High-spectral femtosecond laser radar high-speed precision measurement method for object surface roughness

Abstract

The invention discloses an object surface roughness high-speed precision measurement method based on a hyperspectral femtosecond laser radar. According to the system, femtosecond laser is filtered through an electric control optical filter, various detection lasers are generated and irradiated to the surface of an object, and reflected light signals are obtained. The returned optical signals are captured and recorded through the optical power detection module, and then optical power data are transmitted to a field programmable gate array (FPGA) for real-time processing. And the FPGA calculates the surface roughness index of the object by using an improved Ore-Nayar model so as to improve the measurement precision. In addition, the system is provided with an X-axis and Y-axis displacement table, movement of the sample in the scanning process is achieved, and roughness information of the whole surface is obtained. According to the technical scheme, high-precision, real-time and high-speed measurement of the surface roughness of the object is realized, and the method has important application value.

Description

Technical Field

[0001] The present invention relates to the field of optical measurement technology, and in particular to a high-speed and precise measurement method of the surface roughness of an object using a hyperspectral femtosecond laser radar. Background Art

[0002] With the continuous development of science and technology, the measurement of surface roughness of objects plays an increasingly important role in many fields, such as materials science, aerospace, and electronic device manufacturing. This parameter not only directly affects the physical properties of the object (such as friction coefficient, welding quality, etc.), but also significantly affects its optical properties and corrosion resistance. Therefore, it is particularly important to develop an efficient and accurate surface roughness measurement technology.

[0003] There are many methods for roughness detection in the currently disclosed patents, such as stylus measurement, optical interference and close-range photogrammetry, which are often faced with problems such as cumbersome operation, long measurement time and high requirements for the operating environment in practical applications. In addition, the stylus measurement method has the characteristic of direct contact with the surface of the object, which may cause surface damage, thus affecting the accuracy of the measurement results.

[0004] The patents "110kV and above cross-linked polyethylene cable insulation surface roughness detection equipment and method" (CN118583050A) and "A brake disc defect detection device suitable for automated production lines" (CN118425182A) both use stylus measurement for roughness detection. Its direct contact method may cause surface damage, thereby affecting the accuracy of the measurement results.

[0005] Although the patent "Workpiece surface defect detection and early warning method based on 3D vision" (CN118644456A) combines active vision and 3D vision for roughness detection, the system is complex and has low accuracy, making it difficult to achieve precise measurement.

[0006] The patent "A close-range photogrammetry method for surface roughness observation" (CN106989731A) requires multi-angle photography of the surface and is not suitable for fast and accurate surface roughness measurement of objects.

[0007] Although the patent "A method for detecting the surface roughness of a transparent substrate based on optical measurement" (CN118500302A) uses laser scanning technology to detect surface roughness, the laser used is only a monochromatic light source and lacks universal applicability.

[0008] In summary, the present invention provides a more reliable and efficient industrial application solution through the characteristics of high-speed and precise measurement, fully overcomes the shortcomings of the existing technology in terms of measurement accuracy and real-time processing capabilities, and shows a wide range of application potential. With this innovative method, the application prospects of laser technology in the measurement of surface roughness of objects will be broader, promoting technological progress and development in related fields. Summary of the invention

[0009] In order to solve the above problems, the technical solution of the present invention provides a high-spectral femtosecond laser radar for precise, high-speed and accurate measurement of the surface roughness of an object. The system is simple and can measure the roughness of the entire surface of the object.

[0010] A hyperspectral femtosecond laser radar for high-speed and precise measurement of surface roughness of an object, the hyperspectral femtosecond laser radar comprising:

[0011] Light source module, laser transceiver module, optical power detection module, XY translation stage, control module, data solution module;

[0012] The light source module is used to emit a laser beam;

[0013] The laser transceiver module includes: an electrically controlled optical filter, an optical fiber beam splitter and a laser collimator;

[0014] The optical power detection module is located between the data solving module and the light splitting module, and is used to detect the optical power of the first reflected laser;

[0015] The electrically controlled optical filter is used to obtain detection laser beams with different central wavelengths. The detection laser beams are emitted to the sample to be tested after passing through a laser collimator. The reflected laser reflected by the sample to be tested enters the optical fiber splitter through the collimator and then reaches the optical power detection module.

