CN116086338A - Digital holographic deformation detection method - Google Patents
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
- G01B11/164—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means by holographic interferometry
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Abstract
The invention relates to a digital holographic deformation detection method, and belongs to the technical field of photoelectric detection. The method comprises the following steps: carrying out Michelson interference experiments on the emergent light of the semiconductor lasers with different types, and collecting coherent fringes; obtaining a coherence length through calculation, and selecting a proper object plane size; the emergent light of the laser forms a rectangular uniform light field through a square waveguide cavity image overlapping device, and the same object plane information is acquired by adjusting the position information of the CMOS to obtain the non-coplanar phase information before and after the object plane displacement; and (3) performing image processing on the obtained laser holograms with the superimposed object light and reference light before and after the object plane displacement, extracting corresponding phase information, constructing a three-dimensional relationship through the position information between the CMOS and the object plane, and performing three-dimensional reconstruction processing on the phase information to obtain a three-dimensional displacement component. The invention realizes deformation detection on industrial precision on the basis of low cost and no damage.
Description
Technical Field
The invention relates to a digital holographic deformation detection method, and belongs to the technical field of photoelectric detection.
Background
The semiconductor laser has the advantages of low cost, low power consumption, good monochromaticity, small volume, easy modulation and the like, and is widely applied to the fields of optical fiber communication, laser processing, medicine, military and the like. However, the outgoing light beam quality of the semiconductor laser is poor, the divergence angle of the light beam is large, and the divergence angles of two mutually perpendicular light beams are different, so that the light field is unevenly distributed, and the semiconductor laser cannot be directly applied to high-precision optical measurement. But the improvement of the method can be applied to industrial measurement.
Compared with the traditional hologram, the digital hologram has the characteristics of low manufacturing cost, high imaging speed, obvious imaging effect and the like, and the digital hologram optical path built by the optical instrument has better flexibility, can change the wavelength of light, has a large optical path between object light and reference light, or has higher coordination when the model of the laser changes the measuring range.
Disclosure of Invention
The invention provides a digital holographic deformation detection method, which is used for carrying out displacement detection and reducing cost.
The technical scheme of the invention is as follows: the digital holographic deformation detection method comprises the steps of carrying out Michelson interference experiments on emergent light of semiconductor lasers of different types, and collecting coherent fringes; obtaining a coherence length through calculation, and selecting a proper object plane size; the emergent light of the laser forms a rectangular uniform light field through a square waveguide cavity image overlapping device, and the same object plane information is acquired by adjusting the position information of the CMOS to obtain the non-coplanar phase information before and after the object plane displacement; and (3) performing image processing on the obtained laser holograms with the superimposed object light and reference light before and after the object plane displacement, extracting corresponding phase information, constructing a three-dimensional relationship through the position information between the CMOS and the object plane, and performing three-dimensional reconstruction processing on the phase information to obtain a three-dimensional displacement component.
As a further scheme of the invention, the digital holographic deformation detection method comprises the following specific steps:
step1, constructing a Michelson interference light path for Laser emitted by a semiconductor Laser, and measuring the wavelength and diffraction angle of the semiconductor Laser by using the Michelson interference light path;
firstly, a beam of Laser emitted from a semiconductor Laser is divided into two beams by a polarization beam splitter prism (PBS 1), wherein one beam of transmitted beam splitter is reflected by a reflecting mirror (M1) through an optical path with a distance L1, and then reflected by the polarization beam splitter prism (PBS 1) to irradiate on a light screen (P); the other beam of reflected beam splitting light is reflected by the reflecting mirror (M2) through an optical path with a distance L2, is transmitted by the polarization splitting prism (PBS 1) and irradiates on the light screen (P);
the reflection angles of the reflecting mirror (CL 1) and the reflecting mirror (CL 2) are regulated to ensure that the imaging of the two beams of light on the light screen is completely overlapped, and a small hole is added in the light path after beam combination, so that only the completely overlapped information is reserved; the coherent information of a light screen (P) in Step2 is analyzed by adjusting the L1 and L2 optical paths of the two light beams, the coherent length is calculated by an isocratic formula, and the proper object plane size is selected;
