CN105050020B - Free found field device based on optics non-destructive monitoring technology - Google Patents
Free found field device based on optics non-destructive monitoring technology Download PDFInfo
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- CN105050020B CN105050020B CN201510464431.8A CN201510464431A CN105050020B CN 105050020 B CN105050020 B CN 105050020B CN 201510464431 A CN201510464431 A CN 201510464431A CN 105050020 B CN105050020 B CN 105050020B
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- silencer box
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Abstract
The present invention provides a kind of free found field device based on optics non-destructive monitoring technology, is related to e measurement technology.It includes silencer box and optical fiber collimator, silencer box corresponds to two side and is respectively equipped with high diaphragm and lens thoroughly, light trapping, sound source and particulate matter are provided with silencer box, laser sends laser and is divided into the strong equal laser of two-beam through semi-transparent semi-reflecting lens, inject silencer box and incided after crossing in light trapping, scattering light passes through lens entrance to optical fiber collimator in silencer box.It is a kind of mode for intervening measurement that the present invention, which solves measuring microphone sound field in the prior art, and the sound field of measurement can be influenceed by microphone, and can not calibrate the technical problem of nonstandard microphone.Beneficial effects of the present invention are：By dual-beam measurement acoustic pressure, the sound field in silencer box is free found field；By the use of finely ground particles as medium, the autocorrelation technique of light is scattered by particulate matter, the velocity of sound and acoustic pressure at accurate measurement beam interference point.Reception system is simple in construction, and system signal noise ratio is high.
Description
Technical field
The present invention relates to test measurement device, more particularly, to one kind using optics nondestructive technique to microphone calibration measurement
Sound field device.
Background technology
Acoustic detection technology is in field extensive uses such as medical treatment, environmental protection, industry and oceans.Microphone is as a kind of important
Measurement instrument, it is the key sensor of Acoustic detection.It is mainly transaudient using standard source, utilization at present to the calibration of microphone
Device is calibrated in the method for reciprocity to the microphone being calibrated.But two be present：(1) due to microphone size pair itself
The influence of sound field, (such as 1/4 inch, 1/2 inch, 1 inch can only be calibrated to the microphone of specific dimensions in specific orientation
Deng), and some nonstandard microphones can not be calibrated, such as Mems microphone, fiber microphone, these nonstandard microphones are various
It is used widely in electronic product, detection instrument, but magnitude tracing can not be realized；(2) using a microphone array or
The mode that one microphone of person is repeatedly moved measures, and this metering system is a kind of mode for intervening measurement, is measured
Sound field can be influenceed by microphone.Chinese patent Authorization Notice No. CN101895809B, authorized announcement date July 3 in 2013
Day, a kind of a kind of patent of invention of entitled " microphone calibration method ", there is provided microphone calibrator.Including sound source, disappear
Sound device, microphone construction section to be calibrated and standard microphone construction section, it is silencer, standard microphone construction section, to be calibrated transaudient
Device construction section is connected using flange successively from front to back with sound source；Microphone peace to be calibrated is provided with microphone construction section to be calibrated
Hole is filled, for installing microphone to be calibrated；At least three standard microphone mounting holes are provided with standard microphone construction section, are used for
Standard microphone is installed；Thus microphone to be calibrated is arranged on transaudient on microphone construction section vertical section to be calibrated one week
In device mounting hole, then microphone to be calibrated is positioned at by microphone construction section to be calibrated by keeper.This metering system
It is a kind of mode for intervening measurement, that is, the sound field measured can be influenceed by microphone.And metering device is used as, this influence amount
It is often unacceptable.With the development of science and technology, in recent years, obtained widely based on optical acoustic field mode
Research.Denmark, Japan, the researcher of Britain and Germany have studied the mode that acoustooptical effect measures this sound-filed simulation, but this
Kind mode is suitable for ultrasonic wave, and the sensitivity and signal to noise ratio measured for the low-frequency sound wave of audible is low.
The content of the invention
It is a kind of mode for intervening measurement to solve prior art to have measuring microphone sound field, the sound field of measurement can be by
To the influence of microphone, and the technical problem of nonstandard microphone can not be calibrated, the present invention provides one kind and is based on optics non-destructive monitoring
The free found field device of technology.The velocity of sound and acoustic pressure of certain point in light correlation technique measurement free found field are scattered by particulate matter, by
In measuring acoustic pressure by laser beam, any barrier is not introduced in the sound field, it is free found field to make the sound field in anechoic room.
