CN110823117A - Single-step phase-shift electronic speckle interferometry method, system, device and storage medium - Google Patents
Single-step phase-shift electronic speckle interferometry method, system, device and storage medium Download PDFInfo
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- 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
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Abstract
The invention discloses a single-step phase-shift electronic speckle interferometry method, a system, a device and a storage medium, wherein the measuring method is characterized in that the concept of interpolation calculation is added on the basis of the traditional phase-shift electronic speckle interferometry, a plurality of phase-shift images required before a measured object is deformed and a plurality of phase-shift images required after the object is deformed are obtained by the interpolation calculation method, and the phase-shift images acquired one by one in the traditional measuring method before and after the object is deformed are replaced, so that the need of the phase-shift images in the states before and after the object is deformed is eliminated, and the problem that the traditional phase-shift electronic speckle interferometry method can only be used in static or quasi-static measurement is solved, and dynamic measurement is realized; in addition, the dynamic measurement can be realized by only utilizing the traditional phase-shifting electronic speckle interference measuring device without additionally using an additional optical device or arrangement. The invention can be applied to the technical field of optical measurement.
Description
Technical Field
The invention relates to the field of optical measurement, in particular to a single-step phase-shift electronic speckle interferometry method, a system, a device and a storage medium.
Background
The electronic speckle interferometry (ESPI) method has the characteristics of full field, non-contact, high precision, good real-time property and vibration resistance and the like, and is widely applied to the fields of material elastic modulus measurement, surface roughness evaluation, stress strain analysis, vibration analysis, nondestructive testing and the like. Electronic speckle interferometry is a commonly used optical experimental technique for full-field surface displacement measurement, ranging from tens of nanometers to several micrometers, and has a wide range of practical applications, including mechanical stress assessment in the automotive industry, mechanical component vibration mode research, mems quality testing and biological sample health monitoring.
Electronic speckle interferometry obtains the information that needs to be measured by recording the interference pattern observed on an optically rough surface. One common approach is to use four images from a four-step phase shift before the object is deformed and another four images from a four-step phase shift after the deformation; the phase shift is usually done using piezoelectric mirrors, and analysis of the intensity variations within the measured phase shifted image enables the phase variations and hence the surface displacements to be determined at the respective pixels.
The prior art of electronic speckle interferometry generally needs to collect a plurality of groups of speckle images before and after a measured object is deformed, and the requirement of phase shift images generally limits that the traditional phase shift electronic speckle interferometry can only be used in static or quasi-static measurement. If the surface moves significantly during image acquisition, a phase change occurs in addition to the phase change caused by the phase shift. Methods such as frequency scanning or using multi-camera systems based on multiple wavelengths can measure vibration and dynamic motion, but these methods require complex and expensive optical arrangements.
Disclosure of Invention
In order to solve at least one of the above technical problems, it is an object of the present invention to provide a single-step phase-shifting electronic speckle interferometry method, system, apparatus and medium.
The technical scheme adopted by the invention is as follows: in one aspect, an embodiment of the present invention includes a single-step phase-shift electronic speckle interferometry method, including:
collecting an electronic speckle image of a measured object;
extracting a first phase shift image from the electronic speckle image acquired at a first moment;
extracting a second phase-shift image from the electronic speckle image acquired at the second moment;
performing interpolation calculation on the first phase shift image and the second phase shift image;
generating at least one sub-image of the first phase shift image according to the result of the interpolation calculation;
generating at least one sub-image of the second phase-shift image according to the result of the interpolation calculation;
analyzing the first phase shift image, the sub-image of the first phase shift image, the second phase shift image and the sub-image of the second phase shift image, and calculating and extracting to obtain a phase difference between the first moment and the second moment; the phase difference is used to describe the change in surface displacement of the object being measured.
Further, the step of performing interpolation calculation on the first phase-shifted image and the second phase-shifted image specifically includes:
extracting a front phase-shift image group and a rear phase-shift image group from the electronic speckle images; the front phase shift image group comprises a plurality of phase shift images extracted before the target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; the target phase shift images are respectively a first phase shift image and a second phase shift image;
and performing interpolation calculation by using the extracted front phase shift image group and the extracted rear phase shift image group.
Further, the interpolation calculation is performed by the following formula:
in the formula In2、In3、In4Sub-images, I, respectively, of the phase-shifted image of the objectn-6、In-5、In-3、In-2、In-1Forming the front phase shift image group; i isn+1、In+2、In+3、In+5、In+6And forming the post phase shift image group.
