CN110657748A - Laser displacement sensor with automatic focusing function - Google Patents
Laser displacement sensor with automatic focusing function Download PDFInfo
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- CN110657748A CN110657748A CN201910882385.1A CN201910882385A CN110657748A CN 110657748 A CN110657748 A CN 110657748A CN 201910882385 A CN201910882385 A CN 201910882385A CN 110657748 A CN110657748 A CN 110657748A
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- laser
- mirror group
- measured surface
- voice coil
- coil motor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
Abstract
The invention discloses a laser displacement sensor with an automatic focusing function. The laser emits laser, the laser is projected on the surface of a measured object after passing through the emission mirror group, and surface scattered light is imaged on the photosensitive device after passing through the receiving mirror group; according to the distance of the measured object reflected by the position of the light spot on the photosensitive device, the relative position of the transmitting mirror group and the laser is adjusted by the voice coil motor, so that the laser beam can be accurately focused on the measured surface. The invention realizes the light spot focusing on the measured surface with different measuring distances through the automatic focusing mechanism, reduces the measuring error caused by the change of the light spot size in the measuring range and can further improve the repeated measuring precision of the laser triangular displacement sensor.
Description
Technical Field
The invention relates to a sensor in the technical field of optical measurement, in particular to a laser displacement sensor with an automatic focusing function.
Background
The laser displacement sensor has the advantages of simple structure, non-contact, high precision, high measurement speed, real-time processing and the like, and is widely applied to various occasions such as geometric parameter detection, surface topography measurement, three-dimensional modeling and the like.
The laser displacement sensor forms a scattering light spot by a laser beam on the measured surface and images on the photosensitive device, thereby realizing the measurement of displacement. The size of the scattering light spot affects the measurement accuracy of the sensor, the traditional laser displacement sensor fixes the laser focusing position at the central position of the measuring range, and the size of the scattering light spot on the surface of the measured object will be increased along with the approach of the measured distance to the limit of the measuring range, so that the measurement accuracy of the edge area of the sensor is reduced. In the prior art, repeated accuracy reduction caused by the increase of the spot size at the measuring range edge is not researched.
Disclosure of Invention
The invention provides a laser displacement sensor with an automatic focusing function, which can reduce measurement errors caused by the change of the size of a light spot in a measuring range.
The invention is realized by the following technical scheme:
the invention comprises a shell, a laser, an emission lens group and a voice coil motor which are arranged in the shell, the photosensitive device, central processing circuit and receiving mirror group, voice coil motor mainly comprises annular coil stator and the active cell of installing at annular coil stator inner circle, the transmitting mirror group is installed on voice coil motor's active cell, the top of transmitting mirror group is equipped with the laser instrument, the optical axis coincidence of transmitting mirror group and laser instrument and perpendicular to measured surface, voice coil motor's active cell drives the transmitting mirror group and reciprocates along the axial direction of annular coil stator thereby adjust the axial distance between transmitting mirror group and the laser instrument, receiving mirror group and photosensitive device have been arranged from nearly to far direction along the measured surface to one side of voice coil motor in proper order, central processing circuit is connected with photosensitive device and voice coil motor respectively, central processing circuit drives photosensitive device respectively and reads its output, and control voice coil motor's motion.
The laser emitted by the laser device irradiates the measured surface through the emitting mirror group to generate diffuse reflection, reflected light generated by the diffuse reflection is incident into the shell again and is imaged in the photosensitive device through the receiving mirror group, the central processing circuit obtains the distance from the measured surface to the shell according to the position distribution of light spots formed by imaging of the photosensitive device, the central processing circuit adjusts the axial distance between the emitting mirror group and the laser device by controlling the voice coil motor, the laser emitted by the laser device can be focused on the measured surface through the emitting mirror group, and then the distance from the measured surface to the shell is collected again through the laser emitted by the laser device to serve as displacement information of the measured surface.
When the measured surface is close to the laser displacement sensor, the central processing circuit drives the voice coil motor to move towards the direction far away from the laser; when the measured surface is far away from the laser displacement sensor, the central processing circuit drives the voice coil motor to move towards the direction close to the laser.
The photosensitive device adopts a CCD image sensor, a CMOS image sensor or a position sensitive sensor.
The optical axis of the receiving mirror group is arranged obliquely to the surface to be measured, and the photosensitive device is arranged perpendicular to the optical axis of the receiving mirror group. The emission lens group has many variations, so the description is not made. The emission lens group mainly comprises a collimating lens and a focusing lens which are sequentially arranged along the direction of a light path.
The invention has the beneficial effects that:
after the central processing circuit calculates and obtains the position information of the measured object, the voice coil motor is controlled to reach a specific position to adjust the relative distance between the transmitting lens group and the laser, so that the focusing position of the laser beam generated by the laser is close to the vicinity of the measured distance, the influence of the spot sizes of different positions in the measuring range on the measurement repetition precision is reduced, and the repetition precision of the working point outside the measuring range center is improved.