step2, after selecting a proper object plane size, constructing a digital holographic interference light path: setting up a measuring light path, and adjusting the emergent light of the semiconductor Laser with the wavelength lambda=632 nm by using a square waveguide cavity overlapping device, so that the emergent light field is rectangular and uniform in light spot; the uniform emergent light is divided into two beams by a polarization beam splitter prism (PBS 2); one beam of the split light is reflected by a reflecting mirror (CL 1) as reference light, is expanded by a beam expander (SF 1) and is collimated by a collimating lens (L1), and is reflected by a reflecting mirror (CL 3) and then is emitted into a polarization splitting prism (PBS 3); the other beam is used as a detection object light, after being expanded by an expanding lens (SF 2) and collimated by a collimating lens (L2), the detection object light is reflected by a reflecting mirror (CL 2) and then irradiates the surface of a tested piece (S), the light reflected by the surface of the tested piece is injected into a polarization beam splitter prism (PBS 3), and the information after the two beams of light are fitted by the polarization beam splitter prism (PBS 3) is received by an image acquisition system;
step3, performing image processing on the phase hologram acquired by the image acquisition system, performing field average processing on the obtained laser hologram with superimposed object light and reference light before and after the object plane displacement, eliminating smaller noise, performing primary fast Fourier transform (1-FFT) processing on the extracted object plane information through Fresnel diffraction, performing image plane filtering to extract a complete object image, further extracting undisturbed object field light before and after deformation through Fourier inverse operation of Fresnel diffraction, performing angular spectrum diffraction reconstruction, performing Fourier transform filtering noise reduction on the object field light, and finally performing iterative unwrapping based on a least square algorithm to extract corresponding phase information;
step4, performing three-dimensional reconstruction processing on the extracted phase information; and constructing a mathematical relationship model by using included angles between object light reference light and object plane reflected light and included angles between object plane reflected light and three directions of an image acquisition system V1, V2 and V3 and position information thereof, and reconstructing the acquired phase information in the three-dimensional direction to obtain corresponding displacement components in the three directions of x, y and z.
As a further aspect of the present invention, the image capturing system in Step2 includes:
an electric displacement platform is built and used for realizing accurate movement of the CMOS in the x, y and z directions;
the CMOS is enabled to acquire phase information of the object plane and the reference light fitting at the beam splitting prism (PBS 3) at three non-collinear but coplanar positions (V1, V2, V3) respectively by utilizing an electric displacement platform.
The beneficial effects of the invention are as follows:
1. the invention uses the low-cost semiconductor laser to realize the acquisition of the phase information of the object plane through the improvement of the measurement of the coherence length and the beam shaping, and not only realizes the measurement of the three-dimensional deformation at the micron level, but also saves the cost of multi-azimuth information measurement by constructing an electric displacement platform;
2. because a digital holographic acquisition scheme is adopted, the non-contact acquisition is realized, namely the nondestructive acquisition is realized, the obtained information is more comprehensive, the acquisition precision reaches the micron level, and the method can be widely applied to the industrial field;
3. the electric displacement platform and the semiconductor laser can be used for data networking, so that a remote control experimental instrument is realized.
Drawings
FIG. 1 is a Michelson optical path designed in accordance with the present invention;
FIG. 2 is a measurement light path of the present invention;
FIG. 3 is a schematic diagram of an image acquisition system of the present invention;
FIG. 4 is a schematic diagram of a processing flow of data obtained by an image acquisition system according to the present invention;
FIG. 5 is a schematic flow chart of the present invention.
Detailed Description
Example 1: as shown in fig. 1-5, in a digital holographic deformation detection method, by improving the beam quality of a low-cost semiconductor laser, the object plane is collected in multiple directions by using an electric displacement platform, namely, laser holograms of object light and reference light before and after the displacement or deformation of the object plane are collected; the invention is suitable for low-cost semiconductor lasers, and has different divergence angles in the horizontal direction and the vertical direction, and the two split emergent light sources are different.
According to the invention, michelson interference experiments are carried out on the emergent light of semiconductor lasers of different types, and coherent fringes are collected; obtaining a coherence length through calculation, and selecting a proper object plane size; the emergent light of the laser forms a rectangular uniform light field through a square waveguide cavity image overlapping device, and the same object plane information is acquired by adjusting the position information of the CMOS to obtain the non-coplanar phase information before and after the object plane displacement; and (3) performing image processing on the obtained laser holograms with the superimposed object light and reference light before and after the object plane displacement, extracting corresponding phase information, constructing a three-dimensional relationship through the position information between the CMOS and the object plane, and performing three-dimensional reconstruction processing on the phase information to obtain a three-dimensional displacement component.
