Electric adjustable focal length OCT (optical coherence tomography) scanning probe

Abstract

The invention belongs to the technical field of industrial surface imaging, and provides an electrically adjustable focal length OCT (optical coherence tomography) scanning probe which comprises a shell large sleeve, a lens group sleeve and a lens group. The large casing pipe of the shell is a straight casing pipe on the outermost layer, and a small hole is formed in the outer circle of the tail end of the right side of the large casing pipe; the lens group sleeve is arranged in the shell large sleeve, the length of the lens group sleeve is smaller than that of the shell large sleeve, a lens group is arranged in the lens group sleeve, and the lens group is provided with an optical fiber adapter flange, a collimating lens, a focusing lens, an electric adjustable focal length liquid lens and a reflecting prism which are sequentially arranged in the direction from light incidence to a to-be-detected sample along the optical fiber; the lens is tightly pressed in a threaded pressing piece fastening mode. According to the invention, the measuring capability of the probe on to-be-measured samples with different diameters can be improved, the process of replacing the probe is avoided by directly changing the measuring focal length, and the measuring efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial surface imaging and relates to an electrically adjustable focal length OCT scanning probe. Background Art

[0002] Optical Coherence Tomography (OCT) is based on Michelson interferometer technology. It converts the interference signal of light into relative depth information through Fourier transform, so as to obtain three-dimensional data of the superficial layer of the sample to be tested. The 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 reflector. The light beam returns to the original path after being reflected by the reflector; the other beam is directed to the sample arm, which is placed on the sample to be tested. The light beam returns to the original path after being reflected by the sample. The two returning light beams interfere with each other, and the relative depth information of each layer on the sample surface can be obtained through Fourier transform.

[0003] The sample arm end needs a mechanism to collimate and converge the light beams emitted from the optical fiber and obtain the light signals reflected from the sample surface. It is usually called a probe. The shell is made of flexible materials such as silicone or rigid materials such as metal. It has built-in optical fibers for transmitting light signals and lenses for collimation and convergence. Existing probes are usually composed of fixed-focus lenses and simple shells, which cannot adapt to measuring holes of different sizes. If measurements are performed outside the focal length of the probe, the imaging quality will be greatly reduced.

[0004] Some endoscopic 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, the probe faces the problems of small working distance and limited focal depth, and can only measure lumen structures of 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. However, the problem is that the working distance is fixed and only fixed-size lumen structures can be measured.

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

[0008] In order to overcome the shortcomings of the prior art, the present invention provides an electrically adjustable focus OCT scanning probe, which controls the voltage value applied to the electrically adjustable focus liquid lens to change its refractive power, thereby controlling the distance between the focus of the emitted light beam and the axis of the probe to control the working distance, so as to measure holes of different diameters.

[0009] In order to solve the technical problem proposed by the present invention, the technical solution adopted is as follows:

[0010] An electrically adjustable focal length OCT scanning probe, the electrically adjustable focal length OCT scanning probe comprises a large outer casing 17, a lens group casing 3 and a lens group. The large outer casing 17 is an outermost straight tube casing, and a small hole is provided on the wall of the large outer casing 17 at a certain distance from the right end, and the diameter of the small hole is greater than the diameter of the light beam; the lens group casing 3 is placed in the large outer casing 17, and its length is less than the large outer casing 17, and a lens group is placed inside it; the lens group comprises the following arranged in sequence (from left to right) along the direction from the incident light of the optical fiber 2 to the sample to be tested: an optical fiber adapter flange 1, a collimating lens 6, a focusing lens 9, an electrically adjustable focal length liquid lens and a reflecting prism 16, and all lenses are pressed tightly by a threaded pressing sheet. The electrically adjustable focal length liquid lens is composed of a liquid lens casing 18, a liquid unit 19 and a wire 20, and the surface curvature of the liquid unit can be adjusted by adjusting the voltage value applied to the liquid unit to control its refractive power.

[0011] Furthermore, the large outer casing 17 is a thin-walled straight tube with smooth inner and outer surfaces without grooves.

