CN203414165U - Laser measurement system for reflection and transmission coefficients of ultrasonic materials - Google Patents
Laser measurement system for reflection and transmission coefficients of ultrasonic materials Download PDFInfo
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- CN203414165U CN203414165U CN201320520092.7U CN201320520092U CN203414165U CN 203414165 U CN203414165 U CN 203414165U CN 201320520092 U CN201320520092 U CN 201320520092U CN 203414165 U CN203414165 U CN 203414165U
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Abstract
The utility model discloses a laser measurement system for the reflection and transmission coefficients of ultrasonic materials. A conventional method of hydrophone measurement has a certain amount of errors. According to the utility model, a test support frame is placed into a pool. A test sample is placed on the support frame. A sound-absorbing material is placed under the support frame. A focusing transducer which is installed on a mechanical positioning structure is disposed to be exactly opposite to the test sample. A signal of a function generator is inputted to a power amplifier, and drives the focusing transducer to radiate a sound pulse to an aqueous medium after amplification. A laser vibration meter is placed outside the pool and emits a laser beam which transmits to the aqueous medium through a lens disposed on a side wall of the pool. The laser beam is reflected to the laser vibration meter through a reflector. An output signal of the laser vibration meter passes through a pre-amplifier and then is inputted to a digital oscilloscope. According to the utility model, the characteristics of noncontact measurement of a method of laser vibration measurement is used for measuring the characteristic parameters of a sound field of the transducer, thereby overcoming the interference to the sound field during the measurement by using the hydrophone.
Description
Technical field
The utility model belongs to acoustic measurement technical field, relates 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 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, nautical receiving set need to be placed in sound field to be measured, 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 close together between nautical receiving set and specimen, can cause that sound wave, at the multiple reflections of the two, has had 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 utility model is devoted to overcome use nautical receiving set and is carried out the intrinsic shortcoming of material acoustics feature measurement, and the untouchable feature having by application vibration measurement with laser technology is eliminated the interference effect to sound field while using nautical receiving set to measure; Meanwhile, the space integral effect to plane sound wave while utilizing High Strength Plane sound wave that focused transducer produces and laser measurement in the utility model, improves the signal to noise ratio (S/N ratio) of measuring, and has strengthened the measurement capability to all kinds of acoustical materials.
The technical scheme that the utility model technical solution problem is taked is:
The utility model comprises 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 specimen setting.
The signal of function generator inputs to power amplifier, through amplifying 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 specimen upper surface that laser vibration measurer sends incides in aqueous medium by the lens that are placed on the sidewall of pond, and be reflected back laser vibration measurer through catoptron, 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.
The beneficial effects of the utility model:
Utilize the feature of the non-cpntact measurement that vibration measurement with laser method has to carry out the measurement of transducer acoustic field characterisitic parameter, overcome the interference effect to sound field while using nautical receiving set to measure.
The high-strength focused collimated beam of sound that uses focused transducer to produce detects, 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.
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 utility model is further described.
The utility model proposes and utilize 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 material acoustics parameter measurement.
As depicted in figs. 1 and 2, the measuring system that the utility model 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 ball-type ceramic component to be prepared from, and sound wave, after the inside surface radiation of ball-type element, collects formation focused sound waves in its burnt territory, and wave front will present plane form, acoustic pressure amplitude by Gaussian function formal distribution.
Described function generator is 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 regulate according to the requirement of measuring.
Described power amplifier is universal electric instrumentation, can amplify the input signal of signal source, formation can drive the output voltage signal of acoustic transducer, and the output impedance of power amplifier should match with the input impedance of transducer and have certain bandwidth of operation.
Described mechanical navigation system is used for fixed-focus transducer, and can regulate the angle of transducer, thereby changes radiated sound direction of wave travel; Can regulate 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 measuring-signal waveform, and can calculate the amplitude size of input signal, the parameters such as oscillographic sample frequency, vertical resolution, average time can regulate according to the needs of measuring.
Described laser vibration measurer is universal electric instrumentation, and this equipment will give off measurement laser beam, acts on after body surface and will produce reflection laser, and vialog reflects the vibration velocity of laser signal measurement body surface by reception.
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 planar wafer shape, and to guarantee that reflected sound wave energy returns by former incident acoustic wave direction, 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 be much larger than the burnt territory of focused transducer, to avoid radiative acoustic wave to produce diffraction effect in sample edge.
