Non-contact length measuring device based on double-end interference method

Abstract

The invention discloses a non-contact length measuring device based on a double-end interference method, which belongs to the technical field of laser measuring instruments and comprises a mounting plate, a frequency stabilized laser fixedly mounted on the upper surface of the mounting plate, a Y-shaped frame fixedly mounted on the upper surface of the frequency stabilized laser, and a laser transmitter of the frequency stabilized laser fixedly mounted in the Y-shaped frame. A converging lens is fixedly mounted at one end in the Y-shaped frame, and a first collimating lens and a reflector are fixedly mounted at one end of the upper surface of the mounting plate, so that measuring light emitted by the laser emitter sequentially passes through the converging lens and the first collimating lens to form quasi-parallel light beams. Through the design of the converging lens, the light splitting mechanism, the reflector, the first collimating lens and the second collimating lens, an interference method is adopted to measure the length of the end degree type length standard device, direct contact with a measured piece is not needed, the situation that the surface of the measured piece is possibly scratched in a traditional measurement mode is avoided, and the maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of laser measuring instruments, in particular to a non-contact length measuring device based on a double-end interferometry method. Background Art

[0002] End measurement technology is a crucial aspect of length metrology. End measurement can be performed in many different ways, such as measuring the length of a gauge block. Traditional end measurement using the lapping method is limited by the thickness of the lapping layer and the technical level of the lapping personnel, making it difficult to achieve higher-precision measurements. With technological advancements, the required accuracy for this type of end measurement is increasing. From lapping measurement to non-lapping double-end measurement, it is possible to measure end length without lapping. Double-end interferometry technology can directly reflect interference light on both surfaces of the test piece to form interference fringes, ultimately achieving end measurement without lapping. Double-end interferometry is a new, non-lapping, non-contact method for measuring gauge block length.

[0003] However, in the field of modern industrial manufacturing and precision metrology, length measurement is a basic and key technical link, and its accuracy and efficiency directly affect product quality and production efficiency. With the rapid development of science and technology, traditional length measurement methods are difficult to achieve high-precision measurement and non-contact measurement requirements. Therefore, a non-contact length measurement device based on double-end interferometry is proposed. Summary of the Invention

[0004] The object of the present invention is to provide a non-contact length measurement device based on double-end interferometry to solve the problem that the traditional length measurement method proposed in the above background technology is gradually unable to meet the requirements of high-precision, non-contact measurement.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A non-contact length measurement device based on a double-end interferometry method, comprising: a mounting plate, a frequency-stabilized laser fixedly mounted on the upper surface of the mounting plate, a Y-shaped frame fixedly mounted on the upper surface of the frequency-stabilized laser, a laser emitter of the frequency-stabilized laser fixedly mounted within the Y-shaped frame, a converging lens fixedly mounted at one end of the Y-shaped frame, the converging lens being flush with the laser emitter, a first collimating lens and a reflector fixedly mounted at one end of the upper surface of the mounting plate, the first collimating lens and the reflector also being flush with the converging lens, and the reflector being tilted;

[0007] Wherein, the measuring light emitted by the laser emitter is sequentially formed into a quasi-parallel beam by the converging lens and the first collimating lens, and then irradiated on one end of the reflector to be reflected and incident on the light splitting mechanism, the light splitting mechanism is fixedly mounted at the center of the upper surface of the mounting plate, and is provided with three groups, the three groups of light splitting mechanisms (2) are arranged in a triangular shape, and the light splitting mechanisms located on both sides are symmetrically arranged, and a workbench is fixedly mounted between the three groups of light splitting mechanisms, and a clamping mechanism is fixedly mounted on the upper surface of the workbench, and the clamping mechanism can clamp the measured object;

[0008] Among them, the measurement light first incident on the spectroscopic mechanism through the reflector will be divided into two paths, and the measurement light divided into two paths will be incident on the other two groups of spectroscopic mechanisms at the bottom respectively, and the two spectroscopic mechanisms at the bottom will again split the measurement beam into two paths, one path is incident on the reference mirror, and the other path is incident on the outer surface of the workpiece clamped by the clamping mechanism, and the reference mirror will return the light along the original path to interfere with the reflected light from the surface of the workpiece and the light beam reflected by the spectroscopic mechanism on the other side, forming interference fringes, and the interference fringes on both sides will be collected by the camera again through the second collimating lens, the second collimating lens is fixedly mounted on both ends of the upper surface of the mounting plate and flush with the camera, and the reference mirror is connected to the PZT phase shifter through the frame to realize phase shift interference measurement;

[0009] Among them, the PZT phase shifter is fixedly installed in the connecting frame, and the frame is fixedly connected to the connecting frame. A connecting arm is rotatably installed on the lower surface of the connecting frame, and a fastening plate is rotatably installed on the other end of the connecting arm. The fastening plate is fixedly installed on both ends of the upper surface of the mounting plate, and the camera is fixedly installed on one end of the flip plate. The flip plate is rotatably installed in the U-shaped frame, and the U-shaped frame is also fixedly installed on both ends of the upper surface of the mounting plate.

[0010] Preferably, the fastening plate and one end of the connecting frame that are rotatably connected to the connecting arm are both threadedly installed with a first butterfly bolt, so that the first butterfly bolt can be screwed in through the thread to press on one end of the connecting arm to achieve rotational locking, and through this rotational connection, the rotatably installed connecting arm and connecting frame can be flipped at an angle.

[0011] Preferably, a second butterfly bolt is rotatably mounted on one end of the C-shaped frame, and the other part of the second butterfly bolt can be threaded through the C-shaped frame thread and pressed against one end of the flip plate to achieve rotational locking, and through this flipping action, the camera fixedly mounted at one end can be flipped at an angle.

[0012] Preferably, the three groups of the spectroscopic mechanisms include three groups of connecting plates, which are fixedly mounted on the upper surface of the mounting plate and arranged in a triangular shape. The outer surfaces of the three groups of connecting plates are slidably mounted with connecting blocks, and the upper surfaces of the three groups of connecting blocks are respectively fixedly mounted with the first spectrometer, the second spectrometer and the third spectrometer, so that the first spectrometer, the second spectrometer and the third spectrometer are arranged together in a triangular shape.

