CN117571108A - Laser vibration meter and laser vibration measuring method based on photon lantern - Google Patents
Laser vibration meter and laser vibration measuring method based on photon lantern Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
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Abstract
The disclosure relates to a laser vibration meter and a laser vibration measuring method based on a photon lantern, which are used in the technical field of laser measurement. This laser vibration meter includes: generating laser by a laser; the first beam splitter is configured to split laser to obtain reference light to be modulated and detection light, and modulate the reference light to be modulated to obtain first reference light; a transmitter configured to transmit probe light to a measured object and to receive reflected light obtained by reflecting the probe light by the measured object; a photon lantern configured to divide the reflected light into M single-mode reflected lights, wherein modes of the M single-mode reflected lights are different; a second beam splitter configured to split the first reference light into M second reference lights; a processor configured to calculate first vibration amplitude information of the object to be measured corresponding to each of the single-mode reflected lights from the M single-mode reflected lights and the M second reference lights; and combining the M pieces of first vibration amplitude information to obtain second vibration amplitude information of the measured object.
Description
Technical Field
The present disclosure relates to the field of laser measurement technologies, and more particularly, to a laser vibration meter and a laser vibration measurement method based on a photon lantern.
Background
The laser vibration meter sends laser to the object to be measured, receives reflected laser obtained by reflecting the laser by the object to be measured, and the reflected laser interferes with preset reference laser to obtain interference light; and obtaining vibration amplitude information of the measured object according to the obtained interference light.
In the process of realizing the inventive concept, it is found that the reflected laser is affected by the surface roughness of the measured object, so that the reflected laser cannot be totally reflected back to the laser vibration meter, the accuracy of the reflected laser is affected, and the accuracy of vibration amplitude information is further affected.
Disclosure of Invention
The disclosure provides a laser vibration meter and a laser vibration measuring method based on a photon lantern.
According to one aspect of the present disclosure, a laser vibrometer based on a photon lantern is presented, comprising: a laser configured to generate laser light; the first beam splitter is configured to split laser to obtain reference light to be modulated and detection light, and modulate the reference light to be modulated to obtain first reference light; a transmitter configured to transmit probe light to a measured object; receiving reflected light obtained by reflecting the detection light by the detected object, and transmitting the reflected light to the photon lantern; a photon lantern configured to divide the reflected light into M single-mode reflected lights, wherein the modes of the M single-mode reflected lights are different, and M is a positive integer greater than 1; a second beam splitter configured to split the first reference light into M second reference lights; and a processor configured to calculate first vibration amplitude information of the object to be measured corresponding to each of the single-mode reflected lights from the M single-mode reflected lights and the M second reference lights; and combining the M pieces of first vibration amplitude information to obtain second vibration amplitude information of the measured object.
According to an embodiment of the present disclosure, wherein the transmitter comprises: a fiber optic circulator including a first end, a second end, and a third end configured to: receiving the probe light through the first end; transmitting detection light to the measured object through the second end; receiving reflected light obtained by reflecting the detection light by the detected object through the second end; and transmitting the reflected light through the third end-to-end photon lantern.
According to an embodiment of the present disclosure, wherein the transmitter comprises: a first point diffractive fiber optic circulator including a fourth end, a fifth end, a sixth end, a polarizer, a first mirror, and a first polarizing beamsplitter configured to: receiving the detection light through the fourth terminal; the polarization state of the detection light is regulated by a polarizer, so that the detection light of the target polarization state is obtained; transmitting the detection light of the target polarization state to a fifth end through a first polarization splitting prism; transmitting detection light of a target polarization state to a measured object through a fifth end, and receiving reflected light obtained by reflecting the detection light of the target polarization state through the measured object through the fifth end; reflecting the reflected light to a first reflecting mirror through a first polarization splitting prism; reflecting the reflected light to the sixth end again by the first reflecting mirror; and transmitting the reflected light to the photon lantern through the sixth end.
According to an embodiment of the present disclosure, wherein the transmitter comprises: a second point diffractive fiber optic circulator including a seventh end, an eighth end, a ninth end, and a prism group configured to: receiving the detection light through a seventh end; transmitting the detection light to the eighth end through twice reflection inside the prism group; transmitting detection light to the detected object through the eighth end, and receiving reflected light obtained by reflecting the detection light by the detected object through the eighth end; transmitting the reflected light to the ninth end through one transmission inside the prism group; and transmitting the reflected light to the photon lantern through the ninth end.
According to an embodiment of the present disclosure, wherein the prism group includes: the device comprises a parallelogram prism, a first light source, a second light source and a third light source, wherein the parallelogram prism is configured to receive detection light through a first side face of the parallelogram prism, and the polarization state of the detection light is adjusted on the first side face to obtain detection light with a target polarization state; the side surface of the longest side of the triangular prism is connected with the second side surface of which the included angle of the first side surface is an acute angle, a reflecting film structure is arranged between the contact surfaces of the triangular prism and the parallelogram prism, and the reflecting film structure is configured to reflect the detection light of the target polarization state; the side surface of the trapezoid prism is connected with a third side surface of which the included angle of the trapezoid edge is an obtuse angle, a semi-transparent and semi-reflective film structure is arranged between the contact surfaces of the trapezoid prism and the parallelogram prism, the semi-transparent and semi-reflective film structure is configured to reflect the detection light of the target polarization state and also configured to transmit the reflected light obtained by the reflection of the detection light of the target polarization state by the measured object.