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

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

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

[0015] Furthermore, the fiber adapter flange 1 is an FC (ferrule connection) adapter flange. An FC optical fiber 2 is also connected to the left side of the fiber adapter flange 1, and the FC optical fiber receives the laser signal emitted from the light source. A flange is provided on the right side of the fiber adapter flange 1, and a conical hole is processed on the flange. The right end face of the optical fiber 2 is installed at the conical hole, and the light beam starts to diverge from the conical hole after leaving the optical fiber 2. The flange on the right side of the fiber adapter flange is attached to the inner surface on the left side of the lens group sleeve 3, and the two are fixed by threaded connection.

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

[0017] Furthermore, the collimating lens 6 is placed in a collimating lens fixing part 4, and the collimating lens 6 is located in the lens group sleeve 3 through the collimating lens fixing part 4, and the convex surface of the collimating lens 6 faces the right side and the concave surface faces the left side; the outer circle part of the collimating lens fixing part 4 is adapted to the middle inner diameter of the lens group sleeve 3, and is fixed with an appropriate amount of optical glue when necessary.

[0018] Furthermore, the collimating lens fixture 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 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 fixture 4. The collimating lens fixture 4 is also equipped with a collimating lens threaded pressing piece 5, the collimating lens threaded pressing piece 5 is adapted to the thread of the first step, and the collimating lens 6 is pressed by the collimating lens threaded pressing piece 5; the collimating lens 6 is coaxially installed with the collimating lens fixture 4, the left end face of the collimating lens fixture 4 is in contact with the left end face of the middle step of the lens assembly sleeve 3, and the two are coaxially installed.

[0019] Furthermore, the focusing lens 9 is placed on a focusing lens fixing member 10, and the focusing lens 9 is located in the lens group sleeve 3 through the focusing lens fixing member 10, the focusing lens 9 has a convex surface facing the left side and a concave surface facing the right side, and is pressed using 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 consistent with those of the collimating lens fixing member 4 and the collimating lens threaded pressing piece 5.

[0020] Furthermore, there is 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 cylinder, and its outer wall surface is in contact with the inner wall surface of the middle part of the lens assembly sleeve 3 .

[0021] Furthermore, there is 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 cylinder, and its outer wall surface is in contact with the inner wall surface of the middle part of the lens assembly sleeve 3 .

[0022] Furthermore, there are two electrically adjustable focus liquid lenses, namely a first electrically adjustable focus liquid lens 12 (left) and a second electrically adjustable focus liquid lens 14 (right). The two electrically adjustable focus liquid lenses have exactly the same properties and functions, and there is a liquid lens sleeve 13 in between.

[0023] Furthermore, the first and second electrically adjustable focal length liquid lenses 12 , 14 are composed of a liquid lens housing 18 , a liquid unit 19 and a wire 20 .

[0024] Furthermore, the left end face of the first electrically adjustable focal length 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 electrically adjustable focal length liquid lens 14 (right) is closely aligned with the left end face of the reflecting prism fixing member 15.

[0025] Furthermore, the surface curvature of the two electrically adjustable focal length liquid lenses can be changed from a positive value to a negative value, that is, under the control of a suitable voltage, the light beam can be converged and diverged.

[0026] Furthermore, the reflecting prism 16 is an external reflecting prism, and its reflecting surface forms an angle of 45° with both right-angled sides. The light beam is reflected by the reflecting prism 16 and can smoothly pass through the light hole located on the side of the reflecting prism fixing member 15 and the light hole located on the right side of the large sleeve 17 of the outer shell.

[0027] Furthermore, the surface of the collimating lens 6, the surface of the focusing lens 9, and the surface of the electrically adjustable focal length lens are all coated with anti-reflection films; the reflecting surface of the reflecting prism 16 is coated with an anti-reflection film; and the collimating lens and the focusing lens are double-cemented lenses.

[0028] A method for using an electrically adjustable focal length OCT scanning probe comprises the following steps:

[0029] The system light source is input into the optical fiber 2. After the light beam diverges from the right side of the optical fiber 2, it is emitted to the collimating lens 6 at a certain angle. The light beam exit point is located at the left focus 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. The light beam is further converged or diverged by two electrically adjustable focal length liquid lenses. Finally, the light beam is vertically reflected by the reflecting prism 16, and is emitted to the sample surface through the small hole of the reflecting prism fixing part 15 and the small hole on the right side of the large sleeve 17 of the outer shell to achieve lateral scanning. In actual measurement, the scanning probe is placed at the center of the circular hole, square hole or cavity, and the voltage applied to the first and second electrically adjustable focal length liquid lenses 12 and 14 is adjusted to change their surface curvature and further change the focus position of the scanning probe so that the focus position falls on the sample surface. At this time, the return light signal that can be obtained reaches the maximum value, and effective measurement is achieved.