[0013] Preferably, the first spectroscope will split the measuring light reflected by the reflector into two paths, and the two beams of light after the initial spectroscope will be incident on the second spectroscope and the third spectroscope respectively, so that the two spectroscopes will split the received light into two beams again, thus generating a total of four beams of light. The two beams of light on both sides will then be directed to the reference mirror and the device under test, and the light directed to the reference mirror will be reflected back along the original path, and the light directed to the device under test will also be reflected back from the surface of the device under test, so that the reflected light from the reference mirror interferes with the reflected light from the device under test and the light reflected by the spectroscope on the other side, thereby forming interference fringes, and the formed interference fringes are collected by the camera after passing through the second collimating lens.

[0014] Preferably, a threaded rod is rotatably installed in the three groups of connecting plates, and the threaded rod passes through the inner thread of the connecting block, and both ends of the threaded rod are rotatably passed out from the connecting plate and fixedly installed with a handwheel, and an insert block is fixedly installed on one end of the connecting block threadedly installed on the outer surface of the threaded rod, and a threaded column is fixedly installed on one end of the insert block, and a locking block is slidably inserted on the outer surface of the insert block, and a pressing column is threadedly installed on the outer surface of the threaded column, so that the pressing column can push the locking block to slide inward on the outer surface of the insert block by screwing in on the outer surface of the threaded column, and then the locking block sliding inwardly can touch one end of the connecting block and one end of the connecting plate at the same time, so as to achieve sliding locking of the connecting block.

[0015] Preferably, the clamping mechanism includes a first motor, which is fixedly mounted on the upper surface of the workbench, a connecting disk is fixedly mounted on the outer surface of the output shaft of the first motor, a mounting frame is fixedly mounted on the upper surface of the connecting disk, and clamping arms are rotatably mounted on the outer surfaces of both ends of the mounting frame, and half teeth are fixedly mounted on the inner outer surfaces of the two groups of clamping arms, and the two groups of opposite half teeth are meshed with each other, so that the two groups of clamping arms can be synchronously driven to flip outward or clamp toward the center.

[0016] Preferably, a second motor is fixedly installed in the installation frame, and an output shaft of the second motor rotates through the installation frame and is fixedly connected to one set of clamping arms.

[0017] Preferably, a suspension frame is fixedly installed on the outer surface of the first motor, and a laser ranging sensor is fixedly installed inside the suspension frame. The laser ranging sensor is flush with the rotating ring, and the rotating ring is fixedly installed on the lower surface of the connecting disk. The outer surface of the rotating ring is elliptical from narrow to wide, so that when it is driven to rotate by the first motor, the distance between the rotating ring and the laser ranging sensor will continue to change, and the laser ranging sensor will continuously detect the distance between the two and transmit the data to the controller. A corresponding relationship model between the spacing and the angle is pre-set in the controller. According to the different spacing data received, the spacing change is converted into the angle information of the rotating ring through algorithm conversion, thereby realizing the measurement and feedback of the rotation angle, and the control output end of the controller is electrically connected to the electrical control end of the first motor.

[0018] Preferably, the models of the laser ranging sensor and controller are AMS307i120 and S7-1500 respectively.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. Through the design of the stabilized frequency laser, laser transmitter, converging lens, first collimating lens, reflector, reference mirror, second collimating lens, PZT phase shifter, camera, spectrometer and clamping mechanism, when in use, the staff can clamp the workpiece to be measured in the clamping mechanism, and then start the stabilized frequency laser to let the laser transmitter first emit measurement light to the converging lens. After the measurement light is converged by the converging lens, it passes through the first collimating lens to form a quasi-parallel beam. The beam is irradiated on the inclined reflector, changes direction after reflection, and accurately enters the triangular and symmetrically arranged spectrometer at the center of the upper surface of the mounting plate. In the spectrometer, first, The first group of light-splitting mechanisms divides the measuring light into two paths, which are respectively directed to the other two groups of light-splitting mechanisms. At the other two groups of light-splitting mechanisms, the measuring light is again divided into two paths, and finally four light beams are formed. Among them, two light beams are respectively directed to the reference mirror, and the other two light beams are directed to the outer surface of the measured object clamped by the clamping mechanism. The light directed to the reference mirror will return the light irradiated on it by its reflection performance. At the same time, the light beam directed to the measured object is also reflected back from the surface of the measured object, so that the reflected light of the reference mirror interferes with the reflected light of the measured object surface and the light beam reflected by the light-splitting mechanism on the other side, thereby forming interference fringes. These interference fringes contain The relevant information of the length of the measured object is injected into the second collimating lens, and the second collimating lens collimates the interference fringes to ensure their clarity and stability, and then is collected by the camera. The camera converts the collected interference fringes image information into electrical signals or digital signals and transmits them to the subsequent data processing system for length analysis, thus realizing a contactless measurement function. In this process, the reference mirror is connected to the PZT phase shifter through a frame. The PZT phase shifter can realize phase-shifting interference measurement. By applying different voltage signals to the PZT phase shifter, the tiny displacement of the reference mirror can be accurately controlled to change the phase of the incident reflected light, so that the interference fringes under different phases can be accurately measured. The data on fringe changes, combined with pre-established mathematical models and algorithms, can more accurately calculate the length of the workpiece under test, effectively improving the accuracy and reliability of the measurement. In addition, the connecting frame is rotatably connected to the fastening plate through a connecting arm, and a first butterfly bolt is installed at the connection. When the angle of the reference mirror needs to be adjusted, the first butterfly bolt is loosened, the connecting arm and the connecting frame are rotated to the appropriate angle, and the first butterfly bolt is tightened to lock it, ensuring that the reference mirror remains stable during the measurement process. Similarly, the U-shaped frame and the flip plate are connected by a second butterfly bolt, which can flexibly adjust and fix the angle of the camera to ensure that the camera can clearly and accurately capture the interference fringes.