According to an embodiment of the present disclosure, wherein the transmitter comprises: a third point diffractive fiber optic circulator including a tenth end, a twelfth end, a second mirror, a second polarizing beamsplitter, and a polarizer configured to: receiving the detection light through a tenth end; reflecting the detection light to a second polarizing beam splitter by a second reflecting mirror; reflecting the detection light to the polaroid through a second polarizing spectroscope; the polarization state of the detection light is regulated by the polaroid to obtain detection light with a first polarization state; transmitting detection light in a first polarization state to the measured object through an eleventh end, and receiving reflected light obtained by reflecting the detection light in the first polarization state through the measured object through the eleventh end; the polarization state of the reflected light is regulated by the polaroid, so that reflected light in a second polarization state is obtained; the reflected light of the second polarization state is transmitted to the twelfth end through the second polarization beam splitter, and the reflected light of the second polarization state is sent to the photon lantern through the twelfth end.
According to an embodiment of the present disclosure, the processor is further configured to: obtaining interference light corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; calculating first vibration amplitude information of the measured object corresponding to each single-mode reflected light according to frequency information of the interference light corresponding to each single-mode reflected light; and weighting and superposing the differential results of the M pieces of first vibration amplitude information, and integrating the weighted and superposed calculation results to obtain second vibration amplitude information of the measured object.
According to an embodiment of the present disclosure, wherein the transmitter further comprises: an optical fiber holder configured to hold an optical fiber transmitting the probe light and the reflected light; and an optical fiber adjuster configured to adjust a position of the optical fiber holder.
In a second aspect of the present disclosure, a laser vibration measuring method based on the laser vibration measuring apparatus is provided, including: splitting laser to obtain reference light to be modulated and detection light, and modulating the reference light to be modulated to obtain first reference light; transmitting detection light to the detected object and receiving reflected light obtained by reflecting the detection light by the detected object; dividing the reflected light into M single-mode reflected lights, wherein the modes of the M single-mode reflected lights are different, and M is a positive integer greater than 1; splitting the first reference light into M second reference lights; calculating first vibration amplitude information of the measured object corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; and combining the M pieces of first vibration amplitude information to obtain second vibration amplitude information of the measured object.
According to an embodiment of the present disclosure, calculating first vibration amplitude information of a measured object corresponding to each single-mode reflected light from M single-mode reflected lights and M second reference lights includes: obtaining interference light corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; and calculating first vibration amplitude information of the object to be measured corresponding to each single-mode reflected light from frequency information of the interference light corresponding to each single-mode reflected light.
In the embodiment of the disclosure, since the detection light is fused with the optical signals of a plurality of modes, the vibration amplitude information of the measured object can be measured by using one beam of detection light, and meanwhile, the vibration amplitude information of the measured object can be measured by using the optical signals of a plurality of modes. The method comprises the steps of obtaining single-mode reflected light of different modes of single wavelength by mode demultiplexing reflected light input from an input end of a photon lantern; and then, a plurality of single-mode reflected lights are subjected to correlation calculation and contrast analysis, so that the influence caused by speckle of optical signals in different modes during detection can be eliminated, and the accuracy of vibration amplitude information measurement can be improved. In addition, when the single-wavelength laser is used for detecting in the multiplexing mode of the same photon lantern device, the lights in different modes do not influence each other, and the accuracy of obtaining vibration information can be improved, meanwhile, the number of optical devices is reduced, and the operation is simpler and more convenient.
Drawings
The above and other objects, features and advantages of the embodiments of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings. It should be noted that throughout the appended drawings, like elements are represented by like or similar reference numerals. In the figure:
fig. 1 shows a schematic structural diagram of a laser vibration meter according to an embodiment of the present disclosure.
Fig. 2A shows a schematic structural diagram of a laser vibrometer according to a specific embodiment of the present disclosure.
Fig. 2B shows a schematic structural diagram of a laser vibrometer according to another specific embodiment of the present disclosure.
Fig. 3 shows a schematic structural diagram of a laser vibration measuring method according to still another embodiment of the present disclosure.
Fig. 4 shows a flow diagram of a laser vibration measurement method according to an embodiment of the present disclosure.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the commonly understood meaning unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where expressions like at least one of "A, B and C, etc. are used, the expressions should be interpreted in a general sense as commonly understood (e.g.," a system having at least one of A, B and C "shall include, but not be limited to, a system having a alone, B alone, C alone, a and B, a and C, B and C, and/or A, B, C, etc.). Where expressions like "at least one of A, B or C, etc." are used, this expression should generally be interpreted in the sense which is commonly understood (e.g. "a system with at least one of A, B or C" shall include, but not be limited to, a system with a alone, B alone, C alone, a and B, a and C with a and C, B and C with A, B, C, etc.).
