Optical fiber Fabry-Perot sensor structure
By introducing a collimating lens and a support plate into the fiber optic Fabry-Perot sensor, the problem of light spot diffusion under high temperature conditions was solved, and high-precision temperature and pressure measurement was achieved.
Patent Information
- Application Number
- CN202423315130.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Existing fiber optic Fabry-Perot sensors suffer from reduced detection accuracy due to light spot diffusion when the optical path is long in high-temperature environments, making it difficult to simultaneously and accurately measure temperature and pressure.
A fiber optic Fabry-Perot sensor structure was designed, which uses a collimating lens to correct the light to a parallel beam, and a support plate is set between the transmissive and reflective plates to control the length of the Fabry-Perot cavity. The thermal expansion changes of the transmissive and reflective plates are used to detect temperature and pressure.
It effectively avoids light spot diffusion, improves detection accuracy, and can accurately measure temperature and pressure under long optical path conditions.
Smart Images
Figure CN223623628U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of sensor technology, and in particular to a fiber optic Fabry-Perot sensor structure. Background Technology
[0002] Currently, the most widely used fiber optic strain sensors are primarily based on fiber Bragg grating (FBG) technology and fiber Fabry-Perot (FAP) interferometry. Utilizing the sensitivity of the cavity length of the fiber Fabry-Perot sensor to external physical quantities, it has been widely applied in various industrial fields to sense parameters such as strain, pressure, temperature, and refractive index. In practical applications, fiber Fabry-Perot sensors are affected by the detection environment, occasionally resulting in a longer optical path between the fiber's output end and the FAP cavity. For example, in high-temperature environments, to reduce the temperature at the fiber and ensure its performance, the output end needs to be moved away from the high-temperature environment. However, an increased optical path leads to a larger emitted light spot, which in turn affects the detection accuracy of the FAP sensor. Utility Model Content
[0003] In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is: how to provide a fiber optic Fabry-Perot sensor structure with a reasonable structural design that can be applied to a long optical path, avoid light spot diffusion, and help ensure detection accuracy.
[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0005] A fiber optic Fabry-Perot sensor structure includes a housing, wherein a first optical channel extends in a straight line within the housing, an incident optical fiber is disposed at one end of the first optical channel, and a transmissive plate and a reflective plate are sequentially disposed at the other end in a direction away from the incident optical fiber, wherein a Fabry-Perot cavity is formed between the transmissive plate and the reflective plate; a collimating lens is disposed within the first optical channel, and the collimating lens is located between the incident optical fiber and the transmissive plate.
[0006] In the above structure, a collimating mirror is placed between the incident optical fiber and the transmission plate to correct the light introduced by the incident optical fiber into a parallel beam before sending it to the transmission plate. After the fiber is collimated, even if the optical path is extended, the light spot at the transmission plate will not diffuse, thus ensuring the detection accuracy of the Fabry-Perot cavity. In addition, a second Fabry-Perot cavity can be formed on both the front and back surfaces of the transmission plate. When the temperature changes, the thickness of the transmission plate will change due to thermal expansion. By detecting the change in thickness, the change in ambient temperature can be calculated, thus enabling simultaneous measurement of temperature and pressure.
[0007] Furthermore, the end of the first optical channel away from the incident optical fiber has a second optical channel that is intersected and connected. The transmissive sheet and the reflective sheet are disposed in the second optical channel. A reflector is disposed at the intersection of the first optical channel and the second optical channel to reflect the incident optical fiber into the second optical channel.
[0008] Furthermore, at least one second optical channel is sequentially connected to the end of the second optical channel away from the first optical channel, and a reflector for propagating incident light along the second optical channel is provided between any two intersecting second optical channels; the transmissive sheet and the reflective sheet are disposed in the second optical channel farthest from the first optical channel.
[0009] Furthermore, the transmissive sheet is made of a high-temperature resistant transparent material.
