CN103471998A - Ultrasonic material reflection and transmission coefficient laser measurement system - Google Patents
Ultrasonic material reflection and transmission coefficient laser measurement system Download PDFInfo
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- CN103471998A CN103471998A CN2013103731748A CN201310373174A CN103471998A CN 103471998 A CN103471998 A CN 103471998A CN 2013103731748 A CN2013103731748 A CN 2013103731748A CN 201310373174 A CN201310373174 A CN 201310373174A CN 103471998 A CN103471998 A CN 103471998A
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Abstract
The invention discloses an ultrasonic material reflection and transmission coefficient laser measurement system. Currently, a hydrophone measurement method has a certain error. According to the invention, a testing bracket is placed in a pool; a test sample is placed on the testing bracket; a sound absorption material is placed below the testing bracket; and a focused transducer arranged on a mechanical positioning mechanism is over against the test sample. A signal of a function generator is input into a power amplifier; and after being amplified, the signal drives the focused transducer to radiate sound pulses into a water medium. A laser vibration meter is placed outside the pool; a laser beam emitted by the laser vibration meter enters the water medium by a lens arranged on the side wall of the pool and is reflected back to the laser vibration meter by a reflector; and an output signal of the laser vibration meter is input into a digital oscillograph after passing through a pre-amplifier. According to the invention, the characteristic of non-contact measurement of a laser vibration measurement method is utilized to carry out measurement on characteristic parameters of a sound field of the transducer and the interference effect on the sound field, which is caused when a hydrophone is used for measurement, is overcome.
Description
Technical field
The invention belongs to the acoustic measurement technical field, relate to a kind of ultrasonic material reflection and transmission coefficient laser measurement system.
Background technology
In industry and medical ultrasound equipment development process and scientific research activity, need to realize with different acoustics passive materials transmission, reflection or the absorption function of sound wave.Except the physical parameters such as density, the velocity of sound, hardness, it is mainly reflection and the transmission coefficient of material that the acoustic equipment performance is had to the parameter of considerable influence, therefore must measure accurately it.
All the time, the measurement of the acoustical parameters such as material reflection and transmission coefficient is all undertaken by use acoustic sensor (nautical receiving set).During measurement, need to be placed on nautical receiving set in sound field to be measured, at first measure the sound radiation pressure value that transmitting transducer produces, then specimen is placed in known sound field, utilize nautical receiving set to measure reflecting acoustic pressure amplitude and the transmission acoustic pressure amplitude of sample, just can calculate reflection coefficient and the transmission coefficient parameter of material.
Because nautical receiving set has certain bulk, be placed in sound field and can produce diffraction to incident acoustic wave, particularly, when the close together between nautical receiving set and specimen, can cause the Multi reflection of sound wave at the two, have a strong impact on the Measurement accuracy to reflected signal and transmission signal.And, along with the rising of survey frequency, the diffraction that nautical receiving set produces affects meeting constantly to be increased, therefore, the measurement of using nautical receiving set to carry out ultrasonic material acoustics characteristic has inevitable defect.
Summary of the invention
The present invention is devoted to overcome and uses nautical receiving set to carry out the intrinsic shortcoming of material acoustics feature measurement, and the untouchable characteristics that have by application vibration measurement with laser technology are eliminated while using nautical receiving set to measure the interference effect to sound field; Simultaneously, when the High Strength Plane sound wave that utilizes in the present invention focused transducer to produce and laser measurement, to the space integral effect of plane sound wave, improve the signal to noise ratio (S/N ratio) of measuring, strengthened the measurement capability to all kinds of acoustical materials.
The technical scheme that technical solution problem of the present invention is taked is:
The present invention includes function generator, power amplifier, mechanical detent mechanism, digital oscilloscope, prime amplifier, laser vibration measurer, focused transducer, catoptron, acoustic absorbant, pond and test bracket.
Test bracket is placed in pond, is placed with specimen on test bracket, places acoustic absorbant below test bracket, is arranged on focused transducer on mechanical detent mechanism over against the specimen setting.
The signal of function generator inputs to power amplifier, through amplifying the rear drive focused transducer to pulses of radiation sound wave in aqueous medium.