In the technical scheme of the disclosure, the related processes of data collection, storage, use, processing, transmission, provision, disclosure, application and the like all conform to the regulations of related laws and regulations, necessary security measures are taken, and the public order harmony is not violated.
In the technical solution of the present disclosure, authorization or consent is obtained before the data involved is obtained or acquired.
Fig. 1 shows a schematic structural diagram of a laser vibration meter according to an embodiment of the present disclosure.
As shown in fig. 1, the laser vibrometer 100 may include a laser 110, a first beam splitter 120, a transmitter 130, a photon lantern 140, a second beam splitter 150, and a processor 160.
The laser 110 may be configured as a generated laser light.
According to an embodiment of the present disclosure, the laser generated laser is a laser comprising a plurality of different modes. For example, different signals may be loaded on different modes to obtain a laser that fuses the multiple modes.
The first beam splitter 120 is configured to split the laser light to obtain reference light to be modulated and probe light, and modulate the reference light to be modulated to obtain first reference light.
According to embodiments of the present disclosure, the first beam splitter 120 may be integrated with a modulator for modulating the phase and/or frequency of the reference light.
And a transmitter 130 configured to transmit the probe light to the object under test. And the photon lantern is also configured to receive reflected light obtained by reflecting the detection light by the detected object and transmit the reflected light to the photon lantern.
According to an embodiment of the present disclosure, the transmitter 130 transmits the detection light to the object to be measured in a different optical path from an optical path that receives the detection light and transmits the detection light to the photon lantern.
In the field of laser vibration measurement, a laser vibration meter can send laser to an object to be measured, receive reflected laser obtained by reflecting the laser by the object to be measured, and interfere the reflected laser with preset reference laser to obtain interference light. Since the parameter of the interference light can characterize the frequency information corresponding to the velocity of the object to be measured, the vibration amplitude information of the object to be measured can be obtained from the frequency information.
In the embodiment of the disclosure, the reflected light is the light which is reflected from the measured object and carries the vibration amplitude information of the measured object after the probe light is transmitted to the measured object.
Photon lantern 140 is configured to split the reflected light into M single-mode reflected lights, where the modes of the M single-mode reflected lights are different and M is a positive integer greater than 1.
According to embodiments of the present disclosure, the number of photon beacons that split reflected light into single mode reflected light is related to the number of modes carried in the laser. After passing through the photon lantern, the reflected light is decomposed into a plurality of modes perpendicular to each other. The single mode reflected light of each mode carries a portion of the information in the reflected light.
The second beam splitter 150 is configured to split the first reference light into M second reference lights.
A processor 160 configured to calculate first vibration amplitude information of the object to be measured corresponding to each of the single-mode reflected lights from the M single-mode reflected lights and the M second reference lights; and combining the M pieces of first vibration amplitude information to obtain second vibration amplitude information of the measured object.
According to an embodiment of the disclosure, the number of second reference lights is the same as the number of single-mode reflected lights split out by the photon lantern, so that each single-mode reflected light interferes with one second reference light to obtain interference light corresponding to each single-mode reflected light. Frequency information of interference light corresponding to each single-mode reflected light is calculated to obtain first vibration amplitude information of the measured object corresponding to each single-mode reflected light; and then obtaining second vibration amplitude information of the measured object by combining the first vibration amplitude information of the measured object corresponding to each single-mode reflected light, namely M pieces of first vibration amplitude information.
According to the embodiment of the present disclosure, the first vibration amplitude information may be understood as vibration amplitude information of the measured object measured in a mode corresponding to each single-mode reflected light, and the second vibration amplitude information eliminates noise caused by stray light.
In the embodiment of the disclosure, since the detection light is fused with the optical signals of a plurality of modes, the vibration amplitude information of the measured object can be measured by using one beam of detection light, and meanwhile, the vibration amplitude information of the measured object can be measured by using the optical signals of a plurality of modes. The method comprises the steps of obtaining single-mode reflected light of different modes of single wavelength by mode demultiplexing reflected light input from an input end of a photon lantern; and then, a plurality of single-mode reflected lights are subjected to correlation calculation and contrast analysis, so that the influence caused by speckle of optical signals in different modes during detection can be eliminated, and the accuracy of vibration amplitude information measurement can be improved. In addition, when the single-wavelength laser is used for detecting in the multiplexing mode of the same photon lantern device, the lights in different modes do not influence each other, and the accuracy of obtaining vibration information can be improved, meanwhile, the number of optical devices is reduced, and the operation is simpler and more convenient.
According to embodiments of the present disclosure, the transmitter may include a fiber optic circulator. The fiber optic circulator includes a first end, a second end, and a third end.
The optical fiber circulator receives the detection light through the first end and transmits the detection light to the tested object through the second end. The optical fiber circulator also can receive reflected light obtained by reflecting the detection light through the detected object through the second end and send the reflected light to the photon lantern through the third end.
