Optical temperature sensor
Through optical temperature sensors, the generation of interference fringes using lasers and glass columns, combined with the change of refractive index, the problem of insufficient long-distance detection and accuracy in smart homes and wearable devices is solved, and high sensitivity and high-precision temperature measurement is achieved.
Patent Information
- Application Number
- CN202411472149.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-01-10
AI Technical Summary
Traditional temperature sensors are difficult to meet the needs of long-distance detection and stability of signal transmission media in new intelligent devices, especially in smart home and wearable device application scenarios, where measurement accuracy is insufficient.
An optical temperature sensor was designed to generate interference fringes using laser, semi-permeable prism, glass column and image screen. The temperature at the glass column is determined by the relationship between temperature and the movement amount of interference fringes, and combined with the change of refractive index of glass column materials, the temperature is realized. Long-distance temperature detection and improve measurement accuracy.
High-sensitivity temperature measurement is achieved, which can clearly reflect slight temperature fluctuations, and reduce errors by taking into account the characteristics of glass column materials, improving measurement accuracy and anti-interference ability.
Smart Images
Figure CN119290186A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of temperature sensors, and in particular to an optical temperature sensor. Background Art
[0002] With the rapid development of artificial intelligence, the development of new intelligent equipment has continuously put forward higher performance requirements for various sensor devices. As one of the important branches in the field of sensors, temperature sensors are widely used in many aspects such as industrial automation, environmental monitoring, and medical health. For new application scenarios such as smart homes and wearable devices, traditional temperature sensors are difficult to meet the requirements of long-distance detection and stable signal transmission media. Summary of the invention
[0003] The purpose of this application is to provide an optical temperature sensor that can achieve long-distance detection while improving temperature measurement accuracy.
[0004] To achieve the above objectives, this application provides the following solutions:
[0005] The present application provides an optical temperature sensor, comprising: a laser, a first plane mirror, a second plane mirror, a glass column, a semi-transparent prism, an image screen and a temperature calculation module;
[0006] The laser light emitted by the laser is transmitted to the semi-transparent prism through an optical fiber, and the laser light is divided into a first beam of light and a second beam of light through the semi-transparent prism, the first beam of light is the light of the laser light after being reflected from the semi-transparent prism, and the second beam of light is the light of the laser light passing through the semi-transparent prism; the first beam of light is reflected back to the semi-transparent prism after hitting the first plane mirror, and the second beam of light is reflected back to the semi-transparent prism after hitting the second plane mirror; the glass column is arranged on the optical path between the second beam of light and the second plane mirror, and the second beam of light passes through the glass column; the reflected light of the first beam of light is reflected from the semi-transparent prism to obtain a third beam of light, and the reflected light of the second beam of light passes through the semi-transparent prism to obtain a fourth beam of light; the third beam of light and the fourth beam of light are simultaneously irradiated to the image screen along the same direction, and interference fringes are generated on the image screen; the temperature calculation module is used to determine the temperature at the glass column according to the corresponding relationship between the temperature and the movement amount of the interference fringes.
[0007] Optionally, the semi-transparent prism is a glass plate with a first plane and a second plane parallel to each other, the first plane is an entrance plane for the laser emitted by the laser, and the second plane is an exit plane for the second light beam.
[0008] Optionally, a semi-transparent and semi-reflective film is coated on the second plane.
[0009] Optionally, the process of determining the corresponding relationship between the temperature and the movement amount of the interference fringes includes:
[0010] The glass column is heated by using a variable temperature heating stage to determine the corresponding relationship between each temperature at the glass column and the movement amount of the interference fringes on the image screen.
[0011] Optionally, when the glass column is heated by a variable temperature hot plate, the glass column is placed in an aluminum foil tube.
[0012] Optionally, the movement amount of the interference fringes is determined according to the optical path difference between the third light beam and the fourth light beam, and the change of the optical path difference is expressed as: δ=Δn·L, Δn=α·n·ΔT;
[0013] Among them, δ is the change in the optical path difference, Δn is the change in the refractive index of the glass column between the current temperature and the set temperature T, α is the refractive index temperature coefficient, ΔT is the temperature change between the current temperature and the set temperature T, L is twice the length of the glass column, and n is the refractive index at the set temperature T.
