Laser interference measuring device and method for thermal power plant

Abstract

The invention relates to a laser interference measuring device and method for a thermal power plant. The device comprises a parallel light emitting assembly, a flat plate optical splitter, a fixed total reflection mirror, a movable total reflection mirror and a receiving assembly. The parallel light emitting assembly is used for emitting parallel light beams to the flat plate optical splitter; the fixed total reflection mirror and the parallel light emitting assembly are located on the same side of the flat plate optical splitter, and the fixed total reflection mirror is perpendicular to a reflection light beam of the flat plate optical splitter to form a reference light beam; the movable total-reflection mirror and the receiving assembly are located on the side, away from the fixed total-reflection mirror, of the flat plate optical splitter, the movable total-reflection mirror is arranged on an object to be measured, and the movable total-reflection mirror is perpendicular to a refracted light beam of the flat plate optical splitter to form a measuring light beam; the receiving assembly is used for receiving interference fringes formed by the reference beam and the measuring beam. Compared with the prior art, the method has the advantages of high measurement precision, wide application range and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of measurement in thermal power plants, and in particular to a laser interference measurement device and method for thermal power plants. Background Art

[0002] Currently, most of the measurement devices for length, surface topography, pipe wall thickness, etc. in thermal power plants are measured by manual contact or manual operation of instruments. During the measurement process, it is inevitable to cause damage or interference to the sample. At the same time, there are also certain drawbacks in the selection of existing measurement methods. For example, when measuring the pipe wall thickness and surface topography, X-ray radiography technology is generally used, which will generate a large amount of radiation and pose a safety hazard. In addition, the data processing after the detection will also consume a lot of time. Therefore, how to perform safe detection has become a difficult problem for thermal power plants.

[0003] With the development of the Internet of Things and artificial intelligence, there is also a great demand for optical detection technology. The technology of connecting sensors and measurement devices to a computer system to achieve real-time monitoring, rapid data analysis, and automatic control is becoming increasingly mature, and automatic detection systems have been widely used throughout the country. Currently, the installed capacity of large power plant generators is increasing day by day, and ensuring the safe operation of the units is a very important task today. Any measurement in thermal power plants requires very high precision. Coincidentally, the use of optical detection technology is becoming more and more widespread. Optical detection has the advantages of high precision and high sensitivity, and its unique advantages will contribute to the measurement technology of thermal power plants.

[0004] For example, the utility model with the publication number CN209910592U discloses a pipeline length measurement device, which includes: a laser emitter, a reflector, a signal generator, a phase-locked loop, a first mixer, a laser receiver, a second mixer, a phase meter, and a processing chip. The phase meter receives the difference-frequency reference signal sent by the first mixer and the length measurement signal sent by the second mixer, and measures the phase difference between the difference-frequency reference signal and the length measurement signal; the processing chip receives the phase difference sent by the phase meter and outputs the pipeline length data of the pipeline to be measured according to the phase difference.

[0005] In summary, the existing measurement devices need to contact the object to be measured, which is likely to cause interference to the object to be measured. The measurement device has a complex structure, low measurement accuracy, and large measurement errors. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the existing measurement devices that need to contact the object to be measured during the measurement process, which is likely to cause interference and affect the measurement accuracy and accuracy, and to provide a laser interference measurement device and method for thermal power plants.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] This solution provides a laser interference measurement device for a thermal power plant, including a parallel light emitting component, a flat beam splitter, a fixed total reflector, a movable total reflector and a receiving component; the parallel light emitting component is used to emit parallel light beams to the flat beam splitter; the fixed total reflector and the parallel light emitting component are located on the same side of the flat beam splitter, and the fixed total reflector is perpendicular to the reflected light beam of the flat beam splitter to form a reference light beam; the movable total reflector and the receiving component are located on the side of the flat beam splitter away from the fixed total reflector, the movable total reflector is arranged on the item to be measured, and the movable total reflector is perpendicular to the refracted light beam of the flat beam splitter to form a measurement light beam; the receiving component is used to receive the interference fringes formed by the reference light beam and the measurement light beam.

