Bridge micro-deformation non-contact measurement system and measurement method based on laser speckles

Abstract

The invention discloses a bridge micro-deformation non-contact measurement system based on laser speckles. The bridge micro-deformation non-contact measurement system is applied to a measured bridge. The measuring system comprises a laser emitting device, a light spot control device, a speckle receiving device and a data processing and analyzing device, laser emitted by the laser emitting device is irradiated to a measured bridge through the light spot control device, and a speckle image formed after the laser is subjected to diffuse reflection through the measured bridge is sent to the speckle receiving device; and the speckle receiving device uploads the speckle image to the data processing and analyzing device. The invention also discloses a bridge micro-deformation non-contact measurement method based on laser speckles, and the method has the advantages of high measurement precision, small influence of environmental factors, simple equipment, no mechanical influence on a measured object, capability of being applied to an object difficult to approach, no need of arranging a target on a bridge or around the bridge, and the like. And the real-time monitoring and evaluation of the bridge structure state are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge structure health monitoring, and particularly to a non-contact measurement system and method for bridge micro-deformation based on laser speckle. Background Art

[0002] As an important transportation infrastructure, the safety performance of bridges is directly related to people's lives and property. However, during the use of bridges, they are affected by various external factors (such as wind force, temperature changes, traffic loads, etc.), resulting in small deformations of the bridge structure. Although these micro-deformations usually do not pose a direct threat to the overall safety of the bridge, long-term accumulation may lead to serious structural damage and even bridge collapse. Therefore, the monitoring and evaluation of bridge micro-deformations are particularly important.

[0003] In the current engineering field, traditional measuring tools for bridge micro-deformations are dial gauges and levels. During the measurement process, the dial gauge needs to be installed at the bottom of the bridge, while the level needs to be set up in the vertical direction of specific measurement points. These two traditional methods respectively require the installation of measuring equipment at the bottom of the bridge and directly below the bridge. In recent years, with the development of laser technology, laser measurement technology has been widely used in bridge deformation monitoring.

[0004] The Chinese invention with the patent number CN118463838A discloses a bridge deflection measuring instrument and a bridge deflection measuring method. Signal receiving devices are arranged at intervals on the cross-section of the bridge beam. By emitting linear laser light, when the bridge deforms, the signal receiving devices sense the laser, and the displacement generated by the bridge deformation is inversely calculated through potential changes, thereby calculating the bridge deflection. This method also requires the installation of signal receiving devices for measurement on the bridge beam and is arranged at intervals, and a certain amount of work is required for the preliminary deployment of the measurement. Most of the existing laser measurement methods require the setting of targets or reflectors on the bridge, which not only increases the complexity and cost of the measurement, but also may interfere with the traffic on the bridge. At the same time, due to the existence of the targets or reflectors, the accuracy of the measurement results may also be affected to a certain extent. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to propose a non-contact measurement system for bridge micro-deformations based on laser speckle, which uses the laser speckle phenomenon to perform high-precision and long-distance measurement and digital recording of the small deformations of the bridge structure in a non-contact manner, and has the advantages of high measurement accuracy, small influence of environmental factors, simple equipment, no mechanical influence on the measured object, can be applied to objects that are difficult to access, and does not require the setting of targets on or around the bridge, etc., realizing the real-time monitoring and evaluation of the bridge structure state.

[0006] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0007] The present invention provides a non-contact measurement system for micro-deformation of bridges based on laser speckle, which is applied to the bridge to be measured; the measurement system includes: a laser emission device, a speckle control device, a speckle receiving device, and a data processing and analysis device. The laser emitted by the laser emission device is irradiated onto the bridge to be measured through the speckle control device. After the laser undergoes diffuse reflection on the bridge to be measured, the formed speckle image is sent to the speckle receiving device, and the speckle receiving device uploads the speckle image to the data processing and analysis device;

[0008] The laser emission device is used to emit laser and irradiate the bridge to be measured; the speckle control device is installed on the optical path between the laser emission device and the bridge to be measured, and is used to adjust the spot size and position of the laser irradiated onto the bridge to be measured; the speckle receiving device is used to synchronously measure and record the change of the speckle image formed after the laser undergoes diffuse reflection on the bridge to be measured; the data processing and analysis device is used to process and analyze the speckle image collected by the speckle receiving device.