[0021] 2. Through the design of the first beam splitter, the second beam splitter and the third beam splitter, the connecting block, the threaded rod, the threaded column, the locking block and the top pressure column, the measuring light is reflected by the reflector and will be incident on the first beam splitter arranged in a triangle on the mounting plate at a specific angle. The first beam splitter is fixed on the upper surface of the connecting block and uses its optical properties to accurately split the incident measuring light into two paths to complete the initial beam splitting. This process uses the reflection and transmission principle of the first beam splitter to separate the light beam according to a preset ratio, providing basic optical path branches for subsequent measurements. The two beams after the initial beam splitting will be respectively emitted to the second beam splitter and the third beam splitter, which are also installed on the corresponding connecting block, and will again split the received light beam into two beams. A total of four beams of light are generated, among which the two beams on both sides are emitted to the reference mirror and the device under test respectively. The light reflected by the reference mirror and the surface of the device under test interferes with the light beam reflected by the beam splitter on the other side, forming a beam carrying the device under test. The interference fringes of length information are collected by the camera for measurement and calculation, and in the structural design of the spectroscopic mechanism, the connecting block and the threaded rod installed on the outer surface of the connecting plate constitute a flexible adjustment system, which can be used by the staff to drive the threaded rod to rotate by turning the handwheel. Since the threaded rod and the connecting block thread cooperate, the connecting block will slide along the outer surface of the connecting plate, thereby realizing the precise adjustment of the positions of the first spectrometer, the second spectrometer and the third spectrometer, so that it can flexibly change the position of the spectrometer according to different measurement requirements, different sizes of test pieces and optical path calibration requirements, ensuring that the measurement light can be accurately incident and split. When the position of the spectrometer is adjusted to the right position, the pressing column is tightened on the threaded column to push the locking block to slide inward on the outer surface of the plug until the locking block touches the connecting block and the connecting plate at the same time, and the connecting block is firmly locked, thereby avoiding the position deviation of the spectrometer due to vibration, collision and other factors during the measurement process, and ensuring the stability of the spectroscopic optical path and the accuracy of the measurement.

[0022] 3. Through the design of the first motor, the second motor, the clamping arm, the half teeth, the laser ranging sensor and the rotating ring, when the workpiece to be measured is placed, the second motor can be started to drive a set of clamping arms fixedly connected to it to rotate, and because the half teeth on the inner sides of the two sets of clamping arms are meshed with each other, the rotating clamping arm can drive the other set of clamping arms to move synchronously, so that the two sets of clamping arms are clamped toward the center, thereby firmly clamping the workpiece to be measured in the middle, and the structural design of the two sets of half teeth meshing with each other ensures the synchronization of the clamping arm movement, can provide uniform clamping force, ensure that workpieces of different shapes and sizes can be stably fixed, reduce measurement errors caused by unstable clamping, and this symmetrical synchronous clamping method can not only adapt to workpieces of different shapes and sizes, but also provide uniform and stable clamping force, avoid the position deviation of the workpiece to be measured due to uneven force, effectively reduce measurement errors, and significantly improve the reliability of measurement results. After the workpiece to be measured is clamped, the first motor can be started to drive the connecting disk to rotate, and the connecting disk can bring The mounting frame fixed on the upper surface of the movable body and the clamped workpiece rotate together, and the rotating ring fixed on the lower surface of the connecting disk is also driven to rotate accordingly. The outer surface of the rotating ring is a special elliptical shape and is opposite to the laser ranging sensor in the suspension frame. During the rotation of the connecting disk, as the elliptical contour of the rotating ring changes, the distance between the rotating ring and the laser ranging sensor continues to change. During this process, the laser ranging sensor detects the distance between the two in real time and transmits the data to the controller. The controller has a preset corresponding relationship model between the distance and the angle. The received distance data is converted into the angle information of the rotating ring through the algorithm. At the same time, the controller is connected to the electronic control end of the first motor to form a closed-loop control system. When the controller determines that there is a deviation in the rotation angle based on the angle information, it will adjust the operating state of the first motor in time to ensure that the workpiece is driven to rotate to the accurate angle, providing an accurate positioning basis for the subsequent length measurement based on the double-end interferometry method, thereby ensuring the accuracy and effectiveness of the entire measurement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 Schematic diagram of the structure of the first collimating lens and the second collimating lens of the present invention;

[0025] Figure 3 It is a schematic diagram of the overall top view of the structure of the present invention;

[0026] Figure 4 Schematic diagram of the structure of the light splitting mechanism of the present invention;

[0027] Figure 5 It is a structural schematic diagram of the clamping and grasping mechanism of the present invention;

[0028] Figure 6This is a schematic diagram of the structure in which the laser ranging sensor of the present invention is flush with the rotating ring;

[0029] Figure 7 It is a structural schematic diagram of the reflection and branching of the measurement light path of the present invention.

[0030] In the figure: 1. Mounting plate; 101. Frequency-stabilized laser; 102. Laser transmitter; 103. Y-shaped frame; 104. Converging lens; 105. First collimating lens; 106. Reflector; 107. Workbench; 108. U-shaped frame; 109. Flip plate; 110. Fastening plate; 111. Connecting arm; 112. Connecting frame; 113. Frame; 114. Reference mirror; 115. First butterfly bolt; 116. Second collimating lens; 117. Second butterfly bolt; 118. PZT phase shifter; 119. Camera; 2 , spectroscopic mechanism; 201, connecting plate; 202, threaded rod; 203, handwheel; 204, connecting block; 205, plug-in block; 206, threaded column; 207, locking block; 208, pressure column; 209, first spectrometer; 210, second spectrometer; 211, third spectrometer; 3, clamping mechanism; 301, mounting frame; 302, second motor; 303, half gear; 304, clamping arm; 305, first motor; 306, suspension frame; 307, laser ranging sensor; 308, connecting disk; 309, swivel. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments 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 efforts are within the scope of protection of the present invention.