[0009] Preferably, the parallel light emitting component includes a laser, a first cylindrical lens and a second cylindrical lens. The second cylindrical lens is located between the laser and the flat beam splitter, and the first cylindrical lens is located between the laser and the second cylindrical lens. The light beam emitted by the laser is expanded into a parallel light beam through the first cylindrical lens and the second cylindrical lens.

[0010] Preferably, an optical path difference compensation plate is provided between the flat beam splitter and the fixed total reflector. The optical path difference compensation plate is parallel to the flat beam splitter, and the material and thickness of the optical path difference compensation plate are the same as those of the flat beam splitter.

[0011] Preferably, the movable total reflector is a corner cube prism.

[0012] Preferably, the receiving component is a photodetector or a CCD camera.

[0013] Preferably, the device further includes a mounting frame. The flat beam splitter and the fixed total reflector are both fixed on the mounting frame, and a damping anti-vibration pad is installed at the bottom end of the mounting frame.

[0014] This solution also provides a method for a laser interference measurement device for a thermal power plant, including the following steps:

[0015] S1: Fix the fixed total reflector at the reference position, and movably install the movable total reflector at one end of the pipeline to be measured. The moving direction of the movable total reflector is parallel to the direction of the measurement light beam;

[0016] S2: Calibrate the coaxiality of the optical path so that the parallel light beams generated by the parallel light emitting component are respectively perpendicularly incident on the surfaces of the fixed total reflector and the movable total reflector;

[0017] S3: Move the movable total reflector along the axial direction of the pipeline to be measured, obtain the number of fringe movements through the receiving component, and calculate the length of the pipeline to be measured.

[0018] Preferably, the parallel light emitting assembly includes a laser and a lens group, and the optical path coaxiality calibration in step S2 includes the following specific steps:

[0019] S201: Turn on the laser and adjust the relative position of the lens group so that the laser beam forms a parallel beam after passing through the lens group;

[0020] S202: adjusting the angle of the flat beam splitter so that the parallel light beam is split into two beams, vertical and horizontal, through the flat beam splitter, and adjusting the fixed total reflector and the movable total reflector so that the light beam is vertically incident on the surfaces of the fixed total reflector and the movable total reflector.

[0021] Preferably, the method is used to measure the expression of the pipeline length:

[0022]

[0023] Where L is the length of the pipe to be measured, N is the number of moving fringes, and λ is the wavelength of the light beam.

[0024] Preferably, the receiving component uses a high-sensitivity linear array CCD or a photoelectric detector array, and cooperates with a high-speed acquisition card to capture the movement of stripes in real time.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) In this scheme, the reflected light beam and the refracted light beam based on the flat beam splitter cooperate with the fixed total reflector and the movable total reflector to form the reference light beam and the fixed light beam, and the interference fringes of the double light beams are obtained on the receiving component. Based on the changes in the interference fringes, the pipeline length and pipeline surface morphology are analyzed. The measuring device is non-contact, avoiding damage or interference to the object to be measured. It is suitable for scenes such as length measurement and pipeline surface morphology analysis, with a wide range of applications and strong practicality. It can measure length changes at the nanometer level or even smaller, and is extremely sensitive to changes in optical path difference. It is suitable for the detection of small changes. Compared with traditional measuring devices, it has the advantages of high measurement accuracy and sensitivity.

[0027] (2) This scheme takes into account that the optical path difference between the fixed total reflector and the movable total reflector is inconvenient to adjust. A path difference compensation plate with the same material and thickness as the flat plate beam splitter is set between the flat plate beam splitter and the fixed total reflector, and is distributed parallel to the flat plate beam splitter so that the reference beam and the measurement beam have zero path difference, so as to obtain zero-order fringes with obvious marks during white light interference, which is convenient for subsequent observation and improves measurement accuracy.

