WO1998003852A1 - Sonde de mesure et procede correspondant - Google Patents

Sonde de mesure et procede correspondant Download PDF

Info

Publication number
WO1998003852A1
WO1998003852A1 PCT/GB1997/001890 GB9701890W WO9803852A1 WO 1998003852 A1 WO1998003852 A1 WO 1998003852A1 GB 9701890 W GB9701890 W GB 9701890W WO 9803852 A1 WO9803852 A1 WO 9803852A1
Authority
WO
WIPO (PCT)
Prior art keywords
acoustic
sensor according
fluid
housing
pulses
Prior art date
Application number
PCT/GB1997/001890
Other languages
English (en)
Inventor
Hugh Alexander Mackenzie
Scott Freeborn
John Hannigan
Original Assignee
Optel Instruments Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Optel Instruments Limited filed Critical Optel Instruments Limited
Priority to GB9901080A priority Critical patent/GB2330656B/en
Priority to AU35502/97A priority patent/AU3550297A/en
Publication of WO1998003852A1 publication Critical patent/WO1998003852A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids

Definitions

  • This invention relates to the use of a combined optical and acoustic technique for the detection and measurement of selected analytes in fluids.
  • a sensor for measuring the concentration of one or more selected analytes within a body of fluid, the sensor comprising a housing adapted to be positioned directly in or near the surface of a body of fluid; light transmission means for receiving light pulses from a laser source; lens means carried by the housing and having optical components to direct the light with a desired geometry and form from the light transmission means to a target location outside the housing, the target location in use being within the body of fluid; acoustic transducer means mounted on the housing so as to be positioned, in use, in the vicinity of said target location; and electric signal means coupling the output of the transducer means to display and/or data processing means remote from the housing.
  • the transducer means is positioned, in use, within said body of fluid.
  • the body of fluid may be a stationary body, such as the liquid within a tank or a borehole, or may be a fluid stream such as a liquid flowing within a pipe.
  • the housing is of generally cylindrical form and has a front end which forms an open measurement region which, in use, is introduced into a pipeline via a circular port. This is particularly useful in measuring and monitoring applications in an industrial environment, one example being the measurement of small proportions of hydrocarbons in process or produced water, other outfalls and discharges and groundwater.
  • the lens means may comprise a lens assembly within the housing operating in conjunction with a fluid-tight optically transmissive window in the housing.
  • a graded (or gradient) refractive index lens may be used, and this may itself form a window in the housing.
  • the transducer means may suitably be carried on an extension projecting from the front end of the housing.
  • the transducer means comprises an element of piezoelectric material (for example, a disc-shaped crystal of lead zirconate titanate or the like) with the disc axis aligned perpendicularly to the optical axis.
  • the transducer means comprises one or more piezoelectric elements shaped, ideally, to match the wavefront of the acoustic pulse; for example by presenting one or more part-cylindrical surfaces disposed around the optical axis .
  • the piezoelectric element (s) preferably have a thickness which is substantially equal to the product of the duration of the compressive part of the acoustic impulse and the velocity of sound in the piezoelectric material.
  • the damping mass is in the form of a volume of lead or other suitable material secured to the rear face of the or each crystal and shaped to inhibit the generation of acoustic resonances.
  • the invention provides a method of measuring the concentration of one or more selected analytes within a body of fluid, the method comprising forming pulses of laser light of an optical frequency absorbed by the selected analyte(s), coupling the light pulses into a body of fluid to be focused at a target location within the body of fluid, detecting acoustic pressure pulses at a location adjacent said target location, and analysing the resultant signals to determine the relative concentration of the selected analyte ( s ) .
  • the body of fluid may be a stationary body, or a flowing stream.
  • said pulses have a pulse duration which is shorter than the time required for thermal diffusion across the diameter of the optical interaction region. In general terms, this could be in the range Ins to less than l s. In the embodiments discussed herein, the pulse length will typically be in the range 5 - 200ns, most preferably 50 - 75ns.
  • a particular application of the method is in detecting the presence of hydrocarbons in water, in which case the light pulses may suitably have a vacuum wavelength of 600 to 3500nm.
  • the analysis of the acoustic signal may suitably be carried out on values averaged over a number (suitably up to 10,000, and typically between 100 and 5000) of discrete signal samples.
  • the analysis may simply be a peak-to-peak measurement, or may include examination of the rise and fall times of the acoustic waveform, or may be based on a Fourier analysis of the waveform, and other temporal properties of the acoustic response.