[0032] See also Figure 1-Figure 7 , this embodiment provides the following technical solutions:

[0033] like Figure 1-Figure 3 As shown, a non-contact length measuring device based on a double-end interferometry method belongs to the technical field of laser measuring instruments, comprising: a mounting plate 1, a frequency-stabilized laser 101 fixedly mounted on the upper surface of the mounting plate 1, a Y-shaped frame 103 fixedly mounted on the upper surface of the frequency-stabilized laser 101, a laser emitter 102 of the frequency-stabilized laser 101 fixedly mounted in the Y-shaped frame 103, and a converging lens 104 fixedly mounted at one end of the Y-shaped frame 103, the converging lens 104 being flush with the laser emitter 102, a first collimating lens 105 and a reflector 106 fixedly mounted at one end of the upper surface of the mounting plate 1, and both the first collimating lens 105 and the reflector 106 are also flush with the converging lens 104, and the reflector 106 is inclined;

[0034] In this way, the measuring light emitted by the laser emitter 102 will sequentially pass through the converging lens 104 and the first collimating lens 105 to form a quasi-parallel beam, and then illuminate one end of the reflector 106 to be reflected and incident into the spectroscopic mechanism 2. The spectroscopic mechanism 2 is fixedly installed at the center of the upper surface of the mounting plate 1, and is provided with three groups. The three groups of spectroscopic mechanisms (2) are arranged in a triangle, and the spectroscopic mechanisms 2 located on both sides are symmetrically arranged. A workbench 107 is fixedly installed between the three groups of spectroscopic mechanisms 2, and a clamping mechanism 3 is fixedly installed on the upper surface of the workbench 107. The clamping mechanism 3 can clamp the measured object;

[0035] Among them, the measurement light first incident on the spectroscopic mechanism 2 through the reflector 106 will be divided into two paths, and the measurement light divided into two paths will be incident on the other two groups of spectroscopic mechanisms 2 at the bottom respectively, and the two groups of spectroscopic mechanisms 2 at the bottom will again split the measurement beam into two paths, one path is incident on the reference mirror 114, and the other path is incident on the outer surface of the workpiece clamped by the clamping mechanism 3, and the reference mirror 114 will return the light along the original path to interfere with the reflected light from the surface of the workpiece and the light beam reflected by the spectroscopic mechanism 2 on the other side, forming interference fringes, and the interference fringes on both sides will be collected by the camera 119 again through the second collimating lens 116, the second collimating lens 116 is fixedly mounted on both ends of the upper surface of the mounting plate 1 and flush with the camera 119, and the reference mirror 114 is connected to the PZT phase shifter 118 through the frame 113 to realize phase shift interference measurement;

[0036] Among them, the PZT phase shifter 118 is fixedly installed in the connecting frame 112, and the frame 113 is fixedly connected to the connecting frame 112. The connecting arm 111 is rotatably installed on the lower surface of the connecting frame 112, and the other end of the connecting arm 111 is rotatably installed with a fastening plate 110. The fastening plate 110 is fixedly installed at both ends of the upper surface of the mounting plate 1, and the camera 119 is fixedly installed at one end of the flip plate 109. The flip plate 109 is rotatably installed in the U-shaped frame 108, and the U-shaped frame 108 is also fixedly installed at both ends of the upper surface of the mounting plate 1.

[0037] The fastening plate 110 and one end of the connecting frame 112 that are rotatably connected to the connecting arm 111 are both threadedly installed with a first butterfly bolt 115, so that the first butterfly bolt 115 can be screwed in through the thread to press against one end of the connecting arm 111 to achieve rotational locking, and through this rotational connection, the rotatably installed connecting arm 111 and the connecting frame 112 can be flipped at an angle.

[0038] A second butterfly bolt 117 is rotatably mounted on one end of the C-shaped frame 108, and the other part of the second butterfly bolt 117 can be threaded through the C-shaped frame 108 and pressed against one end of the flip plate 109 to achieve rotational locking. Through this flipping action, the camera 119 fixed at one end can be flipped in angle.

[0039] Through the design of the stabilized frequency laser 101, the laser emitter 102, the converging lens 104, the first collimating lens 105, the reflector 106, the reference mirror 114, the second collimating lens 116, the PZT phase shifter 118, the camera 119, the spectrometer 2 and the clamping mechanism 3, when in use, the staff can clamp the workpiece to be measured in the clamping mechanism 3, and then start the stabilized frequency laser 101 to let the laser emitter 102 first emit measurement light to the converging lens 104. After the measurement light is converged by the converging lens 104, it passes through the first collimating lens 105 to form a quasi-parallel light beam. The light beam is irradiated on the inclined reflector 106, changes direction after reflection, and accurately enters the spectrometer 2 arranged in a triangular and symmetrical manner at the center of the upper surface of the mounting plate 1 In the spectroscopic mechanism 2, the first group of spectroscopic mechanisms 2 first divides the measuring light into two paths, and these two paths of light are respectively directed to the other two groups of spectroscopic mechanisms 2. At the other two groups of spectroscopic mechanisms 2, the measuring light is again divided into two paths, and finally four light beams are formed, among which two light beams are respectively directed to the reference mirror 114, and the other two light beams are directed to the outer surface of the measured object clamped by the clamping mechanism 3. The light directed to the reference mirror 114 will return the light irradiated thereon to the original path by virtue of its reflection performance. At the same time, the light beam directed to the measured object is also reflected back from the surface of the measured object, so that the reflected light of the reference mirror 114 interferes with the reflected light of the surface of the measured object and the light beam reflected by the spectroscopic mechanism 2 on the other side, thereby forming interference fringes. These interference fringes contain the length of the measured object. The relevant information is injected into the second collimating lens 116, and the second collimating lens 116 performs collimation processing on the interference fringes to ensure that they are clear and stable, and then they are collected by the camera 119, and the camera 119 converts the collected interference fringes image information into electrical signals or digital signals and transmits them to the subsequent data processing system for length analysis, that is, a contactless measurement function is realized. In this process, the reference mirror 114 is connected to the PZT phase shifter 118 through the frame 113. The PZT phase shifter 118 can realize phase-shifting interference measurement. By applying different voltage signals to the PZT phase shifter 118, the tiny displacement of the reference mirror 114 can be accurately controlled to change the phase of the incident reflected light, so that the interference fringes change data under different phases can be combined with the predicted The mathematical model and algorithm established first can more accurately calculate the length of the measured object and effectively improve the measurement accuracy and reliability. In addition, the connecting frame 112 is rotatably connected to the fastening plate 110 through the connecting arm 111, and a first butterfly bolt 115 is installed at the connection. When the angle of the reference mirror 114 needs to be adjusted, the first butterfly bolt 115 is loosened, and the connecting arm 111 and the connecting frame 112 are rotated to a suitable angle, and then the first butterfly bolt 115 is tightened to lock it, ensuring that the reference mirror 114 remains stable during the measurement process. Similarly, the U-shaped frame 108 and the flip plate 109 are connected by the second butterfly bolt 117, and the angle of the camera 119 can be flexibly adjusted and fixed to ensure that the camera 119 can clearly and accurately capture the interference fringes.

