Telescopic varifocal OCT (optical coherence tomography) scanning probe

Abstract

The invention belongs to the technical field of industrial surface imaging, and provides a telescopic varifocal OCT (optical coherence tomography) scanning probe which comprises a shell large sleeve, a telescopic small sleeve and a probe. The large casing pipe of the shell is a straight casing pipe at the outermost layer; the telescopic small sleeve is arranged in the shell large sleeve, a probe is arranged in the telescopic small sleeve, the probe comprises a capillary glass tube, a self-focusing lens and a plano-convex lens which are sequentially arranged in the direction from light incidence to a to-be-detected sample along the optical fiber, and the probe part is bonded by using optical cement. A reflecting prism is further arranged on the right side of the large casing pipe of the shell and arranged in a reflecting prism fixing piece. By controlling the relative distance between the telescopic small sleeve and the reflecting prism and adjusting the distance between the focused light beam and the axis of the scanning probe, the working size of the scanning probe can be quickly and accurately adjusted; by introducing the telescopic varifocal structure, the scanning probe can measure deep holes of multiple sizes, and the measurement efficiency and the measurement capability are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial surface imaging and relates to a telescopic variable-focus 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 diverging from the optical fiber, and to 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, and 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 deep 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 a telescopic variable focal length scanning probe, which controls the distance between the plano-convex lens (focusing lens) and the reflecting prism to change the distance between the focus and the probe axis, thereby controlling the measuring distance 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] A telescopic variable focal length OCT scanning probe, the telescopic variable focal length OCT scanning probe comprises a large outer casing 1, a telescopic small casing 9 and a probe 13. The large outer casing 1 is an outermost straight casing; the telescopic small casing 9 goes deep into the large outer casing 1 from the left side of the large outer casing 1, and the probe 13 is placed inside the telescopic small casing 9. The probe comprises an optical fiber 3, a capillary glass tube 5, a self-focusing lens 7, and a plano-convex lens 8 arranged in sequence (from left to right) along the direction from the incident light of the optical fiber to the sample to be tested, wherein a gap is left between the self-focusing lens 7 and the plano-convex lens 8, and each part is bonded with optical glue. A reflecting prism 10 is provided on the right side of the large outer casing 1, and the end of the large outer casing is sealed by a casing cover 12.

[0011] Furthermore, the outer shell large sleeve 1 is straight-cylindrical, with smooth inner and outer surfaces without grooves, and there is a light hole inside the outer shell large sleeve 1 at a certain distance from the end face where the sleeve cover 12 is located, and the diameter of the light hole is larger than the diameter of the light beam.

[0012] Furthermore, the telescopic small sleeve 9 is placed in the large sleeve 1 of the outer shell, and the two can slide smoothly and steadily, and the sliding distance is the same as the zoom distance. The sliding distance is the distance that the telescopic small sleeve 9 slides relatively in the large sleeve 1 of the outer shell; because the reflective prism 10 obliquely reflects the focused light beam, the focus of the light beam is no longer located at the axis position of the scanning probe, and the zoom distance is the change distance between the focus of the light beam and the axis of the scanning probe. When the telescopic small sleeve 9 slides a certain distance in the direction of approaching the reflective prism 10, the focus of the light beam moves the same distance farther away from the axis of the scanning probe; when the telescopic small sleeve 9 slides a certain distance in the direction of moving away from the reflective prism 10, the focus of the light beam moves the same distance closer to the axis of the scanning probe.

[0013] Furthermore, the probe includes a probe sleeve, an optical fiber, a capillary glass tube, a self-focusing lens, a plano-convex lens, a self-focusing lens sleeve and a plano-convex lens sleeve. Specifically:

[0014] The probe 13 is placed in the telescopic small sleeve 9 through the probe sleeve 2.

[0015] The capillary glass tube 5 and the self-focusing lens 7 are placed together in the self-focusing lens sleeve 6, and the self-focusing lens 7 and the capillary glass tube 5 are placed at a distance.

