CN118408473A - Interference type laser ruler - Google Patents

Abstract

The invention belongs to the technical field of metering equipment, and particularly relates to an interference type laser ruler, which comprises a laser ranging sensor assembly, a dust cover and a reflecting mirror assembly, wherein the dust cover is arranged at a laser transmitting end of the laser ranging sensor assembly; the laser ranging device comprises a laser ranging sensor assembly, a reflecting mirror assembly, a laser ranging sensor assembly, a reflecting mirror assembly and a reflecting mirror assembly, wherein the reflecting mirror assembly is arranged in the dustproof cover and connected with a measured mobile object, the reflecting mirror assembly is arranged opposite to the laser ranging sensor assembly and can move close to or away from the laser ranging sensor assembly, and the reflecting mirror assembly is used for receiving laser emitted by the laser ranging sensor assembly and then reflecting the laser to the laser ranging sensor assembly. The laser ranging sensor component of the interference type laser ruler is fixed, only the reflecting mirror component moves along with the measured object, the length is not limited by physics by taking the free space as a measuring medium, long-distance measurement can be carried out, and the interference type laser ruler has the outstanding advantages of long service life and miniaturization.

Description

An interferometric laser encoder

Technical Field

The invention belongs to the technical field of measuring equipment, and in particular relates to an interference laser ruler.

Background technique

The working principle of laser interferometer is based on the interference of light waves. When two coherent light waves meet, they superimpose on each other to form constructive and destructive signals, which can be used to measure distance or displacement changes very accurately. This high-precision measurement capability makes laser interferometer an ideal precision measurement tool in the field of high-end manufacturing, especially for calibrating grating rulers in machine tools or automation equipment. However, existing laser interferometers are usually composed of discrete optical devices, which makes them bulky and difficult to modularize. This design makes laser interferometers particularly sensitive to environmental interference, so existing laser interferometers can usually only be used as calibration tools and cannot be directly integrated into automation equipment.

The grating ruler, also known as the grating ruler displacement sensor or grating ruler sensor, is a measurement feedback device that works on the optical principle of the grating. The grating ruler is often used in the closed-loop servo system of CNC machine tools, and can be used to detect linear displacement or angular displacement. The traditional grating ruler consists of two parts: the scale grating and the grating reading head. For example, the grating ruler is disclosed in the existing patent applications 2020223733008 and 2020219697776. The scale grating is usually made of steel or glass, and its grating spacing will change due to the thermal expansion and contraction of the material caused by changes in ambient temperature, which will have a certain impact on the measurement accuracy; in addition, the grating reading head is composed of a light source, a converging lens, an indicating grating, a photoelectric element, and an adjustment mechanism. The complex optical structure makes the service life short and is easily affected by pollution and vibration.

Summary of the invention

In order to solve the problems of complex structure, large volume and short service life of linear displacement measuring equipment in the prior art, the present invention provides an interference laser ruler.

In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: an interferometric laser ruler, comprising:

Laser ranging sensor assembly;

A dust cover, wherein the dust cover is arranged at the laser emitting end of the laser ranging sensor assembly;

And a reflector assembly, wherein the reflector assembly is arranged in a dust cover, the reflector assembly is connected to the moving object to be measured, the reflector assembly is arranged opposite to the laser ranging sensor assembly, the reflector assembly can move closer to or away from the laser ranging sensor assembly, and the reflector assembly is used to receive the laser emitted by the laser ranging sensor assembly and then reflect the laser to the laser ranging sensor assembly.

Preferably, the laser ranging sensor assembly includes a sensor housing and an optical chip measuring device, wherein the optical chip measuring device is arranged in the sensor housing, wherein the angle of the optical chip measuring device is adjustable around the X-axis, and the angle of the optical chip measuring device is also adjustable around the Y-axis, and the moving directions of the X-axis, Y-axis and reflector assembly are arranged perpendicular to each other. The laser emission angle of the optical chip measuring device can be adjusted around the X-axis and the Y-axis to ensure that the emitted laser is coaxial with the reflector assembly, to ensure the measurement accuracy and reliability of the interferometric laser ruler, and to facilitate the later maintenance, maintenance and calibration of the interferometric laser ruler, thereby increasing the service life of the interferometric laser ruler, wherein the reflector assembly can select the reflection device disclosed in the existing patent application 2024100769741.

