CN116223451A - Optical phased array-based subsurface damage detection method and device - Google Patents
Optical phased array-based subsurface damage detection method and device Download PDFInfo
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Abstract
The invention belongs to the technical field of optical precision measurement, and discloses a method and a device for detecting subsurface damage based on an optical phased array, wherein the method comprises the following steps: transmitting laser beams, polarizing and shaping the laser beams into flat-top beams, dividing the flat-top beams into multiple paths of parallel beams, and collimating and incidence the parallel beams on a sample to be detected through a phased array; generating a specific phase difference between adjacent array elements of the phased array, further enabling parallel light beams to interfere and strengthen in a specific direction, enabling the light beams to deflect a specific angle and be injected into a sample to be tested for scanning, and performing multiple scattering at an subsurface damage position to form scattered light beams; collecting light intensity data of the scattered light beam by using a silicon photomultiplier; repeating the scanning for a plurality of times until the surface of the sample to be detected is scanned completely, and analyzing and comparing the collected multiple groups of light intensity data with the light intensity data of the normal sample to determine the position and the appearance of subsurface damage of the sample to be detected. The invention can realize rapid and high-precision detection of subsurface damage and has wide application prospect.
Description
Technical Field
The invention belongs to the technical field of optical precision measurement, and particularly relates to a method and a device for detecting subsurface damage based on an optical phased array.
Background
In material science and engineering, detection and analysis of surface and subsurface defects is very important. Surface and subsurface defects can lead to reduced material properties, component failure, and worse yet, accidents. Conventional material defect detection methods generally detect defects on the surface of the material, and require more complex techniques for subsurface defect detection.
One common method of detecting subsurface defects is by optical techniques, which can be used to infer the location and morphology of subsurface defects by illuminating the surface of the sample with a laser beam and then observing the intensity and distribution of the scattered light. As disclosed in patent document CN113607750a, a detection method of the device is to focus excitation laser and detection laser to different depths of an optical element simultaneously through a dispersive lens group, induce ultrasonic vibration on the subsurface of the optical element by the excitation laser, observe and record the ultrasonic vibration, and obtain spatial distribution information and scattering spectrum information of scattered light at the subsurface defect position by a spectral confocal technology; by utilizing the technology, multi-dimensional information such as a reflection spectrum, a scattering spectrum, a three-dimensional shape, a defect depth and the like of the defect is obtained, and the subsurface defect is accurately detected. However, the optical detection technology has the defects of complex structure and difficult operation of the detection device when detecting the subsurface defects, and the very small defects can not be detected due to the limited optical resolution of the detection device, and meanwhile, the detection accuracy of the method has the defects because the control of the incident light angle depends on the mechanical control of the motion platform and the motion control error is large.
In order to overcome these limitations, a detection method and a detection device capable of improving the detection accuracy of subsurface damage of a material are urgently needed to obtain more light intensity information of subsurface defects of the material so as to realize rapid and accurate detection of the morphology and the position of subsurface damage.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a detection method and a detection device for subsurface damage based on an optical phased array, which are used for solving the problems that the existing detection device is complex in structure, the corresponding detection method is complex in step and difficult to operate, and the detection is difficult to carry out fast and accurate detection during detection, so that the obtained detection result is inaccurate.
In order to achieve the above object, the present invention provides a method for detecting subsurface damage based on an optical phased array, comprising the following steps:
s1, emitting laser beams, polarizing and shaping the laser beams into flat-top beams, dividing the flat-top beams into multiple paths of parallel beams, and enabling the parallel beams to be collimated and incident on a sample to be detected through a phased array;
s2, adjusting the array element phase of the phased array to enable adjacent array elements to generate specific phase differences, further enabling the parallel light beams to generate interference enhancement in a specific direction in the phased array based on the specific phase differences to form deflection light beams, enabling the deflection light beams to deflect a specific angle and jet into a sample to be detected for scanning, and performing multiple scattering at subsurface damage to form scattering light beams with changed polarization states;
s3, collecting light intensity data of the scattered light beams by utilizing a plurality of silicon photomultiplier;
s4, repeating the steps S2-S3 for a plurality of times until the surface of the sample to be detected is scanned completely, and analyzing and comparing the collected multiple groups of light intensity data with the light intensity data of the normal sample to determine the position and the appearance of subsurface damage of the sample to be detected.