[0016] The plano-convex lens 8 is placed in the telescopic small sleeve 9 through the plano-convex lens sleeve 4, wherein the outer surface of the plano-convex lens sleeve 4 is in contact with the inner surface of the telescopic small sleeve 9 and the outer surface of the probe sleeve 2, that is, the left end of the plano-convex lens sleeve 4 is inserted into the probe sleeve 2, and the right end is inserted into the plano-convex lens 8.

[0017] The reflecting prism 10 is placed at the right end of the large sleeve of the housing through a reflecting prism fixing member 11 .

[0018] Furthermore, the optical fiber 3 enters from the left side of the probe sleeve 2 and exits from the right side; the end of the optical fiber 3 is inserted into the capillary glass tube 5.

[0019] Furthermore, the left end surface of the capillary glass tube 5 is aligned with the left end surface of the self-focusing lens sleeve 6 .

[0020] Furthermore, the left end surface of the capillary glass tube 5 is coaxially bonded to the right end surface of the probe sleeve 2 .

[0021] Furthermore, the side (ie, the left side) of the plano-convex lens 8 opposite to the self-focusing lens 7 is a convex surface, and the other side (the right side) is a flat surface.

[0022] Furthermore, the right radial end face of the capillary glass tube 5 is inclined 8° clockwise, the left radial end face of the self-focusing lens 7 is inclined 8° clockwise, and the right end face of the capillary glass tube is parallel to the left end face of the self-focusing lens.

[0023] Furthermore, the center of the right side of the capillary glass tube 5 is located at the focal position of the self-focusing lens 7 , and the light beam is emitted from the end of the optical fiber 3 and diverges, and is collimated by the self-focusing lens 7 , and is emitted in parallel from the right side of the self-focusing lens 7 .

[0024] Furthermore, the reflecting prism 10 is cylindrical as a whole, and the left reflecting plane forms a certain angle with the axis of the large sleeve 1 of the outer shell, and the angle ranges from 30° to 60°.

[0025] Furthermore, the sleeve cover 12 provided on the right side of the reflecting prism is adapted to the inner diameter of the large sleeve 1 of the outer shell, and the right end surface of the sleeve cover 12 is flush with the right end surface of the large sleeve 1 of the outer shell.

[0026] Furthermore, the surface of the self-focusing lens 7 and the surface of the plano-convex lens 8 are provided with anti-reflection films; the reflective surface of the reflective prism 10 is provided with an anti-reflection film.

[0027] The system light source is input into the optical fiber 3, then scattered from the end of the optical fiber 3, and collimated by the self-focusing lens 7. After collimation, the light beam is parallely incident into the plano-convex lens 8, and then converged by the plano-convex lens 8 to achieve focusing, and is obliquely reflected by the reflecting prism 10 and incident on the sample surface. The sample is usually a circular hole, a square hole or a cavity structure, and the distance between its inner surface and the axis of the scanning probe is between 5-20 mm. The variable focal length principle of the probe is that the plano-convex lens 8 converges the light to obtain a convergent beam with a certain focal length. After the reflective prism 10 obliquely reflects the convergent beam, the focus of the convergent beam is located on the side of the scanning probe. The convergent beam is reflected from different cross sections, and the distance between the focus and the axis of the scanning probe after reflection is different. Specifically, the telescopic small sleeve 9 slides a certain distance in the direction close to the reflective prism 10, and the focus of the beam moves the same distance farther from the axis of the scanning probe accordingly. If the focus of the beam is far away, a larger hole can be measured; the telescopic small sleeve 9 slides a certain distance in the direction away from the reflective prism 10, and the focus of the beam moves the same distance closer to the axis of the scanning probe accordingly. If the focus of the beam is close, a smaller hole can be measured. When using the scanning probe, place it at the center of the sample (circular hole, square hole or cavity structure), adjust the distance between the telescopic small sleeve 9 and the reflective prism 10 according to the sample size, and start the measurement until the focus of the beam falls on the surface of the sample.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention can adjust the distance between the focused light beam and the axis of the scanning probe by controlling the relative distance between the telescopic small sleeve 9 and the reflecting prism 10, so as to quickly and accurately adjust the working size of the scanning probe. In summary, the present invention introduces a telescopic variable focal length structure, so that the scanning probe can measure deep holes of multiple sizes, thereby improving the measurement efficiency and measurement capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a basic structural diagram of a telescopic variable-focus OCT scanning probe;