Laser vibration measurer is placed on outside pond, the laser beam that is parallel to the specimen upper surface that laser vibration measurer sends incides in aqueous medium by the lens that are placed on the sidewall of pond, and return laser vibration measurer through mirror reflects, the output signal of laser vibration measurer is input to digital oscilloscope after prime amplifier, to obtain the signal amplitude value of required measurement.
Described laser vibration measurer measure respectively transmission sound pressure amplitudes that the focused transducer reflecting acoustic pressure amplitude that sound pressure amplitudes produces after sample after tested along the diametric integration value in burnt territory, focus beam on focal plane produces after sample after tested along the diametric integration value in burnt territory, focus beam along burnt territory diametric integration value, utilize above-mentioned three integration values to complete the calculating of specimen reflection and transmission coefficient.
Beneficial effect of the present invention:
The characteristics of the non-cpntact measurement that utilizes the vibration measurement with laser method to have carry out the measurement of transducer acoustic field characterisitic parameter, have overcome while using nautical receiving set to measure the interference effect to sound field.
The high-strength focused collimated beam of sound that uses focused transducer to produce is detected, and has increased the signal to noise ratio (S/N ratio) of measuring, and has improved the measurement capability to acoustical material.
Utilize the measured acoustic pressure integration value of laser vibration measurer to carry out reflection coefficient and transmission coefficient calculating, overcome inhomogeneous the produced measuring error of sample making.
The accompanying drawing explanation
Fig. 1 is ultrasonic material reflection and transmission coefficient laser method measuring principle block diagram.
Fig. 2 is sample measurement supporting structure schematic diagram.
Fig. 3 is laser method focused transducer sound field sound pressure measurement schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described.
The present invention proposes and utilize the vibration measurement with laser technology material acoustics characteristic to be carried out to the technical scheme of non-intrusion measurement, reflection and transmission acoustic pressure that sound radiation pressure by use laser vibration measurer measurement focused transducer on focal plane and measurement sample produce under identical sound field condition, can calculate exactly reflection coefficient and the transmission loss of material, overcome shortcoming intrinsic while using nautical receiving set to carry out the material acoustics parameter measurement.
As depicted in figs. 1 and 2, the measuring system that the present invention mainly consists of following instrument and equipment realizes: focused transducer 7, function generator 1, power amplifier 2, mechanical detent mechanism 3, laser vibration measurer 6, prime amplifier 5, digital oscilloscope 4, pond 11, catoptron 8, test bracket 12 and acoustic absorbant 10 etc.
Described focused transducer adopts the ball-type ceramic component to be prepared from, and sound wave, after the inside surface radiation of ball-type element, collects the formation focused sound waves in its burnt territory, and wave front will present plane form, acoustic pressure amplitude by the Gaussian function formal distribution.
Described function generator is the universal electric instrumentation, and the parameters such as the frequency of the needed filler pulse ripple of exportable measurement signal, signal, wave number, recurrence interval, signal amplitude can be regulated according to the requirement of measuring.
Described power amplifier is the universal electric instrumentation, can the input signal of signal source be amplified, formation can drive the output voltage signal of acoustic transducer, and the output impedance of power amplifier should be complementary with the input impedance of transducer and have certain bandwidth of operation.
Described mechanical navigation system is used for the fixed-focus transducer, and can be regulated the angle of transducer, thereby changes the radiated sound direction of wave travel; Can be regulated the underwater penetration of transducer, so that the focal plane of transducer can match with the surface of specimen simultaneously.
Described prime amplifier is general electronic instrument equipment, and the output signal of laser vibration measurer is amplified, and can in wider operating frequency range, work, and have lower background noise.
Described digital oscilloscope is general electronic instrument equipment, can carry out quantification treatment to the output signal of prime amplifier, demonstrate the measuring-signal waveform, and can calculate the amplitude size of input signal, the parameters such as oscillographic sample frequency, vertical resolution, average time can be regulated according to the needs of measuring.
Described laser vibration measurer is the universal electric instrumentation, and this equipment will give off the measurement laser beam, will produce reflector laser after acting on body surface, and vialog is by receiving the vibration velocity of reflector laser signal measurement body surface.