According to the embodiment of the disclosure, the three-terminal structure of the optical fiber circulator can realize isolation of detection light and reflected light. Due to the arrangement of the internal structure of the optical fiber circulator, the detection light received from the first end can only be output from the second end and cannot be output from the third end; light reflected from the second end receiving end can only be output from the third end, and cannot be output from the first end.
In addition, the optical path of the detection light is different from the optical path of the reflected light in the optical fiber circulator, so that the detection light and the reflected light with the same wavelength pass through the same optical fiber circulator device, but do not interfere in the optical fiber circulator, thereby improving the accuracy of laser vibration measurement.
According to embodiments of the present disclosure, the transmitter may include a first point diffraction fiber optic circulator. The first point diffraction fiber circulator may include a fourth end, a fifth end, a sixth end, a polarizer, a first polarizing beamsplitter, and a first mirror.
After the detection light enters the first point diffraction optical fiber circulator from the fourth end, the polarizer can adjust the polarization state of the detection light to obtain the detection light with the target polarization state. The target polarization state may be s polarization state or p polarization state.
The first polarization spectroscope can transmit the detection light of the target polarization state output by the polarizer to the fifth end, and send the transmitted detection light of the target polarization state to the measured object through the fifth end.
In an embodiment of the disclosure, the first point diffraction optical fiber circulator may further receive, through the fifth end, reflected light obtained by reflecting the probe light of the target polarization state by the measured object. The reflected light includes reflected light of the same polarization state as the target polarization state and reflected light mutually orthogonal to the target polarization state due to roughness of the surface of the object under test. Thus, after receiving the reflected light through the fifth end, the reflected light orthogonal to the target polarization state may be reflected to the first mirror again through the first polarization splitting prism, and the reflected light may be reflected again by the first mirror, so as to be transmitted to the sixth end. For the reflected light with the same polarization state as the target, based on the principle of reversible optical path, the reflected light with the same polarization state as the target can be output from the fourth end along the reverse optical path of the probe light.
However, since only reflected light that is mutually orthogonal to the target polarization state needs to be collected, the sixth end of the first point-diffraction fiber optic circulator is connected to the photonic lantern such that the first point-diffraction fiber optic circulator can transmit reflected light that is mutually orthogonal to the target polarization state to the photonic lantern through the sixth end.
It should be noted that, in the embodiment of the present disclosure, the fourth end of the first point diffraction fiber circulator is connected to only the transmitting-end optical fiber, so as to input the probe light into the first point diffraction fiber circulator; the sixth end is connected to only the output optical fiber for inputting the reflected light into the photon lantern, so that the reflected light returned along the reverse path of the probe light does not affect the laser vibration measurement.
According to embodiments of the present disclosure, the chamfer surface of the first polarizing beam splitter may be coated with a semi-transparent and semi-reflective film, so that the first polarizing beam splitter can transmit the detection light of the target polarization state while also reflecting the reflected light.
According to the embodiment of the disclosure, the micro small holes close to the wavelength of the detected light are formed at the fourth end, the fifth end and the sixth end, so that the detected light can generate ideal spherical wave front, the influence of wave front disturbance caused by parallel light beams formed by laser emission Gaussian beams or collimating lenses on subsequent interference is eliminated, and the energy loss of the detected light at polarizing devices such as a polarizer, a first polarizing spectroscope and the like is reduced. The polarizer, the first polarization spectroscope and the first reflecting mirror are structured so that the end face of the receiving optical fiber is parallel to the optical fiber for transmitting the detection light, and the optical path from the fourth end to the first polarization spectroscope of the detection light is ensured to be equal to the optical path from the sixth end to the first polarization spectroscope of the reflection light, so that the conjugation of the fourth end and the sixth end of the point diffraction optical fiber circulator is ensured, the additional phase caused by the inhibition of the optical path change is realized, the beam quality of the detection light is improved, and the generation of additional stray light except the detection light is avoided.
According to an embodiment of the present disclosure, a transmitter includes: the second point diffraction optical fiber circulator comprises a seventh end, an eighth end, a ninth end and a prism group. The second point diffractive fiber optic circulator is configured to: receiving the detection light through a seventh end; transmitting the detection light to the eighth end through twice reflection inside the prism group; transmitting detection light to the detected object through the eighth end, and receiving reflected light obtained by reflecting the detection light by the detected object through the eighth end; transmitting the reflected light to the ninth end through one transmission inside the prism group; and transmitting the reflected light to the photon lantern through the ninth end.
In an embodiment of the present disclosure, a semi-transparent and semi-reflective film structure is also disposed in the second point diffraction optical fiber circulator, so that the probe light is transmitted to the eighth end through two reflections inside the prism group; and transmits the reflected light to the ninth end through one transmission inside the prism group.
According to an embodiment of the present disclosure, the prism group includes triangular prisms, parallelogram prisms, and trapezoidal prisms.
The probe light may enter the prism group of the second point diffraction fiber optic circulator from the seventh end.