[0010] Furthermore, the transmissive sheet is a sapphire sheet.
[0011] Furthermore, the reflective sheet is a reflective cover plate that is placed on the housing.
[0012] In this way, the reflective cover can sense the external pressure, thereby changing the length of the Fabry-Perot cavity between the reflective cover and the transmissive sheet, and thus realizing the detection of pressure.
[0013] Furthermore, a support sheet is provided between the transmissive sheet and the reflective sheet, the thickness of which is consistent with the initial cavity length of the Fabry-Perot cavity; the support sheet has a through hole in its middle.
[0014] By using the thickness of the support sheet to control the initial Fabry-Perot cavity length between the transmissive and reflective sheets, better product consistency can be achieved.
[0015] Furthermore, the support sheet is made of metal.
[0016] Furthermore, the housing is made of a single piece of material, and the housing has a plunger hole that communicates with the first optical channel. The collimating lens is disposed at the intersection of the plunger hole and the first optical channel. A plunger is sealed on the plunger hole.
[0017] Furthermore, the width and height of the housing are 1 to 5 mm.
[0018] In summary, this utility model has the advantages of reasonable structural design, applicability to long optical paths, avoidance of light spot diffusion, and improved detection accuracy. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the overall structure of Example 1.
[0020] Figure 2 for Figure 1 A cross-sectional structural diagram.
[0021] Figure 3 This is a cross-sectional structural diagram of Example 2.
[0022] Figure 4 This is a cross-sectional structural diagram of Example 3. Detailed Implementation
[0023] The present invention will now be described in further detail with reference to an optical fiber Fabry-Perot pressure sensor employing the structure of the present invention.
[0024] Example 1: As Figure 1 and Figure 2 As shown, a fiber optic Fabry-Perot pressure sensor includes a housing 1 made of a single piece of material. The housing 1 has a first optical channel 2 extending in a straight line. An incident optical fiber 3 is disposed at one end of the first optical channel 2. The incident optical fiber 3 passes through an incident plug and is made of gold-plated optical fiber sintered, ground, and then inserted into the entrance aperture of the first optical channel. In this embodiment, the end of the first optical channel 2 away from the incident optical fiber 3 has a second optical channel 7 that is intersected and connected. The end of the second optical channel 7 away from the first optical channel 2 has a transmissive plate 4 and a reflective plate 5 arranged sequentially in a direction away from the incident optical fiber 3, forming a Fabry-Perot cavity between the transmissive plate 4 and the reflective plate 5. A reflector 8 is disposed at the intersection of the first optical channel 2 and the second optical channel 7 to reflect the incident optical fiber into the second optical channel 7. A collimating mirror 6 is disposed within the first optical channel 2, located between the incident optical fiber 3 and the reflector 8. Specifically, the housing 1 has a plunger hole that communicates with the first optical channel 2, and the collimating lens 6 is disposed at the intersection of the plunger hole and the first optical channel 2; a plunger is sealed on the plunger hole.
[0025] In this embodiment, the transmissive sheet 4 is a sapphire sheet; however, it can also be made of other high-temperature resistant transparent materials. The reflective sheet 5 is a reflective cover plate that covers the outside of the housing 1. The reflective cover plate can sense external pressure, thereby changing the Fabry-Perot cavity length between the reflective cover plate and the transmissive sheet to detect the pressure.
[0026] To control the initial length of the Fabry-Perot cavity between the reflector 5 and the transmissor 4, a support plate 9 is provided between the transmissor 4 and the reflector 5. The thickness of the support plate 9 is consistent with the initial cavity length of the Fabry-Perot cavity. The support plate 9 has a through hole in its center. To withstand high-temperature environments, the support plate 9 is made of metal.