As a further scheme of the invention, the digital holographic deformation detection method comprises the following specific steps:
step1, constructing a Michelson interference light path for Laser emitted by a semiconductor Laser, and measuring the wavelength and diffraction angle of the semiconductor Laser by using the Michelson interference light path; the relevant parameters of the semiconductor laser are measured by referring to the Michelson interference experimental schematic diagram in FIG. 1, namely, the relevant parameters of the optical path of the digital holographic image are established in the subsequent construction;
firstly, a beam of Laser emitted from a semiconductor Laser is divided into two beams by a polarization beam splitter prism (PBS 1), wherein one beam of transmitted beam splitter is reflected by a reflecting mirror (M1) through an optical path with a distance L1, and then reflected by the polarization beam splitter prism (PBS 1) to irradiate on a light screen (P); the other beam of reflected beam splitting light is reflected by the reflecting mirror (M2) through an optical path with a distance L2, is transmitted by the polarization splitting prism (PBS 1) and irradiates on the light screen (P);
the reflection angles of the reflecting mirror (CL 1) and the reflecting mirror (CL 2) are regulated, so that the imaging of two beams of light on the light screen is completely overlapped, the divergence angles and the light emitting effects of the semiconductor laser in the horizontal direction and the vertical direction are different, the light emitting effects are different, and only the completely overlapped information is reserved by adding small holes in the light path after beam combination; analyzing the coherent information of a light screen (P) in Step2 by adjusting the L1 and L2 optical paths of the two light beams, calculating the coherent length to be 5cm by an isocratic formula, and selecting an object plane as a circular deformation standard component;
step2, after selecting a proper object plane size, constructing a digital holographic interference light path: and (3) constructing a measuring light path, carrying out multidirectional movement on the CMOS by using an electric displacement platform, and collecting corresponding phase information. The phase information acquisition before and after displacement is carried out on the obtained phase hologram, the emergent light of the semiconductor Laser with the wavelength of lambda=632 nm is regulated by a square waveguide cavity overlapping device, and the proper distance is regulated, so that the emergent light field is rectangular uniform light spots; the uniform emergent light is divided into two beams by a polarization beam splitter prism (PBS 2); one beam of the split light is reflected by a reflecting mirror (CL 1) as reference light, is expanded by a beam expander (SF 1) and is collimated by a collimating lens (L1), and is reflected by a reflecting mirror (CL 3) and then is emitted into a polarization splitting prism (PBS 3); the other beam is used as a detection object light, after being expanded by an expanding lens (SF 2) and collimated by a collimating lens (L2), the detection object light is reflected by a reflecting mirror (CL 2) and then irradiates the surface of a tested piece (S), the light reflected by the surface of the tested piece is injected into a polarization beam splitter prism (PBS 3), and the information after the two beams of light are fitted by the polarization beam splitter prism (PBS 3) is received by an image acquisition system;
step3, performing image processing on the phase hologram acquired by the image acquisition system by using a digital image processing method shown in fig. 4, performing field average processing on the obtained laser hologram with superimposed object light and reference light before and after object plane displacement, performing phase difference subtraction algorithm on the image before and after deformation, only retaining phase information generated by deformation, eliminating irrelevant environmental noise, performing primary fast Fourier transform (1-FFT) processing of Fresnel diffraction on the extracted object plane information, performing image plane filtering to extract a complete object image, further performing Fourier inverse operation of Fresnel diffraction, extracting undisturbed object field light before and after deformation, performing angular spectrum diffraction reconstruction, performing Fourier transform filtering noise reduction, and finally performing iterative unwrapping based on a least square algorithm to extract corresponding phase information;
step4, performing three-dimensional reconstruction processing on the extracted phase information; and constructing a mathematical relationship model by using included angles between object light reference light and object plane reflected light and included angles between object plane reflected light and three directions of an image acquisition system V1, V2 and V3 and position information thereof, and reconstructing the acquired phase information in the three-dimensional direction to obtain corresponding displacement components in the three directions of x, y and z.
As a further aspect of the present invention, the image capturing system in Step2 includes:
an electric displacement platform is built and used for realizing accurate movement of the CMOS in the x, y and z directions;
the CMOS is enabled to acquire phase information of the object plane and the reference light fitting at the beam splitting prism (PBS 3) at three non-collinear but coplanar positions (V1, V2, V3) respectively by utilizing an electric displacement platform.
The invention uses a low-cost semiconductor to irradiate an object plane, utilizes relevant parameters of a semiconductor laser by applying a Michelson interference experimental principle, shapes emergent light with different divergence angles and beam quality in horizontal and vertical directions by applying a square waveguide cavity and a beam expander, realizes the acquisition of holograms before and after deformation of the object plane, reduces the cost of a plurality of cameras by utilizing an electric displacement platform, acquires a plurality of deformation fields of the object plane, and analyzes the acquired graph by utilizing a digital image processing method. On the basis of low cost and no damage, the deformation detection in industrial precision is realized.
While the present invention has been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.