Further, in step S2, the specific phase difference between adjacent array elements after each adjustment is different from the previous one, so that the deflection angle of the deflected beam formed each time is different from the previous one.
Further, the data collection end of each silicon photomultiplier faces the surface to be measured of the sample to be measured.
Furthermore, the silicon photomultiplier takes the sample to be detected as a sphere center and is arranged on a hemispherical outline surface above the sample to be detected, and the radii of the hemispherical outline surfaces are the same or different.
Further, the intervals between the adjacent silicon photomultiplier are equal or unequal; preferably, when the pitches between the adjacent silicon photomultipliers are not equal, the pitch of the spherical center angles of the adjacent silicon photomultipliers is 5 degrees within the range of the spherical center angles of +/-30 degrees; preferably, in the range of-80 ° to-30 ° of the sphere center angle, the sphere center angle interval between adjacent silicon photomultiplier is 10 °; more preferably, the pitch of the sphere center angles of adjacent silicon photomultipliers is 10 ° in the range of 30 ° to 80 °.
Further, the phased array is made of electro-optic crystals; preferably, different voltages are applied to the phased array in real time, so that different phase differences are generated between adjacent array elements in real time; more preferably, the relationship between the phase difference and the voltage is expressed by the following mathematical expression:
wherein, the liquid crystal display device comprises a liquid crystal display device,
is a phase difference, n o The refractive index of the electro-optic crystal to o light is r, the linear electro-optic coefficient is r, V is the applied voltage, and lambda is the wavelength of Gaussian beam.
Further, before collecting the light intensity data of the scattered light beams, the interference scattered light beams irradiated to the rough surface of the sample to be detected, the polarization states of which are not changed, are filtered, so that the scattered light beams with the polarization states changed are reserved.
Further, the maximum power of the Gaussian beam is 100mW; preferably, the distance between adjacent array elements in the phased array is 1um-3um; more preferably, the distance between adjacent array elements in the phased array is 2um.
According to another aspect of the present invention, there is also disclosed an optical phased array-based subsurface damage detection device, including a central control processor, and a laser light source, a light source modulation system, a phased array, and a scattered data detection system respectively connected in communication with the central control processor, wherein:
the laser light source is used for emitting laser beams and enabling the laser beams to be directed into the light source modulation system;
the light source modulation system is used for converting the laser beam into a polarized Gaussian beam, shaping the Gaussian beam into a flat-top beam and dividing the flat-top beam into multiple parallel beams to enter a phased array;
the phased array is used for changing the phase of array elements so that the parallel light beams are interfered and enhanced in a specific direction to form deflection light beams, the deflection light beams deflect a specific angle and are injected into a sample to be tested along the specific direction, and the deflection light beams are scattered for multiple times at the subsurface damage position of the sample to be tested to form scattered light beams with changed polarization states;
the scattered data detection system is used for collecting light intensity signals of the scattered light beams and sending the light intensity signals to the central control processor;
the central control processor is used for controlling the phased array to change the phase of the array element, receiving the light intensity data, and comparing the light intensity data with the light intensity data of a normal sample to determine the position and the appearance of subsurface damage of the sample to be detected.
Further, the light source modulation system comprises a beam shaping system and a beam splitter, which are coaxially arranged with the laser light source beam emission end, wherein the beam shaping system is used for converting the laser beam into a polarized Gaussian beam, shaping the polarized Gaussian beam into a flat-top beam and injecting the flat-top beam into the beam splitter, and the beam splitter is used for dividing the flat-top beam into multiple paths of parallel beams and collimating and injecting the multi-path parallel beams into the phased array; preferably, the scattering data detection system comprises a hemispherical supporting shell and a plurality of silicon photomultiplier arranged on the hemispherical supporting shell, wherein the hemispherical supporting shell is arranged above the sample to be detected, and the data acquisition ends of the silicon photomultiplier face the sample to be detected; more preferably, the shell surface of the hemispherical supporting shell is coated with a light-absorbing coating and/or light-absorbing micro-nano structure for preventing light beams passing through the shell from scattering; still further preferably, the data acquisition ends of the silicon photomultiplier are each provided with an analyzer for filtering the interference scattered light beam irradiated to the rough surface of the sample to be measured without changing the polarization state.