Furthermore, the optical chip measurement device includes an optical chip measurement module, a first bracket and a second bracket, wherein the optical chip measurement module is arranged on the second bracket, the second bracket is arranged on the first bracket for rotation around the X axis, and the first bracket is arranged in the sensor housing for rotation around the Y axis. The circuit layout of the optical chip measurement module uses the optical chip integrated circuit layout disclosed in the existing application number BS.195593421, or uses the optical chip integrated circuit layout disclosed in the existing application number BS.20555542X. The adjustment structure of the laser emission angle of the optical chip measurement device is simple and compact, ingeniously designed, and easy to adjust.

Furthermore, the first bracket is provided with a first fastener along the Y-axis direction, and the second bracket is provided with a second fastener along the X-axis direction. The reliability and stability of the optical chip measurement device are greatly improved, and the service life of the interferometric laser ruler is effectively extended.

Furthermore, the first fastener is a first fastening screw, and the first bracket is provided with a first top screw along the X-axis direction; the second fastener is a second fastening screw, and the second bracket is provided with a second top screw along the Y-axis direction. The first top screw is rotated to adjust the laser emission angle of the optical chip measurement module around the Y direction, and the second top screw is rotated to adjust the laser emission angle of the optical chip measurement module around the X direction to ensure that the laser emitted by the optical chip measurement module is coaxial with the reflector assembly, and then the first fastening screw and the second fastening screw are tightened to firmly fix the optical chip measurement module, which is convenient to operate and reliable and stable as a whole.

Furthermore, the optical chip measurement device further includes a collimating lens, and the laser emitted by the optical chip measurement module reaches the reflector assembly after passing through the collimating lens, and is then reflected by the reflector assembly and received by the optical chip measurement module after passing through the collimating lens, thereby greatly improving the utilization rate of the laser, the measurement accuracy and sensitivity, and the adaptability.

Preferably, a through groove is provided on one side of the dust cover along its length direction, and special-shaped sealing strips are provided on both sides of the through groove, and the tail ends of the special-shaped sealing strips on both sides are in contact and sealed with each other, and the connecting end of the reflector assembly extends out of the dust cover between the special-shaped sealing strips on both sides and is connected to the moving object to be measured. The dust cover effectively protects the reflector assembly, ensures the measurement accuracy, reliability and stability of the interferometric laser ruler, and prolongs its service life.

Furthermore, the tail end of the special-shaped sealing strip has a plurality of grooves, and the grooves are filled with lubricating oil. The grooves allow the lubricating oil to stay for a long time, so that the connecting end of the reflector assembly can move smoothly along the through groove.

Preferably, the sensor housing is provided as a split housing, the inner cavity of the sensor housing is sealed; an air duct is integrated in the sensor housing, an air pipe joint is provided on the sensor housing, and the two ends of the air duct are respectively connected to the air pipe joint and the dust cover. The air pipe joint can be connected to an external air pipe, so that the dust cover is ventilated and pressurized through the air duct, so as to achieve the purpose of dustproof and waterproof inside the dust cover.

Preferably, the dust cover is provided in plurality, and the plurality of dust covers are connected in sequence, one end of the plurality of dust covers is connected to the laser emitting end of the laser ranging sensor assembly, and the other end is provided with a dust cover. According to the actual measurement length requirements, the appropriate number of dust cover sections is selected, the dust cover has a simple structure, is not limited in length, and has a low cost.

Preferably, the laser ranging sensor assembly further comprises a PCBA board, which is arranged in a sensor housing, and a connector is arranged on the sensor housing, and the optical chip measuring device, the PCBA board and the connector are electrically connected in sequence. The integration level is high, and the PCBA board is connected to the outside through the connector to realize power supply to the optical chip measuring device and information input and output.

