White light interference-based SMD (Surface Mount Device) strain gauge and sensor

Abstract

The utility model discloses a white light interference-based surface-mounted strainmeter and a white light interference-based surface-mounted strainmeter sensor. The strain gauge comprises a strain gauge base material, round holes are formed in the two ends of the strain gauge base material, a solid ceramic rod and an MU insertion core penetrate through the two round holes respectively, a collimation sleeve is arranged in the strain gauge base material, a collimation optical fiber is arranged at one end of the MU insertion core, and the MU insertion core and the collimation optical fiber are fixed through UV glue to form a collimator. The collimation sleeve plays a role in fixing the positions of the collimator and the solid ceramic rod and protecting the collimator and the solid ceramic rod, the interference cavity is automatically collimated without manual adjustment by designing the collimation sleeve, and in order to enable the interference cavity of the strain gauge to respond more accurately during deformation monitoring, a gap is formed when the collimation sleeve is designed, so that the interference cavity is more accurate in deformation monitoring. According to the utility model, damping between the collimator and the solid ceramic rod and between the collimator and the collimation sleeve can be reduced, so that the design enables the optical sensing cavity to be more stable, damping caused by surface contact is reduced, mechanical lag of the sensor is reduced, and measurement repeatability of the sensor is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to white light interference technical field especially relates to a kind of patch type strain gauge and sensor based on white light interference. BACKGROUND

[0002] White light phase shift interference technology (PSI): the light in specific wavelength range is emitted to target surface and reference surface, and there will be light interference between target surface reflection light and reference surface reflection light.The phase between target surface reflection light and reference surface reflection light is related to the distance between target surface and reference surface, and by means of phase measurement method, the phase difference of multiple interference fringes is obtained, that is, the distance between target surface and reference surface can be calculated.

[0003] The existing strain gauge based on white light interference mostly adopts laboratory type structure, and the formation and adjustment of its interference cavity require high assembly precision, and in use process, it usually needs to use six-dimensional adjusting frame to finely adjust the cavity length and coaxiality of interference cavity in multiple dimensions, so as to cause complex debugging process and low efficiency, and it is difficult to meet the needs of rapid installation and batch layout in engineering site.

[0004] In addition, the existing strain gauge usually has mechanical hysteresis in strain loading and unloading process, thereby affecting the stability and measurement repeatability of interference signal.For application scenarios that need long-term online monitoring, the above problems are particularly prominent.

[0005] Therefore, it is urgent to provide a white light interference strain gauge and sensor with simple structure, convenient assembly and debugging, high stability of interference cavity and suitable for patch type installation, to overcome the deficiencies in the prior art. UTILITY MODEL CONTENT

[0006] Therefore, the utility model aims at providing a patch type strain gauge and sensor based on white light interference, which solves the technical problems that the existing strain gauge based on white light interference requires high production debugging tool when in use, needs to rely on six-dimensional adjusting frame for multidimensional adjustment of interference cavity, has great difficulty and low efficiency in debugging, and the interference cavity of existing structure has poor stability, large mechanical damping and is easy to cause measurement repeatability and response accuracy to decrease.

[0007] To solve the above technical problems, the utility model provides a patch type strain gauge based on white light interference:

[0008] It includes strain gage substrate, both ends of the strain gauge substrate are provided with round holes, a solid ceramic rod and MU plug are respectively penetrated in the two round holes, a collimating sleeve is arranged in the strain gage substrate, a collimating optical fiber is arranged at one end of the MU plug, the MU plug and collimating optical fiber are fixed to form collimator by UV glue, the solid ceramic rod and collimator are inserted into the collimating sleeve, and a gap is formed in the collimating sleeve.

[0009] As a preferred scheme of the patch type strain gauge based on white light interference, the strain gauge base is provided with a waist-shaped hole at each end, and the waist-shaped hole and the circular hole are communicated.

[0010] As a preferred scheme of the patch type strain gauge based on white light interference, the MU ferrule is provided with a micropore for fixing the collimating optical fiber.

[0011] As a preferred scheme of the patch type strain gauge based on white light interference, the MU ferrule is a cylindrical precision ceramic with a diameter of 1.25 mm.

[0012] As a preferred scheme of the patch type strain gauge based on white light interference, the end surface reflectivity of the solid ceramic rod is 58% to 65%.

[0013] As a preferred scheme of the patch type strain gauge based on white light interference, the height of the gap is 0.2 mm.

[0014] As a preferred scheme of the patch type strain gauge based on white light interference, the solid ceramic rod and the collimator are respectively inserted into the circular hole and then pass through the collimating sleeve to form an interference cavity, and the cavity length of the interference cavity is adjusted to 150 to 200 microns.

[0015] The utility model also provides a kind of sensor, including above based on white light interference patch type strain gauge.