Compared with the prior art, the technical scheme of the invention mainly has the following advantages:
1. the invention can reshape Gaussian beams into collimated flat-top beams with evenly distributed output energy, divide the collimated flat-top beams into multiple paths of parallel beams, inject the collimated flat-top beams into a phased array, and generate specific phase differences between adjacent array elements by adjusting the array element phases of the phased array, and generate optical path differences based on different phases when the parallel beams pass through the phased array, so that the parallel beams with different phases interfere, namely interfere and overlap in a specific direction, interfere and offset in other directions, and finally deflect laser by a specific angle in the specific direction, thereby realizing rapid and accurate incident angle adjustment.
2. According to the invention, through rapid and accurate incident angle adjustment, the parallel light beams interfere in a specific direction, the light beams deflect a specific angle and are emitted into a sample to be detected along the specific direction, and a scattered light beam is formed at the subsurface damage position of the sample to be detected, so that the polarization state of the scattered light beam is changed due to multiple scattering, and then the low-noise defect light signals in the scattered light beam are amplified by the silicon photomultiplier to acquire the light intensity data of the scattered light beam to be used as analysis data for determining the subsurface damage morphology, so that damage and pollution to the sample to be detected are avoided through non-contact detection.
3. The phase of the phase array is changed at any time by applying different voltages in real time due to the birefringence property of the electro-optic crystal material, so that the optical path difference is generated when the light beam passes through the phase array to generate interference, and the deflection angle and the incidence direction of the reinforced light beam generated by the interference can also be changed in real time along with the change of the phase of the adjacent array elements, thereby the phase array can accurately and rapidly finish the deflection of the incident light beam, and the incident light beam can be scanned faster and more accurately, so that the detection efficiency and the accuracy can be greatly improved; in addition, the array element spacing is between 1 μm and 3 μm, and corresponds to the scanning range of different angles, and for the same subsurface damage in a sample, laser beams with different incidence angles in different directions are incident, so that scattered light with different field intensity distribution can be caused.
4. The invention collects light intensity data by utilizing a plurality of silicon photomultiplier tubes positioned above the sample to be detected, and the silicon photomultiplier tubes have the advantages of high sensitivity, large signal amplification ratio, high response speed and the like, and can efficiently collect and amplify low noise defect signals from the sample to be detected in the detection process; the data acquisition ends of the silicon photomultiplier face the sample to be detected, the sample to be detected is taken as a sphere center, the silicon photomultiplier is uniformly distributed above the sample to be detected along the hemispherical outline, and according to different acquisition requirements, the arrangement mode and the distribution density of the silicon photomultiplier are different, so that scattered light signals can be accurately collected under different azimuth angles and scattering angles, and converted into electric signals for amplification, and a reliable data basis is provided for subsequent data processing and visual detection result output.
5. Before collecting the light intensity data of the scattered light beams, the invention filters the scattered light with unchanged deflection state, because the scattered light is scattered from the rough surface of the sample, the incident light is simply scattered on the rough surface, the polarization state is not changed, and the scattered light with unchanged polarization is repeatedly scattered at the subsurface damage, and the polarization state is changed, so the scattered light with unchanged polarization is filtered, the influence of the roughness of the surface of the sample can be eliminated, and the detection application range of the invention is enlarged.
6. The detection device is simple in structure and only comprises a laser light source, a light source modulation system, a phased array, a scattered data detection system and a central control processor, wherein the central control processor can control the phased array to adjust the phase of the array element in real time so as to quickly and accurately adjust the direction of incident laser; meanwhile, the method can also receive the scattered light intensity information of different azimuth angles and different scattering angles acquired by the scattered data detection system, and can process the acquired data in real time, so that the light intensities of different scattering angles corresponding to different incident angles are integrated in one scattering matrix, further more change information related to subsurface damage depth morphology is obtained, and visual light intensity information is output.
Drawings
FIG. 1 is a schematic diagram of an optical phased array-based subsurface damage detection device provided by the invention;
FIG. 2 is a schematic diagram of beam shaping principle in a light source modulation system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a phased array controlled laser beam deflection by a specific angle in an embodiment of the invention;
fig. 4 is a schematic diagram of the arrangement of silicon photomultiplier on hemispherical support shell in accordance with an embodiment of the present invention.