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

[0031] The electrically adjustable focus 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 convergence ability is weakened. When the voltage is high, the curvature of the liquid lens increases and the convergence ability is enhanced. The focal length change achieved by the electrically adjustable focus liquid lens is: when the diopter of the two electrically adjustable focus liquid lenses is at the negative limit, the light beam further diverges and the focal length increases, and at this time, holes with larger diameters can be measured; when the diopter of the two electrically adjustable focus liquid lenses is at the positive limit, the light beam further converges and the focal length decreases, and at this time, holes with smaller diameters can be measured.

[0032] In summary, the electrically adjustable focal length OCT scanning probe provided by the present invention improves the probe's ability to measure samples of different diameters, avoids the process of replacing the probe by directly changing the measurement focal length, and improves the measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a basic structural diagram of an electrically adjustable focal length OCT scanning probe;

[0034] Figure 2 This is the basic structure diagram of the electrically adjustable focal length liquid lens;

[0035] Figure 3 A large-aperture optical path diagram for an electrically adjustable focus OCT scanning probe;

[0036] Figure 4 This is a pinhole optical path diagram for an electrically adjustable focus OCT scanning probe;

[0037] In the figure: 1 fiber adapter flange; 2 optical fiber; 3 lens group sleeve; 4 collimating lens fixing piece; 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 piece; 11 focusing-liquid lens sleeve; 12 first electrically adjustable focal length liquid lens; 13 liquid lens sleeve; 14 second electrically adjustable focal length liquid lens; 15 reflecting prism fixing piece; 16 reflecting prism; 17 large outer casing; 18 liquid lens outer casing; 19 liquid unit; 20 wire. DETAILED DESCRIPTION

[0038] The structure of the invention is further described below in conjunction with the accompanying drawings and preferred specific embodiments of the invention. It should be noted that, under the premise of no conflict, the embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0039] like Figure 1 As shown, the present invention provides an electrically adjustable focal length OCT scanning probe, the scanning probe comprising a large outer casing 17, a lens group casing 3 and a lens group. The large outer casing 17 is an outermost straight tube casing, used to protect and support the lens group, and a small hole is provided on the wall of the large outer casing 17 at the outer circle of the right end, and the diameter of the small hole is greater than the diameter of the light beam; the lens group casing 3 is placed in the large outer casing 17, and the length is less than the large outer casing 17, and a lens group is placed inside it, and the lens group is arranged in sequence along the direction of the optical fiber 2 from the incident light to the sample to be tested: optical fiber adapter flange 1, collimating lens 6, focusing lens 9, first and second electrically adjustable focal length liquid lenses 12, 14, reflecting prism 16, and all lenses are pressed by threaded pressing sheet fastening.

[0040] Preferably, the large outer casing 17 is a thin-walled straight tube with smooth inner and outer surfaces without grooves.

[0041] Furthermore, the lens assembly sleeve 3 is a thin-walled straight cylinder with a stepped inner surface, the inner diameter on the left side is smaller than the inner diameter on the right side, and a reflecting prism fixing part 15 for fixing the reflecting prism 16 is provided on the right side, and the right end surface of the reflecting prism fixing part 15 is flush with the right end surface of the outer shell large sleeve 17. The reflecting prism fixing part 15 is a boss structure, and the outer circle of the bottom is consistent with the inner diameter of the outer shell large sleeve 17. There is a square hole in the center of the boss, and the reflecting prism 16 is placed inside the square hole. There is a light hole on the side, and the light hole is coaxially installed with the small hole on the right outer circle of the outer shell large sleeve 17.