[0040] like Figure 4 As shown, the three-group beam splitting mechanism 2 includes three groups of connecting plates 201, which are fixedly mounted on the upper surface of the mounting plate 1 and arranged in a triangular shape. The outer surfaces of the three groups of connecting plates 201 are all slidably mounted with connecting blocks 204, and the upper surfaces of the three groups of connecting blocks 204 are respectively fixedly mounted with a first beam splitter 209, a second beam splitter 210 and a third beam splitter 211, so that the first beam splitter 209, the second beam splitter 210 and the third beam splitter 211 are arranged together in a triangular shape.

[0041] The first beam splitter 209 will split the measuring light reflected by the reflector 106 into two paths, and the two beams of light after the initial splitting will be incident on the second beam splitter 210 and the third beam splitter 211 respectively, so that the two beam splitters will split the received light into two beams again, thus generating a total of four beams of light. The two beams of light on both sides will then be emitted to the reference mirror 114 and the device under test, and the light emitted to the reference mirror 114 will be reflected back along the original path, and the light emitted to the device under test will also be reflected back from the surface of the device under test, so that the reflected light from the reference mirror 114 interferes with the reflected light from the device under test and the light reflected by the beam splitter on the other side, thereby forming interference fringes, which are collected by the camera 119 after passing through the second collimating lens 116.

[0042] The three sets of connecting plates 201 are all rotatably installed with threaded rods 202, which pass through the internal threads of the connecting block 204, and both ends of the threaded rod 202 are also rotatably passed through the connecting plate 201 and fixedly installed with hand wheels 203 at the ends, and one end of the connecting block 204 threadedly installed is fixedly installed with an insert block 205, and one end of the insert block 205 is fixedly installed with a threaded column 206. The outer surface of the insert block 205 is slidably inserted with a locking block 207, and the outer surface of the threaded column 206 is threadedly installed with a pressing column 208, so that the pressing column 208 can push the locking block 207 to slide inwardly on the outer surface of the insert block 205 by screwing in on the outer surface of the threaded column 206, thereby allowing the locking block 207 sliding inwardly to contact one end of the connecting block 204 and one end of the connecting plate 201, thereby achieving sliding locking of the connecting block 204.

[0043] Through the design of the first beam splitter 209, the second beam splitter 210 and the third beam splitter 211, the connecting block 204, the threaded rod 202, the threaded column 206, the locking block 207 and the top pressure column 208, the measuring light is reflected by the reflector 106 and then incident on the first beam splitter 209 arranged in a triangular shape on the mounting plate 1 at a specific angle. The first beam splitter 209 is fixed to the upper surface of the connecting block 204 and accurately splits the incident measuring light into two paths by virtue of its optical properties, completing the initial beam splitting. This process utilizes the reflection and transmission of light by the first beam splitter 209 The principle is to separate the light beam according to a preset ratio to provide a basic optical path branch for subsequent measurement. The two beams of light after the initial splitting will be directed to the second beam splitter 210 and the third beam splitter 211 respectively. The second beam splitter 210 and the third beam splitter 211 are also installed on the corresponding connecting block 204, and the received light beams are divided into two beams again. So far, a total of four beams of light are generated, among which the two beams on both sides are directed to the reference mirror 114 and the measured object respectively. The light reflected by the reference mirror 114 and the surface of the measured object interferes with the light beam reflected by the beam splitter on the other side to form a beam carrying the length of the measured object. The interference fringes of the information are collected by the camera 119 for measurement and calculation, and in the structural design of the spectroscopic mechanism 2, the connecting block 204 installed on the outer surface of the connecting plate 201 and the threaded rod 202 constitute a flexible adjustment system, which can be used by the staff to rotate the hand wheel 203 to drive the threaded rod 202 to rotate. Since the threaded rod 202 and the connecting block 204 are threadedly matched, the connecting block 204 will slide along the outer surface of the connecting plate 201, thereby realizing the precise adjustment of the positions of the first spectroscope 209, the second spectroscope 210 and the third spectroscope 211, so that it can be adjusted according to different The position of the spectrometer can be flexibly changed according to the same measurement requirements, different sizes of test pieces and optical path calibration requirements to ensure that the measurement light can be accurately incident and split. When the position of the spectrometer is adjusted to the right position, the pressing column 208 is tightened on the threaded column 206 to push the locking block 207 to slide inward on the outer surface of the insert block 205 until the locking block 207 touches the connecting block 204 and the connecting plate 201 at the same time, firmly locking the connecting block 204, thereby avoiding the position deviation of the spectrometer due to factors such as vibration and collision during the measurement process, thereby ensuring the stability of the spectroscopic optical path and the accuracy of the measurement.

[0044] like Figure 5-Figure 7 As shown, the clamping mechanism 3 includes a first motor 305, which is fixedly mounted on the upper surface of the workbench 107. A connecting disk 308 is fixedly mounted on the outer surface of the output shaft of the first motor 305, and a mounting frame 301 is fixedly mounted on the upper surface of the connecting disk 308. Clamping arms 304 are rotatably mounted on the outer surfaces of both ends of the mounting frame 301, and half teeth 303 are fixedly mounted on the inner outer surfaces of the two groups of clamping arms 304. The two groups of opposite half teeth 303 are meshed with each other, so that the two groups of clamping arms 304 can be synchronously driven to flip outward or clamp toward the center.