[0028] (3) In this solution, a corner cube prism is used as the movable total reflection mirror. Since the movable total reflection mirror needs to move along the axial direction of the pipeline during the measurement of the pipeline length and the reference beam needs to return along the original path, the operation is difficult. Based on the characteristics of the corner cube prism, even if the movable total reflection mirror is slightly tilted during the movement, it can still ensure that the optical path returns along the original path, guarantee the stability of the double-light interference, significantly reduce the installation and operation accuracy, and enhance the anti-vibration ability of the device. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the laser interference measurement device provided by the present invention for thermal power plants;

[0030] In the figure: 1. Laser; 2. First cylindrical lens; 3. Second cylindrical lens; 4. Flat beam splitter; 5. Optical path difference compensation plate; 6. Fixed total reflection mirror; 7. Movable total reflection mirror; 8. Receiving component. Detailed Embodiments

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0034] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0035] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] Example

[0038] like Figure 1 As shown, this embodiment provides a laser interferometer measurement device for a thermal power plant, including a parallel light emitting component, a flat beam splitter 4, a fixed total reflector 6, a movable total reflector 7 and a receiving component 8; the parallel light emitting component is used to emit a parallel light beam to the flat beam splitter 4; the fixed total reflector 6 and the parallel light emitting component are located on the same side of the flat beam splitter 4, and the fixed total reflector 6 is perpendicular to the reflected light beam of the flat beam splitter 4 to form a reference light beam; the movable total reflector 7 and the receiving component 8 are located on the side of the flat beam splitter 4 away from the fixed total reflector 6, the movable total reflector 7 is arranged on the object to be measured, and the movable total reflector 7 is perpendicular to the refracted light beam of the flat beam splitter 4 to form a measuring light beam; the receiving component 8 is used to receive interference fringes formed by the reference light beam and the measuring light beam.

[0039] Based on the reflected light beam and refracted light beam of the flat beam splitter 4, the reference light beam and the fixed light beam are formed in cooperation with the fixed total reflector 6 and the movable total reflector 7, and the interference fringes of the double light beams are obtained on the receiving component. Based on the changes in the interference fringes, the pipeline length and pipeline surface morphology are analyzed. The measuring device is non-contact, avoiding damage or interference to the object to be measured, and is suitable for scenes such as length measurement and pipeline surface morphology analysis. It has a wide range of applications and strong practicality. It can measure nanometer-level or even smaller length changes, and is extremely sensitive to changes in optical path difference, suitable for the detection of small changes, and has the advantages of high measurement accuracy and sensitivity compared to traditional measuring devices.

[0040] In this embodiment, the parallel light emitting assembly includes a laser 1, a first cylindrical lens 2 and a second cylindrical lens 3. The second cylindrical lens 3 is located between the laser 1 and the flat plate beam splitter 4, and the first cylindrical lens 2 is located between the laser 1 and the second cylindrical lens 3. The light beam emitted by the laser 1 is expanded into a parallel light beam through the first cylindrical lens 2 and the second cylindrical lens 3.

[0041] In a preferred embodiment, a path difference compensation plate 5 is provided between the flat beam splitter 4 and the fixed total reflection mirror 6. The path difference compensation plate 5 is distributed in parallel with the flat beam splitter 4, and the material and thickness of the path difference compensation plate 5 are the same as those of the flat beam splitter 4.

[0042] Considering that the optical path difference between the fixed total reflection mirror 6 and the movable total reflection mirror 7 is inconvenient to adjust, a path difference compensation plate 5 with the same material and thickness as the flat beam splitter 4 is provided between the flat beam splitter 4 and the fixed total reflection mirror 6, and it is distributed in parallel with the flat beam splitter 4, so that the reference beam and the measurement beam achieve zero optical path difference, in order to obtain a distinct zero-order fringe during white light interference, which is convenient for subsequent observation and improves the measurement accuracy.

[0043] In a preferred embodiment, the movable total reflection mirror 7 is a corner cube prism.

[0044] The movable total reflection mirror 7 is a corner cube prism because the movable total reflection mirror 7 needs to move along the axial direction of the pipeline during the process of measuring the pipeline length and needs to keep the reference beam return along the original path. Based on the characteristics of the corner cube prism, even if the movable total reflection mirror 7 has a slight tilt during the movement, it can still ensure that the optical path returns along the original path, ensuring the stability of the double-beam interference, and significantly reducing the installation and operation accuracy, and enhancing the anti-vibration ability of the device.