[0016] From the above technical scheme, the present application has the following beneficial effects:

[0017] The collimating sleeve plays a role in fixing the position of the collimator and the solid ceramic rod and protecting them, and by designing the collimating sleeve, the interference cavity is automatically collimated without manual adjustment.

[0018] When the strain gauge is applied to a sensor, only the collimator and the solid ceramic rod are fixed by adhesive points after the sensor is installed, while the collimating sleeve provides non-rigid connection through plug-in structure and can also keep the optical axis aligned, thereby isolating stress, reducing fatigue and drift.

[0019] In order to make the interference cavity of the strain gauge more accurate in response when monitoring deformation, a gap provided in the design of the collimating sleeve can reduce the damping between the collimator, the solid ceramic rod and the collimating sleeve, which reduces the damping caused by surface contact, reduces the mechanical hysteresis of the strain gauge / sensor and improves the measurement repeatability of the strain gauge / sensor. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0021] Fig. 1 A front view structural schematic diagram of a patch strain gauge based on white light interference is provided.

[0022] Fig. 2 A structural schematic diagram of a patch strain gauge based on white light interference is provided.

[0023] Fig. 3 A side view structural schematic diagram of a collimating sleeve is provided.

[0024] BRIEF DESCRIPTION OF DRAWINGS: 1, strain gauge substrate; 2, round hole; 3, solid ceramic rod; 4, MU ferrule; 5, collimating sleeve; 6, collimating fiber; 7, waist hole; 8, gap. DETAILED DESCRIPTION

[0025] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application and uses. It should be understood that throughout the drawings, the same or similar reference numerals can indicate the same or similar parts or features. Each of the drawings only schematically represents the concepts and principles of the embodiments of the present disclosure, and does not necessarily show the specific dimensions and their proportions of the various embodiments of the present disclosure. The specific parts in the specific drawings can be exaggerated to illustrate the relevant details or structures of the embodiments of the present disclosure.

[0026] Term explanation: MU (Miniature unit) is a kind of optical fiber connector specification, its structure design is derived from the push-pull connection mechanism of SC (Subscriber Connector, user connector) type optical fiber connector, and the miniaturization of single-core optical fiber connector is realized by reducing the ferrule and the size of the outer shape. Therefore, the MU ferrule is a miniaturized optical fiber ferrule conforming to the MU optical fiber connector specification.

[0027] Reference Figs. 1-3 :

[0028] For an embodiment of the utility model, provide a kind of based on white light interference patch strain gauge, including strain gauge substrate 1, strain gauge substrate 1 is polyimide material, two ends of strain gauge substrate 1 are equipped with round hole 2, two round holes 2 are respectively penetrated with solid ceramic rod 3 and MU insertion core 4, collimating sleeve 5 is provided in strain gauge substrate 1;MU insertion core 4 one end is provided with collimating optical fiber 6, MU insertion core 4 and collimating optical fiber 6 are fixed by UV glue and form collimator;Solid ceramic rod 3 and collimator are inserted into collimating sleeve 5.MU insertion core 4 is ZrO2 material, MU insertion core 4 is the cylindrical precision ceramic of diameter 1.25mm.

[0029] In a preferred embodiment, the MU insertion core 4 is provided with a micropore in the center for fixing the collimating optical fiber 6.

[0030] It should be noted that, since the MU insertion core 4 is made of ZrO2 material, it has high toughness and high strength, and is not easy to break. Moreover, since the MU insertion core 4 is provided with a micropore in the center for fixing a single optical fiber, it can be precisely aligned, ensuring that the core of the collimating optical fiber 6 inserted therein can be completely and accurately overlapped on a straight line, so that the optical signal can be transmitted in the optical fiber with minimal loss (attenuation). By utilizing this characteristic, the collimating optical fiber 6 can be quickly and accurately inserted into the MU insertion core 4 to form a collimator.

[0031] The end face of the solid ceramic rod 3 is polished to form an optical surface and is coated with a film. After coating, the reflectivity of the end face of the solid ceramic rod 3 is 58% to 65%. After the solid ceramic rod 3 and the collimator are respectively inserted into the round hole 2 and then into the collimating sleeve 5, an interference cavity is formed between the end face of the solid ceramic rod 3 and the end face of the collimating optical fiber 6. The cavity length of the interference cavity is adjusted to 150 to 200 μm. When the strain gauge is used in a sensor, a large range measurement of ±10000 με can be achieved, and the linearity reaches 0.05% F.S. The strain gauge substrate 1 is provided with a waist-shaped hole 7 at both ends, and the waist-shaped hole 7 is in communication with the round hole 2. The solid ceramic rod 3 and the MU insertion core 4 are fixed on the strain gauge substrate 1 by dispensing glue into the waist-shaped hole 7. A slit 8 is formed in the collimating sleeve 5, and the height of the slit 8 is 0.2 mm.