  • the analysis may be based on integration of the acoustic waveform to obtain an energy-related signal.
  • the present invention further provides an acoustic sensor comprising means for emitting pulses of light of selected wavelength to produce acoustic pulses in a fluid, and a pressure sensitive element for detecting said acoustic pulses, the pressure sensitive element having a rear face against which is secured a backing element to provide both inertial loading and vibrational damping.
  • the pressure sensitive element is a piezoelectric ceramic crystal, for example of lead zirconate titanate, or other piezoelectric material and the backing element is of lead.
  • the backing element is preferably configured to minimise acoustic reflections, as by being formed with non-parallel surfaces, or by any surfaces which are parallel being formed with discontinuities.
  • Fig. 1 is a schematic cross-sectional side view of one embodiment of photoacoustic detector instrument in accordance with the invention
  • Fig. 2a is a cross-sectional side view showing part of a second embodiment
  • Fig. 2b is an end view of the detector of Fig. 2a
  • Fig. 3a is a cross-sectional side view of a third embodiment
  • Fig. 3b is an end view of the detector of Fig. 3a
  • Fig. 3c is a cross-section on C-C of Fig. 3a
  • Fig. 4 is a cross-sectional side view of a further embodiment of photoacoustic detector instrument
  • Fig. 5 is a graph illustrating waveforms generated in use of the system.
  • a detector instrument comprises a generally cylindrical fluid-tight housing 10 formed from two cylindrical members 12 and 14 joined together at flanges 16 and 18.
  • the forward cylindrical member 12 is inserted into a pipeline (not shown) through a conventional ball valve and muff coupling (not shown) with O-rings or other sealing elements and provision for clamping and safety interlocks.
  • Light from a laser source is coupled to the instrument via a fibre optic system 20 to a launching unit 22.
  • the launching unit 22 produces a beam which passes via a fluid-tight window 24 into fluid flowing within the pipeline.
  • An acoustic sensor 26 is located adjacent the window 24 in an extension 28 projecting from the housing 10.
  • the sensor 26 suitably comprises a disc of a piezoelectric ceramic material and is backed by a lead cylinder 30 secured within the extension 28 by a plug 32.
  • the lead cylinder 30 acts to damp ringing of the PZT crystal and to better perform this function is preferably bonded to the crystal 26, for example by electrically conductive epoxy which acts as an electrical connection to the rear face of the crystal 26, from which the piezoelectric signal is obtained.
  • the connection to the front face of the crystal 26 is achieved with wrap-around electrodes which permit contact wires to be bonded via the side of the crystal 26.
  • the electrical output from the crystal 26 is coupled to amplifying electronics mounted on a printed circuit board 34 within the housing 10, to provide output signals via electrical connections 36.
  • the optical pulse has an energy of the order of typically a micro-Joule, and generates a low energy photoacoustic signal which propagates radially from the optic axis with a particular acoustic wavefront geometry which depends on the absorption of the analyte and the optical beam geometry.
  • Fig. 2 illustrates a modified instrument in which it is sought to improve the interaction between the photoacoustic pulse and the sensor.
  • the instrument is of basically cylindrical form for insertion into a pipeline, and laser light pulses from a fibre optic cable and focusing lens assembly (not seen in the Fig) are transmitted via a window 40 into liquid flowing within the pipeline.
  • the detector comprises a pair of piezoelectric crystals 42 and 44 (suitably of lead zirconate titanate) each of part-tubular shape arranged within part-cylindrical housings 46, 48 forming projections from the main cylindrical housing 50 of the instrument.
  • the housings 46, 48 define between them a passage 52 for flow of liquid within which the photoacoustic interaction occurs.
  • the shape and disposition of the crystals 42, 44 is chosen to maximise the area available for reception of the photoacoustic pulse, to keep the angle of incidence of the acoustic wavefront on the crystal within acceptable limits, and also to minimise timing differences in the pressure wavefront reaching the crystal.
  • Each of the crystals 42, 44 is once again provided with damping, in the form of lead backing pieces 54, 56 of complementary shape.
  • This embodiment gives improved coupling between the photoacoustic wave and the piezoelectric material for the optical geometry utilised.
  • the construction is relatively complex, and the channel 52 is relatively restricted.
  • Fig. 3 shows a presently preferred embodiment. This follows similar principles to Fig. 2, but has a window 60 displaced from the centre line of housing 62, and a single transducer crystal 64 of part-cylindrical shape backed by a lead body 66. The liquid in the vicinity of the instrument is therefore not restricted to a channel, but the coupling efficiency approaches that of Fig. 2.
