Optical fiber probe based on suspended vortex-shaped membrane structure

Abstract

The invention relates to the technical field of optical fiber sensors, and discloses an optical fiber probe based on a suspended vortex-shaped membrane structure, the optical fiber probe comprises a probe head, the tail end of the probe head comprises a collimation sleeve, a sensing optical fiber body is coaxially arranged in the collimation sleeve, the bottom end of the sensing optical fiber body penetrates out of the tail end of the probe head; the top end of the sensing optical fiber body is provided with a mirror surface and extends into a counter bore of the collimation sleeve, the counter bore in the collimation sleeve is communicated with an optical micro-cavity at the front end of the probe through a through hole, the top end of the probe is bonded or fixedly connected with the elastic membrane, the elastic membrane is composed of a central reflection area, a vortex-shaped structure cantilever and a membrane outer ring, and the vortex-shaped structure cantilever is arranged in the central reflection area. And an Fabry-Platinum cavity is formed between the elastic diaphragm and the reflecting mirror surface of the sensing optical fiber body. The central reflection area of the elastic membrane is connected with the edge of the membrane through the cantilever of the vortex-shaped structure, and compared with a sensing probe of a complete membrane structure, the vortex-shaped elastic membrane enables the device to have high sensitivity when detecting small pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensors, in particular to an optical fiber probe based on a suspended vortex membrane structure. Background Art

[0002] Fabry-Perot (FP) interferometric fiber sensors are widely used in metrology, atomic spectroscopy, astronomy, light scattering, and plasma diagnostics. They can be categorized into intrinsic and extrinsic types. Compared to intrinsic fiber FP resonators, extrinsic fiber FP resonators offer higher finesse, shorter cavity lengths (as short as a few microns), a wider free spectral range, and a very wide wavelength tuning range (up to several hundred nanometers), making them more suitable for high-precision pressure sensing.

[0003] Blood pressure is a type of fluid dynamic pressure. When endoscopic and invasive measurement of blood pressure inside a blood vessel is required, the sensor's pressure-sensitive diaphragm deforms, causing the optical microcavity's cavity length to change, which in turn causes the interference fringes to change, achieving the measurement purpose. However, blood pressure has pulsating micropressure characteristics. Traditional pressure-sensitive diaphragms mostly use a complete diaphragm structure with peripheral supports. The diaphragm structure has high rigidity and cannot cause the pressure-sensitive diaphragm to deform or deform very little when subjected to pulsating micropressure. This results in the measurement process not producing valid results or poor linearity of the measurement results. There is an urgent need for a fiber optic probe with low deformation stiffness, high sensitivity, and high stability. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides an optical fiber probe based on a suspended vortex membrane structure, which solves the problem of having high sensitivity when detecting smaller pressures.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an optical fiber probe based on a suspended vortex membrane structure, comprising a probe, the tail end of the probe comprising a collimating sleeve, a sensing optical fiber body coaxially arranged in the collimating sleeve, the bottom end of the sensing optical fiber body passing through the tail end of the probe, the top end of the sensing optical fiber body being set as a mirror and extending into the countersunk hole of the collimating sleeve, the countersunk hole in the collimating sleeve being connected to the optical microcavity at the front end of the probe through a through hole, the top end of the probe being bonded or fixed to an elastic diaphragm, the elastic diaphragm being composed of a central reflection area, a vortex structure cantilever and an outer ring of the diaphragm, and a platinum enamel cavity being formed between the elastic diaphragm and the reflecting mirror surface of the sensing optical fiber body.

[0006] Preferably, the elastic diaphragm is bonded or fixed to the top of the probe through the outer ring of the diaphragm, and the elastic diaphragm and the top of the sensing optical fiber body form an enamel platinum cavity.

[0007] Preferably, the central reflection area of ​​the elastic diaphragm and the sensing optical fiber body are arranged opposite to each other.

[0008] Preferably, the sensing optical fiber body is a single-mode sensing optical fiber, a multi-mode sensing optical fiber or a photonic crystal, and the end face is a reflecting mirror.

[0009] A method for preparing an optical fiber probe based on a suspended vortex membrane structure comprises the following steps:

[0010] S1: Use MEMS micro-nano processing technology to prepare sensor probes and elastic diaphragms with vortex structures.

[0011] S2: The sensing fiber body is placed in the countersunk hole of the alignment sleeve of the sensing probe, and the reflective mirror surface of the sensing fiber body is placed opposite to the central reflective area of ​​the elastic diaphragm;

[0012] S3: A platinum enamel cavity is formed between the top reflective mirror of the sensing optical fiber body and the central reflective area of ​​the elastic diaphragm;

[0013] S4: The elastic diaphragm is bonded or fixed to the top of the probe.