In the figure: 1-laser source, 2-polaroid, 3-beam shaping system, 301-Gaussian beam, 302-aspheric shaping lens, 303-flat-top beam, 4-beam splitter, 5-phased array, 6-sample to be measured, 7-hemispherical support shell, 8-silicon photomultiplier, 81-analyzer, 9-central control processor and 10-wave controller.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like indicate orientations or positional relationships that are shown based on the drawings, merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
The invention provides a detection method of subsurface damage based on an optical phased array, which can be realized on a detection device of subsurface damage based on the optical phased array, and the device comprises the following components: the method comprises the following steps of:
s1, emitting laser beams, dividing the laser beams into multiple paths of parallel beams after polarizing and shaping the laser beams into flat-top beams, enabling the parallel beams to be collimated and incident into a phased array, and enabling the parallel beams to be emitted from the phased array and then collimated and incident into a sample to be detected;
s2, adjusting the array element phases of a phased array to generate specific phase differences between adjacent array elements, further enabling parallel light beams to interfere and strengthen in a specific direction in the phased array based on the specific phase differences to form deflection light beams, deflecting the deflection light beams by a specific angle, injecting the deflection light beams into a sample to be detected in the specific direction for scanning, and performing multiple scattering at subsurface damage positions of the sample to be detected to form scattered light beams with changed polarization states;
s3, collecting light intensity data of the scattered light beams by utilizing a plurality of silicon photomultiplier;
s4, repeating the steps S2-S3 for a plurality of times until the surface of the sample to be detected is scanned completely, and analyzing and comparing the collected multiple groups of light intensity data with the light intensity data of the normal sample to determine the position and the appearance of subsurface damage of the sample to be detected.
In a preferred embodiment, the steps S3-S4 are repeated to collect light intensity data of multiple groups of scattered light beams, and each time of collection, the phase of each array element is adjusted to be different from the previous time, so that the deflection angle of each formed deflection light beam is different from the previous time.
In the preferred embodiment, the data acquisition end of each silicon photomultiplier faces the surface to be measured of the sample to be measured, so that the light intensity data of the scattered light beams can be acquired more accurately and comprehensively;
in a more preferred embodiment, the above-mentioned plurality of silicon photomultipliers are arranged on the same or different hemispherical outline surface above the sample to be tested by taking the sample to be tested as a sphere center, that is, the hemispherical surface where each silicon photomultiplier is located takes the sample to be tested as a sphere center, but the radius of the hemispherical surface can be the same or different, so that the position of the silicon photomultiplier can be regulated and controlled more accurately, and the light intensity data of the required scattered light beams can be acquired more accurately.
In a preferred embodiment, in step S5, the spacing between adjacent silicon photomultipliers is equal or unequal; when the intervals between the adjacent silicon photomultiplier are unequal, the interval between the spherical center angles of the adjacent silicon photomultiplier is 5 degrees within the sphere center angle range of +/-30 degrees, namely the distribution density is more dense, and more light intensity data can be acquired;
in a more preferred embodiment, the center-of-sphere angle spacing between adjacent silicon photomultipliers is 10 ° in the range of-80 ° to-30 ° center-of-sphere angle;
in a still further preferred embodiment, the center-of-sphere angle spacing of adjacent silicon photomultipliers is 10 ° in the range of 30 ° to 80 ° center-of-sphere angle; the different silicon photomultiplier arrangement modes can realize that the silicon photomultiplier is controlled to rapidly acquire the light intensity data of scattered light beams with different azimuth angles and different scattering angles when the reinforced polarized light beams with specific phase differences are irradiated to the sample to be detected to be scattered.
In a preferred embodiment, the phased array is made of an electro-optic crystal, and the change in refractive index of the electro-optic crystal is proportional to the strength of the electric field, known as the linear electro-optic effect or Pockels effect, i.e. Δn=re, r being the linear electro-optic coefficient. The optical path difference of the light beam passing through the electro-optic crystal material can be changed through the change of the refractive index, and then the phase difference is changed, so that the phase adjustment can be completed by simply applying linear voltage, wherein the applied voltage V=E×L, and L is the length of the light beam passing through the electro-optic crystal, and the operation steps are simple;
in a more preferred embodiment, different voltages are applied to the phased array in real time, so that different phase differences are generated between adjacent array elements in real time; the relationship between the phase difference and the voltage is expressed by the following mathematical expression:
wherein, the liquid crystal display device comprises a liquid crystal display device,
is a phase difference, n o The refractive index of the electro-optical crystal to o light, r is a linear electro-optical coefficient, V is an applied voltage, lambda is the wavelength of Gaussian beam, and o light is the ordinary light.