[0009] Further, the laser emission device includes a laser, and the laser emits a beam of laser and irradiates a certain position on the bridge to be measured.

[0010] Further, the laser emission device includes a laser, a plurality of beam splitting prisms, and a plurality of rotating mirrors. The laser emitted by the laser sequentially passes through different optical paths composed of the plurality of beam splitting prisms and the plurality of rotating mirrors and is divided into multiple beams of laser, which are irradiated onto multiple positions on the bridge to be measured.

[0011] Further, the speckle control device includes a spot size adjuster and a spot position adjuster. The spot size adjuster is used to adjust the spot size of the laser irradiated onto the bridge to be measured, and the spot position adjuster is used to adjust the spot position of the laser irradiated onto the bridge to be measured.

[0012] Further, a narrowband filter is included, and the narrowband filter is installed on the optical path between the speckle receiving device and the bridge to be measured.

[0013] Further, the wavelength of the narrowband filter is consistent with the wavelength of the laser light source of the laser emission device

[0014] Further, the speckle receiving device uses a photodetector, and the data processing and analysis device is a PC.

[0015] Further, it further includes a first protection device and a second protection device. The first protection device is installed at the laser emission end of the laser emission device and tightly covers the optical path part between the laser emission device and the spot control device; the second protection device is installed at the optical receiving end of the speckle receiving device; in case of haze weather, the laser light source wavelength of the laser emission device is in the near-infrared and mid-infrared bands, and its wavelength range is between 700 nm and 50 μm.

[0016] The present invention also provides a non-contact measurement method for bridge micro-deformation based on laser speckle, which specifically includes the following steps:

[0017] Step 1: Adjust the laser emission device to make the laser irradiate on the specified position of the bridge to be measured, and adjust the spot size and position through the spot control device;

[0018] Step 2: Start the speckle receiving device, collect the bridge speckle images through the speckle receiving device, and record the changes of the speckle images at different time points;

[0019] Step 3: Transmit the collected speckle images to the data processing and analysis device, and calculate the deformation amount and deformation trend of the bridge to be measured by comparing the speckle images at different time points;

[0020] Step 4: Evaluate the health status of the bridge to be measured according to the analysis results and provide maintenance suggestions.

[0021] Further, in step 2, the speckle receiving device collects the speckle images of the bridge to be measured at a preset frequency.

[0022] Adopting the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. No need to set up a target: The present invention can realize non-contact measurement of the micro-deformation of a long-distance target bridge without setting up a target on the bridge beam structure or around the bridge. This greatly reduces the complexity and cost of measurement, and at the same time avoids the interference caused by the target to the bridge traffic.

[0024] 2. Multi-point simultaneous measurement: The laser emission device can emit multiple laser beams and hit multiple positions on the bridge. By collecting the speckle changes at multiple points through the speckle receiving device, multi-point simultaneous measurement can be realized, improving the measurement efficiency.

[0025] 3. High-precision measurement: The present invention uses a laser with high directivity and high coherence as the light source, and a speckle receiving device with high resolution and high sensitivity, which can capture tiny speckle changes, thus realizing high-precision measurement.

[0026] 4. Digital recording and analysis: The data collected by the speckle receiving device in the present invention is transmitted to the data processing and analysis device for processing and analysis, realizing digital recording and analysis. This can not only improve the measurement accuracy, but also provide long-term and continuous data support for the health monitoring of bridges. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 FIG. is a schematic structural diagram of a non-contact measurement system for bridge micro-deformation based on laser speckle provided by an embodiment of the present invention.

[0029] Figure 2 FIG. is a schematic structural diagram of a beam of laser light irradiating the bridge to be measured provided by an embodiment of the present invention.

[0030] Figure 3 FIG. is a schematic structural diagram of a laser emission device in an embodiment of the present invention emitting multiple beams of laser light.

[0031] Figure 4 FIG. is a schematic structural diagram of multiple beams of laser light irradiating the bridge to be measured provided by an embodiment of the present invention.

[0032] Figure 5 FIG. is a flowchart of the execution of a non-contact measurement method for bridge micro-deformation based on laser speckle provided by an embodiment of the present invention.