Beneficial Effects

1. In the interferometric laser ruler of the present invention, the laser distance sensor component emits a laser, which returns after reaching the reflector component and is received by the laser distance sensor component. Then, the distance value between the laser distance sensor component and the reflector component is calculated based on the FMCW method. Since the laser distance sensor component is fixed and only the reflector component moves with the object to be measured, the interferometric laser ruler of the present application has the advantage of long service life by using free space as the measurement medium. The interferometric laser ruler has a simple and compact structure, a reasonable and reliable layout, and an excellent miniaturization advantage. At the same time, unlike the grating ruler that needs to have a built-in scale grating and causes a physical limitation in length, the interferometric laser ruler of the present application can measure long distances.

2. When assembling or calibrating the interferometric laser ruler of the present invention, the first screw is rotated to adjust the laser emission angle of the optical chip measurement module around the Y direction, and the second screw is rotated to adjust the laser emission angle of the optical chip measurement module around the X direction, so as to ensure that the laser emitted by the optical chip measurement module is coaxial with the reflector assembly, and then the first fastening screw and the second fastening screw are tightened to firmly fix the chip measurement module. The interferometric laser ruler is easy to assemble and calibrate, and is reliable and stable as a whole, greatly improving the utilization rate of the laser, improving the measurement accuracy and sensitivity, and having stronger adaptability.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

FIG1 is a schematic diagram of the three-dimensional structure of an interferometric laser ruler of the present invention;

FIG2 is a schematic diagram of the internal structure of the interferometric laser ruler of the present invention, wherein the arrow indicates the direction of the laser;

FIG3 is a schematic side view of a dust cover of an interferometric laser ruler according to the present invention;

FIG4 is a schematic diagram of the internal structure of the laser ranging sensor assembly of the interferometric laser ruler of the present invention;

FIG5 is an exploded schematic diagram of a laser ranging sensor assembly of an interferometric laser ruler according to the present invention;

FIG6 is an exploded schematic diagram of an optical chip measuring device of an interferometric laser ruler according to the present invention;

In the figure: 1. laser ranging sensor assembly, 11. sensor housing, 12. optical chip measuring device, 120. optical chip measuring module, 121. first bracket, 122. second bracket, 123. first rotating shaft, 124. first fastening screw, 125. first top screw, 126. second rotating shaft, 127. second fastening screw, 128. second top screw, 129. collimating lens, 13. air duct, 14. trachea joint, 15. PCBA board, 151. first PCBA sub-board, 152. second PCBA sub-board, 16. connector, 2. dust cover, 21. through groove, 22. special-shaped sealing strip, 221. groove, 23. dustproof end cap, 3. reflector assembly.

Detailed ways

The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

As shown in Figures 1 to 6, an interferometric laser ruler includes a laser ranging sensor assembly 1, a dust cover 2 and a reflector assembly 3. The dust cover 2 is arranged at the laser emitting end of the laser ranging sensor assembly 1; the reflector assembly 3 is arranged in the dust cover 2. The reflector assembly 3 of this embodiment selects the reflection device disclosed in the existing patent application 2024100769741. The reflector of the reflector assembly 3 of this embodiment is a focusing total reflector, which is not described in detail in this application. The reflector assembly 3 is connected to the moving object to be measured, and the reflector assembly 3 is arranged opposite to the laser ranging sensor assembly 1. The reflector assembly 3 can move close to or away from the laser ranging sensor assembly 1. The reflector assembly 3 is used to receive the laser emitted by the laser ranging sensor assembly 1, and then reflect the laser to the laser ranging sensor assembly 1.