Further, a single-step phase-shift electronic speckle interferometry method further comprises:
collecting electronic speckle images of a measured object at multiple moments;
processing the electronic speckle images at any first moment and any second moment according to a single-step electronic speckle interferometry method to output a phase difference between the first moment and the second moment; the phase difference is used to describe the change in surface displacement of the object being measured.
In another aspect, an embodiment of the present invention further includes a single-step phase-shift electronic speckle interferometry system, including:
the acquisition module is used for acquiring an electronic speckle image of a measured object;
the extraction module is used for extracting a first phase shift image from the electronic speckle images acquired at a first moment and extracting a second phase shift image from the electronic speckle images acquired at a second moment;
the calculation module is used for carrying out interpolation calculation on the first phase shift image and the second phase shift image;
the generating module is used for generating at least one sub-image of the first phase shift image according to the result of the interpolation calculation; and generating at least one sub-image of the second phase-shifted image;
the processing module is used for analyzing the first phase shift image, the sub-image of the first phase shift image, the second phase shift image and the sub-image of the second phase shift image, calculating and extracting the phase difference between the first moment and the second moment; the phase difference is used for describing the change of the surface displacement of the measured object;
and the output module is used for outputting the extracted phase difference.
Further, the calculation module includes:
the device comprises an extraction unit, a phase shift unit and a phase shift unit, wherein the extraction unit is used for extracting a front phase shift image group and a rear phase shift image group from an acquired electronic speckle image of a measured object, the front phase shift image group comprises a plurality of phase shift images extracted before a target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; the target phase shift images are respectively a first phase shift image and a second phase shift image;
and the computing unit is used for carrying out interpolation computation by utilizing the extracted front phase shift image group and the extracted rear phase shift image group.
Further, the processing module comprises:
an analysis unit for analyzing the first phase-shifted image, the sub-image of the first phase-shifted image, the second phase-shifted image at the second time, and the sub-image of the second phase-shifted image;
a calculation unit for calculating a phase difference between the first time and the second time;
and the extraction unit is used for extracting the calculated phase difference.
In another aspect, an embodiment of the present invention further includes a single-step phase-shift electronic speckle interferometry apparatus, including: the device comprises a laser, a camera and a computer, wherein the laser is used for irradiating a measured object so as to generate an electronic speckle image; the camera is used for collecting electronic speckle images; the computer is used for executing a single-step phase-shift electronic speckle interferometry method to process the acquired electronic speckle images.
In another aspect, embodiments of the present invention also include a storage medium having stored therein processor-executable instructions that, when executed by a processor, are configured to perform a single-step phase-shifting electronic speckle interferometry method.
The invention has the beneficial effects that: the embodiment provides a single-step phase-shift electronic speckle interferometry, wherein a plurality of phase-shift images required by measurement are obtained by mainly utilizing an interpolation calculation method, and a plurality of phase-shift images acquired one by one in the existing measurement method are replaced; therefore, the problem that the existing phase-shifting electronic speckle interferometry can only be used in static or quasi-static measurement is solved, and dynamic measurement is realized; in addition, the dynamic measurement can be realized only by utilizing the traditional phase-shifting electronic speckle interference measuring device without additional optical equipment or arrangement.
Drawings
FIG. 1 is a flow chart illustrating the steps of the single-step phase-shifting electronic speckle interferometry method according to an embodiment of the present invention;
FIG. 2 is a block diagram of a single-step phase-shifting electronic speckle interferometry system according to an embodiment of the present invention;
fig. 3 is a distribution of four phase shift maps at each time obtained by interpolation according to the embodiment of the present invention.
Detailed Description
The existing phase-shift electronic speckle interferometry method is specifically as follows:
the light intensity I at each pixel within the measurement image can be expressed as:
I＝A+Bcosφ，
where A is the background light intensity, B is the modulation degree, and phi is the random phase.
The phase-shift electronic speckle interference measuring method on static object or quasi-static state is to collect four phase-shift images before the object is deformed, and the phase-shift step length is
Can be expressed as:
I01＝A+Bcosφ
I03＝A+Bcos(φ+π)
in the formula, 0 in the subscripts 01, 02, 03, 04 represents a certain time before the object is deformed, and the number is 0, and 1, 2, 3, 4 in the subscripts 01, 02, 03, 04 represents a first, a second, a third, and a fourth phase-shifted images at a certain time before the object is deformed, and the four phase-shifted images are acquired by a phase-shift electronic speckle interferometry method.
