CN110749371A - Polarization laser Doppler vibration measurement system - Google Patents
Polarization laser Doppler vibration measurement system Download PDFInfo
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- CN110749371A CN110749371A CN201911157846.5A CN201911157846A CN110749371A CN 110749371 A CN110749371 A CN 110749371A CN 201911157846 A CN201911157846 A CN 201911157846A CN 110749371 A CN110749371 A CN 110749371A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
Abstract
The invention provides a polarized laser Doppler vibration measurement system which comprises a light source component, an interference light path component and a signal processing component, wherein the light source component comprises a linear polarized laser, a half wave plate, a first reflector and a first polarized beam splitter; the half wave plate is provided with a main shaft structure and can rotate along the circumferential direction; the interference light path component comprises a frequency shifter, a second polarization beam splitter, a quarter wave plate, a beam expanding focusing lens, a second reflecting mirror, a polarization rotator, a polarization-independent combiner, a third reflecting mirror and a balanced photoelectric detector; the signal processing assembly comprises an analog-to-digital conversion circuit and a wireless transceiving circuit, receives the electric signal of the balanced photoelectric detector and completes analog-to-digital conversion and digital signal sampling through the analog-to-digital conversion circuit; in conclusion, the method has the advantages of high signal utilization rate, increased signal-to-noise ratio, good overall use flexibility and automatic adjustment.
Description
Technical Field
The invention belongs to the technical field of vibration measurement equipment, and particularly relates to a polarization laser Doppler vibration measurement system.
Background
The laser vibration measuring technology is a new laser measuring technology developed based on the Doppler modulation effect of a vibrating object on a laser beam, and a heterodyne interference laser vibration measuring optical path system comprising a laser, a frequency shifter, a beam splitter, a collimating lens and a detector generally adopts a Mach-Zehnder (M-Z) type interference system to complete the interference of light beams, so as to extract information such as frequency, speed, displacement and the like of object vibration from interference signals. The laser measuring system utilizing the interference technology has the characteristics of non-contact, high precision, real-time performance and high resolution, and is widely applied to the fields of machinery, electronics, buildings, aerospace, navigation and the like.
Most current vibration meter optical path systems adopt a common broadband light beam splitting element as a core optical element of an optical path, so that half of energy of an optical signal returned from a measured object is lost after the optical signal enters an interferometer, and the utilization rate of the signal is low; for the low scattering effect of a plurality of measured objects, the technology also belongs to the field of weak signal detection, and for a single-tube detector, on one hand, a high-amplitude signal cannot be realized, and simultaneously, a high signal-to-noise ratio cannot be achieved, so that the resolution is not high; in addition, in the application fields of a plurality of different objects to be measured, the scattering effects of the measured objects are different, and the vibration meter cannot realize the measurement of each object through automatic adjustment; meanwhile, the vibration meter is connected with a computer through a wire for use, and often one computer can only be matched with one vibration meter for use, so that the flexibility of the vibration meter is greatly limited.
Aiming at the defects of the existing laser vibration measurement technology in the aspects of signal utilization rate, signal to noise ratio, flexibility and automatic adjustment, the invention provides a polarization laser Doppler vibration measurement system which utilizes the polarization characteristic of light according to the vibration Doppler effect and can effectively solve the problems.
Disclosure of Invention
The invention aims to provide a polarization laser Doppler vibration measurement system, which solves the problems of certain defects in the aspects of signal utilization rate, signal-to-noise ratio, flexibility and automatic adjustment in the actual use process of the existing vibration meter.
The invention provides the following technical scheme:
a polarized laser Doppler vibration measurement system comprises a light source assembly, an interference light path assembly and a signal processing assembly, wherein the light source assembly comprises a linear polarization laser, a half wave plate, a first reflector and a first polarization beam splitter; the half wave plate is provided with a main shaft structure and can rotate along the circumferential direction; linearly polarized light emitted by the linear polarization laser passes through the half-wave plate, is reflected by the first reflector, enters the first polarization beam splitter and is divided into vertical polarized light and first horizontal polarized light, and the polarization directions of the vertical polarized light and the first horizontal polarized light are orthogonal; the interference light path component comprises a frequency shifter, a second polarization beam splitter, a quarter wave plate, a beam expanding focusing lens, a second reflecting mirror, a polarization rotator, a polarization-independent combiner, a third reflecting mirror and a balanced photoelectric detector; the vertical linearly polarized light is converted into second horizontally polarized light after passing through the frequency shifter, the second horizontally polarized light sequentially passes through the second polarization beam splitter, the quarter-wave plate and the beam expanding focusing lens and then irradiates the surface of the measured object, and scattered light on the surface of the measured object is converted into signal light by the quarter-wave plate after being collected by the beam expanding focusing lens; the first horizontally polarized light enters the polarization rotator after being reflected by the second reflecting mirror and is converted into vertically polarized reference light; the signal light and the reference light are divided into two paths for interference after entering the polarization-independent combiner, wherein one path of interference light directly enters the balanced photoelectric detector, and the other path of interference light enters the balanced photoelectric detector after being reflected by the third reflector; the signal processing assembly comprises an analog-to-digital conversion circuit and a wireless transceiving circuit, receives the electric signal of the balanced photoelectric detector and completes analog-to-digital conversion and digital signal sampling through the analog-to-digital conversion circuit.