The present application integrates a laser interferometer and a grating ruler, and is mainly composed of a laser distance sensor component 1, a dust cover 2, and a reflector component 3, achieving a perfect combination of miniaturization and integration. The laser distance sensor component 1 emits a laser, which returns after reaching the reflector component 3 and is received by the laser distance sensor component 1. Then, the distance value between the laser distance sensor component 1 and the reflector component 3 is calculated based on the FMCW method, which is used for high-precision distance measurement of moving objects. Since the laser distance sensor component 1 is fixed and only the reflector component 3 moves with the object to be measured, the interferometric laser ruler of the present application has the advantages of miniaturization and long life by using free space as the measurement medium. At the same time, unlike the grating ruler that needs to have a built-in scale grating and causes physical length limitations, the interferometric laser ruler of the present application can perform long-distance measurements, such as CNC machine tools, three-coordinate measuring machines, etc. Among them, the frequency modulated continuous wave (FMCW) ranging method is based on the principle of sending a continuous signal with a certain bandwidth and linear frequency change, and then performing fast Fourier transform on the received continuous signal, and calculating the time difference between the two signals by the frequency difference between the sent and received signals, and finally obtaining the corresponding distance value from the time difference. The FMCW method is based on the coherence principle, has strong anti-interference, and has the advantages of high signal-to-noise ratio, and has attracted widespread attention. Due to its high-precision measurement, it has begun to be widely used to measure the distance value of moving objects.

Specifically, in this embodiment, as shown in FIGS. 4 to 6 , the laser ranging sensor assembly 1 includes a sensor housing 11 and an optical chip measuring device 12, the optical chip measuring device 12 is arranged in the sensor housing 11, the angle of the optical chip measuring device 12 is adjustable around the X axis, the angle of the optical chip measuring device 12 is also adjustable around the Y axis, the moving direction of the reflector assembly 3 is the Z axis direction, and the X axis, the Y axis and the Z axis are arranged perpendicular to each other. Further, in this embodiment, the optical chip measuring device 12 includes an optical chip measuring module 120, a first bracket 121 and a second bracket 122, the optical chip measuring module 120 is arranged on the second bracket 122, the second bracket 122 is arranged on the first bracket 121 by rotating around the X axis through the second rotating shaft 126, and the first bracket 121 is arranged in the sensor housing 11 by rotating around the Y axis through the first rotating shaft 123. Further, in the present embodiment, a first fastener is provided on the first bracket 121 along the Y-axis direction, the first fastener is a first fastening screw 124, and a first top screw 125 is provided on the first bracket 121 along the X-axis direction; a second fastener is provided on the second bracket 122 along the X-axis direction, the second fastener is a second fastening screw 127, and a second top screw 128 is provided on the second bracket 122 along the Y-axis direction. In the present embodiment, the optical chip measurement module 120 has an internal interference optical path and an integrated circuit, and the internal interference optical path of the present embodiment adopts the existing "Mach-Zehnder" interferometric measurement technology; the integrated circuit layout of the optical chip measurement module 120 of the present embodiment selects the optical chip integrated circuit layout disclosed in the existing application number BS.195593421, or selects the optical chip integrated circuit layout disclosed in the existing application number BS.20555542X.

The laser emission angle of the optical chip measuring device 12 can be adjusted around the X-axis and the Y-axis, and the adjustment structure is simple and compact, the design is ingenious, and the adjustment is convenient, so as to ensure that the emitted laser is coaxial with the reflector assembly 3, ensure the measurement accuracy and reliability of the interferometric laser ruler, and facilitate the subsequent maintenance, maintenance and calibration of the interferometric laser ruler, thereby increasing the service life of the interferometric laser ruler.

Specifically, in this embodiment, as shown in Figures 4 and 6, the optical chip measurement device 12 also includes a collimating lens 129. The collimating lens 129 of this embodiment is integrated with the optical chip measurement module 120. The laser emitted by the optical chip measurement module 120 reaches the reflector assembly 3 after passing through the collimating lens 129, and is then reflected by the reflector assembly 3 and received by the optical chip measurement module 120 after passing through the collimating lens 129, thereby greatly improving the utilization rate of the laser, improving the measurement accuracy and sensitivity, and being more adaptable.