Described test bracket is prepared from, by two annulus and four support bars, is formed (structural representation is shown in Fig. 2) by nonmetallic materials.Specimen is placed on support, when measuring the transmission coefficient of sample, should guarantee that laser beam can pass from the lower surface of material by the support bar of test bracket.
Described catoptron adopts optical coating flat glass eyeglass, and this catoptron will be fixed on the sidewall of pond, for laser beam is reflected back to laser vibration measurer.
Described acoustic absorbant is formed by the Polymer materialspreparation with Wedge structure, for absorbing the sound wave of focused transducer, reduces the impact of reflective sound wave on test result.
Described specimen 9 need to be prepared to the planar wafer shape, to guarantee the reflected sound wave energy, by former incident acoustic wave direction, returns, and does not depart from the direction of propagation of transmitted acoustic pulse.The thickness of sample should be long much smaller than Jiao of focused transducer, to guarantee that focused sound waves does not have obvious variation in the upper and lower lip-deep intensity distributions of sample; The diameter of specimen should, much larger than the burnt territory of focused transducer, produce diffraction effect to avoid radiative acoustic wave in sample edge.
Form test macro as shown in Figure 1 by the said equipment, by utilizing laser vibration measurer to measure the focused transducer radiation signal on focal plane, the reflected signal produced through sample and transmission signal under identical drive signals, can calculate reflection coefficient and the transmission coefficient of specimen material.
The course of work of the present invention: form measuring system by shown in Fig. 1, be ready to instrumentation, inject degassed water in pond, focused transducer is arranged on mechanical detent mechanism and by specimen and is placed on test bracket.Place acoustic absorbant below test bracket, for absorbing the sound wave of focused transducer.
Function generator emission filler pulse signal is set, and the frequency of filler pulse is sample treats measured frequency, and the cycle of filler pulse need should guarantee that the sound wave energy given off through transducer reaches steady-state signal much larger than the reverberation time in pond, the length of filler pulse.The signal of function generator will be input to power amplifier, through amplifying the rear drive focused transducer to pulses of radiation sound wave in aqueous medium.The angle of focused transducer will be regulated by mechanical detent mechanism, so that the radiated sound wave energy impinges perpendicularly on the surface of specimen; Simultaneously, can regulate the underwater penetration of focused transducer by detent mechanism, the upper surface of specimen and the focal plane of focused transducer are coincided.Laser vibration measurer is placed on outside pond, and laser beam incides in aqueous medium by the lens that are placed on the sidewall of pond, and returns laser vibration measurer through mirror reflects.Laser beam should parallel with the upper surface of specimen, and with the surface of the sample suitable distance of being separated by, in order to can distinguish reflected signal and incident acoustic wave signal by laser vibration measurer.The output signal of laser vibration measurer is imported into digital oscilloscope after prime amplifier, to obtain the signal amplitude value of required measurement.In measuring process, at first by laser vibration measurer, obtain the radiative acoustic wave intensity on the focused transducer focal plane, then measure the reflected signal produced when sample is placed on the transducer focal plane; By the position of mobile laser vibration measurer, laser beam is passed from the direction paralleled with the specimen lower surface, measure the transmitted acoustic pulse signal.
By using the data such as radiation signal amplitude on measured transducer focal plane, reflection that specimen produces and transmission signal amplitude, just can calculate reflection coefficient and the transmission coefficient of detected materials.
Ultrasonic material reflection and transmission coefficient laser method surveying work principle:
Use principle of work that laser method measures ultrasonic material acoustics characteristic as shown in Figure 3, wherein, focused transducer is fixed on mechanical detent mechanism, and acoustic axis is adjusted on the z of vertical direction axle.Laser vibration measurer is placed on to be measured outside sound field, and the laser beam given off is vertical with the acoustic axis direction.Place catoptron outside the transducer radiated sound field, laser beam after inciding mirror surface along original route return laser light vialog.