  • laser pulses are coupled via a fibre optic cable 68 to a lens assembly 70 which includes a beam splitter 72.
  • the beam splitter 72 diverts a known proportion of the laser energy to a photosensitive detector such as a photodiode 74. This permits the applied laser energy to be monitored, and the detected acoustic signal can be normalised in relation to the applied optical energy.
  • the housing 62 is suitably of 38mm diameter in stainless steel, and contains an electronics module 76 which communicates with a remote processing and display circuit via a multi-way cable 78.
  • the cable 78 may use a combination of fibre optic signal paths and low voltage, low power electrics for intrinsically safe operation in hazardous locations .
  • Fig. 4 shows another approach in which a sensor 100 of generally cylindrical form projects into a flow channel (not shown).
  • the sensor body has a cylindrical passage 102 transverse to the main axis of the body, and thus aligned with the fluid flow, the passage 102 containing an insert 104 shaped to define a venturi.
  • An optical fibre cable 106 delivers laser light to a GRIN (graded refractive index) lens 110 located at the venturi throat.
  • GRIN graded refractive index
  • a passage 112 communicates with a tubular conduit 114 whose other end is open to the fluid flow passage.
  • venturi in use, fluid flow through the venturi causes a reduction in pressure at the venturi throat which draws fluid through the conduit 114.
  • An ultrasonic transducer is provided in the form of a lead zirconate titanate tube 108 which is backed by a lead mass 116 and butted against an insulating pad 118 and solid end cap 120.
  • the lead mass 116 has the shape of a hollow tapered cylinder, the shape being chosen for effective damping.
  • This embodiment has the advantage of using a complete cylinder of piezoelectric material, and thus achieving higher sensitivity and coupling for the optical geometry utilised.
  • the piezoelectric element should be dimensioned to give an optimum response to the generated acoustic wave.
  • the thickness corresponds to the equivalent distance travelled by the compressive part of the acoustic impulse in the particular piezoelectric material; that is, the product of the duration of the compressive part and the velocity of sound in the piezoelectric material.
  • the efficiency of operation is maintained by installing the piezoelectric element behind a thin layer of stainless steel, preferably 0.1mm in thickness although thicker layers are possible.
  • An example is illustrated at 150 in Fig. 4.
  • the backing or damping material with appropriate acoustic impedance matching to the piezoelectric element(s) should minimise the formation of back reflections or standing waves from the incident acoustic wave, and also damp the natural acoustic resonances of the piezoelectric crystal.
  • This can be approached by using a shape which has a minimum of parallel surfaces, for example as in the shapes of lead backings shown in Figs. 3 and 4.
  • additional features such as conical holes may be introduced to disrupt the formation of acoustic resonances.
  • a further preferred feature of the invention is the use of very short pulses of laser light.
  • the object is to choose a pulse length which is shorter than the time required for diffusion of thermal energy in the region of interaction in the medium concerned, in order that the process of energy conversion occurs in a very localised way within the optical interaction region.
  • This very rapid heating results in an acoustic impulse which has a distinctive compression followed by a rarefaction without significant bulk thermal expansion taking place.
  • the frequency content of the waveform may be used to characterise the components of the system under examination.
  • a suitable pulse length may be between Ins and l ⁇ s. Typically, a pulse length of 10 - 200ns will be suitable, and most commonly 50 - 75ns is preferred for best results.
  • a further advantage of an ultrashort pulse regime is that the range of frequencies within the acoustic wave is in the ultrasound region, and thus the sensor is substantially immune to the effects of normal mechanical vibration and the effects of turbulence in flowing liquids. In this regime the acoustic signal is also substantially immune to the effects of optical scattering.
  • An additional advantage is that the transient response can be used to characterise the component analytes in the system.
  • the choice of laser system to be used will be determined by the analyte(s) under consideration, and may take the form of a set of diode lasers, or a solid state tunable laser such as a Neodymium YAG laser with an optical parametric oscillator (OPO) .
  • the laser source may be a diode laser operating in the near infrared spectral range at wavelengths between 600 and 2500nm.
  • the invention makes it possible to measure low (ppm) concentrations of hydrocarbons in water, but it can also be optimised for medium (1%) concentrations and high (up to 100%) concentrations.
  • the exact choice of laser wavelength depends on the particular hydrocarbon analyte or mixture of analytes in the system. A number of laser sources at different wavelengths may be used as determined by the required measurement accuracy and the particular calibration procedure adopted.