Four further phase-shifted images are then acquired after the deformation of the object of interest has occurred, which can be expressed as:
I11＝A+Bcos(φ+Δ)
I13＝A+Bcos(φ+Δ+π)
in the formula, 1 in the subscripts 11, 12, 13, and 14 indicates a certain time after the object is deformed, and is numbered 1, and 1, 2, 3, and 4 in the subscripts 11, 12, 13, and 14 indicate first, second, third, and fourth phase-shifted images at the certain time after the object is deformed, and the four phase-shifted images are acquired by a phase-shift electronic speckle interferometry.
Where Δ can be solved by:
where Δ is the phase difference between the object before and after deformation, said phase difference being used to describe the change in the surface displacement of the measured object, I01、I02、I03、I04、I11、I12、I13、I14The four phase-shift images are respectively acquired before the object is deformed and after the object is deformed.
When four phase-shift images are acquired before and after the object is deformed, the object is in a static or quasi-static state, which limits that the existing phase-shift electronic speckle interferometry method can only be used for static measurement.
Example 1
As shown in fig. 1, a single-step phase-shift electronic speckle interferometry method specifically includes the following steps:
s1, collecting an electronic speckle image of a measured object;
s2, extracting a first phase shift image from the electronic speckle image acquired at the first moment;
s3, extracting a second phase shift image from the electronic speckle image acquired at the second moment;
s4, performing interpolation calculation on the first phase shift image and the second phase shift image;
s5, generating at least one sub-image of the first phase shift image according to the result of interpolation calculation;
s6, generating at least one sub-image of the second phase-shift image according to the result of interpolation calculation;
s7, analyzing the first phase shift image, the sub-image of the first phase shift image, the second phase shift image and the sub-image of the second phase shift image, and calculating and extracting to obtain a phase difference between the first moment and the second moment; the phase difference is used to describe the change in surface displacement of the object being measured.
As a preferred implementation manner of this embodiment of the measurement method, the step S4, that is, the step of performing interpolation calculation on the first phase-shifted image and the second phase-shifted image, specifically includes:
s401, extracting a front phase shift image group and a rear phase shift image group from the electronic speckle image; the front phase shift image group comprises a plurality of phase shift images extracted before the target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; the target phase shift images are respectively a first phase shift image and a second phase shift image;
s402, performing interpolation calculation by using the extracted front phase shift image group and the extracted rear phase shift image group.
As a preferred implementation of the present measurement method embodiment, the interpolation calculation in step S402 is performed by the following formula:
in the formula In2、In3、In4The sub-images are respectively the target phase shift image, and the target phase shift image is respectively a first phase shift image and a second phase shift image; i isn-6、In-5、In-3、In-2、In-1Forming the front phase shift image group; i isn+1、In+2、In+3、In+5、In+6And forming the post phase shift image group. For example, the first phase-shifted image extracted is I71Then I72、I73、I74Respectively, sub-images of the first phase-shifted image obtained by interpolation1、I2、I3、I4、I5、I6The first 6 phase-shifted images, I, constituting the set of front phase-shifted images, i.e. the first phase-shifted image8、I9、I10、I11、I12、I13Forming the rear phase shift image group, namely the rear 6 phase shift images of the first phase shift image; and the second phase-shifted image extracted is I81Then I82、I83、I84Respectively, sub-images of the second phase-shifted image obtained by interpolation, I2、I3、I4、I5、I6、I7The first 6 phase-shifted images, I, constituting said set of front phase-shifted images, i.e. the second phase-shifted image9、I10、I11、I12、I13、I14Composing the post phase shift mapThe image group, i.e. the last 6 phase-shifted images of the second phase-shifted image.
In this embodiment, the step S1, that is, the step of acquiring the electronic speckle image of the object to be measured specifically includes: generating and collecting electronic speckle images by using a traditional phase-shifting electronic speckle interferometry device, wherein the collection method adopts the way that the phase shift amount between the images keeps increasing progressively
The method (1) uses a camera to continuously collect pictures; that is, if the phase step of the acquired first time image is 0, the phase step of the second time image is
The phase step of the image at the third moment is pi, and the phase step of the image at the fourth moment is
The image phase step at the fifth moment is 0, and the image phase step at the sixth moment is
And so on in the following.
In this embodiment, only one phase shift image, i.e., the first phase shift image, needs to be acquired before the object is deformed, and the other three images can be obtained by interpolation calculation. Similarly, another phase-shift image, i.e. the second phase-shift image, is acquired only after the deformation of interest occurs, and the other three images can be obtained by interpolation calculation.