[0014] The present invention provides an optical fiber probe based on a suspended vortex membrane structure. It has the following beneficial effects:

[0015] The present invention connects the reflective area of ​​the elastic diaphragm to the diaphragm edge via a vortex-shaped cantilever. This vortex-shaped elastic diaphragm enables the device to achieve high sensitivity even when detecting relatively low pressures. Furthermore, the optical microcavity is connected to the outside world. When the static pressure changes, the pressure difference between the inside and outside of the optical microcavity remains unchanged, ensuring a stable operating point and unaffected performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional schematic diagram of the present invention;

[0017] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 3 It is a partial schematic diagram of the probe of the present invention;

[0019] Figure 4 It is a schematic diagram of the suspended vortex membrane structure of the present invention.

[0020] Among them, 1. Sensing optical fiber body; 2. Coating layer; 3. Collimation sleeve; 4. Probe; 5. Elastic diaphragm; 6. Through hole; 7. Optical microcavity; 8. Diaphragm outer ring; 9. Vortex structure cantilever; 10. Central reflection area. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example:

[0023] Please see the attached Figure 1 -Attached Figure 4 An embodiment of the present invention provides an optical fiber probe based on a suspended vortex membrane structure, including a probe 4, the tail end of the probe 4 includes a collimating sleeve 3, a sensing optical fiber body 1 is coaxially arranged in the collimating sleeve 3, the bottom end of the sensing optical fiber body 1 passes through the tail end of the probe 4, the outer wall of the sensing optical fiber body 1 is provided with a coating layer 2, the top end of the sensing optical fiber body 1 is set as a mirror and extends into the countersunk hole of the collimating sleeve 3, the countersunk hole in the collimating sleeve 3 is connected to the optical microcavity 7 at the front end of the probe 4 through a through hole 6, the top end of the probe 4 is bonded or fixed to the elastic diaphragm 5, the elastic diaphragm 5 is composed of a central reflection area 10, a vortex structure cantilever 9 and a diaphragm outer ring 8, and an enamel platinum cavity is formed between the elastic diaphragm 5 and the reflecting mirror surface of the sensing optical fiber body 1.

[0024] The enamel cavity is used to generate interference light signals and is connected to the outside world. When the probe is used in different static pressure environments, the pressure difference between the cavity and the external environment remains constant. Therefore, regardless of changes in the background static pressure, the interference fringes will not shift, thus ensuring that the probe's operating point remains stable at its initial position. When dynamic pressure acts on the elastic diaphragm 5, it deforms, causing the length of the enamel cavity to change. This allows the interference fringes in the fiber-optic enamel cavity to effectively reflect changes in the external dynamic pressure.

[0025] The elastic diaphragm 5 is bonded or fixed to the top of the probe 4 through the diaphragm outer ring 8 , and the elastic diaphragm 5 and the top of the sensing optical fiber body 1 form an enamel platinum cavity.

[0026] The central reflection area 10 of the elastic diaphragm 5 and the sensing optical fiber body 1 are arranged opposite to each other.

[0027] The sensing optical fiber body 1 is a single-mode sensing optical fiber, a multi-mode sensing optical fiber or a photonic crystal, and the end face is a reflective mirror.

[0028] A through hole 6 is coaxially opened in the probe 4, and the end face of the sensing optical fiber body 1 is connected to the front end microcavity 7 of the probe 4 through the through hole 6. The elastic diaphragm 5 adopts a suspended vortex membrane structure. The elastic diaphragm 5 is perpendicular to the axis of the probe 4. The central reflection area 10 of the elastic diaphragm 5 is arranged opposite to the top reflection mirror surface of the sensing optical fiber body 1. The elastic diaphragm 5 is bonded to the top end of the probe 4 through the diaphragm outer ring 8.

[0029] A method for preparing an optical fiber probe based on a suspended vortex membrane structure comprises the following steps:

[0030] S1: Use MEMS micro-nano processing technology to prepare a sensor probe 4 and a vortex-shaped elastic diaphragm 5.

[0031] S2: The sensing fiber body 1 is placed in the countersunk hole of the alignment sleeve 3 of the sensing probe 4, and the reflective mirror surface of the sensing fiber body 1 is placed opposite to the central reflective area 10 of the elastic diaphragm 5;

[0032] S3: A platinum enamel cavity is formed between the top reflective mirror of the sensing optical fiber body 1 and the central reflective area 10 of the elastic diaphragm 5;

[0033] S4: The elastic diaphragm 5 is bonded or fixed to the top of the probe 4 .

[0034] An elastic diaphragm 5 is bonded to the top of the probe 4. The central reflection area 10 of the elastic diaphragm 5 is coaxial with the through hole 6 in the probe 4. The coating layer 2 at the front end of the sensing optical fiber is peeled off and inserted into the countersunk hole of the alignment sleeve 3 at the tail end of the probe 4. The reflective mirror surface of the sensing optical fiber is arranged opposite to the central reflection area 10 of the elastic diaphragm 5 to form an optical microcavity.