Drawings
Fig. 1 is a diagram showing a typical laser gaussian beam focusing spot size.
Fig. 2 is a hardware configuration diagram of laser measurement according to the present invention.
Fig. 3 is a schematic diagram of the laser displacement sensor with an automatic focusing function according to the present invention, which realizes the automatic focusing function for different measuring distances within a measuring range.
Fig. 4 is a flow chart of the laser displacement sensor with auto-focusing function according to the present invention.
In the figure: the device comprises a shell 1, a laser 2, a transmitting mirror group 3, a voice coil motor 4, a photosensitive device 5, a central processing circuit 6, a receiving mirror group 7 and a measured surface 8.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
As shown in fig. 2, the present invention includes a housing 1, and a laser 2, an emission mirror group 3, a voice coil motor 4, a photosensitive device 5, a central processing circuit 6, and a receiving mirror group 7 mounted in the housing, wherein the emission mirror group 3 is mounted on the voice coil motor 4. Laser emitted by the laser 2 irradiates the measured surface 8 through the transmitting mirror group 3 to generate diffuse reflection, and the diffusely reflected light is imaged on the photosensitive device 5 through the receiving mirror group 7. The position of the imaging light spot on the photosensitive device 5 is calculated by the central processing circuit 6 to obtain the distance of the corresponding measured surface 8. The emission mirror group 3 is mounted on the voice coil motor 4, and the voice coil motor 4 is driven to make the emission mirror group 3 and the laser 2 generate different relative displacement amounts, thereby leading to different focusing distances of the laser beams.
After the central processing circuit 6 calculates and obtains the distance information of the measured object, the central processing circuit controls and drives the voice coil motor 4 to reach a specific position, so that the relative positions of the emission lens group 3 and the laser 2 enable the focusing position of the laser beam to be close to the vicinity of the measured distance. Thereby reducing the influence of the increase of the spot size caused by defocusing on the measurement precision.
The specific implementation and principle of the invention are as follows:
in the hardware structure of the existing laser measurement sensor, the emission mirror group 3 is fixed, the focusing position of the emission mirror group is fixedly arranged at the measuring range center position of the sensor in advance, in other positions in the measuring range, the light spot on the measured surface 8 is increased due to the fact that the light spot is far away from the focusing plane, errors are easily generated in the measuring result, and the measuring repetition precision is inaccurate. As shown in fig. 1, the laser gaussian beam is focused at the central position of the measurement range, i.e. the beam waist position in the figure, the spot size at this time is minimum, and the spot sizes at both sides of the measurement range are increased by a certain divergence angle. As shown in figure 2, the emitting mirror group 3 is arranged on the voice coil motor, laser emitted by the laser 2 forms laser spots on a measured surface 8 through the emitting mirror group 3, and diffuse reflection light of the spots forms imaging spots on the photosensitive device 5 through the receiving mirror group 7. The central processing circuit 6 calculates the position of the laser spot to obtain distance information of the measured surface 8, and drives and adjusts the position of the voice coil motor 4 so that the final laser focusing position is positioned near the measured position. The measuring range of the laser sensor refers to the measuring range of the sensor, which can achieve effective measuring results. The invention can realize the effect of automatically focusing the measured surface 8 which is positioned in the measuring range of the laser sensor but at different positions.
When the measured surface 8 is at the near end of the measuring range, the voice coil motor 4 is driven to move away from the laser 2, so that the laser focusing position is near the measured surface; when the measured surface is at the far end of the measuring range, the voice coil motor 4 is driven to move close to the laser 2, so that the laser focusing position is near the measured surface, as shown in fig. 3 (b). When the laser focusing position is adjusted to be close to the measured surface, the displacement measurement of the measured surface 8 is carried out again through the laser emitted by the laser 2, so that the influence of the increase of the spot size on the two sides of the measuring range on the measurement precision can be reduced.
As shown in fig. 4, the sensor system does not control the movement of the driving voice coil motor 4, directly reads the relative distance of the measured surface 8 at this time, and controls the voice coil motor 4 to move to a specific position according to the value of the distance. The relationship between the distance of the measured surface 8 and the motion displacement of the voice coil motor 4 is in one-to-one correspondence, which approximately meets the Gaussian formula of the collection optics, and during actual operation, the displacement required by the voice coil motor 4 corresponding to the distance of different measured surfaces 8 can be obtained by calibrating in advance and maintaining a Look-Up Table (Look-Up Table) in the central processing circuit 6.
In conclusion, the invention realizes the light spot focusing on the measured surface with different measuring distances through the automatic focusing mechanism, reduces the measuring error caused by the change of the light spot size in the measuring range and can further improve the repeated measuring precision of the laser triangular displacement sensor.