The first contact surface of the detection light and the parallelogram prism is the first side surface of the parallelogram prism. The first side of the parallelogram prism may be coated with a polarizing film for adjusting the polarization state of the detection light to obtain the detection light of the target polarization state.
The contact surface of the parallelogram prism and the triangle prism is a second side surface, and a reflecting film structure is arranged between the triangle prism and the second side surface of the parallelogram prism and is used for reflecting the detection light of the target polarization state to the other surface parallel to the second side surface, namely a third side surface, of the parallelogram prism.
A semi-transparent and semi-reflective film structure is also arranged between the third side surface of the parallelogram prism and the trapezoid prism, and is used for continuously reflecting the detection light reflected to the third side surface to the eighth end; the transflective film structure is further configured to partially transmit the reflected light incident from the eighth end to the trapezoidal prism and transmit the reflected light to the ninth end via the trapezoidal prism.
According to an embodiment of the present disclosure, the transmitter may include a third point diffractive fiber optic circulator. The third point diffractive fiber optic circulator may include a tenth end, a twelfth end, a second mirror, a second polarizing beamsplitter, and a 1/4 wave plate.
The third point diffraction fiber circulator receives the detection light through the tenth end and transmits the detection light to the second reflecting mirror. The second reflecting mirror reflects the detection light to the second polarizing beam splitter.
The second polarization spectroscope is provided with a semi-transparent semi-reflective film. In one aspect, the second polarizing beamsplitter may reflect the probe light reflected by the second mirror to the 1/4 wave plate. The 1/4 wave plate adjusts the polarization state of the detection light to obtain detection light of a first polarization state respectively, and transmits the detection light of the first polarization state to the tenth end.
The detection light with the first polarization state can be sent to the tested object through the tenth end of the third point diffraction optical fiber circulator; the reflected light reflected by the measured object can also be received.
And for the reflected light entering from the eleventh end, continuously adjusting the polarization state of the reflected light through the 1/4 wave plate, wherein the polarization state of the reflected light passing through the 1/4 wave plate is a second polarization state, and the first polarization state and the second polarization state are mutually orthogonal.
Since the polarization state of the reflected light and the polarization state of the detection light are mutually orthogonal after being adjusted by the 1/4 wave plate, the reflected light is not output from the tenth end along the reverse optical path of the detection light, but is output from the twelfth end to the photon lantern through the transmission of the second polarization spectroscope.
According to the embodiment of the disclosure, the second point diffraction optical fiber circulator and the third point diffraction optical fiber circulator are similar to the first point diffraction optical fiber circulator, and the three ports of the optical fiber circulators are respectively provided with a micro small hole close to the wavelength of the detected light, so that the detected light generates ideal spherical wave front, the influence of wave front disturbance caused by parallel light beams formed by laser emission Gaussian beams or collimating lenses on subsequent interference is eliminated, and the energy loss of the detected light at a prism group or a polarization state adjusting device such as a polarization spectroscope and a prism group is reduced. In addition, the prism group in the second point diffraction circulator, the second reflecting mirror in the third point diffraction circulator, the second polarization spectroscope and the 1/4 wave plate are all used for guaranteeing that the optical path of the detection light reaching the semi-transparent semi-reflective film structure is equal to the optical path of the reflection light reaching the semi-transparent semi-reflective film structure, so that the additional phase caused by the change of the optical path is restrained, the beam quality corresponding to the detection light is improved, and the generation of additional stray light except the detection light is avoided.
According to an embodiment of the present disclosure, the processor may be further configured to: obtaining interference light corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; calculating first vibration amplitude information of the measured object corresponding to each single-mode reflected light according to frequency information of the interference light corresponding to each single-mode reflected light; and weighting and superposing the differential results of the M pieces of first vibration amplitude information, and integrating the weighted and superposed calculation results to obtain second vibration amplitude information of the measured object.
Under the condition of actual detection, certain roughness exists on the surface of the detected object, so that speckle information can exist on the obtained reflected light under the condition that the detected light is reflected on the surface of the detected object, and the measurement accuracy is affected.
According to the embodiment of the disclosure, after the processor receives the second reference light and the interference light obtained by the single-mode reflected light, the interference light can be passed through the photoelectric converter to obtain an interference electric signal. Since the speckle of each single-mode reflected light when detecting the detected object affects the measurement accuracy of the first vibration amplitude information and is difficult to restrain, the second vibration amplitude information after restraining the speckle can be obtained by combining the first vibration amplitude information measured by the M single-mode reflected lights.
For example, the corresponding speckle information is obtained by analyzing the interference electric signal of each single-mode reflected light, and the error information is obtained from the speckle information of each single-mode reflected light. And then, obtaining the vibration amplitude information of the measured object by restraining error information corresponding to each single-mode reflected light.
Fig. 2A shows a schematic structural diagram of a laser vibrometer according to a specific embodiment of the present disclosure.
As shown in fig. 2A, the laser vibrometer may include a laser 201, a first beam splitter 202, a second beam splitter 203, a photon lantern 204, a transmitter 205, and a processor 206. The detection of the vibration amplitude information of the object 207 to be measured is realized by a laser vibrometer.