The free found field device is also used as calibrating installation, the calibration for the microphone to non-size.
The technical scheme is that：A kind of free found field device based on optics non-destructive monitoring technology, it includes laser
Device, semi-transparent semi-reflecting lens, speculum, silencer box and optical fiber collimator, silencer box are cuboid airtight cavity structure, and silencer box is relative
Answer two side to be respectively equipped with high diaphragm and lens thoroughly, be provided with light trapping, sound source and particulate matter in silencer box, laser sends sharp
Light is divided into the strong equal laser of two-beam through semi-transparent semi-reflecting lens, and two beam laser are reflected through high diaphragm thoroughly and injected through speculum to disappear
Sound case and incide in light trapping after crossing, lens entrance to optical fiber collimator is passed through by the light of particulate matter scattering in silencer box.
Acoustic pressure is measured by dual-beam, without any barrier in the sound field, it is free found field to make the sound field in silencer box；Utilize silencer box
In finely ground particles as medium, scatter the autocorrelation technique of light by particulate matter, the sound at accurate measurement beam interference point
Speed and acoustic pressure.Using back scattering, scattering light, the letter of reception system structure are received by a piece of lens and an optical fiber collimator
It is single, make the signal to noise ratio of system higher.
Preferably, two beam laser inject the geometric center that silencer box joint is silencer box, the laser-formed folder of two beams
Angle is θ, between θ values are 12 ° to 18 °；Ensure that two beam laser interferencefringeses have more preferable visibility and uniformity, signal to noise ratio height.
Preferably, sound source is arranged in silencer box longitudinal asymmetric axis above two beam laser joints, the center of sound source
Axle position is in the laser-formed plane of two beams；The favourable sound pressure improved at measured point.
Preferably, lens are convex lens, a diameter of 45-55mm, focal length 100-150mm, lens are located at silencer box horizontal stroke
To on the axis of symmetry；Scattering light is converged into optical fiber collimator.
Preferably, noise elimination chamber interior wall is provided with wedge absorber, wedge absorber wedge-shaped in cross-section, wedge shape height is 30-
42cm；It is 200Hz to make silencer box cut-off frequency.
Preferably, laser is wavelength 532nm single longitudinal mode laser, beam divergence angle 0-1.2mrad；Light beam is sent out
Angle is dissipated in the range of less than 1.2mrad, reduces interference fringe spacing inhomogeneities.
Preferably, particulate matter is smoke particle thing, particle size 0.1-2um；Smoke particle produces in the range of being somebody's turn to do
Stronger scattering light, and produce Doppler frequency shift caused by light intensity change.
Compared with prior art, the beneficial effects of the invention are as follows：Using smoke particle thing as medium, by the use of laser beam as
Measurement means, the auto-correlation time of light is scattered by measuring, the velocity of sound and acoustic pressure of sound field at beam interference point is obtained, is not disappearing
Solid obstacle is introduced in sound case, it is free found field to make sound field in silencer box, and demarcates acoustic pressure by lossless optical detection means,
Technological means is provided for the demarcation of free found field, the calibration for the microphone of non-size provides device and calibration method.Adopt
With back scattering, scattering light is received by a piece of lens and an optical fiber collimator, reception system is simple in construction, makes the letter of system
Make an uproar than higher, raising sensitivity.
Brief description of the drawings
Accompanying drawing 1 is connection diagram of the present invention；
Accompanying drawing 2 is the autocorrelation function graph when frequency of source is 1kHz, and intensity is 125dB.
In figure：1- lasers；2- semi-transparent semi-reflecting lens；3- speculums；4- silencer boxs；5- optical fiber collimators；6- photon countings
Device；7- autocorrelation function analyzers；The high saturating diaphragms of 41-；42- lens；43- light trappings；44- sound sources；45- wedge absorbers.
Embodiment
Below by embodiment, and with reference to accompanying drawing, technical scheme is described in further detail.