[0016] The control module is connected to the optical power detection module, the XY displacement stage, and the laser transceiver module respectively, and is used to control the motion trajectory of the optical power detection module and the XY displacement stage and the central wavelength of the detection laser beam returned by the laser transceiver module, wherein the XY displacement stage is used to fix the sample to be tested and can be displaced in the X and Y directions;

[0017] The data solving module is connected to the optical power detection module, the XY displacement stage, and the laser transceiver module respectively, and is used to receive and collect the optical power data collected by the optical power detection module, the motion trajectory data of the XY displacement stage, and the detection laser beam center wavelength data returned by the laser transceiver module, and perform real-time processing;

[0018] In the precision measuring device for the surface roughness of an object, the light source module comprises: a fiber femtosecond laser and a laser pump source;

[0019] The fiber femtosecond laser emits a femtosecond laser pulse, and the laser pump source is used to emit pump light to excite the femtosecond laser pulse to form an outgoing laser beam that enters the laser transceiver module.

[0020] Preferably, in the hyperspectral femtosecond laser radar, the light source module includes: a diode laser, a fiber femtosecond laser, a fiber isolator, a wavelength division multiplexer and a FC / APC jumper.

[0021] The light of the fiber femtosecond laser passing through the fiber isolator and the light of the diode laser are input into the wavelength division multiplexer, and the light coming out of the wavelength division multiplexer enters the wavelength division multiplexer and is emitted by the FC / APC jumper. The light emitted by the diode laser is used as a pump source to excite the light emitted by the fiber femtosecond laser.

[0022] The light source module emits an outgoing laser beam which enters the laser transceiver module and then passes through the electrically controlled optical filter and then emits a detection laser beam from the laser collimator.

[0023] The optical power detection module is a photoelectric optical power meter, including a photosensitive element, a signal processing circuit and an output interface. The detection laser beam is first reflected by the sample to be tested on the XY displacement stage to the collimator provided in the laser transceiver module, and then transmitted to the photosensitive element through the optical fiber. The photosensitive element converts the received optical signal into an electrical signal, and after being processed by the signal processing circuit, it outputs a standard voltage signal through the output interface and transmits it to the data solution module.

[0024] The present invention also provides a high-speed and precise measurement method for the surface roughness of an object, the detection method comprising:

[0025] The light source module emits an outgoing laser;

[0026] Send out detection laser through the laser transceiver module;

[0027] Acquire the size of the detection laser spot, adjust the distance and pitch angle of the XY translation stage according to the size of the detection laser spot, and set the displacement parameters of the XY translation stage in the control module;

[0028] Controlling the XY translation stage to move so that the detection light beam scans the sample to be tested;

[0029] Acquiring the electrical signal of the optical power detection module, and using the improved Oren-Nayar model in the data solving module to solve the electrical signal of the optical power detection module to calculate the roughness of the surface of the sample to be tested;

[0030] The data solving module matches the position information of the XY translation stage and the roughness of the surface of the sample to be tested, obtains point cloud data and stores it in the FPGA;

[0031] The technical solution of the present invention provides a high-speed and precise measurement method of the surface roughness of an object using a hyperspectral femtosecond laser radar. The system has a simple structure and can efficiently complete the roughness measurement of the entire surface of an object. The hyperspectral femtosecond laser radar includes a light source module, a laser transceiver module, an optical power detection module, an XY translation stage, a control module, and a data solution module. Each module works together, from laser emission to signal processing, to achieve high-precision surface roughness measurement;

[0032] Specifically, the light source module can emit femtosecond laser pulses, while the optical power detection module is between the data solution module and the spectrometer module, responsible for detecting the optical power of the reflected laser. When the surface of an object is irradiated by the laser, the reflected light is converted into an electrical signal by the optical power detection module, and processed in real time by the data solution module, and finally outputs the roughness information of the surface of the sample to be tested;