[0045] A second motor 302 is fixedly installed in the installation frame 301 , and an output shaft of the second motor 302 rotates through the installation frame 301 and is fixedly connected to one set of clamping arms 304 .

[0046] A suspension frame 306 is fixedly mounted on the outer surface of the first motor 305, and a laser ranging sensor 307 is fixedly mounted inside the suspension frame 306. The laser ranging sensor 307 is flush with the rotating ring 309, and the rotating ring 309 is fixedly mounted on the lower surface of the connecting plate 308. The outer surface of the rotating ring 309 is elliptical from narrow to wide, so that when it is driven to rotate by the first motor 305, the distance between the rotating ring 309 and the laser ranging sensor 307 will continue to change, and the laser ranging sensor 307 will continuously detect the distance between the two and transmit the data to the controller. The controller has a pre-set correspondence model between the distance and the angle. According to the different distance data received, the distance change is converted into the angle information of the rotation of the rotating ring 309 through algorithm conversion, thereby realizing the measurement and feedback of the rotation angle, and the control output end of the controller is electrically connected to the electrical control end of the first motor 305.

[0047] The models of the laser distance sensor 307 and the controller are AMS307i120 and S7-1500 respectively.

[0048] The specific relationship model between spacing and angle is as follows:

[0049] 1. Geometric model establishment

[0050] Assumptions:

[0051] The swivel is a standard ellipse, the equation Major axis a, minor axis b;

[0052] The laser ranging sensor is fixed to the central axis of the ellipse, and the initial position corresponds to the rotation angle θ = 0°;

[0053] Coordinate transformation:

[0054] After the ring rotates by angle θ, the coordinates of the contact point on the ellipse are (acosθ, bsinθ);

[0055] Distance formula:

[0056] Distance from sensor to contact point in

[0057] (x0, y0) is the offset of the sensor installation position relative to the center of the ellipse.

[0058] If the sensor is located at the center of the ellipse (x0=0, y0=0), it can be simplified to:

[0059]

[0060] 2. Calibration method

[0061] step:

[0062] a. Rotate the swivel to a known angle θ i (such as 0°, 90°, 180°), record the sensor output distance d i ;

[0063] b. Fit the d(θ) curve to solve the ellipse parameters a, b and the installation offset (x0, y0);

[0064] c. During real-time measurement, the rotation angle is obtained by inversely solving the equation θ = f(d).

[0065] Error compensation:

[0066] Introduce a temperature sensor to correct the elliptical deformation caused by thermal expansion, or use an ellipse fitting algorithm for dynamic calibration.

[0067] 3. Controller Implementation

[0068] A calibration algorithm is written in the PLC / S7-1500 to calculate θ in real time and feed it back to the first motor 305 to form a closed-loop control.

[0069] Through the design of the first motor 305, the second motor 302, the clamping arm 304, the half teeth 303, the laser distance sensor 307 and the rotating ring 309, when the workpiece is placed, the second motor 302 can be started to drive the set of clamping arms 304 fixedly connected thereto to rotate, and because the half teeth 303 inside the two sets of clamping arms 304 are meshed with each other, the rotating clamping arm 304 can drive the other set of clamping arms 304 to move synchronously, so that the two sets of clamping arms 304 are clamped toward the center, thereby firmly clamping the workpiece in the middle, and through the meshing of the two sets of half teeth 303 The structural design ensures the synchronization of the clamping arm 304 movement, can provide uniform clamping force, ensure that the workpieces of different shapes and sizes can be stably fixed, and reduce the measurement error caused by unstable clamping. Moreover, this symmetrical and synchronous clamping method can not only adapt to the workpieces of different shapes and sizes, but also provide uniform and stable clamping force, avoid the position deviation of the workpiece due to uneven force, effectively reduce the measurement error, and significantly improve the reliability of the measurement result. After the workpiece is clamped, the first motor 305 can be started to drive the connecting disk 308 to rotate, and the connecting disk 308 can be rotated. 08 can drive the mounting frame 301 fixed on the upper surface and the clamped measured object to rotate together, and the rotating ring 309 fixed on the lower surface of the connecting plate 308 is also driven to rotate accordingly, and the outer surface of the rotating ring 309 is a special elliptical shape, and is opposite to the laser ranging sensor 307 in the suspension frame 306, so that when the connecting plate 308 rotates, as the elliptical outline of the rotating ring 309 changes, the distance between the rotating ring 309 and the laser ranging sensor 307 changes continuously, and in this process, the laser ranging sensor 307 detects the distance between the two in real time and sends the data The data is transmitted to the controller, and a corresponding relationship model between spacing and angle is preset in the controller. The received spacing data is converted into the angle information of the rotation of the rotating ring 309 through an algorithm. At the same time, the controller is connected to the electronic control end of the first motor 305 to form a closed-loop control system. When the controller determines that there is a deviation in the rotation angle based on the angle information, it will adjust the operating state of the first motor 305 in time to ensure that the measured object is driven to rotate to the accurate angle, providing a precise positioning basis for the subsequent length measurement based on the double-end interferometry method, thereby ensuring the accuracy and effectiveness of the entire measurement process.