Embodiment 1：
As shown in figure 1, dotted line represents light path in figure.A kind of free found field device based on optics non-destructive monitoring technology, it
Including laser 1, semi-transparent semi-reflecting lens 2, speculum 3, silencer box 4, optical fiber collimator 5, photon counter 6 and autocorrelation function analyzer 7.Swash
Light device 1, semi-transparent semi-reflecting lens 2 and speculum 3 are arranged on 4 outer front end of silencer box.Laser 1 is wavelength 532nm single longitudinal mode laser
Device, beam divergence angle are less than 1.2mrad.The power of laser 1 is 200mW, spot diameter 2mm.Semi-transparent semi-reflecting lens 2 one, reflection
Mirror 3 has two.Silencer box 4 is cuboid airtight cavity structure, and the present embodiment uses 2m × 2m × 2m appearance and sizes.Silencer box 4
Corresponding two side is respectively equipped with high diaphragm 41 and lens 42 thoroughly.The left side wall of silencer box 4 is provided with the window of two insertion left side walls
Mouth film perforation, two window film perforations are symmetrical with 4 horizontal axis of silencer box.High diaphragm 41 thoroughly has two pieces, high saturating diaphragm
41 couples of 532nm light transmission rate is more than 99.5%.The saturating diaphragm 41 of two pieces of height is respectively embedded into window film perforation and close with window film perforation
Envelope connection.The right side wall of silencer box 4 is located at 4 lateral symmetry axis of silencer box and is provided with lens opening.The right side of lens opening insertion silencer box 4
Wall.Lens 42 are convex lens, a diameter of 50mm, focal length 150mm.Lens 42 are embedded in lens opening and are tightly connected with lens opening.
Light trapping 43, sound source 44, wedge absorber 45 and particulate matter are provided with silencer box 4.Light trapping 43 has two, respectively with silencer box 4
Right side wall is fixed.Two light trappings 43 are symmetrical with 4 horizontal axis of silencer box.It is longitudinally asymmetric that sound source 44 is located at silencer box 4
On axis.Sound source 44 is connected with the top plate of silencer box 4.Generating surface is directed at the geometric center of silencer box 4, the central shaft of sound source and noise elimination
The vertical axis of case 4 overlaps, that is, falls in the laser-formed plane of two beams.The wedge-shaped in cross-section of wedge absorber 45.Sound absorption point
The bottom surface for splitting 45 wedge shapes is fixed with the internal chamber wall of silencer box 4.The point of wedge shape to the distance of bottom surface be wedge-shaped height.The present embodiment is
The cut-off frequency of silencer box 4 is set to be 200Hz, wedge-shaped height is 40cm.Particulate matter is smoke particle thing, and particle size is
0.1-2um, specifically determined by the width of two beam laser interferencefringeses, particle size is less than the width of two beam laser interferencefringeses
Degree.Particulate matter is full of the whole inner chamber of silencer box 4.Optical fiber collimator 5, photon counter 6 and autocorrelation function analyzer 7 are arranged on silencer box 4
Outer rear end.Optical fiber collimator 5 passes through fiber coupling to photon counter 6.The signal output part and autocorrelation function analyzer of photon counter 6
7 input is connected.The output end of autocorrelation function analyzer 7 is connected with computer (not shown).It is supporting equipped with autocorrelation function analyzer 7 in computer
Handle software.
It is theoretical according to auto-correlation function, velocity of sound u and the relation with the auto-correlation time can be obtained：
Wherein, λ is optical maser wavelength, and θ is the angle of light beam, tminFor the time corresponding to first minimum value of auto-correlation coefficient.
Acoustic pressure P is represented by
P=u ρ c (b)
Wherein, ρ is Media density, and c is the velocity of sound.
The present embodiment silencer box 4 is operated in the laboratory of constant temperature and humidity.Laser 1 sends laser directive semi-transparent semi-reflecting lens
2, divide by semi-transparent semi-reflecting lens 2 for the strong equal laser of two-beam.Two beam laser reflect by two speculums 3 respectively, then divide
Not Chuan Guo the saturating diaphragm 41 of two height inject in silencer box 4.Two beam laser form identical angle with 4 horizontal axis of silencer box,
Two beam laser joints are the geometric center of silencer box 4, i.e. 4 horizontal axis of silencer box and the crosspoint of longitudinal central axis line,
That is two-beam interference position.The laser-formed angle of two beams is θ, and θ values are 13.8 °.Two beam laser incide light respectively after crossing
In trap 43.Aerosol producer (not shown) is opened, caused smog is filled with silencer box 4, allows smoke particle thing full of whole
The individual inner chamber of silencer box 4.The light scattered by particulate matter incides optical fiber collimator 5 by lens 42, and optical fiber collimator 5 passes through photon
Counter 6 is by signal output to autocorrelation function analyzer 7.The count intensity that shows in the observation software of autocorrelation function analyzer 7, when reaching about 50kcps
When, aerosol producer is cut off, allows smog to stablize about 1min in silencer box 4.Driving sound source 44 sends certain frequency, some strength
Voice signal, runs software, generation autocorrelator trace (such as Fig. 2).Extraction correlation function value reach first minimum value when
Between tmin, the acoustic pressure that two-beam interference points out is calculated according to formula (a), (b).Laser 1 is closed, tested microphone is put
Put two-beam interference position, sensitive face alignment sound source 44, drive sound source 44, send be not put into microphone phase same frequency and
The acoustical signal of intensity, record microphone acoustic pressure.The acoustic pressure before and after two-beam interference position is placed according to tested microphone, provide by
Survey microphone test or calibration result.