In this embodiment, in the step S4, the first phase shift image needs to be extracted first in the step of performing interpolation calculation; the front phase shift image group comprises a plurality of phase shift images extracted before the target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; for example, if the first phase-shifted image acquired is I71Before the interpolation calculation is carried out on the first phase shift image, a front phase shift image needs to be extracted from the electronic speckle imageThe groups, i.e. the 6 phase-shifted images preceding the first phase-shifted image, are denoted I respectively1、I2、I3、I4、I5、I6And a post-phase shift image group, i.e. 6 phase shift images after the first phase shift image, i.e. I, respectively, needs to be extracted from the electronic speckle image8、I9、I10、I11、I12、I13. Then, by utilizing an interpolation calculation formula, calculating to obtain three other phase-shift images at the first moment, wherein the three phase-shift images are I72、I73And I74The specific calculation process is as follows:
similarly, in this embodiment, in the step of performing interpolation calculation on the second phase shift image in step S4, it is necessary to extract the previous phase shift image group and the subsequent phase shift image group; the front phase shift image group comprises a plurality of phase shift images extracted before the target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; for example, assume that the second phase-shifted image acquired is I81Before the interpolation calculation is performed on the second phase-shifted image, it is necessary to extract a group of previous phase-shifted images from the electronic speckle image, i.e. 6 phase-shifted images before the first phase-shifted image, which are respectively denoted as I2、I3、I4、I5、I6、I7And a post-phase shift image group, i.e. 6 phase shift images after the first phase shift image, i.e. I, respectively, needs to be extracted from the electronic speckle image9、I10、I11、I12、I13、I14. Then is reusedThe interpolation calculation formula calculates to obtain other three phase-shift images at the second moment, which are respectively I82、I83And I84The specific calculation process is as follows:
by utilizing an interpolation calculation method, four phase-shift images I required by the first moment are obtained71、I72、I73、I74Wherein, I71Is extracted from the collected electronic speckle image, I72、I73、I74Is obtained by interpolation calculation, and similarly, by the interpolation calculation method, four phase-shifted images I respectively needed by the second time can be obtained81、I82、I83、I84In which I81Is extracted from the collected electronic speckle image, I82、I83、I84Is obtained by interpolation calculation. Then, the existing phase-shift electronic speckle interferometry is utilized, and the I obtained by the interpolation calculation method is utilized71、I72、I73、I74、I81、I82、I83、I84And calculating the phase difference between the first moment and the second moment, wherein the phase difference can be used for describing the change of the surface displacement of the measured object.
In summary, the single-step phase-shift electronic speckle interferometry described in this embodiment has the following advantages:
by utilizing an interpolation calculation method, a plurality of phase shift images required before a measured object is deformed and a plurality of phase shift images required after the object is deformed are obtained, and the method replaces a plurality of phase shift images which are acquired one by one in the existing phase shift electronic speckle interference measurement method before the object is deformed and after the object is deformed, eliminates the need for the plurality of phase shift images in the states before and after the object is deformed, thereby solving the problem that the existing phase shift electronic speckle interference measurement method can only be used in static or quasi-static measurement and realizing dynamic measurement; in addition, the measurement method described in this embodiment is based on the concept of adding interpolation calculation to the existing phase-shifting electronic speckle interferometry, so that dynamic measurement can be realized by using the existing phase-shifting electronic speckle interferometry measurement device without adding extra optical devices or arrangements, and the phase difference can be finally calculated, so that the change of the surface displacement of the measured object can be described.
Example 2
A single-step phase-shifting electronic speckle interferometry method, comprising the steps of:
collecting electronic speckle images of a measured object at multiple moments; for example, electronic speckle images at one hundred times, t1, t2 … … t100, etc., are acquired.
Selecting any two moments from t1 and t2 … … t100 as the first moment and the second moment, extracting phase shift images of the first moment and the second moment, and executing the single-step phase shift electronic speckle interferometry method described in embodiment 1 to output a phase difference between the first moment and the second moment; the phase difference is used to describe the change in surface displacement of the object being measured. That is, the single-step phase-shift electronic speckle interferometry method described in this embodiment can acquire 4 phase-shift images required at any time, and calculate the phase difference between any two times according to actual needs, thereby implementing dynamic measurement and acquiring the change information of the surface displacement of the measured object.