Furthermore, the vibration measurement system further comprises a remote client, and the remote client is a computer or a server with a human-computer interaction interface.
Further, the remote client receives the digital signal of the signal processing component through the wireless transceiver circuit.
Further, the wireless transceiver circuit comprises a 4G module, a WIFI module or an NB-IOT module.
Furthermore, the remote client analyzes the digital signal, and obtains and stores the frequency, speed and amplitude information of the vibration of the measured object.
Further, the first polarization beam splitter and the second polarization beam splitter adopt a single-wavelength high-transmission polarization separation cube for separating out orthogonal polarization components and simultaneously fully utilizing the collected signal light.
Further, the quarter wave plate has a polarization direction rotation characteristic independent of the propagation direction of the light beam, and is used for rotating the polarization direction of the forward transmission light beam clockwise and the polarization direction of the reverse transmission light beam anticlockwise by 45 degrees and fully utilizing the measurement signal.
Furthermore, the balance photoelectric detector is used for enhancing the signal quality and improving the signal to noise ratio, and the resolution and the measurement precision of the vibration measurement system are improved.
Furthermore, the beam expanding focusing lens has the characteristic of firstly expanding and then focusing the laser beam, is used for focusing the laser beam and simultaneously achieving collimation output, and enables the vibration measuring system to respectively measure a short-distance measured object and a long-distance measured object by adjusting the lens.
The invention has the beneficial effects that:
according to the polarized laser Doppler vibration measurement system, the half wave plate is additionally arranged at the rear end of the online polarized laser, so that the system can change the intensity ratio of measurement light and reference light to adapt to measured objects with different scattering rates;
the interference light path of the vibration measurement system utilizes polarization-related devices, so that the nondestructive utilization of return light signals can be realized, the utilization rate of scattered signals is improved, and the measurement sensitivity of the system is increased;
by balancing the utilization of the photoelectric detector, the signal-to-noise ratio of a system detection signal is increased, and the measurement resolution is improved;
the beam expanding focusing lens has the characteristics of expanding and then focusing the laser beam, so that the emitted laser beam can be focused and the aim of collimating and outputting can be fulfilled, and the system can measure a short-distance target and a long-distance target by adjusting the lens;
through the wireless transceiving circuit and the remote client, the trouble of wiring can be avoided, the remote client can receive data of a plurality of vibration measurement systems at the same time, and the data can be analyzed and stored, so that the use flexibility is better.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic structural view of the present invention;
labeled as: 1. the linear polarization laser comprises a linear polarization laser, 2, a half wave plate, 31, a first reflector, 4, a first polarization beam splitter, 5, a frequency shifter, 7, a second polarization beam splitter, 10, a quarter wave plate, 11, an expanded beam focusing lens, 32, a second reflector, 6, a polarization rotator, 8, a polarization-independent combiner, 33, a third reflector, 9, a balanced photoelectric detector, 12, an analog-to-digital conversion circuit, 13, a wireless transceiver circuit and 14, a measured object.
Detailed Description
As shown in fig. 1, a polarization laser doppler vibration measurement system includes a light source assembly, an interference light path assembly, and a signal processing assembly, where the light source assembly includes a linear polarization laser 1, a half-wave plate 2, a first reflector 31, and a first polarization beam splitter 4; the half wave plate 2 is provided with a main shaft structure and can rotate along the circumferential direction, and the intensity ratio of the measuring beam and the reference beam is changed by changing the included angle between the main shaft and the polarization direction of the linearly polarized laser beam; the interference light path component comprises a frequency shifter 5, a second polarization beam splitter 7, a quarter wave plate 10, an expanded beam focusing lens 11, a second reflecting mirror 32, a polarization rotator 6, a polarization independent coupler 8, a third reflecting mirror 33 and a balanced photoelectric detector 9;
the first polarization beam splitter 4 and the second polarization beam splitter 7 adopt a single-wavelength high-transmission polarization separation cube for separating out orthogonal polarization components and simultaneously fully utilizing the collected signal light; the quarter-wave plate 10 has a polarization direction rotation characteristic irrelevant to the propagation direction of the light beam, and is used for rotating the polarization direction of the forward transmission light beam clockwise and the polarization direction of the reverse transmission light beam anticlockwise by 45 degrees and fully utilizing the measurement signal; the balance photoelectric detector 9 is used for enhancing the signal quality and improving the signal-to-noise ratio, and increasing the resolution and the measurement precision of the vibration measurement system; the beam expanding and focusing lens 11 has the characteristics of expanding and then focusing laser beams, is used for focusing the laser beams and achieving collimation output at the same time, and enables the vibration measuring system to measure a short-distance measured object 14 and a long-distance measured object 14 respectively by adjusting the lens.