Claims (5)
1. The utility model provides a laser displacement sensor with automatic focusing function which characterized in that: comprises a shell (1), a laser (2) arranged in the shell, a transmitting mirror group (3), a voice coil motor (4), a photosensitive device (5), a central processing circuit (6) and a receiving mirror group (7), wherein the voice coil motor (4) mainly comprises an annular coil stator and a rotor arranged at the inner ring of the annular coil stator, the transmitting mirror group (3) is arranged on the rotor of the voice coil motor (4), the laser (2) is arranged above the transmitting mirror group (3), the optical axes of the transmitting mirror group (3) and the laser (2) are superposed and are vertical to a measured surface (8), the rotor of the voice coil motor (4) drives the transmitting mirror group (3) to move up and down along the axial direction of the annular coil stator so as to adjust the axial distance between the transmitting mirror group (3) and the laser (2), the receiving mirror group (7) and the photosensitive device (5) are sequentially arranged on one side of the voice coil motor (4) along the direction from near to far from the measured surface (8, the central processing circuit (6) is respectively connected with the photosensitive device (5) and the voice coil motor (4).
2. The laser displacement sensor with automatic focusing function as claimed in claim 1, wherein: the laser emitted by the laser (2) irradiates the measured surface (8) through the emitting mirror group (3) and is subjected to diffuse reflection, the reflected light generated by the diffuse reflection is incident into the shell (1) again and is imaged on the photosensitive device (5) through the receiving mirror group (7), the central processing circuit (6) obtains the distance from the measured surface (8) to the shell (1) according to the position distribution of light spots formed by imaging of the photosensitive device (5), the central processing circuit (6) adjusts the axial distance between the emitting mirror group (3) and the laser (2) by controlling the voice coil motor (4), laser emitted by the laser (2) can be focused on the measured surface (8) through the emitting mirror group (3), and then the distance from the measured surface (8) to the shell (1) is collected again through the laser emitted by the laser (2) to serve as displacement information of the measured surface (8).
3. The laser displacement sensor with automatic focusing function as claimed in claim 2, wherein: when the measured surface (8) is close to the laser displacement sensor, the central processing circuit (6) drives the voice coil motor (4) to move towards the direction far away from the laser (2); when the measured surface (8) is far away from the laser displacement sensor, the central processing circuit (6) drives the voice coil motor (4) to move towards the direction close to the laser (2).
4. The laser displacement sensor with automatic focusing function as claimed in claim 1, wherein: the photosensitive device (5) adopts a CCD image sensor, a CMOS image sensor or a position sensitive sensor.
5. The laser displacement sensor with automatic focusing function as claimed in claim 1, wherein: the optical axis of the receiving mirror group (7) is arranged obliquely to the measured surface (8), and the photosensitive device (5) is arranged perpendicular to the optical axis of the receiving mirror group (7).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910882385.1A CN110657748A (en) | 2019-09-18 | 2019-09-18 | Laser displacement sensor with automatic focusing function |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910882385.1A CN110657748A (en) | 2019-09-18 | 2019-09-18 | Laser displacement sensor with automatic focusing function |
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| CN110657748A true CN110657748A (en) | 2020-01-07 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1056930A (en) * | 1991-05-08 | 1991-12-11 | 中国科学院工程热物理研究所 | Process for measuring on line length by laser microcomputer and device |
| JP2009258022A (en) * | 2008-04-18 | 2009-11-05 | Sony Corp | Displacement detecting device |
| JP2013096853A (en) * | 2011-11-01 | 2013-05-20 | Omron Corp | Displacement sensor |
| CN203069143U (en) * | 2012-12-25 | 2013-07-17 | 深圳市威盟光电科技有限公司 | Voice coil motor detecting device |
| CN206281454U (en) * | 2016-08-31 | 2017-06-27 | 常州高晟传感技术有限公司 | Universal integrated laser displacement sensor structure |
-
2019
- 2019-09-18 CN CN201910882385.1A patent/CN110657748A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1056930A (en) * | 1991-05-08 | 1991-12-11 | 中国科学院工程热物理研究所 | Process for measuring on line length by laser microcomputer and device |
| JP2009258022A (en) * | 2008-04-18 | 2009-11-05 | Sony Corp | Displacement detecting device |
| JP2013096853A (en) * | 2011-11-01 | 2013-05-20 | Omron Corp | Displacement sensor |
| CN203069143U (en) * | 2012-12-25 | 2013-07-17 | 深圳市威盟光电科技有限公司 | Voice coil motor detecting device |
| CN206281454U (en) * | 2016-08-31 | 2017-06-27 | 常州高晟传感技术有限公司 | Universal integrated laser displacement sensor structure |
Non-Patent Citations (2)
| Title |
|---|
| 段泽明等: "便携式微束Ｘ射线荧光谱仪的研发", 《原子能科学技术》 * |
| 钟英: "基于DVD激光头的微位移检测技术研究", 《中国优秀硕士学位论文全文数据库 信息科技辑》 * |
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Application publication date: 20200107 |