[0070] According to the above technical solution, the working steps of this solution are summarized and sorted out: when measuring the workpiece to be measured, the second motor 302 can be started to drive a group of clamping arms 304 fixedly connected to it to rotate, and because the half teeth 303 on the inner sides of the two groups of clamping arms 304 are engaged with each other, the rotating clamping arms 304 can drive the other group of clamping arms 304 to move synchronously, so that the two groups of clamping arms 304 are clamped toward the center, thereby firmly clamping the workpiece to be measured in the middle. After the clamping of the workpiece to be measured is completed, the first motor 305 can be started to drive the connecting disk 308 to rotate, and the connecting disk 308 can drive the mounting frame 301 fixedly installed on the upper surface and the clamped workpiece to be measured to rotate together, and the rotating ring 309 fixedly installed on the lower surface of the connecting disk 308 is also driven to rotate, and the outer ring 309 is rotated. The surface is in a special elliptical shape and is opposite to the laser ranging sensor 307 in the suspension frame 306, so that when the connecting disk 308 rotates, as the elliptical outline of the rotating ring 309 changes, the distance between the rotating ring 309 and the laser ranging sensor 307 changes continuously. In this process, the laser ranging sensor 307 detects the distance between the two in real time and transmits the data to the controller. The controller has a preset corresponding relationship model between the distance and the angle, and converts the received distance data into the angle information of the rotating ring 309 through the algorithm. At the same time, the controller is connected to the electronic control end of the first motor 305 to form a closed-loop control system. When the controller determines that there is a deviation in the rotation angle based on the angle information, it will adjust the operating state of the first motor 305 in time to ensure that the measured object is brought The laser beam 102 is rotated to the correct angle until the measured object is rotated to the required angle, and then the stabilized frequency laser 101 is started to make the laser emitter 102 emit the measuring light to the converging lens 104 first. After the measuring light is converged by the converging lens 104, it passes through the first collimating lens 105 to form a quasi-parallel beam. The beam is irradiated on the inclined reflector 106, and the direction is changed after reflection, and it is accurately incident on the first beam splitter 209 arranged in a triangle and symmetrically arranged at the center of the upper surface of the mounting plate 1. The first beam splitter 209 is fixed on the upper surface of the connecting block 204, and accurately divides the incident measuring light into two paths by virtue of its optical characteristics. The two beams after the initial splitting will be respectively emitted to the second beam splitter 210 and the third beam splitter 211, and the second beam splitter 210 and the third beam splitter 211 are respectively incident on the second beam splitter 210 and the third beam splitter 211. The tri-beam mirror 211 is also mounted on the corresponding connecting block 204, and again splits each received light beam into two beams, thus generating a total of four light beams. The two light beams on either side are directed toward the reference mirror 114 and the object under test, respectively. The light reflected by the reference mirror 114 and the surface of the object under test interferes with the light beam reflected by the beam splitter on the other side, forming interference fringes carrying the length information of the object under test. These interference fringes contain relevant information about the length of the object under test and are emitted into the second collimating lens 116. The second collimating lens 116 collimates the interference fringes to ensure their clarity and stability. The interference fringes are then captured by the camera 119, which converts the captured interference fringe image information into electrical signals or digital signals and transmits them to the subsequent data processing system for length analysis.This achieves a contactless measurement function. During this process, the reference mirror 114 is connected to the PZT phase shifter 118 via the frame 113. The PZT phase shifter 118 can perform phase-shifting interferometry. By applying different voltage signals to the PZT phase shifter 118, the tiny displacement of the reference mirror 114 can be precisely controlled, changing the phase of the incident reflected light. The interference fringes at different phases, combined with pre-established mathematical models and algorithms, can more accurately calculate the length of the measured object, effectively improving the accuracy and reliability of the measurement.

[0071] In summary: This device uses the interferometry method to measure the length of end-length standards without direct contact with the workpiece being measured, avoiding damage to the surface of the workpiece such as scratches and wear caused by traditional measurement methods. It is particularly suitable for measuring precise and fragile workpieces, while also reducing the loss of measuring tools and lowering maintenance costs.

[0072] The parts not mentioned in the present invention are the same as the existing technology or can be implemented by using the existing technology. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is determined by the following formula:

[0073] The following claims and their equivalents are defined.

Claims

1. A non-contact length measuring device based on double-ended interferometry, characterized in that: include: A mounting plate (1) is provided, wherein a frequency-stabilized laser (101) is fixedly mounted on the upper surface of the mounting plate (1), a Y-shaped frame (103) is fixedly mounted on the upper surface of the frequency-stabilized laser (1), a laser emitter (102) of the frequency-stabilized laser (1) is fixedly mounted in the Y-shaped frame (103), and a converging lens (104) is fixedly mounted at one end of the Y-shaped frame (103), the converging lens (104) is flush with the laser emitter (102), and a first collimating lens (105) and a reflector (106) are fixedly mounted at one end of the upper surface of the mounting plate (1), and the first collimating lens (105) and the reflector (106) are also flush with the converging lens (104), wherein the reflector (106) is inclined.

2. The non-contact length measurement device based on double-end interferometry according to claim 1, characterized in that: The measuring light emitted by the laser emitter (102) will sequentially pass through the converging lens (104) and the first collimating lens (105) to form a quasi-parallel beam, and then illuminate one end of the reflector (106) to be reflected and incident into the light splitting mechanism (2). The light splitting mechanism (2) is fixedly mounted at the center of the upper surface of the mounting plate (1). Three groups of light splitting mechanisms (2) are arranged in a triangular shape, and the light splitting mechanisms (2) located on both sides are symmetrically arranged. A workbench (107) is fixedly mounted between the three groups of light splitting mechanisms (2). A clamping mechanism (3) is fixedly mounted on the upper surface of the workbench (107). The clamping mechanism (3) can clamp the measured object. The measuring light first incident on the spectroscopic mechanism (2) through the reflector (106) will be divided into two paths, and the measuring light divided into two paths will be incident on the other two groups of spectroscopic mechanisms (2) at the bottom, and the two spectroscopic mechanisms (2) at the bottom will again divide the measuring light beam into two paths, one path is incident on the reference mirror (114), and the other path is incident on the outer surface of the measured object clamped by the clamping mechanism (3), and the reference mirror (114) will return the light to the original path to interfere with the reflected light on the surface of the measured object and the light beam reflected by the spectroscopic mechanism (2) on the other side, forming interference fringes, and the interference fringes on both sides will be collected by the camera (119) again through the second collimating lens (116), and the second collimating lens (116) is fixedly mounted on both ends of the upper surface of the mounting plate (1) and flush with the camera (119), and the reference mirror (114) is connected to the PZT phase shifter (118) through the frame (113) to realize phase-shifting interference measurement; The PZT phase shifter (118) is fixedly mounted in a connecting frame (112), a frame (113) is fixedly connected to the connecting frame (112), a connecting arm (111) is rotatably mounted on the lower surface of the connecting frame (112), a fastening plate (110) is rotatably mounted on the other end of the connecting arm (111), the fastening plate (110) is fixedly mounted on both ends of the upper surface of the mounting plate (1), and the camera (119) is fixedly mounted on one end of a flip plate (109), the flip plate (109) is rotatably mounted in a U-shaped frame (108), and the U-shaped frame (108) is also fixedly mounted on both ends of the upper surface of the mounting plate (1).