As shown in fig. 2A, the laser 201 outputs a beam of laser light fusing a plurality of modes, and the first beam splitter 202 splits and modulates the laser light received from the laser 201 to obtain probe light and first reference light. The probe light is transmitted to the object 207 to be measured through the transmitter 205, and the reflected light reflected from the object 207 to be measured is transmitted to the photon lantern 204.
Photon lantern 204 separates different modes in the reflected light to obtain M single-mode reflected light. As shown in fig. 2A, M is 3. The second reflected light 203 may also split the first reference light into 3 beams of second reference light. One of the second reference light interferes with one of the single-mode reflected lights to form interference lights, and the processor 206 receives the interference lights corresponding to each of the single-mode reflected lights, i.e., 3 interference lights. The processor 206 calculates first vibration amplitude information of the measured object in 3 modes according to the frequency information of the 3 interference lights; and obtaining second vibration amplitude information for inhibiting speckle by combining the first vibration amplitude information of the measured object in 3 modes.
In the embodiment shown in fig. 2A, the transmitter 205 may be a second point diffraction fiber circulator.
Fig. 2B shows a schematic structural diagram of a laser vibrometer according to another specific embodiment of the present disclosure.
The laser 201, first beam splitter 202, second beam splitter 203, photon lantern 204, and processor 206 in fig. 2B are similar to those in fig. 2A and are not described again here. The conveyor 208 in fig. 2B adds 1/4 slide to the rear of the prism set on the basis of the conveyor 205 in fig. 2A.
As shown in fig. 2B, the transmitter 208 includes a prism set 2081 and 1/4 slide 2082,1/4 slide 2082 for adjusting the polarization state of the detection light output from the prism set 2081 and the polarization state of the reflected light to enter the prism set 2081.
According to an embodiment of the present disclosure, the transmitter further comprises: an optical fiber holder configured to hold an optical fiber transmitting the probe light and the reflected light; and an optical fiber adjuster configured to adjust a position of the optical fiber holder.
In embodiments of the present disclosure, a processor may be a generalized description of a plurality of devices in aggregate. For example, the processor includes a wavelength division multiplexer, a detector, and an upper computer. The host computer may be a computer device.
Fig. 3 shows a schematic structural diagram of a laser vibration measuring method according to still another embodiment of the present disclosure.
As shown in fig. 3, the laser vibrometer includes a laser 301, a first beam splitter 302, a second beam splitter 303, a photon lantern 304, a transmitter 305, a first detector 3061, a second detector 3062, a third detector 3063, and a host computer 3064. The detection of the vibration amplitude information of the measured object 307 is realized by a laser vibrometer. The functions of the laser 301, the first beam splitter 302, the second beam splitter 303, the photon lantern 304, and the transmitter 305 are the same as those of fig. 2A and 2B, and will not be described herein.
After the photon lantern 304 divides the reflected light into 3 single-mode reflected lights, each single-mode reflected light and the corresponding second reference light form interference light, and the interference light enters the first detector 3061, the second detector 3062 and the third detector 3063 respectively. Information of the interference light of the 3 modes collected by the first detector 3061, the second detector 3062, and the third detector 3063 is transmitted to the upper computer 3064. The upper computer 3064 may calculate first vibration amplitude information of the measured object corresponding to each single-mode reflected light, and combine 3 pieces of the first vibration amplitude information to obtain second vibration amplitude information of the measured object.
Fig. 4 shows a flow diagram of a laser vibration measurement method according to an embodiment of the present disclosure.
As shown in fig. 4, the laser vibration measuring method 400 includes operations S410 to S460.
In operation S410, the laser is split to obtain reference light to be modulated and probe light, and the reference light to be modulated is modulated to obtain first reference light.
In operation S420, probe light is transmitted to the object to be measured, and reflected light obtained by reflecting the probe light by the object to be measured is received.
In operation S430, the reflected light is divided into M single-mode reflected lights, wherein the modes of the M single-mode reflected lights are different, and M is a positive integer greater than 1.
In operation S440, the first reference light is split into M second reference lights.
In operation S450, first vibration amplitude information of the measured object corresponding to each single-mode reflected light is calculated from the M single-mode reflected lights and the M second reference lights.
In operation S460, the M pieces of first vibration amplitude information are combined to obtain second vibration amplitude information of the measured object.
In the embodiment of the disclosure, since the detection light is fused with the optical signals of a plurality of modes, the vibration amplitude information of the measured object can be measured by using one beam of detection light, and meanwhile, the vibration amplitude information of the measured object can be measured by using the optical signals of a plurality of modes. The method comprises the steps of obtaining single-mode reflected light of different modes of single wavelength by mode demultiplexing reflected light input from an input end of a photon lantern; and then, a plurality of single-mode reflected lights are subjected to correlation calculation and contrast analysis, so that the influence caused by speckle of optical signals in different modes during detection can be eliminated, and the accuracy of vibration amplitude information measurement can be improved. In addition, when the single-wavelength laser is used for detecting in the multiplexing mode of the same photon lantern device, the lights in different modes do not influence each other, and the accuracy of obtaining vibration information can be improved, meanwhile, the number of optical devices is reduced, and the operation is simpler and more convenient.
