CN108398489B - Method for accurately measuring transverse resolution of focused ultrasonic transducer - Google Patents
Method for accurately measuring transverse resolution of focused ultrasonic transducer Download PDFInfo
- Publication number
- CN108398489B CN108398489B CN201810006549.XA CN201810006549A CN108398489B CN 108398489 B CN108398489 B CN 108398489B CN 201810006549 A CN201810006549 A CN 201810006549A CN 108398489 B CN108398489 B CN 108398489B
- Authority
- CN
- China
- Prior art keywords
- test block
- gray value
- ultrasonic transducer
- focused ultrasonic
- accurately measuring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000012360 testing method Methods 0.000 claims abstract description 48
- 230000008859 change Effects 0.000 claims abstract description 17
- 238000003384 imaging method Methods 0.000 claims abstract description 16
- 238000012545 processing Methods 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims abstract description 6
- 238000012935 Averaging Methods 0.000 claims abstract description 5
- 238000009795 derivation Methods 0.000 claims abstract description 5
- 238000001914 filtration Methods 0.000 claims abstract description 5
- 238000009499 grossing Methods 0.000 claims abstract description 5
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 4
- 239000010935 stainless steel Substances 0.000 claims abstract description 4
- 238000002604 ultrasonography Methods 0.000 claims description 25
- 238000001514 detection method Methods 0.000 abstract description 3
- 238000002474 experimental method Methods 0.000 abstract description 3
- 238000002360 preparation method Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000008569 process Effects 0.000 description 2
- 239000010963 304 stainless steel Substances 0.000 description 1
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
Abstract
The invention provides a method for accurately measuring the transverse resolution of a focused ultrasonic transducer, belonging to the technical field of ultrasonic detection. Firstly, processing a stainless steel material into a cubic test block, wherein the edges of the test block are sharp and have no chamfer angle; then, performing high-precision C-scan imaging on the edge of the test block by using a focused ultrasonic transducer to be tested; then, randomly selecting 10 gray value curves V (x) vertical to the edge of the test block in the C-scan image, averaging the gray value curves, and smoothing the gray value curves by adopting a mean filtering method; carrying out derivation operation on the smoothed gray value curve to obtain a gray value change rate curve
And finally, calculating the transverse resolution of the focused ultrasonic transducer by adopting a-6 dB descent method for the gray value change rate curve. The method provides a simple and convenient method for accurately measuring the transverse resolution of the focused ultrasonic transducer from experiments, and visually displays the influence of the transverse resolution on the C-scan imaging definition. The method has low preparation requirement on the test block, and the same test block can be suitable for different types of axisymmetric transducers.
Description
Technical Field
The invention relates to the technical field of ultrasonic detection, in particular to a method for accurately measuring the transverse resolution of a focused ultrasonic transducer.
Background
The lateral resolution of the focused ultrasound transducer is one of the important parameters affecting the detection accuracy and imaging quality of the ultrasonic microscope, and determines the definition of C-scan imaging. The transverse resolution of the focused ultrasonic transducer is related to the numerical aperture and the acoustic wavelength of the transducer, and the transverse resolution of the focused ultrasonic transducer can be effectively improved by improving the convergence degree of the acoustic waves emitted by the transducer in a material to be measured. Currently, methods for determining the lateral resolution of a focused ultrasound transducer are roughly classified into the following three types: 1) calculating the transverse resolution of the focused ultrasonic transducer by adopting a formula omega of 0.51 lambda/N.A. according to a Rayleigh criterion; 2) according to the radial sound pressure distribution of the sound wave emitted by the focusing transducer at the focal plane, calculating the transverse resolution of the sound wave by adopting a-6 dB descent method; 3) and judging the transverse resolution of the focused ultrasonic transducer according to the resolvable degree of the standard grating in the C-scan image. Although the three methods described above are used in different situations, they have certain disadvantages more or less. The lateral resolution calculated according to the rayleigh criterion is only suitable for spherical focusing transducers with a single frequency or approximately a single frequency, and the calculation result error is large for wide-frequency focusing transducers with