  • the calibration procedure may be in the form of a look-up table, a multiple regression analysis, a neural network procedure, or other statistical procedure.
  • the laser output is coupled to a fibre optic delivery system via a suitable lens system.
  • a fibre optic wavelength multiplexing or other optical coupling can be used to combine the outputs of the laser sources into a single delivery fibre.
  • the optical pulse is finally delivered through a conventional lens assembly as in Fig. 1 , or a GRIN lens as in Fig. 4, or other refractive or diffractive optical elements .
  • the aim is to achieve the optimum optical beam and the optimal pulse duration, based on the optical absorption and acoustic transit time within the beam.
  • the end faces of the lens system used may be coated to minimise optical reflections, and/ or to increase abrasion resistance, and/or for inhibition of organic or other fouling.
  • a hard transparent material such as diamond or sapphire may be used.
  • the output lens can be coupled to an additional piezoelectric element and vibrated to achieve ultrasonic cleaning of the optical element.
  • This facility can be deployed either continuously or intermittently. In the latter case, cleaning may be initiated in response to the appearance of a small preliminary acoustic signal which has been generated at the output interface and transmitted to the main piezoelectric element via the body of the detector head.
  • amplifying electronics within the detector head in close proximity to the piezoelectric element.
  • a suitable arrangement is for the electric signal from the piezoelectric element to be amplified by a voltage or charge pre-amplifier, further amplified in a programmable gain amplifier, and then digitised by an analog-to-digital converter, the digitised signal then being transmitted to a location remote from the detector head for further processing.
  • the detector head is connected to the remote location by a flexible umbilical containing both electrical signal paths and optical fibres.
  • the detector head may also be provided with means for monitoring the laser pulse energy, to permit the acoustic signal to be normalised to the value of the optical pulse energy.
  • the optical energy may be measured at the point where the diode laser is coupled to the optical fibre, or at the detector head, for example by diverting a small proportion of the light from the main fibre optic path to a photosensitive detector, as in Fig. 3.
  • an interfacial reflection at the fibre output end may be utilised for this purpose via detection at the input end.
  • a suitable form of processing is to average the digital signal over a number of samples, which may be up to 10,000 (typically between and 100 and 5000) depending on application.
  • the value of the peak to peak voltage of the transducer for the acoustic pulse is then recorded for each of the wavelengths of operation, and divided by the amplitude of a signal which relates to the input energy, for normalisation and comparison with calibration data. Either the full wave form or the peak to peak values can be stored for later analysis.
  • Calibration of the system may be carried out through standard routines of comparison, linear regression, multivariate analysis, or a neural network system.
  • the signal analysis may alternatively be based on analysis of the inherent temporal information contained in the acoustic signal.
  • the optical pulse 160 results in an acoustic pulse 162 being generated, the acoustic pulse 162 comprising a compressive pulse followed by a rarefaction pulse.
  • One aspect of using the temporal information is to use the time delay TI between initiation of the optical pulse 160 and the receipt of the acoustic pulse 162 to determine the velocity of sound in the fluid medium. Subsequently, the detail of the rise time T2 of the compressive acoustic wave contains information of the way that the different analytes take up the optical energy.
  • the complete waveform can be analysed on a temporal basis. This can be interpreted either directly by measurement of rise and fall times, or via a Fourier analysis to ascertain the characteristic frequencies contained within the waveform and relate them to concentrations of particular analytes.
  • a further possibility is to integrate the total area of the average acoustic waveform to obtain a measure of the energy absorption dissipated as thermal energy by the analyte of interest.
  • the invention is not limited to such applications.
  • the same principles can be applied to monitoring industrial outfalls, measuring concentration of alcohol in water (for example in the control of distillation), and the investigation of boreholes.
  • Pressure sensors other than piezoelectric crystals may be used, for example piezoelectric polymers such as PVDF, or semiconductor pressure sensors which may be independent or may be part of an integrated semiconductor circuit, or optical methods including fibre optic interferometers.
  • piezoelectric polymers such as PVDF
  • semiconductor pressure sensors which may be independent or may be part of an integrated semiconductor circuit, or optical methods including fibre optic interferometers.