Calculating first vibration amplitude information of the object to be measured corresponding to each single-mode reflected light from the M single-mode reflected lights and the M second reference lights includes: obtaining interference light corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; and calculating first vibration amplitude information of the object to be measured corresponding to each single-mode reflected light from frequency information of the interference light corresponding to each single-mode reflected light.
According to the embodiment of the disclosure, since the speckle information of each single-mode reflected light can be obtained by parameters related to external noise, partial cancellation can be realized after the speckle information of each single-mode reflected light is superimposed by weighting and then superimposing the first vibration amplitude information of a plurality of single-mode reflected lights, and the ratio of the vibration amplitude information to the speckle information is improved, thereby realizing that the speckle information caused by noise in the first vibration amplitude information is restrained and the accuracy of the second vibration amplitude information is improved.
According to the embodiment of the present disclosure, in the case of actual vibration measurement, interference light obtained by interference of the mth single-mode reflected light with the second reference light can be expressed by the following formula (1).
Wherein f m (t) is the frequency information of the mth interference light under the actual vibration measurement condition; a is that m (t) is amplitude information corresponding to the mth interference light under the actual vibration measurement condition; w is heterodyne frequency; lambda is the wavelength of the mth interference light under the actual vibration measurement condition, and the wavelengths of the M interference lights are equal; s is(s) m (t) first vibration amplitude information of the measured object corresponding to the mth interference light under the actual vibration measurement condition; b is the noise coefficient under the actual vibration measurement condition, and rand (t) is the noise information under the actual vibration measurement condition. M is more than or equal to 1 and less than or equal to M.
According to the embodiment of the disclosure, according to the frequency information of the mth interference light under the actual vibration measurement condition, the first vibration amplitude information of the measured object corresponding to the mth interference light under the actual vibration measurement condition can be obtained through the orthogonal demodulation algorithm, and can be represented by the following formula (2).
Wherein s (t) is the vibration average of the first vibration amplitude information of M interference lights under the actual vibration measurement conditionThe value of the sum of the values,is the speckle information of the mth interference light.
The first vibration amplitude information of the measured object corresponding to the M interference lights under the actual vibration measurement condition is differentiated (Diff) and then weighted and overlapped and integrated (Int), the differentiation purpose can remove the interference of s01 and s02, the noise information can be restrained, and the specific operation can be represented by the following formula (3):
wherein s3 (t) is vibration amplitude information of the measured object after noise suppression; c1 and c2 … cM are suppression coefficients corresponding to each interference light.
In accordance with an embodiment of the present disclosure,c m the specific value of (2) can be based on +.>The specific value of (a) is determined, and the suppression of rand (t) is realized through superposition of M suppression coefficients, namely, the suppression of noise information is realized.
It is to be understood that the features recited in the various embodiments of the present application and/or in the claims may be combined in various combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the present application. In particular, the features recited in the various embodiments and/or the claims of the present application may be combined and/or combined in various ways without departing from the spirit and teachings of the present application. All such combinations and/or combinations fall within the scope of the present application.
In the description of the present specification, a description referring to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The embodiments of the present application are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present application. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the application is defined by the appended claims and equivalents thereof. Various substitutions and modifications may be made without departing from the scope of the present application, and these substitutions and modifications are intended to fall within the scope of the present application.
Claims (10)
1. A laser vibrometer based on a photon lantern, comprising:
a laser configured to generate laser light;
the first beam splitter is configured to split the laser to obtain reference light to be modulated and detection light, and modulate the reference light to be modulated to obtain first reference light;
a transmitter configured to transmit the probe light to a measured object; receiving reflected light obtained by reflecting the detection light by the detected object, and transmitting the reflected light to a photon lantern;
a photon lantern configured to divide the reflected light into M single-mode reflected light, wherein the modes of the M single-mode reflected light are different, M being a positive integer greater than 1;
a second beam splitter configured to split the first reference light into M second reference lights; and
a processor configured to calculate first vibration amplitude information of the object to be measured corresponding to each single-mode reflected light from the M single-mode reflected lights and the M second reference lights; and combining M pieces of the first vibration amplitude information to obtain second vibration amplitude information of the measured object.
2. The laser vibrometer of claim 1, wherein the transmitter comprises:
a fiber optic circulator including a first end, a second end, and a third end configured to:
receiving the probe light through the first end;
transmitting the detection light to the detected object through the second end;
receiving reflected light obtained by reflecting the detection light by the tested object through the second end; and
and transmitting the reflected light to the photon lantern through the third end.