When laser beam incident, in sound field the time, due to piezooptical effect, sound wave will produce modulating action to laser.When laser vibration measurer passes the sound field of focused transducer along the y direction of principal axis, according to acoustooptical interaction principle, output signal
v(
x) can be expressed as:
In formula,
=0.32 equivalent refraction coefficient that is aqueous medium, w is angular frequency,
p(
x,y) be in sound field (
x,y) acoustic pressure of position.
When laser beam during through the focal plane of focused transducer, as the burnt territory of establishing transducer be in (
y 1 , y 2 ) interval in, in burnt territory, the mean value of sound pressure amplitudes is A
0but the output approximate representation of laser vibration measurer is:
Therefore, the output of laser vibration measurer is directly proportional to the average sound pressure amplitude in burnt territory, burnt territory diameter.
Specimen is placed in the burnt territory of focused transducer, and the focal plane of its upper surface and transducer is coincided, by adjusting the position of laser vibration measurer, laser beam is skipped over along the direction paralleled with the specimen upper surface, can detect the reflective sound wave that the material upper surface produces.If the average sound pressure amplitude of this reflective sound wave in burnt territory is A
1, the output of laser vibration measurer can be expressed as:
Adjust the position of laser vibration measurer, laser beam is skipped over along the direction paralleled with the specimen lower surface, can detect the transmitted acoustic pulse of sample lower surface.If the average sound pressure amplitude of transmitted acoustic pulse in burnt territory is A
2, the output of laser vibration measurer can be expressed as:
According to the definition of reflection coefficient and transmission coefficient, can draw the reflection coefficient of specimen
rand transmission coefficient
tcomputing formula can be expressed as respectively:
；
（5）
Therefore, by using laser vibration measurer, the sound radiation pressure intensity of measurement transducer on focal plane, reflection and the transmission signal that specimen produces respectively, just can calculate reflection coefficient and the transmission coefficient of detected materials.
Above-mentioned embodiment is used for the present invention that explains, rather than pin limits the invention, and in the protection domain of spirit of the present invention and claim, any modification and change that the present invention is made, all fall into protection scope of the present invention.
Claims (9)
1. ultrasonic material reflection and transmission coefficient laser measurement system, is characterized in that: comprise function generator, power amplifier, mechanical detent mechanism, digital oscilloscope, prime amplifier, laser vibration measurer, focused transducer, catoptron, acoustic absorbant, pond and test bracket;
Test bracket is placed in pond, is placed with specimen on test bracket, places acoustic absorbant below test bracket, is arranged on focused transducer on mechanical detent mechanism over against the specimen setting;
The signal of function generator inputs to power amplifier, through amplifying the rear drive focused transducer to pulses of radiation sound wave in aqueous medium;
Laser vibration measurer is placed on outside pond, the laser beam that is parallel to the specimen upper surface that laser vibration measurer sends incides in aqueous medium by the lens that are placed on the sidewall of pond, and return laser vibration measurer through mirror reflects, the output signal of laser vibration measurer is input to digital oscilloscope after prime amplifier, to obtain the signal amplitude value of required measurement;
Described laser vibration measurer measure respectively transmission sound pressure amplitudes that the focused transducer reflecting acoustic pressure amplitude that sound pressure amplitudes produces after sample after tested along the diametric integration value in burnt territory, focus beam on focal plane produces after sample after tested along the diametric integration value in burnt territory, focus beam along burnt territory diametric integration value, utilize above-mentioned three integration values to complete the calculating of specimen reflection and transmission coefficient.
2. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, it is characterized in that: described function generator emission filler pulse signal, the measured frequency for the treatment of that the frequency of filler pulse is specimen, the cycle of filler pulse should guarantee that much larger than the reverberation time in pond, the length of filler pulse the sound wave energy that the line focus transducer gives off reaches steady-state signal.
3. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, and it is characterized in that: the output impedance of described power amplifier and the input impedance of focused transducer are complementary and have certain bandwidth of operation.
4. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, it is characterized in that: described mechanical detent mechanism is for the fixed-focus transducer, and can be regulated the angle of transducer, thereby change the radiated sound direction of wave travel; Can be regulated the underwater penetration of transducer, so that the focal plane of transducer can match with the surface of specimen simultaneously.
5. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, it is characterized in that: described focused transducer adopts the ball-type ceramic component to be prepared from, sound wave is after the inside surface radiation of ball-type element, collect the formation focused sound waves in its burnt territory, wave front presents plane form, acoustic pressure amplitude by the Gaussian function formal distribution.
6. ultrasonic material reflection according to claim 1 and transmission coefficient laser measurement system, is characterized in that: described catoptron employing optical coating flat glass eyeglass.
7. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, it is characterized in that: described acoustic absorbant is formed by the Polymer materialspreparation with Wedge structure, for absorbing the sound wave of focused transducer, reduce the impact of reflective sound wave on test result.
8. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, it is characterized in that: described test bracket is prepared from by nonmetallic materials, by two annulus and four support bars, formed, specimen is placed on support, when measuring the transmission coefficient of sample, the assurance laser beam can be passed from the lower surface of material by the support bar of test bracket.
9. ultrasonic material according to claim 1 reflects and the transmission coefficient laser measurement system, it is characterized in that: described specimen is the planar wafer shape, with assurance reflected sound wave energy, by former incident acoustic wave direction, return, does not depart from the direction of propagation of transmitted acoustic pulse; The thickness of specimen should be long much smaller than Jiao of focused transducer, to guarantee that focused sound waves does not have obvious variation in the upper and lower lip-deep intensity distributions of sample; The diameter of specimen should, much larger than the burnt territory of focused transducer, produce diffraction effect to avoid radiative acoustic wave in sample edge.
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Cited By (7)
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| CN105050020A (en) * | 2015-07-31 | 2015-11-11 | 浙江省计量科学研究院 | Free sound field device based on optical non-destructive monitoring technology |
| CN108007552A (en) * | 2017-10-11 | 2018-05-08 | 中国船舶重工集团公司第七〇五研究所 | Underwater sound transmitting transducer acoustical behavior measuring method under a kind of high hydrostatic pressure |
| CN110608795A (en) * | 2018-06-14 | 2019-12-24 | 重庆海扶医疗科技股份有限公司 | Dynamic sound pressure detection device and dynamic sound pressure detection method |
| CN111505609A (en) * | 2020-03-26 | 2020-08-07 | 中国船舶重工集团公司第七一五研究所 | Absolute sound pressure measurement method for ultrasonic transducer |
| CN113316419A (en) * | 2018-12-18 | 2021-08-27 | 医视特有限公司 | Echo based focus correction |
| CN114295724A (en) * | 2021-12-29 | 2022-04-08 | 电子科技大学(深圳)高等研究院 | Sound wave test tube |
| CN115276829A (en) * | 2022-08-05 | 2022-11-01 | 天津大学 | Laser acoustic transducer system based on acoustic super surface |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105050020A (en) * | 2015-07-31 | 2015-11-11 | 浙江省计量科学研究院 | Free sound field device based on optical non-destructive monitoring technology |
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| CN108007552A (en) * | 2017-10-11 | 2018-05-08 | 中国船舶重工集团公司第七〇五研究所 | Underwater sound transmitting transducer acoustical behavior measuring method under a kind of high hydrostatic pressure |
| CN110608795A (en) * | 2018-06-14 | 2019-12-24 | 重庆海扶医疗科技股份有限公司 | Dynamic sound pressure detection device and dynamic sound pressure detection method |
| CN113316419A (en) * | 2018-12-18 | 2021-08-27 | 医视特有限公司 | Echo based focus correction |
| CN111505609A (en) * | 2020-03-26 | 2020-08-07 | 中国船舶重工集团公司第七一五研究所 | Absolute sound pressure measurement method for ultrasonic transducer |
| CN111505609B (en) * | 2020-03-26 | 2023-09-12 | 中国船舶重工集团公司第七一五研究所 | Method for measuring absolute sound pressure of ultrasonic transducer |
| CN114295724A (en) * | 2021-12-29 | 2022-04-08 | 电子科技大学(深圳)高等研究院 | Sound wave test tube |
| CN115276829A (en) * | 2022-08-05 | 2022-11-01 | 天津大学 | Laser acoustic transducer system based on acoustic super surface |
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