In a preferred embodiment, the maximum power of the Gaussian beam emitted by the laser source is 100mW, if the maximum power exceeds the maximum power, the detection device is damaged, and if the damage of the device is avoided, the energy of the laser beam is controlled through a complex regulation and control mode;
in the preferred embodiment, in step S3, before collecting the light intensity data of the scattered light beams, the interference scattered light beams irradiated to the rough surface of the sample to be measured without changing the polarization state are filtered, so that the scattered light beams with changed polarization states are reserved, and the light intensity data of the interference scattered light beams are prevented from influencing the subsequent analysis and comparison result; specifically, because the polarized light beam is scattered once on the rough surface of the sample to be detected, the polarization state of the polarized light beam is not changed, and the polarized light beam is scattered multiple times at the damaged part of the subsurface layer, the polarization state of the polarized light beam is changed (the specific principle is shown in Fung AK, li Z, chen KS. Backscattering from a randomly rough dielectric surface, IEEE Trans Geosci Rem Sens 1992; 30:356-69), therefore, the interference scattered light beam which irradiates the rough surface of the sample to be detected and does not change the polarization state is filtered, and only light rays which are different from the polarization state of the incident light beam are allowed to enter, so that the influence of the scattered light intensity of the rough surface can be eliminated, and the detection precision is further improved.
In a preferred embodiment, the distance between adjacent array elements in the phased array is set to be 1um-3um, the most preferred distance between adjacent array elements in the phased array is 2um, and the corresponding scanning angle range is better, so that the scanning angle requirement required by the detection method of the invention can be met;
the aforementioned relationship between the phase difference and the specific angle of deflection of the deflected beam is expressed by the following expression:
wherein lambda is the wavelength of Gaussian beam, theta is a specific angle, d is the distance between adjacent array elements, and delta phi is the phase difference between adjacent array elements;
the calculation is performed by using the formula (2), because the loaded linear voltage can change in real time, the phase difference can also change in real time, the electro-optical crystal can provide 0-2 pi of phase change, the optimal distance between adjacent array elements is 2 microns, the theoretical scanning range which can be achieved by corresponding single light beams is +/-30 degrees, the actual scanning range is related to the arrangement mode of phased array elements and the like, and the phase change can be correspondingly changed according to requirements.
The invention also provides a detection device for the subsurface damage based on the optical phased array, wherein the detection method for the subsurface damage based on the optical phased array in any embodiment can be realized on the detection device, and the device comprises a central control processor 9, and a laser light source 1, a light source modulation system, a phased array 5 and a scattering data detection system which are respectively connected and communicated with the central control processor 9, wherein:
the laser light source 1 is used for emitting Gaussian beams and enabling the Gaussian beams to be directly incident into the light source modulation system;
the light source modulation system is used for shaping the Gaussian beam into a flat-top beam with energy evenly distributed, and is also used for dividing the flat-top beam into at least 2 paths of parallel beams and enabling the parallel beams to enter the phased array 5;
the phased array 5 is composed of a plurality of electro-optic crystal phase shifters, the phased array 5 is used for changing the phase of array elements so that parallel light beams interfere to form deflection light beams, the deflection light beams deflect a specific angle to be injected into a sample to be detected along a specific direction, and the deflection light beams are scattered for a plurality of times at subsurface damage positions of the sample to be detected to form scattered light beams with changed polarization states; specifically, the detection device further comprises a wave controller 10 connected with the phased array 5, and the central control processor 9 controls the wave controller 10 to apply different voltages to the phased array 5, so that a phase difference is generated between adjacent array elements (namely adjacent electro-optic crystal phase shifters) by utilizing the electro-optic effect of the electro-optic crystal.
The scattering data detection system is provided with a silicon photomultiplier which is used for collecting light intensity signals of scattered light beams and sending the light intensity signals to the central control processor 9; specifically, before the light intensity signals of the scattered light beams are collected, the interference light beams with unchanged light beam polarization states are filtered out by the polarization analyzer 81 arranged at the collection end of each silicon photomultiplier and only subjected to single scattering on the rough surface of the sample, because the scattered light is scattered from the rough surface of the sample, the incident light is simply scattered on the rough surface, the polarization states are not changed, multiple scattering is carried out on the subsurface damage position, and the polarization states are changed;
the central control processor 9 is provided with a corresponding control program for controlling the phased array 5 to change the phase of the array element, and is also used for receiving light intensity data and comparing the light intensity data with the light intensity data of a normal sample so as to determine the position and the appearance of subsurface damage of the sample to be detected.