The signal processing assembly comprises an analog-to-digital conversion circuit 12 and a wireless transceiver circuit 13, receives the electric signal of the balanced photoelectric detector 9, and completes analog-to-digital conversion and digital signal sampling through the analog-to-digital conversion circuit 12.
The vibration measurement system further comprises a remote client, the remote client is a computer or a server with a human-computer interaction interface, the remote client receives the digital signals of the signal processing assembly through a wireless receiving and transmitting circuit, the wireless receiving and transmitting circuit comprises a 4G module, a WIFI module or an NB-IOT module, and the remote client analyzes the digital signals, obtains and stores the vibration frequency, speed and amplitude information of the object to be measured 14.
The working process of the specific embodiment is as follows:
linearly polarized light emitted by the linear polarization laser 1 passes through the half-wave plate 2, is reflected by the first reflecting mirror 31, enters the first polarization beam splitter 4, and is divided into vertical polarized light and first horizontal polarized light with orthogonal polarization directions;
the vertical linear polarized light is converted into second horizontal polarized light after passing through the frequency shifter 5, the second horizontal polarized light passes through the second polarization beam splitter 7, the polarization direction of the second horizontal polarized light is changed into the circular polarized light by clockwise rotation of the quarter-wave plate 10 along the light beam propagation direction, the circular polarized light is irradiated to the surface of an object to be measured 14 through the beam expanding focusing lens 11, and the light scattered by the surface of the object to be measured 14 is collected by the beam expanding focusing lens 11, and the polarization direction of the second horizontal polarized light is changed into the vertical polarized signal light by counterclockwise rotation of the quarter-wave plate 10 along the light beam;
the first horizontally polarized light enters the polarization rotator 6 after being reflected by the second reflecting mirror 32, and becomes vertically polarized reference light after the polarization direction is rotated by 90 degrees; the signal light and the reference light are divided into two paths for interference after entering the polarization independent combiner-divider 8, wherein one path of interference light directly enters the balanced photoelectric detector 9, and the other path of interference light enters the balanced photoelectric detector 9 after being reflected by the third reflector 33;
the signal processing assembly receives the electric signal of the balanced photoelectric detector 9, completes analog-to-digital conversion and digital signal sampling through the analog-to-digital conversion circuit 12, sends the mathematical signal to the remote client through the wireless transceiving circuit 13, and the remote client analyzes the digital signal to obtain and store the frequency, speed and amplitude information of the vibration of the object to be measured 14.
When the object 14 to be measured vibrates, the measuring beam modulated by the frequency shifter 5 is further modulated by the vibration speed, and the frequency is fC+fM+fDAnd the frequency of the reference light is fCAfter beam combination interference of the interference light path, the signal frequency is changed into fM+fDThen, the doppler frequency generated by the vibration can be demodulated through frequency mixing processing, so that the instantaneous vibration speed can be calculated, the vibration frequency of the object to be measured 14 can be obtained according to the change period of the doppler frequency, and after the frequency and the speed are obtained, the amplitude information of the vibration of the object to be measured 14 can be obtained through differentiation and integration.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A polarized laser Doppler vibration measurement system comprises a light source component, an interference light path component and a signal processing component, and is characterized in that the light source component comprises a linear polarization laser, a half wave plate, a first reflector and a first polarization beam splitter; the half wave plate is provided with a main shaft structure and can rotate along the circumferential direction;
linearly polarized light emitted by the linear polarization laser passes through the half-wave plate, is reflected by the first reflector, enters the first polarization beam splitter and is divided into vertical polarized light and first horizontal polarized light, and the polarization directions of the vertical polarized light and the first horizontal polarized light are orthogonal;
the interference light path component comprises a frequency shifter, a second polarization beam splitter, a quarter wave plate, a beam expanding focusing lens, a second reflecting mirror, a polarization rotator, a polarization-independent combiner, a third reflecting mirror and a balanced photoelectric detector;
the vertical linearly polarized light is converted into second horizontally polarized light after passing through the frequency shifter, the second horizontally polarized light sequentially passes through the second polarization beam splitter, the quarter-wave plate and the beam expanding focusing lens and then irradiates the surface of the measured object, and scattered light on the surface of the measured object is converted into signal light by the quarter-wave plate after being collected by the beam expanding focusing lens; the first horizontally polarized light enters the polarization rotator after being reflected by the second reflecting mirror and is converted into vertically polarized reference light; the signal light and the reference light are divided into two paths for interference after entering the polarization-independent combiner, wherein one path of interference light directly enters the balanced photoelectric detector, and the other path of interference light enters the balanced photoelectric detector after being reflected by the third reflector;
the signal processing assembly comprises an analog-to-digital conversion circuit and a wireless transceiving circuit, receives the electric signal of the balanced photoelectric detector and completes analog-to-digital conversion and digital signal sampling through the analog-to-digital conversion circuit.