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

La présente invention concerne une sonde faite d'un corps cylindrique (62) dont la partie antérieure peut s'introduire dans un corps liquide. Le procédé consiste à coupler des impulsions laser via un câble à fibres optiques (68) et un bloc optique (70) de façon que ces impulsions pénètrent dans le liquide en traversant une fenêtre (60). L'interaction entre l'énergie laser et un analyte considéré produit des ondes acoustiques dans la région voisine de la fenêtre (60), lesquelles ondes acoustiques se détectent au moyen d'un transducteur acoustique (64). L'invention concerne également des formes préférées de transducteurs et leurs modes de montage.
PCT/GB1997/001890 1996-07-20 1997-07-11 Sonde de mesure et procede correspondant WO1998003852A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9901080A GB2330656B (en) 1996-07-20 1997-07-11 Measurement method
AU35502/97A AU3550297A (en) 1996-07-20 1997-07-11 Measurement sensor and method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9615268.1A GB9615268D0 (en) 1996-07-20 1996-07-20 Measurement sensor and method
GB9615268.1 1996-07-20

Publications (1)

Publication Number Publication Date
WO1998003852A1 true WO1998003852A1 (fr) 1998-01-29

Family

ID=10797233

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/001890 WO1998003852A1 (fr) 1996-07-20 1997-07-11 Sonde de mesure et procede correspondant

Country Status (3)

Country Link
AU (1) AU3550297A (fr)
GB (2) GB9615268D0 (fr)
WO (1) WO1998003852A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1046885A1 (fr) * 1999-04-23 2000-10-25 Halliburton Energy Services, Inc. Méthode de calibration de capteurs de pression et temperature
WO2005068973A1 (fr) * 2004-01-13 2005-07-28 Glucon Inc. Capteur photoacoustique
US7053787B2 (en) 2002-07-02 2006-05-30 Halliburton Energy Services, Inc. Slickline signal filtering apparatus and methods
CN102495028A (zh) * 2011-11-18 2012-06-13 江苏大学 一种混药浓度在线检测方法及其装置
RU2572293C2 (ru) * 2014-05-19 2016-01-10 Российская Федерация, От Имени Которой Выступает Министерство Промышленности И Торговли Российской Федерации Оптоакустический анализатор экологического состояния среды
CN110118728A (zh) * 2018-02-07 2019-08-13 深圳先进技术研究院 一种声学分辨率光声显微系统

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4051371A (en) * 1976-04-26 1977-09-27 Massachusetts Institute Of Technology Opto-acoustic spectroscopy employing amplitude and wavelength modulation
US4303343A (en) * 1980-02-29 1981-12-01 Bell Telephone Laboratories, Incorporated Optoacoustic spectroscopy of condensed matter in bulk form
EP0464902A1 (fr) * 1990-06-25 1992-01-08 CISE- Centro Informazioni Studi Esperienze S.p.A. Cellule optoacoustique pour mesurer des concentrations d'espèces chimiques en fluides en général
EP0478410A1 (fr) * 1990-09-24 1992-04-01 THE DOW CHEMICAL COMPANY (a Delaware corporation) Sonde pour l'analyse photoacoustique
WO1993022649A2 (fr) * 1992-04-23 1993-11-11 Sirraya, Inc. Procede et appareil utilises pour analyser des matieres

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4051371A (en) * 1976-04-26 1977-09-27 Massachusetts Institute Of Technology Opto-acoustic spectroscopy employing amplitude and wavelength modulation
US4303343A (en) * 1980-02-29 1981-12-01 Bell Telephone Laboratories, Incorporated Optoacoustic spectroscopy of condensed matter in bulk form
EP0464902A1 (fr) * 1990-06-25 1992-01-08 CISE- Centro Informazioni Studi Esperienze S.p.A. Cellule optoacoustique pour mesurer des concentrations d'espèces chimiques en fluides en général
EP0478410A1 (fr) * 1990-09-24 1992-04-01 THE DOW CHEMICAL COMPANY (a Delaware corporation) Sonde pour l'analyse photoacoustique
WO1993022649A2 (fr) * 1992-04-23 1993-11-11 Sirraya, Inc. Procede et appareil utilises pour analyser des matieres