By the said equipment, form test macro as shown in Figure 1, by utilizing laser vibration measurer to measure the focused transducer radiation signal on focal plane, the reflected signal producing 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 utility model: 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.Below test bracket, place acoustic absorbant, for absorbing the sound wave of focused transducer.
Function generator transmitting filler pulse signal is set, and the frequency of filler pulse is sample treats measured frequency, and the cycle of filler pulse need be much larger than the reverberation time in pond, the length of filler pulse should guarantee that the sound wave energy giving off through transducer reaches steady-state signal.The signal of function generator will be input to power amplifier, through amplifying rear drive focused transducer to pulses of radiation sound wave in aqueous medium.The angle of focused transducer will regulate by mechanical detent mechanism, so that radiated sound wave energy impinges perpendicularly on the surface of specimen; Meanwhile, by the underwater penetration of the adjustable focused transducer of 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 is reflected back laser vibration measurer through catoptron.Laser beam should parallel with the upper surface of specimen, and with the surface of the sample suitable distance of being separated by, 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, first by laser vibration measurer, obtain the radiative acoustic wave intensity on focused transducer focal plane, then measure the reflected signal producing when sample is placed on transducer focal plane; By the position of mobile laser vibration measurer, laser beam is passed from the direction paralleling with specimen lower surface, measure 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 giving off is vertical with acoustic axis direction.At transducer radiated sound field, place catoptron outward, laser beam after inciding mirror surface along original route return laser light vialog.
When laser beam incident is in sound field 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 y direction of principal axis, according to acoustooptical interaction principle, output signal
v(
x) can be expressed as:
In formula,
=0.32 is the equivalent refraction coefficient of aqueous medium, and w is angular frequency,
p(
x,y) be in sound field (
x,y) acoustic pressure of position.
When laser beam is 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
0, the output of laser vibration measurer can approximate representation be:
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 paralleling with specimen upper surface, can detect the reflective sound wave that 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:
（3）
Adjust the position of laser vibration measurer, laser beam is skipped over along the direction paralleling with 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:
；
（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 utility model of explaining; rather than limit for the utility model; in the protection domain of spirit of the present utility model and claim, any modification and change that the utility model is made, all fall into protection domain of the present utility model.
Claims (1)
1. ultrasonic material reflection and a 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 specimen setting;
The signal of function generator inputs to power amplifier, through amplifying 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 specimen upper surface that laser vibration measurer sends incides in aqueous medium by the lens that are placed on the sidewall of pond, and be reflected back laser vibration measurer through catoptron, 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.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103471998A (en) * | 2013-08-23 | 2013-12-25 | 中国计量学院 | Ultrasonic material reflection and transmission coefficient laser measurement system |
| 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 |
| CN105806466A (en) * | 2016-03-22 | 2016-07-27 | 华中科技大学 | Ultrasonic power measurement system |
| CN106338331A (en) * | 2016-08-11 | 2017-01-18 | 中国船舶重工集团公司第七〇五研究所 | Ultrasonic hydrophone sensitivity multi-frequency point absolute calibration method |
| CN115276829A (en) * | 2022-08-05 | 2022-11-01 | 天津大学 | Laser acoustic transducer system based on acoustic super surface |
-
2013
- 2013-08-23 CN CN201320520092.7U patent/CN203414165U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103471998A (en) * | 2013-08-23 | 2013-12-25 | 中国计量学院 | Ultrasonic material reflection and transmission coefficient laser measurement system |
| 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 |
| CN105050020B (en) * | 2015-07-31 | 2018-02-27 | 浙江省计量科学研究院 | Free found field device based on optics non-destructive monitoring technology |
| CN105806466A (en) * | 2016-03-22 | 2016-07-27 | 华中科技大学 | Ultrasonic power measurement system |
| CN105806466B (en) * | 2016-03-22 | 2018-11-06 | 华中科技大学 | A kind of ultrasonic power measuring system |
| CN106338331A (en) * | 2016-08-11 | 2017-01-18 | 中国船舶重工集团公司第七〇五研究所 | Ultrasonic hydrophone sensitivity multi-frequency point absolute calibration method |
| 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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| C14 | Grant of patent or utility model | ||
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| 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: 20140129 Termination date: 20180823 |