3. The non-contact length measurement device based on double-end interferometry according to claim 2, characterized in that: A first butterfly bolt (115) is threadedly mounted on one end of the fastening plate (110) and the connecting frame (112) that are rotatably connected to the connecting arm (111). The first butterfly bolt (115) can be screwed in through the thread to press against one end of the connecting arm (111) to achieve rotational locking. Through this rotational connection, the rotatably mounted connecting arm (111) and the connecting frame (112) can be angularly flipped.

4. The non-contact length measurement device based on double-end interferometry according to claim 3, characterized in that: A second butterfly bolt (117) is rotatably mounted on one end of the C-shaped frame (108); the other portion of the second butterfly bolt (117) can be threaded through the C-shaped frame (108) and pressed against one end of the flip plate (109) to achieve rotational locking; and through this flipping action, the camera (119) fixedly mounted on one end can be flipped at an angle.

5. The non-contact length measurement device based on double-end interferometry according to claim 4, characterized in that: The three groups of light splitting mechanisms (2) include three groups of connecting plates (201), which are all fixedly mounted on the upper surface of the mounting plate (1) and arranged in a triangular shape. The outer surfaces of the three groups of connecting plates (201) are all slidably mounted with connecting blocks (204), and the upper surfaces of the three groups of connecting blocks (204) are respectively fixedly mounted with a first beam splitter (209), a second beam splitter (210), and a third beam splitter (211), so that the first beam splitter (209), the second beam splitter (210), and the third beam splitter (211) are arranged together in a triangular shape.

6. The non-contact length measurement device based on double-end interferometry according to claim 5, characterized in that: The first spectroscope (209) divides the measuring light reflected by the reflector (106) into two paths, and the two beams of light after the initial spectroscope are respectively incident on the second spectroscope (210) and the third spectroscope (211), so that the two spectroscopes divide the received light into two beams again, thus generating a total of four beams of light. Subsequently, the two beams of light on both sides are directed to the reference mirror (114) and the measured object, and the light directed to the reference mirror (114) is reflected back along the original path, and the light directed to the measured object is also reflected back from the surface of the measured object, so that the reflected light of the reference mirror (114) interferes with the reflected light of the measured object and the light reflected by the spectroscope on the other side, thereby forming interference fringes. The formed interference fringes are collected by the camera (119) after passing through the second collimating lens (116).

7. The non-contact length measurement device based on double-end interferometry according to claim 6, characterized in that: The three groups of connecting plates (201) are all rotatably mounted with threaded rods (202), the threaded rods (202) pass through the inner threads of the connecting blocks (204), and both ends of the threaded rods (202) are also rotatably mounted out of the connecting plates (201) and fixedly mounted with hand wheels (203) at the ends, and an insert block (205) is fixedly mounted at one end of the connecting block (204) threadedly mounted on the outer surface of the threaded rod (202), and a threaded column (206) is fixedly mounted at one end of the insert block (205), and the outer surface of the insert block (205) is fixedly mounted with a threaded column (206). A locking block (207) is inserted into the surface slide, and a pressing column (208) is threadedly installed on the outer surface of the threaded column (206), so that the pressing column (208) can be screwed into the outer surface of the threaded column (206) to push the locking block (207) to slide inward on the outer surface of the insert block (205), and then the locking block (207) sliding inward can touch one end of the connecting block (204) and one end of the connecting plate (201), thereby achieving sliding locking of the connecting block (204).

8. The non-contact length measurement device based on double-end interferometry according to claim 7, characterized in that: The clamping mechanism (3) comprises a first motor (305), the first motor (305) being fixedly mounted on the upper surface of the workbench (107), a connecting disc (308) being fixedly mounted on the outer surface of the output shaft of the first motor (305), a mounting frame (301) being fixedly mounted on the upper surface of the connecting disc (308), clamping arms (304) being rotatably mounted on the outer surfaces of both ends of the mounting frame (301), half teeth (303) being fixedly mounted on the inner outer surfaces of the two groups of clamping arms (304), and the two groups of opposite half teeth (303) being meshed with each other, thereby enabling the two groups of clamping arms (304) to be synchronously driven to flip outward or clamp toward the center.

9. The non-contact length measurement device based on double-end interferometry according to claim 8, characterized in that: A second motor (302) is fixedly installed in the installation frame (301), and an output shaft of the second motor (302) rotates through the installation frame (301) and is fixedly connected to one set of clamping arms (304).

10. The non-contact length measurement device based on double-end interferometry according to claim 9, characterized in that: A suspension frame (306) is fixedly mounted on the outer surface of the first motor (305), and a laser distance sensor (307) is fixedly mounted inside the suspension frame (306). The laser distance sensor (307) is flush with the rotating ring (309), and the rotating ring (309) is fixedly mounted on the lower surface of the connecting plate (308). The outer surface of the rotating ring (309) is elliptical and changes from narrow to wide. When the rotating ring (309) is driven to rotate by the first motor (305), the distance between the rotating ring (309) and the laser distance sensor (307) will continuously change, and the laser distance sensor (307) will continuously detect the distance between the two and transmit the data to the controller. The controller has a pre-set model of the corresponding relationship between the distance and the angle. According to the different distance data received, the distance change is converted into the angle information of the rotating ring (309) through algorithm conversion, thereby realizing the measurement and feedback of the rotation angle. The control output end of the controller is electrically connected to the electric control end of the first motor (305).

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