[0042] Preferably, the fiber adapter flange 1 is an FC adapter flange, and an FC (ferrule connection) optical fiber 2 is also connected to the left side thereof, and the optical fiber 2 receives the laser signal emitted from the light source. A flange is provided on the right side of the fiber adapter flange 1, and a conical hole is processed on the flange, and the right end face of the optical fiber 2 is installed at the conical hole. The light beam starts to diverge from the conical hole after leaving the optical fiber 2. The conical hole is located at the focal position of the collimating lens 6. After the light beam diverges from the conical hole on the right side of the fiber adapter flange 1, it acts on the collimating lens 6, and the light beam passing through the collimating lens 6 is parallel. Furthermore, the flange on the right side of the fiber adapter flange 1 is adapted to the inner diameter on the left side of the lens assembly sleeve 3, and is fixed by threaded connection.

[0043] Furthermore, the collimating lens 6 is placed in a collimating lens fixture 4, and the collimating lens 6 is located in the lens group sleeve 3 through the collimating lens fixture 4, and the convex surface of the collimating lens 6 faces the right side, and the concave surface faces the left side. The outer circumference of the collimating lens fixture 4 is adapted to the middle inner diameter of the lens group sleeve 3, and is fixed with an appropriate amount of optical glue when necessary. The collimating lens fixture 4 has three steps from left to right, the first step has threads, 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 fixture 4. The collimating lens fixture 4 is also equipped with a collimating lens threaded pressing plate 5, and the collimating lens threaded pressing plate 5 is adapted to the threads of the first step. The collimating lens threaded pressing piece 5 is used to press the collimating lens 6, so that the collimating lens 6 and the collimating lens fixing piece 4 are installed coaxially, and the left end surface of the collimating lens fixing piece 4 is in contact with the left end surface of the middle step of the lens group sleeve 3, and the two are installed coaxially.

[0044] Furthermore, the focusing lens 9 is placed on a focusing lens fixture 10, and the focusing lens 9 is located in the lens assembly sleeve 3 through the focusing lens fixture 10, and is pressed by a focusing lens threaded pressing plate 8. The connection method and structure of the focusing lens fixture 10 and the focusing lens threaded pressing plate 8 are consistent with those of the collimating lens fixture 4 and the collimating lens threaded pressing plate 5. The convex surface of the focusing lens 9 faces the left side, and the concave surface faces the right side. There is also a collimating-focusing lens sleeve 7 between the focusing lens fixture 10 and the collimating lens fixture 4. The collimating-focusing lens sleeve 7 is a thin-walled straight cylinder, and its outer wall surface is in contact with the inner wall surface of the middle part of the lens assembly sleeve 3. There is also a focusing-liquid lens sleeve 11 on the right side of the focusing lens fixture 10. The focusing-liquid lens sleeve 11 is a thin-walled straight cylinder, and its outer wall surface is in contact with the inner wall surface of the middle part of the lens assembly sleeve 3.

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

[0046] like Figure 2 As shown, the first and second electrically adjustable focus liquid lenses 12 and 14 are composed of a liquid lens housing 18, a liquid unit 19 and a wire 20. An 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 adjustable focus liquid lenses, namely the first electrically adjustable focus liquid lens 12 (left) and the second electrically adjustable focus liquid lens 14 (right). The two electrically adjustable focus liquid lenses have exactly the same properties and functions, and there is a liquid lens sleeve 13 in between. The surface curvature of the two electrically adjustable focus liquid lenses can change from a positive value to a negative value, that is, under the control of a suitable voltage, the light beams can be converged and diverged.

[0047] Furthermore, the left end face of the first electrically adjustable focal length liquid lens 12 is closely aligned with the left end face of the third step of the lens assembly sleeve 3 , and the right end face of the second electrically adjustable focal length liquid lens 14 is closely aligned with the left end face of the reflecting prism fixture 15 .

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

[0049] Preferably, the reflecting prism 16 is an external reflecting prism, and its reflecting surface forms an angle of 45° with both right-angled sides. The light beam is reflected by the reflecting prism and can smoothly pass through the light-through hole located on the side of the reflecting prism fixing member 15 and the light-through hole located on the right side of the large casing 17 of the housing. Furthermore, the surface of the collimating lens 6, the surface of the focusing lens 9, and the surfaces of the electrically adjustable focal length lenses 12 and 14 are all coated with anti-reflection films; the reflecting surface of the reflecting prism 16 is coated with an anti-reflection film; the collimating lens 6 and the focusing lens 9 are double-cemented lenses.