In the preferred embodiment, the light source modulation system comprises a beam shaping system 3 and a beam splitter 4, which are coaxially arranged at the beam emitting end of the laser light source 1, wherein the beam shaping system 3 is used for processing the laser beam emitted by the laser light source 1 into a polarized Gaussian beam in a polarized mode, shaping the polarized Gaussian beam into a flat-top beam with uniform energy, and then injecting the flat-top beam into the beam splitter 4, and the beam splitter 4 is used for dividing the flat-top beam into multiple parallel beams and collimating and injecting the multi-parallel beams into the phased array 5.
In a more preferred embodiment, the scattered data detecting system comprises a hemispherical supporting shell 7 and a plurality of silicon photomultipliers 8 arranged on the inner spherical surface or the outer spherical surface of the hemispherical supporting shell 7, wherein the hemispherical supporting shell 7 is arranged above the sample to be detected, the data collecting ends of the silicon photomultipliers 8 are all oriented to the sample to be detected, and the central control processor 9 can control the silicon photomultipliers 8 to move on the spherical surface of the hemispherical supporting shell 7 so as to adjust the pose thereof;
in a more preferred embodiment, as shown in fig. 4, the hemispherical supporting shell 7 may also be a plurality of supporting shells with different radii and the same sphere center, and each supporting shell is provided with silicon photomultiplier 8, and the silicon photomultipliers 8 on the multiple layers of supporting shells are uniformly distributed or unevenly distributed;
in other more preferred embodiments, the fixing piece for fixing the silicon photomultiplier may be a supporting rod with different lengths besides the hemispherical supporting shell, the silicon photomultiplier 8 is fixed at the upper end of each supporting rod, and the connecting lines of the silicon photomultipliers form a hemispherical outline with the same sphere center, so that the sample to be detected is placed at the position of the sphere center during detection.
In a more preferred embodiment, the silicon photomultipliers 8 can move on the spherical surface of the hemispherical support shell 7 so as to adjust the positions of the respective silicon photomultipliers 8 at any time.
In a still further preferred embodiment, the shell surface of the hemispherical support shell 7 is coated with a light absorbing coating and/or light absorbing micro-nano structures for preventing scattering of the light beam passing through the shell.
For the purpose of illustrating the details of the practice of the present invention, the following examples are provided to illustrate the particular steps of the evaluation method of the present invention, but are not intended to limit the scope of the invention further.
Example 1
As shown in fig. 1, a schematic structural diagram of a device for detecting subsurface damage based on an optical phased array according to this embodiment includes a central control processor 9, and a laser light source 1, a light source modulation system, a phased array 5 and a scattering data detection system, which are respectively capable of data communication with the central control processor 9.
The laser wavelength emitted by the laser source 1 adopts a Gaussian beam with lambda=1064nm and highest power of 100mW, the Gaussian beam firstly enters a light source modulation system, the light source modulation system comprises a beam shaping system 3 and a beam splitter 4 which are coaxially arranged with a light beam emitting end of the laser source 1, and the beam shaping system 3 comprises a polaroid 2 coaxially arranged with the aspherical shaping lens 302; the gaussian beam is changed into a polarized gaussian beam through the polarizer 2, then the polarized gaussian beam is changed into a flat-top beam with uniformly distributed energy through the aspheric shaping lens 302, the flat-top beam is collimated and emergent to be divided into 5 paths of light, and then the 5 paths of parallel light beams are collimated and incident into the phased array 5, and the distance d=2um between the phased array elements.
The beam shaping principle is as shown in fig. 2, the polarization state of the incident gaussian laser is changed by the polarizer 2, the energy distribution of the gaussian beam 301 is uneven, in fig. 2, the energy distribution of the gaussian beam is represented by the density of light at different spatial positions, the light energy is redistributed through two aspheric shaping lenses 302, the light density at different spatial positions is the same, and the flat-top beam 303 with evenly distributed energy is output, thereby completing beam shaping and collimation, the flat-top beam 303 is divided into n paths of light waves through the beam splitter 4, the n paths of light waves enter the phased array 5, the phased array 5 is made of electro-optic crystal materials, and the distance d=2um between the array elements of each phased array.