The single-step phase-shift electronic speckle interferometry method in the embodiment has the following advantages:
by utilizing an interpolation calculation method, a plurality of phase shift images required by measurement at any moment can be obtained, namely a plurality of phase shift images required by a measured object before deformation and a plurality of phase shift images required by the object after deformation can be obtained, the phase shift images are used for replacing a plurality of phase shift images which are acquired one by one in the existing phase shift electronic speckle interferometry method before and after deformation of the object, and the need of the plurality of phase shift images before and after deformation of the object is eliminated, so that the problem that the existing phase shift electronic speckle interferometry method can only be used in static or quasi-static measurement is solved, and dynamic measurement is realized; in addition, the measurement method described in this embodiment is based on the concept of adding interpolation calculation to the existing phase-shifting electronic speckle interferometry, so that dynamic measurement can be realized by using the existing phase-shifting electronic speckle interferometry measurement device without adding extra optical devices or arrangements, and the phase difference can be finally calculated, so that the change of the surface displacement of the measured object can be described.
Example 3
Referring to fig. 2, the embodiment includes a single-step phase-shift electronic speckle interferometry system, which includes 6 modules, including an acquisition module, an extraction module, a calculation module, a generation module, a processing module, and an output module.
The acquisition module keeps increasing by adopting the phase shift amount between the imagesThe method comprises the steps of continuously acquiring images by using a camera, and acquiring electronic speckle images of a measured object; the collecting module can collect electronic speckle images at a plurality of moments according to actual needs, for example, electronic speckle images at one hundred moments such as t1 and t2 … … t100 can be collected, and the collecting module only needs to collect one electronic speckle image at a certain moment, for example, only needs to collect one electronic speckle image at the moment of t1, only needs to collect one electronic speckle image at the moment of t2, and only needs to respectively collect one electronic speckle image at the moments of t3 and t4 … … t 100.
The extraction module is configured to extract an electronic speckle image required for measurement from the acquired electronic speckle image, for example, when a time t7 is designated as a first time, a time t8 is designated as a second time, the electronic speckle image acquired at the time t7 is extracted as a first phase-shifted image, and the electronic speckle image acquired at the time t8 is extracted as a second phase-shifted image, which specifically operates as follows:
acquiring one electronic speckle image at one hundred moments such as t1, t2 … … t100 by the acquisition module through a camera;
forming the electronic speckle image into a video signal;
connecting the formed video signal to an input of a computer monitor;
the electronic speckle image acquired at time t7 is extracted as a first phase-shifted image and the electronic speckle image acquired at time t8 is extracted as a second phase-shifted image by the computer.
The calculation module is configured to perform interpolation calculation on the first phase-shifted image and the second phase-shifted image, and specifically includes:
analyzing, with a computer, the received first phase-shifted image and the second phase-shifted image;
extracting the first 6 phase-shift images of the first phase-shift image from the acquired electronic speckle images, namely extracting the electronic speckle images acquired at the moments t1, t2, t3, t4, t5 and t6 respectively to form a front phase-shift image group, and extracting the last 6 phase-shift images of the first phase-shift image from the acquired electronic speckle images, namely extracting the electronic speckle images acquired at the moments t8, t9, t10, t11, t12 and t13 respectively to form a back phase-shift image group;
similarly, the first 6 phase-shift images of the second phase-shift image are extracted from the acquired electronic speckle images, that is, the electronic speckle images acquired at the time points t2, t3, t4, t5, t6 and t7 are respectively extracted to form a front phase-shift image group, and the last 6 phase-shift images of the second phase-shift image are extracted from the acquired electronic speckle images, that is, the electronic speckle images acquired at the time points t9, t10, t11, t12, t13 and t14 are respectively extracted to form a back phase-shift image group;
and respectively calculating to obtain other three phase shift images corresponding to the first phase shift image and other three phase shift images corresponding to the second phase shift image according to a formula program of pre-designed interpolation calculation.
The generating module is used for generating four phase shift images including a first phase shift image required by the first moment according to the result of the interpolation calculation; and generating four phase-shifted images including the second phase-shifted image required at the second time.
The processing module is used for analyzing the four phase-shifted images generated by the generating module and required by the first moment and the four dependent images generated by the second moment, and calculating and extracting the phase difference between the first moment and the second moment according to a pre-designed calculation formula program of the phase difference in the existing electronic speckle interferometry; the phase difference can be used to describe a change in surface displacement of the object being measured.
And the output module is used for outputting the extracted phase difference.