Specifically, in this embodiment, as shown in Figures 1 to 3, a through groove 21 is opened on one side of the dust cover 2 along its length direction, and special-shaped sealing strips 22 are arranged on both sides of the through groove 21. The tail ends of the special-shaped sealing strips 22 on both sides are in contact with each other and sealed, and the tail ends of the special-shaped sealing strips 22 have a plurality of grooves 221, and the grooves 221 are filled with lubricating oil. The connecting end of the reflector assembly 3 extends out of the dust cover 2 through the special-shaped sealing strips 22 on both sides and is connected to the moving object to be measured, and the connecting end of the reflector assembly 3 moves smoothly along the through groove 21.

Specifically, in this embodiment, as shown in Figures 2 and 5, the sensor housing 11 is configured as a split housing for easy assembly, and the inner cavity of the sensor housing 11 is sealed; an air duct 13 is also integrated in the sensor housing 11, and an air pipe connector 14 is provided on the sensor housing 11. The two ends of the air duct 13 are respectively connected to the air pipe connector 14 and the dust cover 2, and the air pipe connector 14 can be connected to an external air pipe, so that ventilation and pressurization are applied to the dust cover 2 through the air duct 13, so as to achieve the purpose of dustproof and waterproof inside the dust cover 2.

Specifically, in this embodiment, a plurality of dust covers 2 are provided, and the plurality of dust covers 2 are connected in sequence. One end of the plurality of dust covers 2 is connected to the laser emitting end of the laser ranging sensor assembly 1, and the other end is provided with a dustproof end cover 23. According to the actual need of measuring the length, a suitable number of sections of the dust cover 2 is selected. The dust cover 2 has a simple structure, is not limited in length, and has a low cost.

Specifically, in this embodiment, as shown in FIG5 , the laser ranging sensor assembly 1 further includes a PCBA board 15, the PCBA board 15 is disposed in the sensor housing 11, a connector 16 is disposed on the sensor housing 11, and the optical chip measuring device 12, the PCBA board 15 and the connector 16 are electrically connected in sequence. Further, in this embodiment, the PCBA board 15 of this embodiment includes a first PCBA sub-board 151 and a second PCBA sub-board 152 electrically connected in sequence, with a high degree of integration, and the PCBA board 15 is connected to the outside through the connector 16 to realize power supply to the optical chip measuring device 12 and information input and output.

Here’s how it works:

The laser emitted by the optical chip measurement module 120 reaches the reflector assembly 3 after passing through the collimating lens 129, and then is reflected by the reflector assembly 3 and returned through the collimating lens 129. The optical chip measurement module 120 receives the returned optical signal, and then calculates the distance value between the optical chip measurement module 120 and the reflector assembly 3 based on the existing FMCW method. Since the laser distance sensor assembly 1 is fixed and only the reflector assembly 3 moves with the object to be measured, the interferometric laser ruler has the advantages of miniaturization and long life by using free space as the measurement medium; at the same time, unlike the grating ruler that needs to have a built-in scale grating and causes physical length limitations, the interferometric laser ruler can measure long distances.

When assembling or later calibrating the interferometric laser encoder:

The first top screw 125 is rotated to adjust the laser emission angle of the optical chip measurement module 120 around the Y direction, and the second top screw 128 is rotated to adjust the laser emission angle of the optical chip measurement module 120 around the X direction to ensure that the laser emitted by the optical chip measurement module 120 is coaxial with the reflector assembly 3, and then the first fastening screw 124 and the second fastening screw 127 are tightened to firmly fix the optical chip measurement module 120. The assembly and calibration operations are convenient, and the overall reliability and stability are enhanced, which greatly improves the utilization rate of the laser, improves the measurement accuracy and sensitivity, and has stronger adaptability.