[0031] Figure 2 It is a schematic diagram of the telescopic zoom principle;

[0032] Figure 3 This is the basic structure diagram of the probe;

[0033] Figure 4 A telescopic variable-focus OCT scanning probe measuring the pinhole optical path diagram;

[0034] Figure 5 This is a telescopic zoom OCT scanning probe measuring a large aperture optical path diagram;

[0035] In the figure: 1 large outer casing; 2 probe casing; 3 optical fiber; 4 plano-convex lens casing; 5 capillary glass tube; 6 self-focusing lens casing; 7 self-focusing lens; 8 plano-convex lens; 9 telescopic small casing; 10 reflecting prism; 11 reflecting prism fixing part; 12 casing cover; 13 probe. DETAILED DESCRIPTION

[0036] 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.

[0037] like Figure 1 As shown, the present invention provides a telescopic variable focal length OCT scanning probe, which includes a large outer casing 1, a telescopic small casing 9 and a probe 13. The large outer casing 1 is the outermost casing, which is used to extend into a deep hole and protect the internal probe 13; the telescopic small casing 9 is used to move smoothly and stably in the large outer casing 1 to adjust the distance between the built-in probe 13 and the reflective prism. The probe 13 includes the following components arranged in sequence (from left to right) along the direction from the incident light of the optical fiber 3 to the sample to be tested: an optical fiber 3, a capillary glass tube 5, a self-focusing lens 7, and a plano-convex lens 8, wherein a gap is left between the self-focusing lens 7 and the plano-convex lens 8, and each part is bonded with optical glue.

[0038] Preferably, the outer shell large sleeve 1 is straight-cylindrical, with smooth inner and outer surfaces without grooves. There is also a light hole inside the outer shell large sleeve 1 at a certain distance from the end face where the sleeve cover 12 is located, and the diameter of the light hole is larger than the diameter of the light beam. The telescopic small sleeve 9 is straight-cylindrical, and is placed inside the outer shell large sleeve 1. The two can slide smoothly and smoothly, and the sliding distance is the same as the zoom distance. The sliding distance is the relative sliding distance of the telescopic small sleeve 9 in the outer shell large sleeve 1, and the zoom distance is the changing distance between the focus of the light beam and the axis of the probe 13. When the telescopic small sleeve 9 slides toward the reflecting prism 10, the focus of the light beam moves the same distance farther away from the axis of the probe 13 accordingly. Conversely, the focus of the light beam moves the same distance closer to the axis of the probe 13 accordingly. Figure 2 As shown, the probe 13 is driven to slide a certain distance toward the reflecting prism 10, and the focus of the light beam accordingly moves the same distance farther away from the axis of the probe 13. If the focus of the light beam is far away, a larger hole can be measured. Conversely, the focus of the light beam accordingly moves the same distance closer to the axis of the probe 13. If the focus of the light beam is close, a smaller hole can be measured.

[0039] Furthermore, if Figure 3As shown, the probe 13 includes a probe sleeve 2, an optical fiber 3, a capillary glass tube 5, a self-focusing lens 7, a plano-convex lens 8, a self-focusing lens sleeve 6 and a plano-convex lens sleeve 4. The optical fiber 3 enters from the left side of the probe sleeve 2 and exits from the right side. The end of the optical fiber 3 is inserted into the capillary glass tube 5, and the left end face of the self-focusing lens 7 is aligned with the left end face of the self-focusing lens sleeve 6.