[0033] Explanation of the reference numerals in the figures:

[0034] 100 - Measurement system, 1 - Laser emission device, 11 - Laser, 12 - Beam splitter prism, 13 - Rotary reflector, 2 - Spot control device, 21 - Spot size adjuster, 22 - Spot position adjuster, 3 - Speckle receiving device, 4 - Data processing and analysis device, 5 - Narrowband filter, 200 - Bridge to be measured. Detailed Embodiments

[0035] The following will further describe the present invention in detail in conjunction with the drawings and embodiments. It should be particularly noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0036] The working principle of the present invention is based on the laser speckle phenomenon. When a laser beam irradiates a rough or measured target surface, diffuse reflection occurs, forming a random speckle image. When the measured target deforms, the speckle image also changes accordingly. By measuring and recording the changes in the speckle image, the deformation of the measured target can be deduced.

[0037] Please refer to Figures 1-4 , a non-contact measurement system for micro-deformation of bridges based on laser speckle of the present invention is applied to the measured bridge 200; the measurement system 100 includes: a laser emission device 1, a spot control device 2, a speckle receiving device 3, and a data processing and analysis device 4. The laser emitted by the laser emission device 1 is irradiated onto the measured bridge 200 through the spot control device 2. The speckle image formed after the laser undergoes diffuse reflection by the measured bridge 200 is sent to the speckle receiving device 3, and the speckle receiving device 3 uploads the speckle image to the data processing and analysis device 4;

[0038] It should be noted that due to weather changes (rain, fog, etc.), water droplets or fog in the air will disperse the laser beam, affecting the propagation process of the laser. The laser speckle pattern may become blurred, resulting in a decrease in measurement accuracy. To avoid or reduce the impact, an appropriate measurement time can be selected to conduct the measurement under relatively stable weather conditions, and avoid measuring in rainy, foggy, or windy weather. In addition, a protective device can be installed to design the laser equipment for rain and fog protection, that is, the measurement system 100 further includes a first protective device (not shown) and a second protective device (not shown). The first protective device is installed at the laser emission end of the laser emission device 1, tightly covering the optical path part between the laser emission device 1 and the spot control device 2; the second protective device is installed at the optical receiving end of the speckle receiving device 3. At the optical receiving end, it is necessary to consider installing it at the front end of the speckle receiving device 3. The first protective device and the second protective device can consider using a laser protective cover to isolate the interference of rain and haze on the laser. In case of haze weather, a laser with a longer wavelength (such as infrared laser) can also be used to improve the adaptability to the environment such as haze, because the laser with a longer wavelength has less scattering in haze. In case of haze weather, the wavelength of the laser light source of the laser emission device 1 is in the near-infrared and mid-infrared bands, and its wavelength range is between 700 nm and 50 μm.

[0039] The laser emission device 1 is used to emit laser light, which irradiates the bridge 200 to be measured; the spot control device 2 is installed on the optical path between the laser emission device 1 and the bridge 200 to be measured, and is used to adjust the spot size and position of the laser irradiating the bridge 200 to be measured; the speckle receiving device 3 is used to synchronously measure and record the change of the speckle image formed after the laser undergoes diffuse reflection by the bridge 200 to be measured. It has high resolution and high sensitivity, and can capture tiny speckle changes, thereby reflecting the micro-deformation of the bridge structure; the data processing and analysis device 4 is used to process and analyze the speckle images collected by the speckle receiving device 3, and calculate the deformation amount and deformation trend of the bridge 200 to be measured by comparing the speckle images at different time points.

[0040] By irradiating a specified position of the bridge 200 to be measured with laser light, the speckle receiving device 3 synchronously records the change of the speckle image formed by the laser diffuse reflection, and the data processing and analysis device 4 compares and calculates the collected speckle images, so as to obtain the micro-deformation information of the bridge. The present invention realizes long-distance high-precision non-contact measurement without a target, can monitor multiple points simultaneously, and the data processing realizes digital recording and analysis of bridge deformation. This technology has the characteristics of high precision, high efficiency and low cost, and provides important technical support for bridge health monitoring.

[0041] In this embodiment, the laser emission device 1 includes a laser 11, and the laser 11 emits a beam of laser light, which irradiates a certain position of the bridge 200 to be measured. Using a laser with high directivity and high coherence as the light source, it can irradiate the bridge 200 to be measured at a long distance. The emission wavelength of the laser 11 is a visible light wavelength or an infrared light wavelength.