[0033] From the above description, it can be seen that the present invention realizes a comprehensive scan of the sample to be measured through an efficient control module and a precise XY translation stage, ensuring the measurement coverage and data accuracy, thereby providing an effective measurement solution for related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly explain the technical solutions in the embodiments of the present invention, the drawings required in the embodiments are briefly described below. Obviously, the drawings described below are only some implementation examples of the present invention, and ordinary technicians in this field can derive other feasible drawings based on these drawings without creative work;

[0035] Figure 1 1 is a schematic diagram of the structure of a hyperspectral femtosecond laser radar for high-speed and precise measurement of the surface roughness of an object proposed in an embodiment of the present invention;

[0036] Figure 2 A flow chart of a precision measurement method for measuring the surface roughness of an object provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0038] As described in the background technology, the existing surface roughness measurement technology has certain limitations, and many traditional methods cannot effectively improve the accuracy and real-time performance of the measurement. Therefore, the present invention proposes a high-spectral femtosecond laser radar high-speed and precise measurement method for the surface roughness of an object. This method uses the high temporal and spatial resolution of femtosecond laser pulses for non-contact measurement, which can obtain rich spectral information in real time, significantly improve the accuracy and efficiency of the measurement, and meet the measurement requirements of a variety of materials. In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, it will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0039] Figure 1 1 is a schematic diagram of a hyperspectral femtosecond laser radar for high-speed and precise measurement of surface roughness of an object proposed in an embodiment of the present invention. The laser radar shown includes: a light source module 101, a laser transceiver module 102, an XY translation stage 103, an optical power detection module 104, a control module and a data solution module 105.

[0040] The light source module 101 is used to emit laser light and includes: a fiber femtosecond laser 1011 , a fiber isolator 1012 , a wavelength division multiplexer 1013 , an FC / APC jumper 1014 and a diode laser 1015 .

[0041] The laser transceiver module 102 includes: an electrically controlled optical filter 1021, an optical fiber beam splitter 1022, and a laser collimator 1023. The laser pulse width output by the electrically controlled optical filter 1021 is 5 nm.

[0042] The optical power detection module 104 is a photoelectric optical power meter, which samples and records the optical power value of the reflected laser in real time.

[0043] The control module and the data solving module 105 are FPGAs, which are used to control the optical power detection module, the motion trajectory of the XY translation stage, and the central wavelength of the detection laser beam returned by the laser transceiver module, and to solve and store the collected reflected laser optical power value, the motion trajectory of the XY translation stage, and the central wavelength data of the detection laser beam in real time.

[0044] Figure 2A flow chart of a high-speed and precise measurement method for the surface roughness of an object provided in an embodiment of the present application, the high-speed and precise measurement method for the surface roughness of an object comprising:

[0045] Step 1: Turn on the hyperspectral femtosecond lidar device and set the XY stage and the electronically controlled optical filter parameters;

[0046] By setting the motion trajectory of the XY stage, the coordinates of the detection laser on the XY stage can be obtained, and the subsequent measurement values ​​can be aligned. The electronically controlled filter can set the filter step length. This device generally sets the step length to 5nm;

[0047] Step 2: Place the standard white board on the XY stage and adjust the angle of the XY stage so that the laser incident angle is 0°;

[0048] Step 3: Start measuring the reflected laser light power value of each central wavelength reflected from the standard white board, recorded as ;

[0049] Step 4: Replace the standard white board with the sample;

[0050] Step 5: Start measuring the reflected laser light power value of each central wavelength reflected back from the sample, recorded as ;

[0051] Step 6: Substitute F(λ) and I(λ) into the simplified and well-formed Oren-Nayar model

[0052] After executing steps 1 to 6, FPGA can obtain the reflected laser light power value at each point of the whiteboard. And the reflected laser light power value of each central wavelength reflected back by the sample data and and Align according to their respective coordinates;

[0053] In step 2, the angle of the XY stage is adjusted so that the laser incident angle is 0° and the azimuth of the incident direction of the device is consistent with the azimuth of the outgoing direction, which simplifies the Oren-Nayar model. and Bring in the simplified and improved Oren-Nayar model:

[0054] (1)

[0055] (2)

[0056] From formula (1), we can find the , and then use (2) to obtain the The average , is the standard deviation of the distribution of small plane slope angles on the sample surface, The larger the size, the rougher the sample surface;

[0057] The simplified and improved Oren-Nayar model is written into the FPGA, and the FPGA obtains the sample through steps 1 to 5. And the coordinates are stored.