[0014] Optionally, the glass column is an optical glass column made of BK7 material.
[0015] Optionally, the glass column has a diameter of 6 mm and a length of 10 mm.
[0016] Optionally, the laser is a helium-neon laser.
[0017] Optionally, the optical fiber between the laser and the semi-transparent prism is fixed by an optical fiber clamp.
[0018] According to the specific embodiments provided in this application, this application discloses the following technical effects:
[0019] The present application provides an optical temperature sensor, which uses laser as coherent light and optical elements to generate interference fringes. The temperature of the place to be detected, i.e., the glass column, is determined according to the corresponding relationship between the temperature and the movement amount of the interference fringes. After the laser passes through a semi-transparent prism, the optical path is not affected by the optical fiber connection, thereby realizing long-distance temperature detection. Based on the sensitivity of the refractive index of the glass column material to temperature changes, the invisible temperature change can be converted into a visible interference fringe change based on the interference principle, and the change sensitivity is high. Even slight temperature fluctuations can obtain obvious fringe changes, thereby improving the sensitivity of temperature measurement. In addition, the present application uses an independent and non-continuous glass column medium as the core temperature measurement component. While using the refractive index change to measure the temperature, the influence of temperature on the medium size can be further taken into account in the calculation according to the characteristics of the glass column material, thereby reducing errors and improving measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0021] Figure 1 A schematic diagram of the structure of an optical temperature sensor provided in one embodiment of the present application;
[0022] Figure 2 A schematic diagram of the structure of a variable temperature hot plate simulating heating provided in an embodiment of the present application;
[0023] Figure 3 A schematic diagram of the interference fringe generation principle provided in one embodiment of the present application.
[0024] Reference numerals:
[0025] 1-laser, 2-first plane mirror, 3-second plane mirror, 4-glass column, 5-semi-transparent prism, 6-image screen, 7-variable temperature hot plate, 8-optical fiber, 9-first optical fiber clamp, 10-second optical fiber clamp, S1-reflected light of the first light beam, S2-reflected light of the second light beam, P1-first plane, P2-second plane. DETAILED DESCRIPTION
[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0027] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0028] The present application provides an optical temperature sensor, such as Figure 1 As shown, the optical temperature sensor includes: a laser 1, a first plane mirror 2, a second plane mirror 3, a glass column 4, a semi-transparent prism 5, an image screen 6 and a temperature calculation module.
[0029] The laser light emitted by the laser 1 is transmitted to the semi-transparent prism 5 through the optical fiber 8, and the laser light is divided into a first beam of light and a second beam of light through the semi-transparent prism 5, the first beam of light is the light of the laser light after being reflected from the semi-transparent prism 5, and the second beam of light is the light of the laser light passing through the semi-transparent prism 5; the first beam of light is reflected back to the semi-transparent prism 5 after hitting the first plane mirror 2, and the second beam of light is reflected back to the semi-transparent prism 5 after hitting the second plane mirror 3; the glass column 4 is arranged on the optical path between the second beam of light and the second plane mirror 3, and the second beam of light passes through the glass column 4; the reflected light of the first beam of light is reflected from the semi-transparent prism 5 to obtain a third beam of light, and the reflected light of the second beam of light passes through the semi-transparent prism 5 to obtain a fourth beam of light; the third beam of light and the fourth beam of light are simultaneously irradiated to the image screen 6 along the same direction, and interference fringes are generated on the image screen 6; the temperature calculation module is used to determine the temperature at the glass column 4 according to the corresponding relationship between the temperature and the movement amount of the interference fringes.