[0042] In this embodiment, the laser emission device 1 includes a laser 11, a plurality of beam splitting prisms 12 and a plurality of rotating mirrors 13. The laser light emitted by the laser 11 is divided into multiple beams of laser light through different optical paths composed of a plurality of beam splitting prisms 12 and a plurality of rotating mirrors 13, and irradiates multiple positions of the bridge 200 to be measured. The laser emission device 1 simultaneously emits multiple beams of laser light, which irradiate multiple positions of the bridge 200 to be measured, realizing multi-point simultaneous measurement.

[0043] The preferred range of the irradiated position generally includes stress concentration areas, positions where deformation and vibration exceed the preset allowable values, and dynamic load influence areas, etc. Stress concentration areas such as near the bearings. The bearings of a bridge are the places where stress and deformation concentrate, especially at the connection between the bearings and the bridge structure. These places are often affected by factors such as temperature and load changes, resulting in minor deformations. Positions where deformation and vibration exceed the preset allowable values, such as the middle section of the bridge girder. The middle section of the bridge girder or arch may be the position where deformation is most obvious when subjected to loads. Especially when bearing heavy traffic flow or strong winds, the minor deformation of the middle section of the girder is more significant. If the deformation and vibration exceed the preset allowable values, they will be regarded as obvious deformation and vibration. Different bridge designs and usage requirements may have different thresholds. For example, when the displacement of a bridge exceeds 1% of the design allowable value, early warning usually needs to be considered. Dynamic load influence areas such as areas with greater wind influence. The bridge deck or pylon of a bridge in the area under the action of wind, especially for high bridges or long-span bridges, the minor deformation caused by wind vibration also needs to be monitored keyly. For multi-point synchronous measurement, the reasonably distributed laser measurement points should cover the above key areas. The following strategies can be adopted: uniform distribution, arranging multiple measurement points in different areas of the bridge (bearings, mid-span, ends, joints, etc.) to ensure the comprehensiveness of measurement data; selecting key sensing positions, choosing denser laser irradiation points at places where large deformations may occur, such as the bridge girder or key joints of the bridge; considering the bridge shape and load. If the structure of the bridge is relatively special (such as a cantilever beam, arch bridge, etc.), the positions of the measurement points should be adjusted flexibly according to its load distribution and stress concentration situation.

[0044] In this embodiment, the spot control device 2 includes a spot size adjuster 21 and a spot position adjuster 22. The spot size adjuster 21 is used to adjust the spot size irradiated on the bridge to be measured 200. By precisely controlling the size and shape of the spot, it can ensure that a clear and stable spot is formed on the bridge to be measured 200. The spot position adjuster 22 is used to adjust the spot position irradiated on the bridge to be measured 200. By controlling the position of the spot on the measured target, it ensures that the spot is accurately aligned with the measured area, providing a good basis for subsequent speckle measurement.

[0045] Generally speaking, the ideal spot size should be moderate, usually in the range of several millimeters to several centimeters of the bridge surface area. For example, the diameter of the spot can be controlled between 3 mm and 10 mm. This size range can usually ensure a clear spot pattern while covering a sufficient surface area to ensure measurement accuracy.

[0046] For the laser wavelength, in non-hazy weather conditions, the laser source wavelength range of the laser emission device 1 is between 500 nm and 700 nm; preferably, a laser with a wavelength of 532 nm is used, which can provide a relatively high spatial resolution. When the laser beam irradiates a rough surface, a relatively clear speckle pattern can be generated, enabling the distribution of speckle particles to be more uniform and clearer, which helps to improve the measurement accuracy.

[0047] Among them, the spot size adjuster 21 uses a front focal lens, and the front focal lens is used for beam focusing; the spot position adjuster 22 uses a rear focal lens, and the rear focal lens is used for beam collimation. Use a front lens with as small a focal length as possible and a rear lens with as large a focal length as possible.

[0048] In this embodiment, a narrowband filter 5 is further included, and the narrowband filter 5 is installed on the optical path between the speckle receiving device 3 and the bridge to be measured 200. The wavelength of the narrowband filter 5 is consistent with the laser source wavelength of the laser emission device 1, reducing the influence of environmental stray light and increasing the signal-to-noise ratio of the measurement system 100.