[0027] In operation, the light emitted from the incident fiber is collimated by a spherical lens into parallel light with a very small diameter (approximately 0.3 mm). This parallel light propagates forward to the metal reflective surface, is reflected, and then propagates vertically upwards. After passing through the sapphire sheet, it is reflected by the reflective cover plate, forming an enamel cavity with the upper surface of the sapphire. During operation, pressure compresses the surface of the reflective sheet 5, causing a change in the distance between the reflective surface and the sapphire surface (enamel cavity). The magnitude of the force on the cover plate is measured by measuring the change in the enamel cavity distance. Additionally, a second enamel cavity can be formed on both the front and back surfaces of the transmission sheet. When the temperature changes, the thickness of the transmission sheet changes due to thermal expansion. By detecting the change in thickness, the change in ambient temperature can be calculated, thus enabling simultaneous measurement of temperature and pressure.
[0028] Example 2: Figure 3 As shown, a fiber optic Fabry-Perot pressure sensor includes a housing 1 made of a single piece of material. The housing 1 has a first optical channel 2 extending in a straight line. An incident optical fiber 3 is disposed at one end of the first optical channel 2, passing through an incident plug and inserted into the incident aperture of the first optical channel. In this embodiment, the other end of the first optical channel 2 has a transmissive plate 4 and a reflective plate 5 arranged sequentially in a direction away from the incident optical fiber 3, forming a Fabry-Perot cavity between the transmissive plate 4 and the reflective plate 5. A collimating lens 6 is disposed within the first optical channel 2, located between the incident optical fiber 3 and the transmissive plate 4. Specifically, the housing 1 has a plunger hole communicating with the first optical channel 2, and the collimating lens 6 is disposed at the intersection of the plunger hole and the first optical channel 2; a plug is sealed onto the plunger hole. In this embodiment, the transmissive plate 4 is a sapphire sheet; however, other high-temperature resistant transparent materials can also be used. The reflective plate 5 is a reflective cover plate disposed on the outside of the housing 1. The reflective cover can sense external pressure, thereby changing the Fabry-Perot cavity length between the reflective cover and the transmissive plate to detect the pressure. Additionally, a second Fabry-Perot cavity can be formed on both the front and back surfaces of the transmissive plate. When the temperature changes, the thickness of the transmissive plate changes due to thermal expansion. By detecting this change in thickness, the change in ambient temperature can be calculated, thus enabling simultaneous measurement of both temperature and pressure.
[0029] To control the initial length of the Fabry-Perot cavity between the reflector 5 and the transmissor 4, a support plate 9 is provided between the transmissor 4 and the reflector 5. The thickness of the support plate 9 is consistent with the initial cavity length of the Fabry-Perot cavity. The support plate 9 has a through hole in its center. To withstand high-temperature environments, the support plate 9 is made of metal.
[0030] Example 3: As Figure 4As shown, a fiber optic Fabry-Perot pressure sensor includes a housing 1 made of a single piece of material. The housing 1 has a first optical channel 2 extending in a straight line. An incident optical fiber 3 is disposed at one end of the first optical channel 2. The incident optical fiber 3 passes through an incident plug and is made of gold-plated optical fiber sintered, ground, and then inserted into the entrance hole of the first optical channel. Two intersecting second optical channels 7 are sequentially connected to the end of the first optical channel 2 away from the incident optical fiber 3. The second optical channel 7 away from the second optical channel 2 has a transmissive plate 4 and a reflective plate 5 sequentially arranged in a direction away from the incident optical fiber 3. A reflector 8 is disposed at the intersection of the first optical channel 2 with an adjacent second optical channel 7, and at the intersection of two adjacent second optical channels 7, to sequentially reflect the incident light to the transmissive plate 4. A collimating lens 6 is disposed within the first optical channel 2, located between the incident optical fiber 3 and the reflector 8. Specifically, the housing 1 has a plunger hole that communicates with the first optical channel 2, and the collimating lens 6 is disposed at the intersection of the plunger hole and the first optical channel 2; a plunger is sealed on the plunger hole.