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1046885A1 (fr) * 1999-04-23 2000-10-25 Halliburton Energy Services, Inc. Méthode de calibration de capteurs de pression et temperature
US6594602B1 (en) 1999-04-23 2003-07-15 Halliburton Energy Services, Inc. Methods of calibrating pressure and temperature transducers and associated apparatus
US7053787B2 (en) 2002-07-02 2006-05-30 Halliburton Energy Services, Inc. Slickline signal filtering apparatus and methods
WO2005068973A1 (fr) * 2004-01-13 2005-07-28 Glucon Inc. Capteur photoacoustique
CN102495028A (zh) * 2011-11-18 2012-06-13 江苏大学 一种混药浓度在线检测方法及其装置
CN102495028B (zh) * 2011-11-18 2013-10-23 江苏大学 一种混药浓度在线检测方法及其装置
RU2572293C2 (ru) * 2014-05-19 2016-01-10 Российская Федерация, От Имени Которой Выступает Министерство Промышленности И Торговли Российской Федерации Оптоакустический анализатор экологического состояния среды
CN110118728A (zh) * 2018-02-07 2019-08-13 深圳先进技术研究院 一种声学分辨率光声显微系统

Also Published As

Publication number Publication date
GB2330656A (en) 1999-04-28
AU3550297A (en) 1998-02-10
GB9615268D0 (en) 1996-09-04
GB2330656B (en) 2000-04-12
GB9901080D0 (en) 1999-03-10

Similar Documents

Publication Publication Date Title
EP0478410B1 (fr) Sonde pour l'analyse photoacoustique
Staudenraus et al. Fibre-optic probe hydrophone for ultrasonic and shock-wave measurements in water
CA1214541A (fr) Methode et appareillage de detection des fractures par echographie ultrasonique
US6839496B1 (en) Optical fibre probe for photoacoustic material analysis
US20220050084A1 (en) Device and method for testing a test object
US20140165740A1 (en) Ultrasound transducer and method of generating and/or receiving ultrasound
CN110686771A (zh) 一种基于光声效应的宽光谱脉冲光探测器和探测方法
US20140133280A1 (en) Fiber Optic Hydrophone Sensors And Uses Thereof
CN107560730A (zh) 双腔式光声光谱仪
Tadayon et al. Polymer waveguide Fabry-Perot resonator for high-frequency ultrasound detection
WO1998003852A1 (fr) Sonde de mesure et procede correspondant
Fomitchov et al. Photoacoustic probes for nondestructive testing and biomedical applications
KR20200078514A (ko) 개선된 간섭 신호 억제를 갖는 광 음향 센서 헤드 및 광 음향 측정 장치
US4995260A (en) Nondestructive material characterization
RU2381496C1 (ru) Лазерно-ультразвуковой дефектоскоп
Tam et al. Pulsed opto-acoustics: theory and applications
Kopp et al. Optoacoustic sensor head for depth profiling.
US6756579B2 (en) Optical fiber based apparatus and sensor with enhanced signal for pressure measurements
Quan et al. Photoacoustic generation in liquids with low optical absorption
EP1328782B1 (fr) Dispositif de mesure en ligne de pulsations d'un laser et procede de mesure par spectroscopie photo-acoustique
Hoelen et al. Nondestructive photoacoustic subsurface tissue imaging: a feasibility study
Beard et al. Evaluation of an optical fiber probe for in vivo measurement of the photoacoustic response of tissues
US20170199076A1 (en) Fiber Optic Hydrophone Sensors and Uses Thereof
Acquafresca et al. Fiber optics sensors for ultrasonic virtual biopsy
Kažys et al. Wideband air–coupled ultrasonic transducers

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GE GH HU IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG US UZ VN YU ZW AM AZ BY KG KZ MD RU TJ TM

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH KE LS MW SD SZ UG ZW AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 1997931913

Country of ref document: EP

121 Ep: the epo has been informed by wipo that ep was designated in this application
ENP Entry into the national phase

Ref country code: GB

Ref document number: 9901080

Kind code of ref document: A

Format of ref document f/p: F

WWE Wipo information: entry into national phase

Ref document number: 9901080.3

Country of ref document: GB

WWW Wipo information: withdrawn in national office

Ref document number: 1997931913

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: CA

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 1998506676

Format of ref document f/p: F

122 Ep: pct application non-entry in european phase