Further as a preferred embodiment, the calculation module includes:
the device comprises an extraction unit, a phase shift unit and a phase shift unit, wherein the extraction unit is used for extracting a front phase shift image group and a rear phase shift image group from an acquired electronic speckle image of a measured object, the front phase shift image group comprises a plurality of phase shift images extracted before a target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; the target phase shift images are respectively a first phase shift image and a second phase shift image. For example, a camera is used for acquiring one electronic speckle image at each of one hundred times, such as t1, t2 … … t100, and the like, the time t7 is designated as a first time, the time t8 is designated as a second time, the electronic speckle image acquired at the time t7 is extracted as a first phase-shifted image, the electronic speckle image acquired at the time t8 is extracted as a second phase-shifted image, the electronic speckle images acquired at the times t1, t2, t3, t4, t5 and t6 are respectively extracted to form a first phase-shifted image front phase-shifted image group, and the electronic speckle images acquired at the times t8, t9, t10, t11, t12 and t13 are respectively extracted to form a first phase-shifted image rear phase-shifted image group; similarly, the electronic speckle images acquired at times t2, t3, t4, t5, t6 and t7 are respectively extracted to form a pre-second phase-shift image group, and the electronic speckle images acquired at times t9, t10, t11, t12, t13 and t14 are respectively extracted to form a post-second phase-shift image group.
And the computing unit is used for utilizing the extracted front phase shift image group and the extracted rear phase shift image group to carry out interpolation computation according to a formula program of pre-designed interpolation computation. For example, the extracted front phase-shift image group composed of times t1, t2, t3, t4, t5 and t6 and the extracted rear phase-shift image group composed of times t8, t9, t10, t11, t12 and t13 are used for interpolation calculation according to a formula program of the pre-designed interpolation calculation to obtain three other phase-shift images corresponding to the first phase-shift image at the first time; and performing interpolation calculation according to a formula program of pre-designed interpolation calculation by using the extracted front phase-shift image group consisting of the times t2, t3, t4, t5, t6 and t7 and the extracted rear phase-shift image group consisting of the times t9, t10, t11, t12, t13 and t14 to obtain three other phase-shift images corresponding to the second phase-shift image at the second time.
Further as a preferred embodiment, the processing module includes:
an analyzing unit, configured to analyze the first phase-shifted image, the sub-image of the first phase-shifted image, the second phase-shifted image, and the sub-image of the second phase-shifted image, that is, four phase-shifted images including the first phase-shifted image required at the first time and four phase-shifted images including the second phase-shifted image required at the second time;
the calculating unit is used for calculating the phase difference between the first moment and the second moment according to a pre-designed calculation formula program of the phase difference in the existing electronic speckle interferometry;
and the extraction unit is used for extracting the calculated phase difference.
In summary, the single-step phase-shifting electronic speckle interferometry system described in this embodiment has the following advantages:
by utilizing an interpolation calculation method, a plurality of phase shift images required before a measured object is deformed and a plurality of phase shift images required after the object is deformed are obtained, and the method replaces a plurality of phase shift images which are acquired one by one in the existing phase shift electronic speckle interference measurement method before the object is deformed and after the object is deformed, eliminates the need for the plurality of phase shift images in the states before and after the object is deformed, thereby solving the problem that the existing phase shift electronic speckle interference measurement method can only be used in static or quasi-static measurement and realizing dynamic measurement; in addition, the measurement method described in this embodiment is based on the concept of adding interpolation calculation to the existing phase-shifting electronic speckle interferometry, so that dynamic measurement can be realized by using the existing phase-shifting electronic speckle interferometry measurement device without adding extra optical devices or arrangements, and the phase difference can be finally calculated, so that the change of the surface displacement of the measured object can be described.
The embodiment also comprises a single-step phase-shift electronic speckle interferometry device, which comprises a laser, a camera and a computer, wherein the laser is used for irradiating a measured object so as to generate an electronic speckle image; the camera is used for collecting electronic speckle images; the computer is used for executing the single-step phase-shift electronic speckle interferometry method to process the acquired electronic speckle images.
The present embodiment also includes a storage medium having stored therein processor-executable instructions, which when executed by a processor, are configured to perform the single-step phase-shifting electronic speckle interferometry method of the present embodiment.
When the single-step phase-shift electronic speckle interferometry system in this embodiment is implemented by using a computer or other terminal to run a corresponding program, the medium refers to a storage module in the computer or other terminal. When the functions of the methods and the media are realized, the technical effects same as those of the single-step phase-shift electronic speckle interferometry system can be realized.