[0040] Preferably, the self-focusing lens 7 has a gradient constant of 1.37, a central refractive index of 1.616, and a thickness of 5.6 mm; the plano-convex lens has a focal length of 20 mm and a diameter of 2.3 mm; and the capillary glass tube 5 is spaced 3 mm from the self-focusing lens 7.

[0041] Preferably, the left end face of the capillary glass tube 5 is coaxially bonded to the right end face of the probe sleeve 2. The left end of the plano-convex lens sleeve 4 is inserted into the probe sleeve 2, and the right end is inserted into the plano-convex lens 8. The side (i.e., the left side) of the plano-convex lens 8 opposite to the self-focusing lens 7 is a convex surface, and the other side is a plane. The right end face of the capillary glass tube 5 is inclined 8° clockwise, and the left end face of the self-focusing lens 7 is inclined 8° clockwise. The right end face of the capillary glass tube 5 is parallel to the left end face of the self-focusing lens 7. The center of the right side of the capillary glass tube 5 is located at the focal position of the self-focusing lens 7. The light beam is emitted from the end of the optical fiber and diverges, and is collimated by the self-focusing lens 7 and emitted in parallel from the right side of the self-focusing lens 7.

[0042] Furthermore, the reflecting prism 10 is placed in a reflecting prism fixing member 11. The reflecting prism 10 is cylindrical as a whole, and the left reflecting plane forms a certain angle with the axis of the large sleeve 1 of the outer shell, and the angle range is between 30° and 60°. The sleeve cover 12 provided on the right side of the reflecting prism 10 is adapted to the inner diameter of the large sleeve 1 of the outer shell, and the right end face of the sleeve cover 12 is flush with the right end face of the large sleeve 1 of the outer shell.

[0043] Preferably, the surfaces of the self-focusing lens 7 and the plano-convex lens 8 are provided with anti-reflection films; the reflective surface of the reflective prism 10 is provided with an anti-reflection film.

[0044] In the present invention, the system light source is input into the optical fiber 3, then scattered from the end of the optical fiber 3, and collimated by the self-focusing lens 7. After collimation, the light beam is parallely incident into the plano-convex lens 8, and then converged by the plano-convex lens 8 to achieve focusing, and is obliquely reflected by the reflecting prism 10 and incident on the sample surface. The sample is usually a circular hole, a square hole or a deep cavity structure, and the distance between its inner surface and the axis of the scanning probe is between 5-20 mm. The variable focal length principle of the probe is that the plano-convex lens 8 converges the light to obtain a convergent beam with a certain focal length. After the reflective prism 10 obliquely reflects the convergent beam, the focus of the convergent beam is located on the side of the scanning probe. The convergent beam is reflected from different cross sections, and the distance between the focus and the axis of the scanning probe after reflection is different. Specifically, the telescopic small sleeve 9 slides toward the reflective prism 10, and the focus of the beam moves the same distance farther from the axis of the probe 13 accordingly. If the focus of the beam is far away, a larger hole can be measured; if the telescopic small sleeve 9 slides away from the reflective prism 10, the focus of the beam moves the same distance closer to the axis of the probe 13 accordingly. If the focus of the beam is close, a smaller hole can be measured. When using the scanning probe, place it at the center of the sample (circular hole, square hole or deep cavity structure), adjust the distance between the telescopic small sleeve 9 and the reflective prism 10 according to the sample size, and start the measurement until the focus of the beam falls on the sample surface.

[0045] The present invention can adjust the distance between the focused light beam and the axis of the scanning probe by controlling the relative distance between the telescopic small sleeve 9 and the reflecting prism 10, so as to quickly and accurately adjust the working size of the scanning probe. In summary, the present invention introduces a telescopic variable focal length structure, so that the scanning probe can measure deep holes of multiple sizes, thereby improving the measurement efficiency and measurement capability.