a wide frequency band range. When the transverse resolution of the focused ultrasonic transducer is calculated according to the radial sound pressure distribution, the radial sound pressure distribution of the focal plane of the transducer needs to be accurately obtained through an experimental or theoretical formula. If the radial sound pressure distribution of the focal plane of the focused ultrasonic transducer is measured through experiments, the measurement result is inevitably influenced by a receiving device, and the frequency spectrum characteristic of the actual transducer must be considered when the radial sound pressure distribution of the focal plane of the focused ultrasonic transducer is calculated according to a theoretical formula, so that the whole measurement process is complex. If the transverse resolution of the focused ultrasonic transducer is judged according to the definition of the standard grating pattern in the C-scan image, a series of grating stripes with different intervals need to be prepared on a test block, the method not only has higher requirement on the processing precision of the test block, but also the imaging definition is inevitably influenced by the axial resolution.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for accurately measuring the transverse resolution of a focused ultrasonic transducer, which accurately measures the transverse resolution of the focused ultrasonic transducer through a relatively simple C-scan imaging experiment and an image processing method. The method specifically comprises the steps of processing a cubic test block with sharp edges, carrying out high-precision C-scan imaging on the edges of the test block, and measuring the transverse resolution of the focused ultrasonic transducer by adopting a-6 dB descent method according to the change rate of gray values in the C-scan image in the direction perpendicular to the edges of the test block.
The method comprises the following steps:
(1) processing a stainless steel material into a cubic test block;
(2) carrying out high-precision C-scan imaging on the edges of the cubic test block prepared in the step (1) by using a focused ultrasonic transducer to be tested;
(3) randomly selecting 10 gray value curves V (x) vertical to the edges of the test block in the C-scan image in the step (2), averaging the gray value curves, and smoothing the gray value curves by adopting a mean filtering method, wherein a variable x represents that the gray value curves are parallel to the x-axis direction;
(4) performing derivation operation on the gray value curve smoothed in the step (3) to obtain a gray value change rate curve
(5) And (4) calculating the gray value change rate curve in the step (4) by adopting a-6 dB descent method to obtain the transverse resolution of the focused ultrasonic transducer.
The cube test block in the step (1) is processed in a linear cutting mode, and the edges of the cube test block are sharp and have no chamfer.
The side length of the cube test block in the step (1) is 20mm multiplied by 20 mm.
The relation between the scanning step length l of the high-precision C-scan imaging in the step (2) and the wavelength lambda of the sound wave is as follows: l is less than or equal to lambda/100, and the scanning area is 1mm multiplied by 1 mm.
The technical scheme of the invention has the following beneficial effects:
the method has the characteristics of simple preparation of a standard sample, accurate measurement result, wide application range and the like, and can be used as a standard method for measuring the transverse resolution of the focused ultrasonic transducer.
Drawings
FIG. 1 is a side view of a schematic diagram of a method of accurately measuring the lateral resolution of a focused ultrasound transducer of the present invention;
FIG. 2 is a top view of a schematic diagram of measuring the lateral resolution of a focused ultrasound transducer according to the present invention;
FIG. 3 shows the test results of a 10MHz focused ultrasound transducer in an embodiment of the invention;
FIG. 4 shows the test results of a 30MHz focused ultrasound transducer in an embodiment of the invention;
FIG. 5 is a test result of a 50MHz focused ultrasound transducer in an embodiment of the invention;
FIG. 6 shows the test results of a 100MHz focused ultrasound transducer in an embodiment of the invention;
FIG. 7(a) is a diagram showing the spectral characteristics of a 10MHz focused ultrasound transducer in an embodiment of the present invention;
FIG. 7(b) is a diagram showing the spectral characteristics of a 30MHz focused ultrasound transducer in an embodiment of the present invention;
FIG. 7(c) is a diagram showing the spectral characteristics of a 50MHz focused ultrasound transducer in an embodiment of the present invention;
fig. 7(d) shows the spectral characteristics of a 100MHz focused ultrasound transducer in an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a method for accurately measuring the transverse resolution of a focused ultrasonic transducer.
