and both right-angled sides is 45°. The light beam is reflected by the reflecting prism (16) and passes through the light-transmitting hole on the side surface of the reflecting prism fixing member (15) and the light-transmitting hole on the right side surface of the outer casing large sleeve (17).

6. An electro-adjustable focal length OCT scanning probe according to claim 1, characterized in that, The surfaces of the collimating lens (6), the focusing lens (9), and the electrically tunable focusing lens all have antireflection films; the reflecting surface of the reflecting prism (16) has a high-reflection film; the collimating lens and the focusing lens are doublet lenses.

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