[0030] The present application is based on the fact that laser is coherent light and uses optical elements to generate interference fringes. The temperature of the place to be detected, i.e., the glass column 4, is determined according to the corresponding relationship between the temperature and the movement amount of the interference fringes. After the laser passes through the semi-transparent prism, the optical path is not affected by the optical fiber connection, thereby realizing long-distance temperature detection. Based on the sensitivity of the refractive index of the glass column material to temperature changes, the invisible temperature changes can be converted into visible interference fringe changes based on the interference principle, and the change sensitivity is high. Even slight temperature fluctuations can obtain obvious fringe changes, thereby improving the sensitivity of temperature measurement. In addition, the present application uses an independent and non-continuous glass column medium as the core temperature measurement component. While using the refractive index change to measure the temperature, the influence of temperature on the medium size can be further taken into account in the calculation according to the characteristics of the glass column material, thereby reducing errors and improving measurement accuracy.
[0031] In an exemplary embodiment, the semi-transparent prism 5 is a glass plate with a first plane P1 and a second plane P2 parallel to each other, the first plane P1 is the entry plane of the laser 1, and the second plane P2 is the exit plane of the second beam of light. The second plane P2 is coated with a semi-transparent and semi-reflective film.
[0032] The present application uses a semi-transparent prism 5 to divide a monochromatic light source into two beams of light, namely a first beam of light and a second beam of light, two beams of coherent light. Figure 3As shown, when the reflected light S1 of the first light beam propagates to the second plane P2, a semi-transparent and semi-reflective phenomenon occurs, wherein the reflected light propagates along direction (2), and the transmitted light (third light beam) propagates along direction (1). The reflected light S2 of the second light beam directly irradiates the second plane P2 of the semi-transparent prism 5, and a semi-transparent and semi-reflective phenomenon also occurs, wherein the reflected light (fourth light beam) propagates along direction (1), and the transmitted light is refracted by the first plane P1 of the semi-transparent prism 5 and then emitted, propagating along direction (2), and direction (1) is the direction of irradiating to the image screen 6. Since the partially transmitted light of the reflected light S1 of the first light beam and the partially reflected light of the reflected light S2 of the second light beam propagate along direction (1) at the same time, and there is a constant optical path difference, interference fringes can be obtained at the image screen 6.
[0033] The laser 1 is a helium-neon laser.
[0034] The optical fiber 8 between the laser 1 and the semi-transparent prism 5 is fixed by an optical fiber clamp, and the optical fiber clamp includes a first clamp 9 and a second clamp 10 .
[0035] In an exemplary embodiment, Figure 2 As shown, the process of determining the corresponding relationship between the temperature and the movement amount of the interference fringes includes: heating the glass column 4 with a variable temperature hot stage 7, determining the corresponding relationship between each temperature at the glass column 4 and the movement amount of the interference fringes on the image screen 6, and adjusting the optical path after placing each instrument so that clear interference fringes appear on the image screen 6. Adjust the button of the variable temperature hot stage 7 to set the temperature, and observe the changes in the interference fringes when the temperature changes. The variable temperature hot stage 7 is used to simulate the heat source to realize the calibration of the corresponding relationship between the temperature and the movement amount of the interference fringes. After the parameter calibration is completed, the entire device will finally make full contact between the core temperature measurement part and the object to be measured to achieve temperature measurement. The variable temperature hot stage is no longer used in the actual temperature measurement process.
[0036] When the variable temperature hot stage 7 is used to heat the glass column 4, asbestos is selected as the heat preservation material of the variable temperature hot stage 7, and the glass column 4 is placed in an aluminum foil tube to ensure uniform heat conduction and smooth light path. The present application uses a variable temperature hot stage 7 to simulate a heat source, with an initial temperature of 35.4°C. By changing the temperature of the hot stage, the change of interference fringes (rings) is observed. The set temperature and the actual temperature are the readings of the hot stage control panel, respectively. The change of interference fringes, i.e., the number of ring changes, is shown in Table 1.
[0037] Table 1 Stripe change number record table
[0038]
[0039] The movement amount of the interference fringes is determined according to the optical path difference between the third light beam and the fourth light beam, and the change of the optical path difference is expressed as: δ=Δn·L, Δn=α·n·ΔT.
[0040] Among them, δ is the change in the optical path difference, Δn is the change in the refractive index of the glass column 4 between the current temperature and the set temperature T, α is the refractive index temperature coefficient, ΔT is the temperature change between the current temperature and the set temperature T, L is twice the length of the glass column, and n is the refractive index at the set temperature T.