[0045] In this embodiment, the receiving component 8 can be a photodetector or a CCD camera.

[0046] In this embodiment, the measuring device further includes a mounting frame. The flat beam splitter 4 and the fixed total reflection mirror 6 are both fixed on the mounting frame, and a damping anti-vibration pad is installed at the bottom end of the mounting frame. By the mounting frame, the relative positions of the flat beam splitter 4 and the fixed total reflection mirror 6 are ensured, and combined with the damping anti-vibration pad provided at the bottom of the mounting frame, it can effectively reduce the influence of external vibration on the measuring device and improve the measurement accuracy.

[0047] Combined with the above preferred embodiment, specifically, the measuring device mainly consists of a laser 1, a first cylindrical lens 2, a second cylindrical lens 3, a flat beam splitter 4, a path difference compensation plate 5, a fixed total reflection mirror 6, a movable total reflection mirror 7 and a receiving component 8. Among them, the laser light source emits light through the first cylindrical lens 2 and the second cylindrical lens 3 to form a parallel beam similar to a telescope. This parallel beam is divided into two paths by the flat beam splitter. One path is reflected upward and the other path is transmitted to the right. These two paths of light are reflected by the fixed total reflection mirror 6, that is, the reference mirror, and the movable total reflection mirror 7, that is, the measurement mirror, respectively, to form a reference beam and a measurement beam, and then re-converge on the flat beam splitter and emit downward to become coherent double beams. Through the receiving component 8, typical double-beam interference fringes can be received to obtain the measurement result.

[0048] This embodiment also provides a method for a laser interference measuring device used in a thermal power plant, including the following steps:

[0049] S1: Fix the fixed total reflection mirror 6 at the reference position, and movably install the movable total reflection mirror 7 at one end of the pipeline to be measured. The moving direction of the movable total reflection mirror 7 is parallel to the direction of the measuring beam.

[0050] S2: Calibrate the optical path coaxiality so that the parallel light beam generated by the parallel light emitting component is perpendicularly incident on the surfaces of the fixed total reflection mirror 6 and the movable total reflection mirror 7 respectively.

[0051] S3: Move the movable total reflection mirror 7 along the axial direction of the pipeline to be measured, obtain the number of fringe movements through the receiving component 8, and calculate the length of the pipeline to be measured.

[0052] In this embodiment, the parallel light emitting component includes a laser 1 and a lens group. The optical path coaxiality calibration in step S2 includes the following specific steps:

[0053] S201: Turn on the laser 1 and adjust the relative position of the lens group so that the laser beam forms a parallel light beam after passing through the lens group.

[0054] S202: Adjust the angle of the flat beam splitter 4 so that the parallel light beam is split into two vertical and horizontal light beams by the flat beam splitter 4, and adjust the fixed total reflection mirror 6 and the movable total reflection mirror 7 so that the light beam is perpendicularly incident on the surfaces of the fixed total reflection mirror 6 and the movable total reflection mirror 7.

[0055] Specifically, the expression for the method used to measure the pipeline length is:

[0056]

[0057] In the formula, L represents the length of the pipeline to be measured, N represents the number of moving fringes, and λ represents the light beam wavelength.

[0058] In this embodiment, the receiving component 7 uses a high-sensitivity linear array CCD or a photodetector array, and cooperates with a high-speed acquisition card to capture the fringe movement in real time. Through the high-sensitivity receiving component and the high-frequency acquisition card, the acquisition frequency of the acquisition card in this embodiment is greater than or equal to 10 kHz, which improves the sampling accuracy and the recognition accuracy.

[0059] The test method based on this measuring device is simple to operate and easy to adjust, can generate interference fringes in real time, is suitable for dynamic measurement and real-time monitoring, and can also be used for measuring the surface topography of objects and the thickness of thin films, etc. It has a wide application range and strong practicability.