[0049] In this embodiment, the speckle receiving device 3 uses a photodetector, such as: using a CMOS or CCD image sensor.

[0050] In this embodiment, the data processing and analysis device 4 is a PC.

[0051] As Figure 5 shown, the present invention also provides a non-contact measurement method for bridge micro-deformation based on laser speckle, which specifically includes the following steps:

[0052] Step 1: Adjust the laser emission device 1 so that the laser irradiates a specified position of the bridge to be measured 200, and adjust the spot size and position through the spot control device 2 to ensure that the spot is clear and stable;

[0053] Step 2: Start the speckle receiving device 3, collect the bridge speckle images through the speckle receiving device 3, and record the changes in the speckle images at different time points;

[0054] Step 3: Transmit the collected speckle images to the data processing and analysis device 4, calculate the deformation amount and deformation trend of the bridge to be measured 200 by comparing the speckle images at different time points, and provide an important basis for the health monitoring of the bridge;

[0055] Step 4: Evaluate the health status of the bridge to be measured according to the analysis results and provide maintenance suggestions.

[0056] In this embodiment, in step 2, the speckle receiving device 3 collects the speckle images of the bridge to be measured 200 at a preset frequency to ensure that the micro-deformation of the bridge can be captured.

[0057] The present invention does not need to set a target on the bridge, and directly realizes non-contact measurement through the change of speckle image; it supports multi-point simultaneous measurement to improve measurement efficiency; the data processing and analysis device 4 digitally records the speckle data to provide long-term and continuous health monitoring data support.

[0058] 1. Laser emitting device 1: The laser emitting device 1 is composed of multiple laser light sources and a modulation system, and can emit multiple laser beams at the same time. Each laser beam is adjusted by an optical element and irradiates different positions of the bridge structure. These light sources can be lasers of different wavelengths or lasers of the same wavelength with independent adjustment. The selection of lasers needs to ensure high directivity and high coherence so that the target can be accurately irradiated over a long distance.

[0059] (1) Multi-laser light source: A laser array is composed of multiple lasers, which can independently adjust the emission angle and power to emit independent laser beams. This can be achieved by selecting a suitable laser diode (LD) or gas laser.

[0060] (2) Optical path distribution device (such as fiber distributor): distributes the laser beam to different optical paths to ensure that each beam irradiates the designated location of the bridge structure.

[0061] (3) Laser spot control system: A fine-tuning lens group or a reflector is used to adjust the size and focus of the laser spot. The lens group generally consists of two lenses: a front focus lens for focusing and a rear focus lens for collimation, to ensure that the laser spot size at each measurement point is suitable for the measurement requirements.

[0062] 2. Optical system: The optical system is used to adjust the propagation path of the laser beam and control the receiving angle of the speckle receiving device 3. The specific design includes:

[0063] (1) Multi-beam laser splitting device: Use an optical beam splitter (such as a prism or a beam splitter) to separate the laser beams to ensure that each laser beam can irradiate different positions.

[0064] (2) Adjustment of spot size: Each laser beam is focused by a lens system. The lens system is generally composed of a dual lens group. The dual lens group can adjust the focal length of the corresponding lens according to the distance of different measurement points, and fine-tune the distance between the lenses. In this way, the spot size of the laser beam irradiated on the target bridge structure to be measured is adjusted to suit the needs of each measurement point, so as to ensure that the spot covers the measured area while avoiding the reduction of measurement accuracy due to excessive spot size.

[0065] (3) Optical path adjustment device: A precision stepper motor drive device is used to adjust the emission angle of the light beam to ensure that different light beams can accurately illuminate multiple locations of the target bridge. It is also used to adjust the spot position of the laser beam irradiated on the target bridge structure to ensure that the spot is accurately aligned with the measured area.

[0066] 3. Speckle receiving device 3: The speckle receiving device 3 is responsible for receiving speckle images from multiple measurement points and transmitting the image signals to the data processing system. Each receiving device has the following characteristics:

[0067] (1) High-speed camera or CCD sensor: Used to capture multi-point speckle images. To ensure accuracy, a camera with high resolution and high frame rate is adopted.