[0041] In an exemplary embodiment, the glass column 4 is an optical glass column 4 made of BK7 material. The diameter of the glass column 4 is 6 mm, and the length (height / thickness) is 10 mm. The length of the glass column 4 is the axial length. The present application utilizes the characteristic that the refractive index of BK7 optical glass changes with temperature to change the refractive index of the glass column 4, thereby changing the optical path difference, causing the interference fringes to move. The optical path difference and the number of interference fringes moved satisfy the following relationship: δ=ΔN·λ, where ΔN is the number of fringes moved at the same observation point on the image screen during the temperature change, and λ is the wavelength of the laser light source. Based on the above relationship, the corresponding relationship between the temperature change and the amount of interference fringes moved can be obtained.
[0042] Among them, the refractive index n of the BK7 optical glass column 4 at room temperature is 1.51680, and the refractive index temperature coefficient α is 7.1×10 -6 K -1 , the original length of BK7 glass is L0, and the thermal expansion coefficient β is 7.1×10 -6 m·K -1 . Approximately, ΔL = β·L0·ΔT. The change in optical path difference δ = Δn·L, where Δn is the change in refractive index, and L is the actual length of light propagating in the medium, that is, twice the original length L0 of the glass column 4 in the present application (because the light propagates through the medium twice). When the temperature change causes the refractive index to change, the change in optical path difference will directly affect the interference pattern.
[0043] In the design of continuous optical fiber temperature sensors commonly used in the prior art, a section of the optical fiber is often removed from the outer sheath and used as a temperature detection area. Although the temperature is used to change the refractive index of the medium to achieve temperature measurement, the section of optical fiber used for temperature measurement is still on the entire optical fiber, making it difficult to consider the interference of the optical path difference caused by thermal expansion of the material. The present application uses an independent optical glass column as a core temperature measurement element, which can use the property of the refractive index changing with temperature to achieve temperature measurement through interference fringes. At the same time, since the optical path difference can be corrected based on the thermal expansion coefficient of the material, the interference of the thermal expansion effect during the medium temperature measurement process is eliminated, thereby improving the measurement accuracy of the device. The heat source temperature measured by the system calculated based on the change of the interference fringes before considering the influence of thermal expansion is shown in Table 2. After considering the correction of the influence of thermal expansion, the calculated heat source temperature value measured by the system is shown in Table 3.
[0044] Table 2 Temperature calculation data table (before correction / before considering the influence of material thermal expansion)
[0045] Actual temperature / ℃ ΔN Calculate ΔT / °C Calculation temperature / ℃ 45.6 44 14.7 50.1 55.3 87 29.0 64.4 65.2 132 44.0 79.4 75.3 173 57.7 93.1 85.3 215 71.7 107.1 95.2 257 85.7 121.1 105.2 297 99.0 134.4 115.3 338 112.7 148.1 125.2 381 127.0 162.4 135.2 422 140.7 176.1 145.2 463 154.3 189.7 155.3 506 168.7 204.1 165.1 547 182.3 217.7 175.2 588 196.0 231.4 185.2 633 211.0 246.4 195.1 674 224.7 260.1 205.1 714 238.0 273.4 215.0 757 252.3 287.7
[0046] In Table 2, the initial temperature T0 is 35.4°C, and the calculated temperature is the heat source temperature value measured by this system (before correction). The relationship between ΔN and ΔT before correction is: ΔT = T-T0, Δn = α·n0·ΔT, δL0 = 2·L·Δn, δ = ΔN·λ, so, The temperature change is calculated based on ΔN=3.0ΔT.
[0047] Table 3 Temperature calculation data table (after correction / after considering the influence of material thermal expansion)
[0048]
[0049]
[0050] In Table 3, the initial temperature T0 is 35.4°C, and the calculated temperature is the heat source temperature value measured by this system (after correction). The relationship between ΔN and ΔT after correction is: ΔT = T-T0, Δn = α·n0·ΔT, ΔL = β·L0·ΔT, δL0 = 2·(ΔL+L0)·Δn, δ = ΔN·λ, so, That is, ΔN≈4.2ΔT is obtained. The temperature change is calculated based on ΔN≈4.2ΔT. By comparing Table 2 and Table 3, it can be seen that after considering the influence of material thermal expansion, the error between the calculated temperature and the actual temperature is significantly reduced, thereby improving the measurement accuracy of the device.