[0050] Preferably, the distance between the right end face of the optical fiber adapter 1 and the left concave axis of the collimating lens 6 is 15 mm; the distance between the right convex axis of the collimating lens 6 and the left convex axis of the focusing lens 9 is 10 mm; the distance between the focusing lens 9 and the first electrically adjustable 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 adjustable focal length liquid lens 12 (left) and the second electrically adjustable 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 is input into the optical fiber 2. After the light beam diverges from the right side of the optical fiber 2, it is emitted to the collimating lens 6 at a certain angle. The light beam exit point is located at the left focus 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. The light beam is further converged or diverged by two electrically adjustable focal length liquid lenses. Finally, the light beam is vertically reflected by the reflecting prism 16 and emitted to the sample from the small hole on the right side of the large casing 17 of the outer shell. The focus of the converged light beam falls on the sample surface to achieve lateral scanning. In actual measurement, the scanning probe is placed at the center of a circular hole, a square hole or a deep cavity, and the voltage applied to the electrically adjustable focal length liquid lens is adjusted to change its surface curvature and further change the focal position of the scanning probe so that the focal position falls on the sample surface.

[0052] The electrically adjustable focus 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 convergence ability is weakened. When the voltage is high, the curvature of the liquid lens increases and the convergence ability is enhanced. The focal length change achieved by the electrically adjustable focus liquid lens is: when the refractive power of the two electrically adjustable focus liquid lenses is at the negative limit, the light beam further diverges and the focal length increases. At this time, holes with larger diameters can be measured; when the refractive power of the two electrically adjustable focus liquid lenses is at the positive limit, the light beam further converges and the focal length decreases. At this time, holes with smaller diameters can be measured. In summary, the electrically adjustable focus OCT scanning probe provided by the present invention improves the probe's measurement capability for samples of different diameters to be measured. The measurement focal length is directly changed by the electrically adjustable focus liquid lens, thereby avoiding the process of replacing the probe and improving the measurement efficiency.

[0053] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An electrically adjustable focal length OCT scanning probe, characterized in that: The electrically adjustable focal length OCT scanning probe comprises a large outer casing (17), a lens group casing (3) and a lens group; the large outer casing (17) is an outermost straight casing, a small hole is provided on the right side of the wall of the large outer casing (17), and the diameter of the small hole is larger than the diameter of the light beam; the lens group casing (3) is placed in the large outer casing (17), the length of which is smaller than the large outer casing (17), and the lens group is placed inside the large outer casing; the lens group has a direction from the light incident to the sample to be measured along the optical fiber (2) Direction, arranged from left to right in sequence: an optical fiber adapter flange (1), a collimating lens fixture (4), a collimating lens threaded pressing piece (5), a collimating lens (6), a focusing lens (9), an electrically adjustable focal length liquid lens and a reflecting prism (16), wherein the reflecting prism (16) is fixed by a reflecting prism fixture (15); all lenses are tightened by means of a threaded pressing piece; the electrically adjustable focal length liquid lens adjusts the curvature of the liquid unit surface by adjusting the voltage value applied to the liquid unit, thereby controlling its refractive power; The focusing lens (9) is placed on a focusing lens fixing member (10), and the focusing lens (9) is fixed inside the lens assembly sleeve (3) through the focusing lens fixing member (10); the focusing lens (9) has a convex surface facing the left side and a concave surface facing the right side, and is pressed 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 electrically adjustable focus liquid lens comprises two pieces, namely a first electrically adjustable focus liquid lens (12) on the left and a second electrically adjustable focus liquid lens (14) on the right. The two electrically adjustable focus liquid lenses have completely the same properties and functions, and a liquid lens sleeve (13) is disposed between them. There is also a collimating-focusing lens sleeve (7) between the focusing lens fixing part (10) and the collimating lens fixing part (4), the collimating-focusing lens sleeve (7) is a thin-walled straight cylinder, and its outer wall surface is in contact 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 part (10), the focusing-liquid lens sleeve (11) is a thin-walled straight cylinder, and its outer wall surface is in contact with the inner wall surface of the middle part of the lens group sleeve (3); The first electrically adjustable focal length liquid lens (12) is composed of a liquid lens housing (18), a liquid unit (19) and a wire (20); the second electrically adjustable focal length liquid lens (14) is composed of a liquid lens housing (18), a liquid unit (19) and a wire (20); The left end surface of the first electrically adjustable focal length liquid lens (12) is closely aligned with the left end surface of the third step of the lens assembly sleeve (3), and the right end surface of the second electrically adjustable focal length liquid lens is closely aligned with the left end surface of the reflective prism fixing member (15); The surface curvature of the electrically adjustable focal length liquid lens can be changed from a positive value to a negative value, converging and diverging the light beam under the control of a suitable voltage.