[0068] (2) Multi-channel receiving system: Each receiving device is configured with multiple optical channels. The speckle optical paths of different measurement points are separated by a beam splitter, and the speckle signals of different points are received respectively.

[0069] (3) Synchronous acquisition: All speckle receiving devices 3 can work synchronously to capture speckle images at different points in real time.

[0070] 4. Data processing system: The data processing system is responsible for real-time analysis of the collected multi-point speckle images. Image processing algorithms are used to extract the deformation data of each measurement point, and the state of the bridge is monitored through real-time feedback. The main functions of the data processing system include:

[0071] (1) Speckle image processing algorithm: Using image correlation analysis, speckle texture change detection algorithm, etc., to calculate the micro-deformation amount of each measurement point.

[0072] (2) Multi-channel data fusion: Fusing and comparing the speckle image data from different measurement points to improve the accuracy and reliability of the measurement.

[0073] The above are only some embodiments of the present invention, and thus do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A non-contact measurement system for bridge micro-deformation based on laser speckle, characterized in that: Applied to the measured bridge; the measuring system comprises: a laser emitting device, a light spot control device, a speckle receiving device and a data processing and analysis device, the laser emitted by the laser emitting device is irradiated onto the measured bridge through the light spot control device, the speckle image formed by the diffuse reflection of the laser by the measured bridge is sent to the speckle receiving device, and the speckle receiving device uploads the speckle image to the data processing and analysis device; The laser emitting device is used to emit laser light to irradiate the measured bridge; the light spot control device is installed on the optical path between the laser emitting device and the measured bridge, and is used to adjust the light spot size and position of the laser irradiating the measured bridge; the speckle receiving device is used to synchronously measure and record the changes of the speckle image formed after the laser is diffusely reflected by the measured bridge; the data processing and analysis device is used to process and analyze the speckle image collected by the speckle receiving device.

2. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 1, characterized in that: The laser emitting device comprises a laser, which emits a laser beam and irradiates a certain position of the bridge to be measured.

3. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 1, characterized in that: The laser emitting device includes a laser, multiple beam splitters and multiple rotating reflectors. The laser emitted by the laser passes through different optical paths formed by the multiple beam splitters and multiple rotating reflectors in sequence and is divided into multiple laser beams, which are irradiated onto multiple positions of the bridge to be measured.

4. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 1, characterized in that: The light spot control device comprises a light spot size adjuster and a light spot position adjuster. The light spot size adjuster is used to adjust the light spot size irradiated to the measured bridge, and the light spot position adjuster is used to adjust the light spot position irradiated to the measured bridge.

5. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 1, characterized in that: It also includes a narrowband filter, which is installed on the optical path between the speckle receiving device and the bridge to be measured.

6. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 5, characterized in that: The wavelength of the narrowband filter is consistent with the wavelength of the laser light source of the laser emitting device.

7. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 1, characterized in that: The speckle receiving device adopts a photoelectric detector, and the data processing and analyzing device is a PC.

8. The non-contact measurement system for bridge micro-deformation based on laser speckle as claimed in claim 1, characterized in that: It also includes a first protective device and a second protective device. The first protective device is installed at the laser emitting end of the laser emitting device to tightly cover the optical path between the laser emitting device and the spot control device; the second protective device is installed at the optical receiving end of the speckle receiving device; in haze weather conditions, the laser light source wavelength of the laser emitting device is in the near-infrared and mid-infrared bands, and its wavelength range is between 700nm and 50μm.

9. A non-contact measurement method for bridge micro-deformation based on laser speckle, characterized in that: The specific steps include: Step 1: Adjust the laser emitting device so that the laser irradiates the designated position of the bridge to be measured, and adjust the spot size and position through the spot control device; Step 2, starting a speckle receiving device, collecting a speckle image of the bridge through the speckle receiving device, and recording the changes of the speckle image at different time points; Step 3: The collected speckle images are transmitted to a data processing and analysis device, and the deformation amount and deformation trend of the measured bridge are calculated by comparing the speckle images at different time points; Step 4: Evaluate the health status of the bridge under test based on the analysis results and provide maintenance recommendations.

10. The non-contact measurement method for bridge micro-deformation based on laser speckle according to claim 9, characterized in that: In step 2, the speckle receiving device collects the speckle image of the measured bridge at a preset frequency.

Images