The scattering data detection system comprises a hemispherical supporting shell 7 and 4 uniformly arranged silicon photomultipliers 8 arranged on the hemispherical supporting shell 7, wherein a light absorption coating and a light absorption micro-nano structure are coated on the hemispherical supporting shell 7, 6 silicon photomultipliers 8 are arranged in an array mode along a hemispherical outline inside the hemispherical supporting shell 7, spherical center angles between every two silicon photomultipliers 8 are unequal, namely, the silicon photomultipliers 8 are arranged densely at the top position close to the hemispherical supporting shell 7 and are arranged sparsely at the top position far away from the hemispherical supporting shell 7, the hemispherical supporting shell 7 is arranged above a sample 6 to be detected, the data acquisition ends of the silicon photomultipliers 8 face the sample 6 to be detected, and an analyzer 81 is further arranged at the data acquisition end of the silicon photomultipliers 8 to filter light intensity data of interference beams.
The subsurface damage detection is carried out on the sample to be detected by using the detection device, and the specific detection steps comprise:
step 1, emitting laser beams, specifically, emitting Gaussian beams with laser wavelength lambda=1064nm and laser power of 100mW; the Gaussian beam is firstly changed into a polarized beam through a light source modulation system and then is changed into a flat-top beam with uniformly distributed energy by an aspheric shaping lens 302 through a polarizing plate 2, and the flat-top beam can be collimated and emitted into a beam splitter 4 so as to be divided into 5 paths of beams; the 5 paths of parallel light beams are collimated and incident into the phased array 5, the distance d=2um between adjacent array elements of the phased array, no voltage is applied to the phased array at the moment, namely no phase difference is introduced, the incident angle of the parallel light beams is 0 degrees, and laser collimation irradiates on a quartz sample to be measured to generate scattering.
The invention has the advantages that the phased array and silicon photomultiplier technology is adopted to rapidly and accurately detect the subsurface damage, so that not only can tiny defects and deformation be detected, but also various information related to the subsurface damage, such as the position, the shape, the size, the depth and the like of the subsurface, can be obtained by processing signals output by the detector in real time, and powerful support and experimental basis can be provided for the research of related fields; in addition, compared with the traditional subsurface damage detection method, the invention adopts non-contact detection, avoids damage and pollution to a detected sample, has the characteristics of high efficiency and high speed, and can greatly improve the working efficiency and the detection precision.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. The method for detecting the subsurface damage based on the optical phased array is characterized by comprising the following steps of:
s1, emitting laser beams, polarizing and shaping the laser beams into flat-top beams, dividing the flat-top beams into multiple paths of parallel beams, and enabling the parallel beams to be collimated and incident on a sample to be detected through a phased array;
s2, adjusting the array element phase of the phased array to enable adjacent array elements to generate specific phase differences, further enabling the parallel light beams to generate interference enhancement in a specific direction in the phased array based on the specific phase differences to form deflection light beams, enabling the deflection light beams to deflect a specific angle and jet into a sample to be detected for scanning, and performing multiple scattering at subsurface damage to form scattering light beams with changed polarization states;
s3, collecting light intensity data of the scattered light beams by utilizing a plurality of silicon photomultiplier;
s4, repeating the steps S2-S3 for a plurality of times until the surface of the sample to be detected is scanned completely, and analyzing and comparing the collected multiple groups of light intensity data with the light intensity data of the normal sample to determine the position and the appearance of subsurface damage of the sample to be detected.
2. The method for detecting subsurface damage based on optical phased array as claimed in claim 1, wherein in step S2, the specific phase difference between adjacent array elements after each adjustment is different from the previous one, so that the deflection angle of the deflected beam formed each time is different from the previous one.
3. The method for detecting subsurface damage based on optical phased array as claimed in claim 1, wherein the data acquisition end of each of the silicon photomultipliers is directed toward the surface to be measured of the sample to be measured.
4. The method for detecting subsurface damage based on optical phased array as claimed in claim 3, wherein the silicon photomultiplier is arranged on a hemispherical contour surface above the sample to be detected with the sample to be detected as a sphere center, and the radii of the hemispherical contour surfaces are the same or different.