The method comprises the following steps:
(1) processing a stainless steel material into a cubic test block;
(2) carrying out high-precision C-scan imaging on the edges of the cubic test block prepared in the step (1) by using a focused ultrasonic transducer to be tested;
(3) randomly selecting 10 gray value curves V (x) vertical to the edges of the test block in the C-scan image in the step (2), averaging the gray value curves, and smoothing the gray value curves by adopting a mean filtering method;
(4) performing derivation operation on the gray value curve smoothed in the step (3) to obtain a gray value change rate curve
(5) And (4) calculating the gray value change rate curve in the step (4) by adopting a-6 dB descent method to obtain the transverse resolution of the focused ultrasonic transducer.
The cube test block in the step (1) is processed in a linear cutting mode, and the edges of the cube test block are sharp and have no chamfer.
The side length of the cube test block in the step (1) is 20mm multiplied by 20 mm.
The relation between the scanning step length l of the high-precision C-scan imaging in the step (2) and the wavelength lambda of the sound wave is as follows: l is less than or equal to lambda/100, and the scanning area is 1mm multiplied by 1 mm.
In the concrete implementation process, the attached drawings are combined(see fig. 1-7), the design of the present invention will be described in detail by taking focused ultrasound transducers with nominal center frequencies of 10MHz, 30MHz, 50MHz and 100MHz, respectively, as an example, but not by way of limitation. Fig. 1 and 2 show the basic principle of measuring the lateral resolution of a focused ultrasound transducer. As can be seen from fig. 1 (side view) and fig. 2 (top view), under the condition that the test block edges are sharp and have no chamfer, when the focal spot of the focused ultrasound transducer is gradually scanned from the left area completely on the test block surface to the right area completely in the water, the change of the voltage signal amplitude V caused by the reflected echo depends strictly on the sound pressure change of the incident sound wave which is specularly reflected on the test block surface, so the gray value change V (x) perpendicular to the test block edges (assumed to be parallel to the x-axis direction) in the C-scan image indirectly reflects the radial sound pressure distribution change of the focused ultrasound transducer. By calculating the gray value change rate vertical to the edge of the sample in the C-scan image
The lateral resolution of the focused ultrasound transducer was measured using a-6 dB down-fall method.
The method steps for measuring the transverse resolution of a focused ultrasound transducer are given in detail below:
1. processing 304 stainless steel serving as an experimental material into a cubic test block with the side length of 20mm multiplied by 20mm by adopting a linear cutting mode, and then processing the upper surface and the side surface of the test block smoothly on a milling machine and ensuring that the edge of the test block is sharp and has no chamfer;
2. immersing the test block in a water tank, adjusting the height of a scanning mechanism to enable a focused ultrasonic transducer to accurately focus on the upper surface of the test block, and performing C-scanning imaging on sharp edges of the test block by adopting 2-micrometer stepping precision, wherein the imaging area is 1mm multiplied by 1mm, and the imaging results are respectively shown as C-scanning images on the left sides in the images 3 to 6;
3. randomly selecting 10 gray value curves V (x) vertical to the edge of the test block from the C-scan image, averaging the gray value curves, and smoothing the gray value curves by using a mean filtering method, wherein the length of a filter is 20, and the smoothed curves are respectively shown as gray value curves in the middle of the graphs in FIGS. 3 to 6;
4. performing derivation operation on the smoothed gray value curve to obtain a change rate curve of the gray value
As shown in the right-hand gray-level change rate curves of fig. 3 to 6, respectively;
5. curve of rate of change of gray value
And measuring by adopting a-6 dB descent method to obtain the transverse resolution of the focused ultrasonic transducer. For the four focused ultrasound transducers described above, the lateral resolutions were 316 μm, 98 μm, 150 μm, and 104 μm in this order. To demonstrate the effectiveness of this measurement method, the measurement results were compared with theoretical results calculated using the sharpness criterion formula ω 0.51 λ/n.a., and the results are shown in table 1. In the sharpness criterion formula, λ is the wavelength of sound wave in water, and n.a. ═ D/2F represents the numerical aperture. The columns 2-4 in Table 1 are the geometric parameters of the focused ultrasound transducer.