Claims (7)
1. a kind of free found field device based on optics non-destructive monitoring technology, it includes laser（1）, semi-transparent semi-reflecting lens（2）, it is anti-
Penetrate mirror（3）, silencer box（4）And optical fiber collimator（5）, it is characterised in that：The silencer box（4）For cuboid airtight cavity knot
Structure, silencer box（4）Corresponding two side is respectively equipped with high saturating diaphragm（41）And lens（42）, silencer box（4）It is interior to be fallen into provided with light
Trap（43）, sound source（44）And particulate matter, laser（1）Laser is sent through semi-transparent semi-reflecting lens（2）It is divided into that two-beam is strong equal to swash
Light, two beam laser are through speculum（3）It is reflected through high saturating diaphragm（41）Inject silencer box（4）And light trapping is incided after crossing
（43）In, silencer box（4）The interior light by particulate matter scattering passes through lens（42）Incide optical fiber collimator（5）.
2. the free found field device according to claim 1 based on optics non-destructive monitoring technology, it is characterised in that：Described two
Shu Jiguang injects silencer box（4）Joint is silencer box（4）Geometric center, the laser-formed angle of two beams is θ, and θ values are 12 °
To between 18 °.
3. the free found field device according to claim 1 or 2 based on optics non-destructive monitoring technology, it is characterised in that：Sound
Source（44）It is arranged on silencer box（4）In longitudinal asymmetric axis above two beam laser joints, sound source（44）Central shaft be located at two
In the laser-formed plane of beam.
4. the free found field device according to claim 1 based on optics non-destructive monitoring technology, it is characterised in that：It is described
Mirror（42）For convex lens, a diameter of 45-55mm, focal length 100-150mm, lens（42）Positioned at silencer box（4）Lateral symmetry axle
On line.
5. the free found field device according to claim 1 based on optics non-destructive monitoring technology, it is characterised in that：It is described to disappear
Sound case（4）Inwall is provided with wedge absorber（45）, wedge absorber（45）Wedge-shaped in cross-section, wedge shape height is 30-42cm.
6. the free found field device according to claim 1 based on optics non-destructive monitoring technology, it is characterised in that：It is described to swash
Light device（1）For wavelength 532nm single longitudinal mode laser, beam divergence angle 0-1.2mrad.
7. the free found field device according to claim 1 based on optics non-destructive monitoring technology, it is characterised in that：Described
Grain thing is smoke particle thing, particle size 0.1-2um.
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108801439A (en) * | 2018-07-10 | 2018-11-13 | 河海大学常州校区 | A kind of sound field measuring device and measurement method |
| CN109974641A (en) * | 2019-04-15 | 2019-07-05 | 天津大学 | A kind of acoustic sounding device, system, method, computer equipment and storage medium |
| CN110260968B (en) * | 2019-07-09 | 2021-07-27 | 中国计量科学研究院 | Air ultrasonic sound pressure recurrence system based on sound particle vibration speed measurement |
| CN110290454B (en) * | 2019-07-19 | 2020-10-16 | 中国计量科学研究院 | Microphone high-temperature calibration system based on optical method |
| CN112461719B (en) * | 2020-11-19 | 2022-11-18 | 南京工程学院 | Non-uniform sound field testing method for main particle size of wide-screening particles |
| CN113091881B (en) * | 2021-04-13 | 2023-06-30 | 河南省计量科学研究院 | Method for improving air sound pressure measurement precision by photon correlation method |
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| CN103471998A (en) * | 2013-08-23 | 2013-12-25 | 中国计量学院 | Ultrasonic material reflection and transmission coefficient laser measurement system |
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| CN102141427A (en) * | 2010-12-02 | 2011-08-03 | 中国船舶重工集团公司第七一五研究所 | Method for detecting sound field parameter in fluid medium by using laser vibrometer |
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