FIG. 3 is a distribution of four phase shift maps at each time obtained by interpolation according to an embodiment of the present invention; wherein, the symbol represents the image intensity of the phase shift image extracted from the acquired electronic speckle image, and the solid dots represent the image intensity of the phase shift image calculated by interpolation; the distribution situation of four phase shift graphs at each moment is measured by the single-step phase shift electronic speckle interferometry according to the optical measurement principle by taking the phase shift quantity as 0 as an example; the specific process is as follows:
taking the phase shift amount as 0 as an example, the phase-shifted images extracted from the acquired electronic speckle images are k 1, 5, 9, and 13, and the intensities of these images should follow a smooth curve, so that the corresponding sub-images k 2, 3, 4, k 6, 7, 8, k 10, 11, 12, k 14, 15, and 16 can all be obtained by interpolation; that is, only one phase shift image at a certain moment needs to be collected and extracted, and the other three phase shift images can be obtained in an interpolation calculation mode. The interpolation result can be expressed as:
Imod(k-1，4)+1，k＝Ik
when m is mod (k-1, 4) +1 is 1, the phase-shifted image extracted from the acquired electronic speckle image corresponds to a 0 ° phase step, where mod (,) is a modulo or remainder function; similarly, when m is mod (k-1, 4) +1 is 2, 3, 4, it corresponds to a phase-shifted image of 90 °, 180 °, 270 ° phase step. That is, m is mod (k-1, 4) +1 is the first subscript of I, and when m is mod (k-1, 4) +1 equals 1, it represents a 0 ° phase step, when m is mod (k-1, 4) +1 equals 2, it represents a 90 ° phase step, when m is mod (k-1, 4) +1 equals 3, it represents a 180 ° phase step, and when m is mod (k-1, 4) +1 equals 4, it represents a 270 ° phase step. The second subscript k of I refers to the frame number; it should be noted that this interpolation calculation process requires the acquisition of six "extra" phase-shifted images, namely a front phase-shifted image group and a rear phase-shifted image group, before and after the target phase-shifted image to be measured, wherein the target phase-shifted image is extracted from the acquired electronic speckle image, and the front phase-shifted image group and the rear phase-shifted image group are also extracted from the acquired electronic speckle image.
Using the above equation, the image intensities of the phase-shifted images obtained by interpolation, which are shown by the filled circles in fig. 3, i.e., the remaining three phase-shifted images obtained by interpolation, can be obtained. In this way, four phase-shifted images required at any moment can be obtained during each image measurement, wherein one image is directly measured, and the other three images are obtained through interpolation calculation. Referring to a curve with a phase step of 0 ° in fig. 3, when a phase-shifted image extracted from the acquired electronic speckle image is k 1, 5, 9, 13, the corresponding sub-image k 2, 3, 4, k 6, 7, 8, k 10, 11, 12, k 14, 15, 16 can be obtained by interpolation calculation, where the image intensity of the phase-shifted image extracted from the acquired electronic speckle image is denoted by symbol and the image intensity of the phase-shifted image extracted from the acquired electronic speckle image is denoted by solid dots when k 1, 5, 9, 13 is 1, 7, 8, k 10, 11, 12, k 14, 15, 16; similarly, referring to the curve with a phase step of 90 ° in fig. 3, when the phase-shifted image extracted from the acquired electronic speckle image is k 2, 6, 10, 14, the corresponding sub-images k 3, 4, 5, k 7, 8, 9, k 11, 12, 13, and k 15, 16, 17 can all be obtained by interpolation calculation, where the image intensity of the phase-shifted image extracted from the acquired electronic speckle image when k 2, 6, 10, 14 is denoted by symbol, and the image intensity of the phase-shifted image extracted by interpolation calculation when k is 11, 12, 13, k 15, 16, 17 is denoted by solid point; similarly, referring to the curve with the phase step size of 180 ° in fig. 3, when the phase-shifted image extracted from the acquired electronic speckle image is k 3, 7, 11, 15, the corresponding sub-images k 4, 5, 6, k 8, 9, 10, k 12, 13, 14, and k 16, 17, 18 can be obtained by interpolation calculation, where the image intensity of the phase-shifted image extracted from the acquired electronic speckle image when k 3, 7, 11, 15 is denoted by symbol, and the image intensity of the phase-shifted image extracted by interpolation calculation when k 4, 5, 6, k 8, 9, 10, k 12, 13, 14, k 16, 17, 18 is denoted by solid dots; similarly, referring to the curve with a phase step of 270 ° in fig. 3, when the phase-shifted image extracted from the acquired electronic speckle image is k 4, 8, 12, and 16, the corresponding sub-images k 5, 6, 7, k 9, 10, 11, k 13, 14, and 15, and k 17, 18, and 19 may all be obtained by interpolation calculation, where the image intensity of the phase-shifted image extracted from the acquired electronic speckle image is denoted by symbol when k 4, 8, 12, and 16, and the image intensity of the phase-shifted image obtained by interpolation calculation is denoted by solid dots when k 5, 6, 7, k 9, 10, 11, k 13, 14, 15, k 17, 18, and 19. According to the method, the distribution of four phase shift maps at each moment can be obtained.