2. The electrically adjustable focal length OCT scanning probe according to claim 1, characterized in that: The large outer casing (17) is a thin-walled straight tube with smooth inner and outer surfaces and no grooves; The lens assembly sleeve (3) is in the shape of a thin-walled straight cylinder, and has two steps on its inner surface, wherein the inner diameter of the first step is smaller than the inner diameter of the second step; a reflecting prism fixing piece (15) is provided on the right side of the lens assembly sleeve (3), and the right side end surface of the reflecting prism fixing piece (15) is flush with the right side end surface of the outer shell large sleeve (17).

3. The electrically adjustable focus OCT scanning probe according to claim 2, characterized in that: The reflecting prism fixing part (15) is a boss structure, the right flange of which fits the inner surface of the large outer casing (17), and a square hole is provided at the center of the boss, and the reflecting prism (16) is placed inside the square hole; a light-through hole is provided on the side of the reflecting prism fixing part (15), and is coaxially mounted with the small hole on the right side of the wall of the large outer casing (17).

4. The electrically adjustable focus OCT scanning probe according to claim 1, characterized in that: The optical fiber adapter flange (1) is a ferrule connection adapter flange, namely, an FC adapter flange; an FC optical fiber (2) is connected to the left side of the optical fiber adapter flange (1), and the FC optical fiber (2) receives a laser signal emitted from a light source; a flange is provided on the right side of the optical fiber adapter flange (1), and a conical hole is processed on the flange, and the right end face of the FC optical fiber (2) is installed at the conical hole, and the light beam starts to diverge from the conical hole after leaving the FC optical fiber (2); The right flange of the optical fiber adapter flange (1) is attached to the left inner surface of the lens assembly sleeve (3), and the two are fixedly connected; The tapered hole on the right side of the optical fiber adapter flange (1) is located at the focal position of the collimating lens (6). The light beam diverges from the tapered hole on the right side of the optical fiber adapter flange (1) and acts on the collimating lens (6). The light beam passing through the collimating lens (6) is parallel.

5. The electrically adjustable focus OCT scanning probe according to claim 1, characterized in that: The collimating lens (6) is located in the lens assembly sleeve (3) through the collimating lens fixing piece (4), and the convex surface of the collimating lens (6) faces the right side and the concave surface faces the left side; the outer circumference of the collimating lens fixing piece (4) is adapted to the middle inner diameter of the lens assembly sleeve (3).

6. The electrically adjustable focus OCT scanning probe according to claim 5, characterized in that: 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 sheet; The second step and the third step are smooth, the second step is used for mounting the collimating lens (6), and the third step is used for preventing the collimating lens from sliding out from the right side of the collimating lens fixing member (4); The collimating lens fixing part (4) is also equipped with a collimating lens thread pressing piece (5), the collimating lens thread pressing piece (5) is adapted to the thread of the first step, and the collimating lens (6) is pressed by the collimating lens thread pressing piece (5); the collimating lens (6) and the collimating lens fixing part (4) are coaxially mounted, the left end face of the collimating lens fixing part (4) is in contact with the left end face of the middle step of the lens assembly sleeve (3), and the two are coaxially mounted.

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

8. The electrically adjustable focus OCT scanning probe according to claim 1, characterized in that: The surface of the collimating lens (6), the surface of the focusing lens (9), and the surface of the electrically adjustable focal length lens are all coated with anti-reflection films; the reflecting surface of the reflecting prism (16) is coated with an anti-reflection film; the collimating lens and the focusing lens are double-cemented lenses.

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