[0032] It needs to be explained that the collimating sleeve 5 plays a role of fixing the positions of the collimator and the solid ceramic rod 3 and protection, and by designing the collimating sleeve 5, the interference cavity is automatically collimated, and manual adjustment is not needed. In order to make the interference cavity of the strain gauge more accurate in response when monitoring deformation, a gap 8 is opened when designing the collimating sleeve 5, for example, provided on the side of the collimating sleeve 5, the sleeve is changed from a closed ring structure to an open elastic structure, the ring stiffness is significantly reduced, the radial clamping force of the sleeve on the collimator and the solid ceramic rod is reduced, and then the damping between the collimator and the solid ceramic rod 3 and the collimating sleeve 5 is reduced. The structure design makes the original surface contact reduced to local line contact, reduces the jamming phenomenon, reduces the mechanical hysteresis of the strain gauge or the sensor, and thus improves the response stability and measurement repeatability of the change of the cavity length of the interference cavity. In addition, the distance between the two bonding points (i.e. the glue dispensing position in the waist-shaped hole 7) designed on the strain gauge substrate 1 is the gauge length, which is fixed on the surface of the measured object. Based on the geometric relationship between strain and gauge length, the scale of the surface micro-strain of the object can be amplified, and data response can be obtained even when the deformation is very small. By designing the length of the gauge length, the sensitivity of the sensor can be designed. When the strain gauge is applied to the sensor, after the sensor is installed (for example, installed on the measured structure such as a steel plate, a bridge, a component, etc.), only the collimator and the solid ceramic rod 3 are fixed through the two bonding points, respectively, and the collimating sleeve 5 provides a non-rigid connection through the plug-in structure, while the optical axis is still aligned, so as to isolate stress, reduce fatigue and drift.

[0033] Specifically, in the preparation of the patch type strain gauge, first, the collimating optical fiber 6 is inserted into the micro-hole of the MU ferrule 4, and is fixed with the MU ferrule 4 by UV glue to form a collimator; the end of the solid ceramic rod 3 is ground, so that the end face is polished as an optical surface, and the end face is coated to make the reflectivity reach 58%~65%; then the solid ceramic rod 3 and the collimator are respectively inserted into the round hole 2 at the two ends of the strain gauge substrate 1, and then inserted into the collimating sleeve 5 to form an interference cavity, the cavity length is adjusted to 150~200μm, then glue is dispensed at the waist-shaped hole 7 of the strain gauge substrate 1, and the solid ceramic rod 3 and the collimator are fixed on the strain gauge substrate 1, so that the patch type strain gauge is completed.

[0034] The utility model further provides a kind of sensor, including above-mentioned based on white light interference patch type strain gauge, and with the collimating optical fiber connection white light interference demodulation device, the white light interference demodulation device can be conventional white light interference demodulation equipment in the art, for white light is input to collimating optical fiber and is demodulated to interference signal formed by interference cavity, to obtain corresponding strain information.

[0035] The exemplary implementation of the scheme proposed by the present disclosure is described in detail above with reference to the preferred embodiments, however, it can be understood by those skilled in the art that various modifications and changes can be made to the above specific embodiments, and various technical features and structures proposed by the present disclosure can be combined without departing from the concept of the present disclosure, and the protection scope of the present disclosure is determined by the appended claims.

Claims

1. A white light interferometry based patch gage comprising a strain gage substrate (1), characterized in that, The strain gauge substrate (1) is provided with a circular hole (2) at both ends, a solid ceramic rod (3) and a MU ferrule (4) are respectively penetrated into the two circular holes (2), a collimating sleeve (5) is arranged in the strain gauge substrate (1), the MU ferrule (4) is provided with a collimating optical fiber (6) at one end, the MU ferrule (4) and the collimating optical fiber (6) are fixed by UV glue to form a collimator, the solid ceramic rod (3) and the collimator are both inserted into the collimating sleeve (5) to form an interference cavity, and a slit (8) is formed in the collimating sleeve (5).

2. A white light interferometry based patch gage according to claim 1, wherein, The strain gauge substrate (1) is provided with a waist-shaped hole (7) at both ends, and the waist-shaped hole (7) is communicated with the circular hole (2).

3. The white light interferometry based patch gage of claim 1, wherein, The MU ferrule (4) is provided with a micropore in the center for fixing the collimating optical fiber (6).

4. The white light interferometry based patch gage of claim 1, wherein, The MU ferrule (4) is a cylindrical precision ceramic with a diameter of 1.25 mm.

5. The white light interferometry based patch gage of claim 1, wherein, The end surface reflectivity of the solid ceramic rod (3) is 58% to 65%.

6. The white light interferometry based patch gage of claim 1, wherein, The height of the slit (8) is 0.2 mm.

7. The white light interferometry based patch gage of claim 1, wherein, The cavity length of the interference cavity is 150 to 200 microns.

8. A sensor, characterized by Comprising: The white light interference-based patch strain gauge according to any one of claims 1-7.

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