[0060] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A laser interference measurement device for a thermal power plant, characterized in that, It includes a parallel light emitting component, a flat beam splitter (4), a fixed total reflection mirror (6), a movable total reflection mirror (7) and a receiving component (8); the parallel light emitting component is used to emit parallel light beams to the flat beam splitter (4); the fixed total reflection mirror (6) and the parallel light emitting component are located on the same side of the flat beam splitter (4), and the fixed total reflection mirror (6) is perpendicular to the reflected light beam of the flat beam splitter (4) to form a reference light beam; the movable total reflection mirror (7) and the receiving component (8) are located on the side of the flat beam splitter (4) away from the fixed total reflection mirror (6), the movable total reflection mirror (7) is arranged on the item to be measured, and the movable total reflection mirror (7) is perpendicular to the refracted light beam of the flat beam splitter (4) to form a measurement light beam; the receiving component (8) is used to receive the interference fringes formed by the reference light beam and the measurement light beam.

2. The laser interference measurement device for a thermal power plant according to claim 1, characterized in that, The parallel light emitting component includes a laser (1), a first cylindrical lens (2) and a second cylindrical lens (3), the second cylindrical lens (3) is located between the laser (1) and the flat beam splitter (4), the first cylindrical lens (2) is located between the laser (1) and the second cylindrical lens (3), and the light beam emitted by the laser (1) is expanded into a parallel light beam through the first cylindrical lens (2) and the second cylindrical lens (3).

3. The laser interference measurement device for a thermal power plant according to claim 1, characterized in that An optical path difference compensation plate (5) is provided between the flat beam splitter (4) and the fixed total reflection mirror (6), the optical path difference compensation plate (5) is distributed in parallel with the flat beam splitter (4), and the material and thickness of the optical path difference compensation plate (5) are the same as those of the flat beam splitter (4).

4. A laser interference measuring device for a thermal power plant according to claim 1, characterized in that, The movable total reflection mirror (7) is a corner cube prism.

5. The laser interference measurement device for a thermal power plant according to claim 1, wherein The receiving component (8) is a photodetector or a CCD camera.

6. The laser interference measuring device for a thermal power plant according to claim 1, characterized in that, The device further includes a mounting rack, the flat beam splitter (4) and the fixed total reflection mirror (6) are both fixed on the mounting rack, and a damping anti-vibration pad is installed at the bottom end of the mounting rack.

7. A method for a laser interference measurement device for a thermal power plant according to any one of claims 1-6, characterized in that, It includes the following steps: S1: Fix the fixed total reflection mirror (6) at the reference position, and movably install the movable total reflection mirror (7) at one end of the pipeline to be measured, and the moving direction of the movable total reflection mirror (7) is parallel to the direction of the measurement light beam; S2: Calibrate the coaxiality of the optical path to make the parallel light beams generated by the parallel light emitting component vertically incident on the surfaces of the fixed total reflection mirror (6) and the movable total reflection mirror (7) respectively; S3: Move the movable total reflection mirror (7) along the axial direction of the pipeline to be measured, obtain the number of moving fringes through the receiving component (8), and calculate the length of the pipeline to be measured.

8. The method according to claim 7, wherein The parallel light emitting component includes a laser (1) and a lens group. The optical path coaxiality calibration in step S2 includes the following specific steps: S201: Turn on the laser (1), adjust the relative positions of the lens group to make the laser beam form a parallel light beam after passing through the lens group; S202: Adjust the angle of the flat beam splitter (4) to divide the parallel light beam into two vertical and horizontal light beams by the flat beam splitter (4), and adjust the fixed total reflection mirror (6) and the movable total reflection mirror (7) to make the light beam vertically incident on the surfaces of the fixed total reflection mirror (6) and the movable total reflection mirror (7).

9. The method according to claim 7, wherein The expression for this method to measure the pipeline length is: In the formula, L represents the length of the pipeline to be measured, N represents the number of moving fringes, and λ represents the light beam wavelength.

10. The method according to claim 7, characterized in that, The receiving component (7) adopts a high-sensitivity linear array CCD or a photodetector array, and cooperates with a high-speed acquisition card to capture the movement of the fringes in real time.

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