[0051] The present invention can convert invisible temperature changes into visible phenomena of diffraction ring number movement, and by measuring the movement / change of the diffraction ring number, it can quantify the temperature change, and finally the temperature coefficient (α 仪 ) is used to quantify its sensitivity, which reflects the ratio between the change in optical path difference caused by the actual temperature increase and the change in optical path difference corresponding to the actual observed change in the number of diffraction rings.
[0052] Fiber optic communication has the advantages of fast transmission speed, good confidentiality, and high safety factor. Based on the above advantages of fiber optic signal transmission, this application realizes a new temperature sensor device with long-distance detection, stable signal transmission, high sensitivity and strong anti-interference ability.
[0053] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0054] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.
Claims
1. An optical temperature sensor, characterized in that: The optical temperature sensor comprises: a laser, a first plane mirror, a second plane mirror, a glass column, a semi-transparent prism, an image screen and a temperature calculation module; The laser light emitted by the laser is transmitted to the semi-transparent prism through an optical fiber, and the laser light is divided into a first beam of light and a second beam of light through the semi-transparent prism, the first beam of light is the light of the laser light after being reflected from the semi-transparent prism, and the second beam of light is the light of the laser light passing through the semi-transparent prism; the first beam of light is reflected back to the semi-transparent prism after hitting the first plane mirror, and the second beam of light is reflected back to the semi-transparent prism after hitting the second plane mirror; the glass column is arranged on the optical path between the second beam of light and the second plane mirror, and the second beam of light passes through the glass column; the reflected light of the first beam of light is reflected from the semi-transparent prism to obtain a third beam of light, and the reflected light of the second beam of light passes through the semi-transparent prism to obtain a fourth beam of light; the third beam of light and the fourth beam of light are simultaneously irradiated to the image screen along the same direction, and interference fringes are generated on the image screen; the temperature calculation module is used to determine the temperature at the glass column according to the corresponding relationship between the temperature and the movement amount of the interference fringes.
2. The optical temperature sensor according to claim 1, characterized in that The semi-transparent prism is a glass plate with a first plane and a second plane parallel to each other. The first plane is an entry plane for the laser emitted by the laser, and the second plane is an exit plane for the second beam of light.
3. The optical temperature sensor according to claim 2, characterized in that: The second plane is coated with a semi-transparent and semi-reflective film.
4. The optical temperature sensor according to claim 1, characterized in that: The process of determining the corresponding relationship between the temperature and the movement amount of the interference fringes includes: The glass column is heated by using a variable temperature heating stage to determine the corresponding relationship between each temperature at the glass column and the movement amount of the interference fringes on the image screen.
5. The optical temperature sensor according to claim 4, characterized in that When the glass column is heated by a variable temperature hot plate, the glass column is placed in an aluminum foil tube.
6. The optical temperature sensor according to claim 1, characterized in that: The movement amount of the interference fringes is determined according to the optical path difference between the third light beam and the fourth light beam, and the change of the optical path difference is expressed as: δ=Δn·L, Δn=α·n·ΔT; Among them, δ is the change in the optical path difference, Δn is the change in the refractive index of the glass column between the current temperature and the set temperature T, α is the refractive index temperature coefficient, ΔT is the temperature change between the current temperature and the set temperature T, L is twice the length of the glass column, and n is the refractive index at the set temperature T.
7. The optical temperature sensor according to claim 1, characterized in that: The glass column is an optical glass column made of BK7 material.
8. The optical temperature sensor according to claim 1, characterized in that: The glass column has a diameter of 6 mm and a length of 10 mm.
9. The optical temperature sensor according to claim 1, characterized in that: The laser is a helium-neon laser.
10. The optical temperature sensor according to claim 1, characterized in that: The optical fiber between the laser and the semi-transparent prism is fixed by an optical fiber clamp.