2. The system of claim 1, further comprising a remote client, wherein the remote client is a computer or a server with a human-computer interface.
3. The system of claim 2, wherein the remote client receives the digital signal from the signal processing module via the wireless transceiver circuit.
4. The polarized laser Doppler vibration measurement system according to claim 3, wherein the wireless transceiver circuit comprises a 4G module, a WIFI module or an NB-IOT module.
5. The polarized laser Doppler vibration measurement system according to claim 4, wherein the remote client analyzes the digital signal, and obtains and stores frequency, velocity and amplitude information of the vibration of the object to be measured.
6. The polarization doppler vibrometry system of claim 1, wherein the first polarization beam splitter and the second polarization beam splitter employ a single wavelength high transmission polarization separation cube for separating out orthogonal polarization components while fully utilizing the collected signal light.
7. The polarized laser Doppler vibration measurement system according to claim 1, wherein the quarter-wave plate has polarization direction rotation characteristics independent of the propagation direction of the light beam, and is used for rotating the polarization direction of the forward transmission light beam clockwise and the polarization direction of the backward transmission light beam counterclockwise by 45 degrees to fully utilize the measurement signal.
8. The Doppler vibration measuring system according to claim 1, wherein the balanced photodetectors are used to enhance signal quality and signal-to-noise ratio, and increase the resolution and measurement accuracy of the vibration measuring system.
9. The polarized laser doppler vibration measurement system of claim 1, wherein the beam expanding focusing lens has a characteristic of expanding and then focusing the laser beam, and is configured to focus the laser beam and output the laser beam in a collimated manner, and the vibration measurement system is configured to measure the object to be measured at a short distance and a long distance by adjusting the lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911157846.5A CN110749371A (en) | 2019-11-22 | 2019-11-22 | Polarization laser Doppler vibration measurement system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911157846.5A CN110749371A (en) | 2019-11-22 | 2019-11-22 | Polarization laser Doppler vibration measurement system |
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| CN110749371A true CN110749371A (en) | 2020-02-04 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114679662A (en) * | 2022-05-27 | 2022-06-28 | 安徽至博光电科技股份有限公司 | Signal processing method and system |
| CN115008256A (en) * | 2022-08-04 | 2022-09-06 | 南京木木西里科技有限公司 | Vibration test system in rotary shaft movement process |
-
2019
- 2019-11-22 CN CN201911157846.5A patent/CN110749371A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114679662A (en) * | 2022-05-27 | 2022-06-28 | 安徽至博光电科技股份有限公司 | Signal processing method and system |
| CN115008256A (en) * | 2022-08-04 | 2022-09-06 | 南京木木西里科技有限公司 | Vibration test system in rotary shaft movement process |
| CN115008256B (en) * | 2022-08-04 | 2022-12-16 | 南京木木西里科技有限公司 | Vibration test system in rotary shaft motion process |
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Effective date of registration: 20231009 Address after: Floor 7, Building 51, Nanda Science Park, No. 8 Yuanhua Road, Xianlin Street, Qixia District, Nanjing City, Jiangsu Province, 210000 Applicant after: NANJING GUANGSHENG SUPERSTRUCTURE MATERIALS RESEARCH INSTITUTE Co.,Ltd. Applicant after: NANJING University Address before: 210000 7th floor, building 3, emerging industry incubation base, Science Park, Nanjing University, Jiangsu Province Applicant before: NANJING GUANGSHENG SUPERSTRUCTURE MATERIALS RESEARCH INSTITUTE Co.,Ltd. |
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