3. The laser vibrometer of claim 1, wherein the transmitter comprises:
a first point diffractive fiber optic circulator including a fourth end, a fifth end, a sixth end, a polarizer, a first mirror, and a first polarizing beamsplitter configured to:
receiving the probe light through the fourth end;
the polarization state of the detection light is regulated through the polarizer, so that the detection light with the target polarization state is obtained;
transmitting the detection light of the target polarization state to the fifth end through the first polarization splitting prism;
transmitting the detection light of the target polarization state to the tested object through the fifth end, and receiving the reflected light obtained by reflecting the detection light of the target polarization state by the tested object through the fifth end;
reflecting the reflected light to the first mirror by the first polarization splitting prism;
reflecting the reflected light again to the sixth end by the first mirror; and
and sending the reflected light to the photon lantern through the sixth end.
4. The laser vibrometer of claim 1, wherein the transmitter comprises: a second point diffractive fiber optic circulator including a seventh end, an eighth end, a ninth end, and a prism group configured to:
receiving the probe light through the seventh end;
transmitting the probe light to the eighth end through two reflections inside the prism group;
transmitting the detection light to the tested object through the eighth end, and receiving reflected light, obtained by reflecting the detection light by the tested object, through the eighth end;
transmitting the reflected light to the ninth end through a primary transmission inside the prism assembly; and
and sending the reflected light to the photon lantern through the ninth end.
5. The laser vibration meter of claim 4, wherein the prism set comprises:
a parallelogram prism configured to receive the detection light via a first side of the parallelogram prism, wherein the polarization state of the detection light is adjusted at the first side to obtain detection light of a target polarization state;
the side face of the longest side of the triangular prism is connected with the second side face of the first side face with an acute included angle, a reflecting film structure is arranged between the contact faces of the triangular prism and the parallelogram prism, and the reflecting film structure is configured to reflect the detection light of the target polarization state; and
the side face of the trapezoid prism is connected with the third side face of the first side face, the included angle of the third side face is obtuse, a semi-transparent and semi-reflective film structure is arranged between the contact faces of the trapezoid prism and the parallelogram prism and is configured to reflect the detection light in the target polarization state and also configured to transmit the reflected light obtained by the reflection of the detection light in the target polarization state by the tested object.
6. The laser vibrometer of claim 1, wherein the transmitter comprises:
a third point diffractive fiber optic circulator including a tenth end, a twelfth end, a second mirror, a second polarizing beamsplitter, and a polarizer configured to:
receiving the detection light through the tenth end;
reflecting the probe light to the second polarizing beamsplitter through the second mirror;
reflecting the probe light to the polarizer through the second polarizing beam splitter;
the polarization state of the detection light is regulated through the polaroid, so that the detection light with the first polarization state is obtained;
transmitting the detection light in the first polarization state to the tested object through the tenth end, and receiving reflected light, obtained by reflecting the detection light in the first polarization state by the tested object, through the tenth end;
the polarization state of the reflected light is regulated by the polaroid, so that reflected light with a second polarization state is obtained;
transmitting the reflected light of the second polarization state to the twelfth end through the second polarization spectroscope, and transmitting the reflected light of the second polarization state to the photon lantern through the twelfth end.
7. The laser vibration meter according to any one of claims 2-6, wherein the processor is further configured to:
obtaining interference light corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights;
calculating first vibration amplitude information of the measured object corresponding to each single-mode reflected light according to frequency information of the interference light corresponding to each single-mode reflected light;
and weighting and superposing the differential results of the M pieces of first vibration amplitude information, and integrating the weighted and superposed calculation results to obtain second vibration amplitude information of the measured object.
8. The laser vibration meter according to any one of claims 2-6, wherein the transmitter further comprises:
an optical fiber holder configured to hold an optical fiber that transmits the probe light and the reflected light; and
and a fiber adjuster configured to adjust a position of the fiber holder.
9. A laser vibration measuring method based on the laser vibration measuring instrument according to any one of claims 1 to 8, comprising:
splitting the laser to obtain reference light to be modulated and detection light, and modulating the reference light to be modulated to obtain first reference light;
transmitting the detection light to a detected object, and receiving reflected light obtained by reflecting the detection light by the detected object;
dividing the reflected light into M single-mode reflected lights, wherein the modes of the M single-mode reflected lights are different, and M is a positive integer greater than 1;
splitting the first reference light into M second reference lights;
calculating first vibration amplitude information of the measured object corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; and
and combining M pieces of the first vibration amplitude information to obtain second vibration amplitude information of the measured object.
10. The laser vibration measuring method according to claim 9, wherein the calculating first vibration amplitude information of the object to be measured corresponding to each single-mode reflected light from the M single-mode reflected lights and the M second reference lights includes:
obtaining interference light corresponding to each single-mode reflected light according to the M single-mode reflected lights and the M second reference lights; and
first vibration amplitude information of the object to be measured corresponding to each single-mode reflected light is calculated from frequency information of the interference light corresponding to each single-mode reflected light.
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| CN202311865625.XA CN117571108A (en) | 2023-12-29 | 2023-12-29 | Laser vibration meter and laser vibration measuring method based on photon lantern |
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| CN202311865625.XA CN117571108A (en) | 2023-12-29 | 2023-12-29 | Laser vibration meter and laser vibration measuring method based on photon lantern |
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