5. A method for detecting subsurface damage based on an optical phased array as claimed in claim 3, wherein the spacing between adjacent silicon photomultipliers is equal or unequal; preferably, when the pitches between the adjacent silicon photomultipliers are not equal, the pitch of the spherical center angles of the adjacent silicon photomultipliers is 5 degrees within the range of the spherical center angles of +/-30 degrees; preferably, in the range of-80 ° to-30 ° of the sphere center angle, the sphere center angle interval between adjacent silicon photomultiplier is 10 °; more preferably, the pitch of the sphere center angles of adjacent silicon photomultipliers is 10 ° in the range of 30 ° to 80 °.
6. The method for detecting subsurface damage based on an optical phased array as claimed in claim 1, wherein the phased array is made of electro-optic crystals; preferably, different voltages are applied to the phased array in real time, so that different phase differences are generated between adjacent array elements in real time; more preferably, the relationship between the phase difference and the voltage is expressed by the following mathematical expression:
Δφ＝(2πn o 3 r/λ)*V
wherein Δφ is phase difference, n o The refractive index of the electro-optic crystal to o light is r, the linear electro-optic coefficient is r, V is the applied voltage, and lambda is the wavelength of Gaussian beam.
7. The method for detecting subsurface damage based on optical phased array as claimed in claim 1, wherein, before collecting light intensity data of the scattered light beams, the disturbing scattered light beams irradiated to the rough surface of the sample to be detected without changing polarization state are filtered, so that the scattered light beams with changed polarization state are retained.
8. The method for detecting subsurface damage based on an optical phased array as claimed in claim 1, wherein the maximum power of the gaussian beam is 100mW; preferably, the distance between adjacent array elements in the phased array is 1um-3um; more preferably, the distance between adjacent array elements in the phased array is 2um.
9. The utility model provides a detection device based on optical phased array's subsurface damage, its characterized in that includes central control processor (9) and laser light source (1), light source modulation system, phased array (5) and scattering data detecting system who is connected with central control processor (9) respectively, wherein:
the laser light source (1) is used for emitting laser beams and enabling the laser beams to be directed into the light source modulation system;
the light source modulation system is used for converting the laser beam into a polarized Gaussian beam, shaping the Gaussian beam into a flat-top beam and dividing the flat-top beam into multiple parallel beams to enter the phased array (5);
the phased array (5) is used for changing the phase of array elements so that the parallel light beams interfere and strengthen in a specific direction to form deflection light beams, the deflection light beams deflect a specific angle to be injected into a sample to be detected in the specific direction, and the deflection light beams are scattered for multiple times at the subsurface damage to form scattered light beams with changed polarization states;
the scattered data detection system is used for collecting light intensity signals of the scattered light beams and sending the light intensity signals to the central control processor (9);
the central control processor (9) is used for controlling the phased array (5) to change the phase of the array elements, receiving the light intensity data, and comparing the light intensity data with the light intensity data of a normal sample to determine the position and the appearance of subsurface damage of the sample to be detected.
10. The optical phased array-based subsurface damage detection device according to claim 9, wherein the light source modulation system comprises a beam shaping system (3) and a beam splitter (4) which are coaxially arranged at the light beam emitting end of the laser light source (1), the beam shaping system (3) is used for converting the laser light beam into a polarized gaussian beam, shaping the polarized gaussian beam into a flat-top beam and injecting the flat-top beam into the beam splitter (4), and the beam splitter (4) is used for dividing the flat-top beam into multiple parallel beams and collimating and injecting the flat-top beam into the phased array (5); preferably, the scattering data detection system comprises a hemispherical supporting shell (7) and a plurality of silicon photomultiplier (8) arranged on the hemispherical supporting shell (7), wherein the hemispherical supporting shell (7) is arranged above the sample to be detected, and the data acquisition ends of the silicon photomultiplier (8) face the sample to be detected; more preferably, the shell surface of the hemispherical supporting shell (7) is coated with a light-absorbing coating and/or light-absorbing micro-nano structure for preventing light beams passing through the shell from scattering; still more preferably, the data acquisition ends of the silicon photomultiplier (8) are each provided with an analyzer (81), and the analyzers (81) are used for filtering interference scattered light beams which are irradiated to the rough surface of the sample to be detected and have unchanged polarization states.
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