Table 1 shows that the theoretical calculation results of the lateral resolution are closer to the experimental test results with relative deviations of 3.36% and 9.26% for the focused ultrasound transducers with nominal frequencies of 10MHz and 30MHz, respectively, and are larger with deviations of 47.06% and 153.66% for the focused transducers with nominal frequencies of 50MHz and 100MHz, respectively.
Fig. 7 shows the test results of the frequency spectrum characteristics of the four focused ultrasonic transducers in the factory. Fig. 7(a) and 7(b) show that the frequency bandwidths of the 10MHz focusing transducer and the 30MHz focusing transducer are narrow, the frequency spectrum only includes one peak, the center frequency is closer to the nominal frequency (10MHz and 20MHz), and therefore the deviation between the theoretical calculation result and the experimental test result is small. While fig. 7(c) and 7(d) show that the focused transducers with frequencies of 50MHz and 100MHz have a spectrum with multiple peaks, the actual center frequencies (30 MHz and 35MHz, respectively) are much different from the nominal frequency of the transducer, and therefore the theoretical calculation results deviate much from the experimental test results. Furthermore, it is stated that the sharpness of the C-scan image in actual inspection is not only related to the lateral resolution of the transducer, but also to the axial resolution of the transducer, i.e. the focal column length, the shorter the focal column length, the lower the image sharpness.
TABLE 1 nominal parameters and lateral resolution of differently focused transducers
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (4)
1. A method of accurately measuring the lateral resolution of a focused ultrasound transducer, comprising: the method comprises the following steps:
(1) processing a stainless steel material into a cubic test block;
(2) carrying out high-precision C-scan imaging on the edges of the cubic test block prepared in the step (1) by using a focused ultrasonic transducer to be tested;
(3) randomly selecting 10 gray value curves V (x) vertical to the edges of the test block in the C-scan image in the step (2), averaging the gray value curves, and smoothing the gray value curves by adopting a mean filtering method;
(4) performing derivation operation on the gray value curve smoothed in the step (3) to obtain a gray value change rate curve
(5) And (4) calculating the gray value change rate curve in the step (4) by adopting a-6 dB descent method to obtain the transverse resolution of the focused ultrasonic transducer.
2. The method of accurately measuring the lateral resolution of a focused ultrasound transducer as recited in claim 1, wherein: the cube test block in the step (1) is processed in a linear cutting mode, and the edges of the cube test block are sharp and have no chamfer.
3. The method of accurately measuring the lateral resolution of a focused ultrasound transducer as recited in claim 1, wherein: the side length of the cube test block in the step (1) is 20mm multiplied by 20 mm.
4. The method of accurately measuring the lateral resolution of a focused ultrasound transducer as recited in claim 1, wherein: the relation between the scanning step length l of the high-precision C-scan imaging in the step (2) and the wavelength lambda of the sound wave is as follows: l is less than or equal to lambda/100, and the scanning area is 1mm multiplied by 1 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810006549.XA CN108398489B (en) | 2018-01-04 | 2018-01-04 | Method for accurately measuring transverse resolution of focused ultrasonic transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810006549.XA CN108398489B (en) | 2018-01-04 | 2018-01-04 | Method for accurately measuring transverse resolution of focused ultrasonic transducer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108398489A CN108398489A (en) | 2018-08-14 |
| CN108398489B true CN108398489B (en) | 2020-10-30 |
Family
ID=63094678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810006549.XA Expired - Fee Related CN108398489B (en) | 2018-01-04 | 2018-01-04 | Method for accurately measuring transverse resolution of focused ultrasonic transducer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108398489B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112578024B (en) * | 2020-11-26 | 2022-01-25 | 北京理工大学 | Calculation method, measurement device and measurement method for ultrasonic C scanning detection resolution |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08105869A (en) * | 1994-10-07 | 1996-04-23 | Hitachi Constr Mach Co Ltd | Standard sample for evaluating ultrasonic probe characteristics and method for evaluating ultrasonic probe characteristics |