Claims (3)
1. A digital holographic deformation detection method is characterized in that: carrying out Michelson interference experiments on the emergent light of the semiconductor lasers with different types, and collecting coherent fringes; obtaining a coherence length through calculation, and selecting a proper object plane size; the emergent light of the laser forms a rectangular uniform light field through a square waveguide cavity image overlapping device, and the same object plane information is acquired by adjusting the position information of the CMOS to obtain the non-coplanar phase information before and after the object plane displacement; and (3) performing image processing on the obtained laser holograms with the superimposed object light and reference light before and after the object plane displacement, extracting corresponding phase information, constructing a three-dimensional relationship through the position information between the CMOS and the object plane, and performing three-dimensional reconstruction processing on the phase information to obtain a three-dimensional displacement component.
2. The digital holographic deformation detection method of claim 1, wherein: the digital holographic deformation detection method comprises the following specific steps:
step1, constructing a Michelson interference light path for Laser emitted by a semiconductor Laser, and measuring the wavelength and diffraction angle of the semiconductor Laser by using the Michelson interference light path;
firstly, a beam of Laser emitted from a semiconductor Laser is divided into two beams by a polarization beam splitter prism (PBS 1), wherein one beam of transmitted beam splitter is reflected by a reflecting mirror (M1) through an optical path with a distance L1, and then reflected by the polarization beam splitter prism (PBS 1) to irradiate on a light screen (P); the other beam of reflected beam splitting light is reflected by the reflecting mirror (M2) through an optical path with a distance L2, is transmitted by the polarization splitting prism (PBS 1) and irradiates on the light screen (P);
the reflection angles of the reflecting mirror (CL 1) and the reflecting mirror (CL 2) are regulated to ensure that the imaging of the two beams of light on the light screen is completely overlapped, and a small hole is added in the light path after beam combination, so that only the completely overlapped information is reserved; the coherent information of a light screen (P) in Step2 is analyzed by adjusting the L1 and L2 optical paths of the two light beams, the coherent length is calculated by an isocratic formula, and the proper object plane size is selected;
step2, after selecting a proper object plane size, constructing a digital holographic interference light path: setting up a measuring light path, and adjusting the emergent light of the semiconductor Laser with the wavelength lambda=632 nm by using a square waveguide cavity overlapping device, so that the emergent light field is rectangular and uniform in light spot; the uniform emergent light is divided into two beams by a polarization beam splitter prism (PBS 2); one beam of the split light is reflected by a reflecting mirror (CL 1) as reference light, is expanded by a beam expander (SF 1) and is collimated by a collimating lens (L1), and is reflected by a reflecting mirror (CL 3) and then is emitted into a polarization splitting prism (PBS 3); the other beam is used as a detection object light, after being expanded by an expanding lens (SF 2) and collimated by a collimating lens (L2), the detection object light is reflected by a reflecting mirror (CL 2) and then irradiates the surface of a tested piece (S), the light reflected by the surface of the tested piece is injected into a polarization beam splitter prism (PBS 3), and the information after the two beams of light are fitted by the polarization beam splitter prism (PBS 3) is received by an image acquisition system;
step3, performing image processing on the phase hologram acquired by the image acquisition system, performing field average processing on the obtained laser hologram with superimposed object light and reference light before and after the object plane displacement, eliminating smaller noise, performing primary fast Fourier transform (1-FFT) processing on the extracted object plane information through Fresnel diffraction, performing image plane filtering to extract a complete object image, further extracting undisturbed object field light before and after deformation through Fourier inverse operation of Fresnel diffraction, performing angular spectrum diffraction reconstruction, performing Fourier transform filtering noise reduction on the object field light, and finally performing iterative unwrapping based on a least square algorithm to extract corresponding phase information;
step4, performing three-dimensional reconstruction processing on the extracted phase information; and constructing a mathematical relationship model by using included angles between object light reference light and object plane reflected light and included angles between object plane reflected light and three directions of an image acquisition system V1, V2 and V3 and position information thereof, and reconstructing the acquired phase information in the three-dimensional direction to obtain corresponding displacement components in the three directions of x, y and z.
3. The digital holographic deformation detection method of claim 2, wherein: the image acquisition system in Step2 includes:
an electric displacement platform is built and used for realizing accurate movement of the CMOS in the x, y and z directions;
the CMOS is enabled to acquire phase information of the object plane and the reference light fitting at the beam splitting prism (PBS 3) at three non-collinear but coplanar positions (V1, V2, V3) respectively by utilizing an electric displacement platform.
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| CN117075739A (en) * | 2023-10-13 | 2023-11-17 | 深圳优立全息科技有限公司 | Holographic sand table-based holographic display method and related device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117075739A (en) * | 2023-10-13 | 2023-11-17 | 深圳优立全息科技有限公司 | Holographic sand table-based holographic display method and related device |
| CN117075739B (en) * | 2023-10-13 | 2024-01-23 | 深圳优立全息科技有限公司 | Holographic sand table-based holographic display method and related device |
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