The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (10)

1. An interferometric laser encoder, characterized in that: it comprises: Laser ranging sensor assembly (1); A dust cover (2), wherein the dust cover (2) is arranged at a laser emitting end of the laser ranging sensor assembly (1); and a reflector assembly (3), wherein the reflector assembly (3) is arranged in the dust cover (2), the reflector assembly (3) is connected to the moving object to be measured, the reflector assembly (3) is arranged relative to the laser distance sensor assembly (1), the reflector assembly (3) can move closer to or farther from the laser distance sensor assembly (1), and the reflector assembly (3) is used to receive laser light emitted by the laser distance sensor assembly (1) and then reflect the laser light to the laser distance sensor assembly (1); The laser distance measuring sensor assembly (1) comprises a sensor housing (11) and an optical chip measuring device (12); the optical chip measuring device (12) is arranged in the sensor housing (11); the angle of the optical chip measuring device (12) is adjustable around an X-axis; the angle of the optical chip measuring device (12) is also adjustable around a Y-axis; and the moving directions of the X-axis, the Y-axis and the reflector assembly (3) are arranged perpendicular to each other. 2. The interferometric laser ruler according to claim 1, characterized in that: the optical chip measurement device (12) comprises an optical chip measurement module (120), a first bracket (121) and a second bracket (122), the optical chip measurement module (120) is arranged on the second bracket (122), the second bracket (122) is rotatably arranged on the first bracket (121) around an X-axis, and the first bracket (121) is rotatably arranged in the sensor housing (11) around a Y-axis. 3. The interferometric laser ruler according to claim 2, characterized in that: a first fastener is arranged on the first bracket (121) along the Y-axis direction; and a second fastener is arranged on the second bracket (122) along the X-axis direction. 4. The interferometric laser ruler according to claim 3, characterized in that: the first fastening member is a first fastening screw (124), and a first top screw (125) is arranged on the first bracket (121) along the X-axis direction; the second fastening member is a second fastening screw (127), and a second top screw (128) is arranged on the second bracket (122) along the Y-axis direction. 5. The interferometric laser ruler according to claim 2, characterized in that: the optical chip measurement device (12) further comprises a collimating lens (129), and the laser emitted by the optical chip measurement module (120) reaches the reflector assembly (3) after passing through the collimating lens (129), and is then reflected by the reflector assembly (3) and received by the optical chip measurement module (120) after passing through the collimating lens (129). 6. The interferometric laser ruler according to claim 1, characterized in that: a through groove (21) is provided on one side of the dust cover (2) along its length direction, and special-shaped sealing strips (22) are provided on both sides of the through groove (21), and the tail ends of the special-shaped sealing strips (22) on both sides are in contact with each other and sealed, and the connecting end of the reflector assembly (3) extends out of the dust cover (2) through the special-shaped sealing strips (22) on both sides and is connected to the moving object to be measured. 7. The interferometric laser encoder according to claim 6, characterized in that the tail end of the special-shaped sealing strip (22) has a plurality of grooves (221), and the grooves (221) are filled with lubricating oil. 8. The interferometric laser ruler according to any one of claims 1 to 7, characterized in that: the sensor housing (11) is provided as a split housing, and the inner cavity of the sensor housing (11) is sealed; an air duct (13) is also integrated in the sensor housing (11), and an air pipe joint (14) is provided on the sensor housing (11), and two ends of the air duct (13) are respectively connected to the air pipe joint (14) and the dust cover (2). 9. The interferometric laser ruler according to claim 8, characterized in that: a plurality of dust covers (2) are provided, the plurality of dust covers (2) are connected in sequence, one end of the plurality of dust covers (2) is connected to the laser emitting end of the laser ranging sensor assembly (1), and the other end is provided with a dustproof end cap (23). 10. The interferometric laser ruler according to any one of claims 1 to 5, characterized in that: the laser distance measuring sensor assembly (1) further comprises a PCBA board (15), the PCBA board (15) is arranged in a sensor housing (11), a connector (16) is arranged on the sensor housing (11), and the optical chip measuring device (12), the PCBA board (15) and the connector (16) are electrically connected in sequence.