| CN104634876A (en) * | 2015-01-30 | 2015-05-20 | 北京科技大学 | Method for detecting inclusions in metal material by virtue of ultrasonic scanning microscope |
| CN105403627A (en) * | 2015-12-24 | 2016-03-16 | 大连理工大学 | Method for enhancing lateral resolution of ultrasonic testing images |
| WO2017194832A1 (en) * | 2016-05-10 | 2017-11-16 | Åbo Akademi (Åbo Akademi University) | An artifact for determining resolution of imaging based on electromagnetic radiation and/or mechanical waves |
-
2018
- 2018-01-04 CN CN201810006549.XA patent/CN108398489B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08105869A (en) * | 1994-10-07 | 1996-04-23 | Hitachi Constr Mach Co Ltd | Standard sample for evaluating ultrasonic probe characteristics and method for evaluating ultrasonic probe characteristics |
| CN104634876A (en) * | 2015-01-30 | 2015-05-20 | 北京科技大学 | Method for detecting inclusions in metal material by virtue of ultrasonic scanning microscope |
| CN105403627A (en) * | 2015-12-24 | 2016-03-16 | 大连理工大学 | Method for enhancing lateral resolution of ultrasonic testing images |
| WO2017194832A1 (en) * | 2016-05-10 | 2017-11-16 | Åbo Akademi (Åbo Akademi University) | An artifact for determining resolution of imaging based on electromagnetic radiation and/or mechanical waves |
Non-Patent Citations (2)
| Title |
|---|
| Flaw Sizing Method Based on Ultrasonic Dynamic Thresholds and Neural Network;Song,YF et al;《 AIP Conference Proceedings》;20161231;第1706卷;第180007:1-180007:9 * |
| Using phased array ultrasonic technique for the inspection of straddle;Seunghan Yang et al;《NDT&E International》;20091231;第42卷;第128-132页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108398489A (en) | 2018-08-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP6073389B2 (en) | Ultrasonic immersion inspection of members with arbitrary surface contours | |
| US7694569B2 (en) | Phased array ultrasonic water wedge apparatus | |
| JP4910769B2 (en) | Pipe quality control method and manufacturing method | |
| JP2008209356A (en) | Method of calibrating ultrasonic flaw detection, and quality control method and manufacturing method of tube | |
| KR20090115170A (en) | Tubular object ultrasonic test device and ultrasonic test method | |
| US20140283611A1 (en) | System and a method of adaptive focusing in a phased array ultrasonic system | |
| CN103822971A (en) | Resolution detecting and calibrating method for ultrasonic microscope | |
| CN108398489B (en) | Method for accurately measuring transverse resolution of focused ultrasonic transducer | |
| US5390544A (en) | Method and apparatus for non-destructive evaluation of composite materials with cloth surface impressions | |
| CN108020598A (en) | Become the adaptive linear phased array of wall thickness curved surface member and focus on scan method and detection method | |
| EP3985387A1 (en) | Ultrasound flaw detection method, ultrasound flaw detection device, manufacturing equipment line for steel material, manufacturing method for steel material, and quality assurance method for steel material | |
| CN111458415B (en) | Method for detecting coupling state of ultrasonic phased array transducer and workpiece to be detected | |
| KR20070065934A (en) | Apparatus and method for crack length evaluation by phased array ultrasonic | |
| KR101942792B1 (en) | Steel material quality evaluation method and quality evaluation device | |
| CN112684005A (en) | Full-focusing detection method based on two-dimensional matrix transducer | |
| JP2001027630A (en) | Apparatus and method for measuring flaw height by ultrasonic wave | |
| CN113358751B (en) | Workpiece defect detection method, device and system | |
| CN113075297B (en) | Titanium alloy phased array linear array ultrasonic detection sound field model construction method | |
| Wilcox et al. | Enhanced defect detection and characterisation by signal processing of ultrasonic array data | |
| Potter et al. | Sub-wavelength resolution in air-coupled ultrasound images of spot welds | |
| JP6089805B2 (en) | Measuring device, measuring method, program, and storage medium | |
| Mitri et al. | Surface roughness imaging using the acoustic emission induced by the dynamic radiation force of ultrasound | |
| JP2021156728A (en) | Long object flaw detection system and method | |
| Cherry et al. | Impulse excitation scanning acoustic microscopy for local quantification of Rayleigh surface wave velocity using B-scan analysis | |
| CN112578024B (en) | Calculation method, measurement device and measurement method for ultrasonic C scanning detection resolution |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201030 |