[0058] In the implementation method, the specific steps include setting the measurement equipment parameters, measuring the reflected light power value of the standard white plate, processing the sample data, and calculating the roughness of the object surface through the simplified Oren-Nayar model. In the steps, FPGA implements data acquisition, processing and real-time storage to improve the efficiency and accuracy of the measurement. Theoretically, by calculating the standard deviation of the center of different wavelengths, the distribution of the slope angle of the small plane on the sample surface is obtained, thereby providing a basis for roughness evaluation.

[0059] The detailed description of the embodiments disclosed in the present invention enables professionals and technicians to implement or apply the present invention. Various modifications and adjustments to these embodiments will be apparent to professionals and technicians in the field, and therefore, the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the present invention. Therefore, the scope of protection of the present invention is not limited to the embodiments shown herein, but should be consistent with the principles and novel features disclosed herein and applicable to the widest range.

Claims

1. A hyperspectral femtosecond laser radar for high-speed and precise measurement of surface roughness of an object, characterized in that: include: A light source module, the light source module is used to emit a laser beam; A laser transceiver module, the laser transceiver module is used to adjust the outgoing laser beam to become a detection laser beam; An optical power detection module, which is a photoelectric optical power meter, used to convert the optical signal of the reflected laser reflected from the sample into an electrical signal; An XY translation stage, wherein the XY translation stage is used to fix the sample; The control module and the data solving module are integrated on a field programmable gate array (FPGA).

2. The hyperspectral femtosecond laser radar for high-speed and precise measurement of surface roughness of an object according to claim 1, characterized in that: The light source module includes: a fiber femtosecond laser and a laser pump source; The fiber femtosecond laser is used to emit femtosecond laser pulses, and the laser pump source is used to emit a pump light source to excite the femtosecond laser pulses to form the emitted laser beam.

3. The hyperspectral femtosecond laser radar for high-speed and precise measurement of surface roughness of an object according to claim 1, characterized in that: The laser transceiver module includes: an electrically controlled optical filter, an optical fiber beam splitter and a laser collimator; The electrically controlled optical filter is used to obtain detection laser beams with different central wavelengths, the optical fiber beam splitter is used to split the reflected laser reflected from the sample, and the laser collimator is used to accurately focus the laser beam to improve the accuracy of laser beam measurement.

4. A high-speed and precise measurement method for the surface roughness of an object, characterized in that: The device for measuring the surface roughness of an object according to any one of claims 1 to 3 comprises: Acquire the spot size of the detection laser beam, and set the pitch angle and motion trajectory of the XY translation stage according to the spot size of the detection laser beam, so that the detection laser beam can be vertically projected toward the XY translation stage; Acquire the detection value of the optical power detection module, set the step size of the electrically controlled optical filter and the size of the laser pump source, so that the laser transceiver module emits a suitable detection laser beam; Controlling the XY translation stage to move so that the detection laser beam scans the standard white plate and the sample respectively; The FPGA brings the detection value of the optical power detection module into a simplified and improved Oren-Nayar model to calculate the roughness of the sample surface.

5. The high-speed and precise measurement method for the surface roughness of an object according to claim 4, characterized in that: The method for calculating the roughness of the sample surface includes: The reflected laser light power value of each central wavelength reflected by the standard white board is recorded as ; The reflected laser light power value of each central wavelength reflected back by the sample is recorded as ; Will and By using the simplified and improved Oren-Nayar model, the standard deviation of the distribution of small plane slope angles on the sample surface can be calculated. The larger the standard deviation, the rougher the sample surface.

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