[0035] The collimating sleeve 3 is 150 μm long and 140 μm in diameter, and the through hole 6 has a diameter of 9 μm.

[0036] The elastic diaphragm 5 preferably has a diameter of D = 140 μm, a thickness of 2 μm, a central reflection region diameter of d = 50 μm, and a pitch of 15 μm. The central reflection region 10 of the elastic diaphragm 5 facing the end face of the sensing optical fiber body 1 has a smooth surface, while the other surface is a rough surface. The elastic diaphragm 5 is preferably made of silicon nitride.

[0037] The sensing optical fiber body 1 is a single-mode optical fiber, a multi-mode optical fiber or a photonic crystal.

[0038] like Figure 1 As shown, the sensing fiber body 1 is placed in a through hole 6 coaxial with the alignment sleeve 3 , and the mirror surface of the sensing fiber body 1 is aligned with the center of the elastic diaphragm 5 .

[0039] Suspended vortex elastic diaphragm 5 Figure 3 As shown, the relationship between the vortex line length and the diaphragm related parameters is:

[0040]

[0041] Where n is the number of vortex coils and p is the pitch.

[0042] The elastic diaphragm 5 adopts a vortex suspended membrane structure, so that the optical fiber enamel cavity is connected to the outside world, so that when the probe is placed in different static pressure environments, the pressure difference between the optical fiber enamel cavity and the external environment remains unchanged. Therefore, no matter how the static pressure of the external environment changes, it will not cause the interference fringes to move, thereby ensuring that the working point of the sensor is stable at the initial position; when the environmental dynamic pressure acts on the elastic diaphragm 5, the interference fringes of the optical fiber enamel cavity change accordingly, thereby reflecting the dynamic pressure information. At the same time, its structure can also deform when the external dynamic pressure is small, thereby improving the sensitivity of the pressure sensor, that is, when the external pressure is small, the cavity length of the optical fiber enamel cavity of the pressure sensor can also change, so that the interference fringes of the optical fiber enamel cavity can effectively reflect the change information of the external dynamic pressure.

[0043] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An optical fiber probe based on a suspended vortex membrane structure, comprising a probe (4), characterized in that: The tail end of the probe (4) includes a collimating sleeve (3), a sensing optical fiber body (1) is coaxially arranged in the collimating sleeve (3), the bottom end of the sensing optical fiber body (1) passes through the tail end of the probe (4), the tip of the sensing optical fiber body (1) is stripped of the coating layer (2), the top end of the sensing optical fiber body (1) is set as a mirror and extends into the countersunk hole of the collimating sleeve (3), the countersunk hole in the collimating sleeve (3) is connected to the optical microcavity (7) at the front end of the probe (4) through a through hole (6), the top end of the probe (4) is bonded or fixed to an elastic diaphragm (5), the elastic diaphragm (5) is composed of a central reflection area (10), a vortex structure cantilever (9) and a diaphragm outer ring (8), and an enamel platinum cavity is formed between the elastic diaphragm (5) and the reflecting mirror surface of the sensing optical fiber body (1).

2. The optical fiber probe based on the suspended vortex membrane structure according to claim 1, characterized in that: The elastic diaphragm (5) is bonded or fixed to the top of the probe (4) via a diaphragm outer ring (8), and the elastic diaphragm (5) and the top of the sensing optical fiber body (1) form an enamel platinum cavity.

3. The optical fiber probe based on the suspended vortex membrane structure according to claim 1, characterized in that: The central reflection area (10) of the elastic membrane (5) and the sensing optical fiber body (1) are arranged opposite to each other.

4. The optical fiber probe based on the suspended vortex membrane structure according to claim 1, characterized in that: The sensing optical fiber body (1) is a single-mode sensing optical fiber, a multi-mode sensing optical fiber or a photonic crystal, and the end face is a reflecting mirror surface.

5. A method for preparing an optical fiber probe based on a suspended vortex membrane structure, characterized in that: An optical fiber probe based on a suspended vortex membrane structure as described in any one of claims 1 to 4 comprises the following steps: S1: A sensor probe (4) and an elastic diaphragm (5) with a vortex structure are prepared using MEMS micro-nano processing technology. S2: The sensing optical fiber body (1) is arranged in the counterbore of the alignment sleeve (3) of the sensing probe (4), and the reflecting mirror surface of the sensing optical fiber body (1) is arranged opposite to the central reflecting area (10) of the elastic diaphragm (5); S3: a platinum enamel cavity is formed between the top reflective mirror surface of the sensing optical fiber body (1) and the central reflective area (10) of the elastic diaphragm (5); S4: The elastic membrane (5) is bonded or fixed to the top of the probe (4).

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