[0046] 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. A telescopic variable-focus OCT scanning probe, characterized in that: The telescopic variable-focus OCT scanning probe comprises a large outer casing (1), a telescopic small casing (9) and a probe (13); the large outer casing (1) is an outermost straight casing; the telescopic small casing (9) penetrates into the large outer casing (1) from the left side of the large outer casing (1), and the probe (13) is placed inside the telescopic small casing (9); the probe comprises an optical fiber (3), a capillary glass tube (5), a self-focusing lens (7), and a plano-convex lens (8) arranged in sequence along the direction from the incident light of the optical fiber to the sample to be tested; a reflecting prism (10) is provided on the right side of the large outer casing (1); The probe (13) comprises a probe sleeve (2), an optical fiber (3), a capillary glass tube (5), a self-focusing lens (7), a plano-convex lens (8), a self-focusing lens sleeve (6) and a plano-convex lens sleeve (4); specifically: The probe (13) is placed in the telescopic small sleeve (9) through the probe sleeve (2); The capillary glass tube (5) and the self-focusing lens (7) are placed together in the self-focusing lens sleeve (6), and the self-focusing lens (7) and the capillary glass tube (5) are placed at intervals; The optical fiber (3) enters from the left side of the probe sleeve (2) and exits from the right side, and its end is inserted into the capillary glass tube (5); The plano-convex lens (8) is placed in the telescopic small sleeve (9) through the plano-convex lens sleeve (4), wherein the outer surface of the plano-convex lens sleeve (4) is in contact with the inner surface of the telescopic small sleeve (9) and the outer surface of the probe sleeve (2), that is, the left end of the plano-convex lens sleeve (4) is inserted into the probe sleeve (2), and the right end is inserted into the plano-convex lens (8); The reflecting prism (10) is placed at the right end of the large sleeve (1) of the outer shell via a reflecting prism fixing piece (11).

2. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: A gap is left between the self-focusing lens (7) and the plano-convex lens (8), and the various parts are bonded together using optical glue; the end of the large casing (1) of the outer shell is sealed by a casing cover (12).

3. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: The outer shell large sleeve (1) is in the shape of a straight cylinder, with smooth inner and outer surfaces without grooves. There is also a light hole inside the outer shell large sleeve (1) at a certain distance from the end face where the sleeve cover (12) is located, and the diameter of the light hole is larger than the diameter of the light beam.

4. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: The telescopic small sleeve (9) is placed inside the large sleeve (1) of the outer shell, and the two can slide smoothly, and the sliding distance is the same as the zoom distance; when the telescopic small sleeve (9) slides a certain distance away from the reflection prism (10), the focus of the light beam moves the same distance closer to the axis of the scanning probe accordingly.

5. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: The left end surface of the capillary glass tube (5) is aligned with the left end surface of the self-focusing lens sleeve (6); and the left end surface of the capillary glass tube (5) is coaxially bonded to the right end surface of the probe sleeve (2); The plano-convex lens (8) has a convex surface on one side opposite to the self-focusing lens (7), and a flat surface on the other side; The center of the right side of the capillary glass tube (5) is located at the focal position of the self-focusing lens (7). The light beam is emitted from the end of the optical fiber (3) and diverges, is collimated by the self-focusing lens (7), and is emitted in parallel from the right side of the self-focusing lens (7).

6. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: The right side end face of the capillary glass tube (5) along the radial direction is inclined 8° clockwise, the left side end face of the self-focusing lens (7) along the radial direction is inclined 8° clockwise, and the right side end face of the capillary glass tube is parallel to the left side end face of the self-focusing lens.

7. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: The reflecting prism (10) is cylindrical as a whole, and the left reflecting plane forms a certain angle with the axis of the large casing (1) of the outer shell.

8. The telescopic variable-focus OCT scanning probe according to claim 7, characterized in that: The angle range is between 30° and 60°.

9. The telescopic variable-focus OCT scanning probe according to claim 1, characterized in that: The surface of the self-focusing lens (7) and the surface of the plano-convex lens (8) are provided with anti-reflection films; and the reflecting surface of the reflecting prism (10) is provided with an anti-reflection film.

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