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiment, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention as long as the technical effects of the present invention are achieved by the same means. The invention is capable of other modifications and variations in its technical solution and/or its implementation, within the scope of protection of the invention.
Claims (9)
1. A single-step phase-shifted electronic speckle interferometry method, comprising:
collecting an electronic speckle image of a measured object;
extracting a first phase shift image from the electronic speckle image acquired at a first moment;
extracting a second phase-shift image from the electronic speckle image acquired at the second moment;
performing interpolation calculation on the first phase shift image and the second phase shift image;
generating at least one sub-image of the first phase shift image according to the result of the interpolation calculation;
generating at least one sub-image of the second phase-shift image according to the result of the interpolation calculation;
analyzing the first phase shift image, the sub-image of the first phase shift image, the second phase shift image and the sub-image of the second phase shift image, and calculating and extracting to obtain a phase difference between the first moment and the second moment; the phase difference is used to describe the change in surface displacement of the object being measured.
2. The single-step phase-shifted electronic speckle interferometry method according to claim 1, wherein the step of performing interpolation calculation on the first phase-shifted image and the second phase-shifted image comprises:
extracting a front phase-shift image group and a rear phase-shift image group from the electronic speckle images; the front phase shift image group comprises a plurality of phase shift images extracted before the target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; the target phase shift images are respectively a first phase shift image and a second phase shift image;
and performing interpolation calculation by using the extracted front phase shift image group and the extracted rear phase shift image group.
3. The single-step phase-shifted electronic speckle interferometry method according to claim 2, wherein said interpolation calculation is performed by the following formula:
in the formula In2、In3、In4Sub-images, I, respectively, of the phase-shifted image of the objectn-6、In-5、In-3、In-2、In-1Forming the front phase shift image group; i isn+1、In+2、In+3、In+5、In+6And forming the post phase shift image group.
4. A single-step phase-shift electronic speckle interferometry method is characterized by comprising the following steps:
collecting electronic speckle images of a measured object at multiple moments;
performing the measurement method of any one of claims 1 to 3 for the electronic speckle image at any first and second time instants to output a phase difference between the first and second time instants; the phase difference is used to describe the change in surface displacement of the object being measured.
5. A single-step phase-shifted electronic speckle interferometry system, comprising:
the acquisition module is used for acquiring an electronic speckle image of a measured object;
the extraction module is used for extracting a first phase shift image from the electronic speckle images acquired at a first moment and extracting a second phase shift image from the electronic speckle images acquired at a second moment;
the calculation module is used for carrying out interpolation calculation on the first phase shift image and the second phase shift image;
the generating module is used for generating at least one sub-image of the first phase shift image according to the result of the interpolation calculation; and generating at least one sub-image of the second phase-shifted image;
the processing module is used for analyzing the first phase shift image, the sub-image of the first phase shift image, the second phase shift image and the sub-image of the second phase shift image, calculating and extracting the phase difference between the first moment and the second moment; the phase difference is used for describing the change of the surface displacement of the measured object;
and the output module is used for outputting the extracted phase difference.
6. The system of claim 5, wherein the computing module comprises:
the device comprises an extraction unit, a phase shift unit and a phase shift unit, wherein the extraction unit is used for extracting a front phase shift image group and a rear phase shift image group from an acquired electronic speckle image of a measured object, the front phase shift image group comprises a plurality of phase shift images extracted before a target phase shift image, and the rear phase shift image group comprises a plurality of phase shift images extracted after the target phase shift image; the target phase shift images are respectively a first phase shift image and a second phase shift image;
and the computing unit is used for carrying out interpolation computation by utilizing the extracted front phase shift image group and the extracted rear phase shift image group.
7. The system of claim 5, wherein the processing module comprises:
an analysis unit for analyzing the first phase-shifted image, the sub-image of the first phase-shifted image, the second phase-shifted image at the second time, and the sub-image of the second phase-shifted image;
a calculation unit for calculating a phase difference between the first time and the second time;
and the extraction unit is used for extracting the calculated phase difference.
8. A single-step phase-shift electronic speckle interferometry device is characterized by comprising a laser, a camera and a computer, wherein the laser is used for irradiating a measured object so as to generate an electronic speckle image; the camera is used for collecting electronic speckle images; the computer is configured to perform the method of any one of claims 1-3 to process the acquired electronic speckle images.
9. A storage medium having stored therein processor-executable instructions, which when executed by a processor, are configured to perform the method of claims 1-3.
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