[0031] In this embodiment, the transmissive sheet 4 is a sapphire sheet; however, it can also be made of other high-temperature resistant transparent materials. The reflective sheet 5 is a reflective cover plate covering the outside of the housing 1. The reflective cover plate can sense external pressure, thereby changing the Fabry-Perot cavity length between the reflective cover plate and the transmissive sheet to detect the pressure. Furthermore, a second Fabry-Perot cavity can be formed on both the front and back surfaces of the transmissive sheet. When the temperature changes, the thickness of the transmissive sheet will change due to thermal expansion. By detecting the change in thickness, the change in ambient temperature can be calculated, thus enabling simultaneous measurement of temperature and pressure.
[0032] To control the initial length of the Fabry-Perot cavity between the reflector 5 and the transmissor 4, a support plate 9 is provided between the transmissor 4 and the reflector 5. The thickness of the support plate 9 is consistent with the initial cavity length of the Fabry-Perot cavity. The support plate 9 has a through hole in its center. To withstand high-temperature environments, the support plate 9 is made of metal.
[0033] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A fiber optic Fabry-Perot sensor structure, characterized in that, The device includes a housing (1), which has a first optical channel (2) extending in a straight line. One end of the first optical channel (2) is provided with an incident optical fiber (3), and the other end has a transmissive plate (4) and a reflective plate (5) arranged sequentially in a direction away from the incident optical fiber (3). A Fabry-Perot cavity is formed between the transmissive plate (4) and the reflective plate (5). A collimating lens (6) is provided in the first optical channel (2), and the collimating lens (6) is located between the incident optical fiber (3) and the transmissive plate (4).
2. The fiber optic Fabry-Perot sensor structure as described in claim 1, characterized in that, The first optical channel (2) has a second optical channel (7) that is intersected and connected at one end away from the incident optical fiber (3). The transmissive plate (4) and the reflective plate (5) are disposed in the second optical channel (7). A reflector (8) for reflecting the incident optical fiber into the second optical channel (7) is disposed at the intersection of the first optical channel (2) and the second optical channel (7).
3. The fiber optic Fabry-Perot sensor structure as described in claim 2, characterized in that, The end of the second optical channel (7) away from the first optical channel (2) is connected to at least one second optical channel (7) in sequence, and a reflector (8) for propagating incident light along the second optical channel (7) is provided between any two intersecting second optical channels (7); the transmissive sheet (4) and the reflective sheet (5) are located in the second optical channel (7) farthest from the first optical channel (2).
4. The fiber optic Fabry-Perot sensor structure as described in any one of claims 1 to 3, characterized in that, The transmissive sheet (4) is made of a high-temperature resistant transparent material.
5. The fiber optic Fabry-Perot sensor structure as described in claim 4, characterized in that, The transmissive sheet (4) is a sapphire sheet.
6. The fiber optic Fabry-Perot sensor structure as described in claim 4, characterized in that, The reflective sheet (5) is a reflective cover plate that is placed on the housing (1).
7. The fiber optic Fabry-Perot sensor structure as described in any one of claims 1 to 3, characterized in that, A support plate (9) is provided between the transmissive plate (4) and the reflective plate (5), and the thickness of the support plate (9) is consistent with the initial cavity length of the Fabry cavity; the support plate (9) has a through hole in the middle.
8. The fiber optic Fabry-Perot sensor structure as described in claim 7, characterized in that, The support sheet (9) is made of metal.
9. The fiber optic Fabry-Perot sensor structure according to any one of claims 1 to 3, characterized in that, The housing (1) is made of a single material. The housing (1) has a plunger hole that is connected to the first optical channel (2). The collimating lens (6) is located at the intersection of the plunger hole and the first optical channel (2). A plunger is sealed on the plunger hole.
10. The fiber optic Fabry-Perot sensor structure according to any one of claims 1 to 3, characterized in that, The width and height of the shell (1) are 1 to 5 mm.