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BS EN IEC 61828:2021 Ultrasonics. Transducers. Definitions and measurement methods regarding focusing for the transmitted fields, 2021
- undefined
- Annex ZA(normative)Normative references to international publicationswith their corresponding European publications
- English [Go to Page]
- CONTENTS
- FOREWORD
- INTRODUCTION
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Symbols
- 5 Independent measurement of total acoustic output power
- 6 Acoustic field measurement: equipment [Go to Page]
- 6.1 Hydrophone [Go to Page]
- 6.1.1 General
- 6.1.2 Sensitivity of a hydrophone
- 6.1.3 Directional response of a hydrophone
- 6.1.4 Effective hydrophone radius
- 6.1.5 Choice of the size of a hydrophone active element
- 6.1.6 Hydrophone pressure limits
- 6.1.7 Hydrophone intensity limits
- 6.1.8 Hydrophone cable length and amplifiers
- 6.2 Requirements for positioning and water baths [Go to Page]
- 6.2.1 General
- 6.2.2 Positioning systems
- 6.2.3 Water bath
- 6.3 Requirements for data acquisition and analysis systems
- 6.4 Requirements and recommendations for ultrasonic equipment being characterized
- 7 Measurement procedure [Go to Page]
- 7.1 General
- 7.2 Preparation and alignment [Go to Page]
- 7.2.1 General drive and field conditions
- 7.2.2 Initial adjustment to driving voltage
- 7.2.3 Preparation of source transducer
- 7.2.4 Aligning an ultrasonic transducer and hydrophone
- 7.2.5 Finding the beam axis
- 7.2.6 Measurements to determine field level conditions
- 7.2.7 Determining if transducer is focusing
- 7.2.8 Measuring other beamwidth parameters of a focusing transducer
- 7.2.9 Measuring the beam area parameters
- 7.2.10 Measuring additional beam maximum based parameters
- 7.2.11 Alternative: calculation of focal parameters using numerical projection
- 7.2.12 Plane wave transmitted fields
- 7.2.13 Steered plane waves
- 7.2.14 Measurements of high intensity therapeutic ultrasound fields
- 7.2.15 Calculation of Isa
- 7.2.16 Further evaluation for sidelobes and pre-focal maxima
- 7.3 Considerations for scanning transducers and transducers with multiple sources [Go to Page]
- 7.3.1 Automatic scanning transducers
- 7.4 Spatial impulse response and beamplots [Go to Page]
- 7.4.1 General
- 7.4.2 Point target
- 7.4.3 Beamplots and beam contour plots
- 7.5 Plane wave compounding
- Annex A (informative)Background for the transmission/ Characteristics of focusing transducers [Go to Page]
- A.1 General
- A.2 Field of piston source
- A.3 Focusing with a lens
- A.4 Focusing with a concave transducer
- A.5 Geometric focusing gains
- A.6 Beamwidth estimation
- Figures [Go to Page]
- Figure A.1 – Beam contour plot: contours at −6 dB, −12 dB, and −20 dBfor a 5 MHz transducer with a radius of curvature of D = 50 mmcentred at location 0,0 (bottom centre of graph)
- Figure A.2 – Types of geometric focusing
- Figure A.3 – Transducer options
- Figure A.4 – Parameters for describing a focusing transducer of known geometry
- Figure A.5 – Path difference parameters for describinga focusing transducer of known geometry
- Annex B (informative)Rationale for focusing and nonfocusing definitions [Go to Page]
- B.1 Overview [Go to Page]
- B.1.1 Background information
- B.1.2 General
- B.1.3 Focusing transducers
- B.1.4 Focusing methods
- B.1.5 Known and unknown focusing transducers
- B.1.6 Focusing and beamwidth
- B.1.7 Focusing parameter definitions
- B.1.8 Applications of focusing definitions
- B.1.9 Relation of present definitions to physiotherapy transducers (treatment heads)
- B.1.10 Relation of present definitions to therapeutic transducers
- B.2 System and measurement requirements [Go to Page]
- B.2.1 General
- B.2.2 Transmitted pressure waveforms
- B.2.3 Transmitted fields
- B.2.4 The scan plane and the steering of beams
- B.2.5 Pulse echo field measurements
- Figure B.1 – Electronic focusing along z by transmit beamforming in the scan plane xz
- Figure B.2 – Field parameters for a nonfocusing transducer of known geometry.For example, for a circularly symmetric geometry,transducers have a diameter 2a and a beam axis along z
- Figure B.3 – Phased array geometry and construction for electronic focusing in the azimuth plane and mechanical lens focusing in the elevation plane
- Figure B.4 – Field parameters for a focusing transducer of known geometry
- Figure B.5 – Definitions for pressure-based field measurementsfor an unknown transducer geometry
- Figure B.6 – Beamwidth focus for transducers of known and unknown geometry
- Figure B.7 – Beam maximum parameters
- Figure B.8 – Pressure focus for a transducer of known geometry (design case)
- Figure B.9 – Pressure focus for a transducer of unknown geometry (measurement case)
- Figure B.10 – Beam area parameters
- Figure B.11 – Beam axis parameters: pulse-pressure-squared-integral level relative to the beam maximum in decibels (dB) plotted against axial distance
- Figure B.12 – Beamplot parameters
- Figure B.13 – Schematic diagram of the different planes and linesin an ultrasonic field for a rectangular transducer
- Figure B.14 – Schematic diagram of the different planes andlines in an ultrasonic field for a circular transducer
- Annex C (informative)Methods for determining the beam axis for well-behaved beams [Go to Page]
- C.1 Comparisons of beam axis search methods
- Tables [Go to Page]
- Table C.1 – Standard deviations for x and y scans usingthree methods of determining the centre of the beam
- C.2 Beamwidth midpoint method
- Figure C.1 – x-axis scan at 9 cm depth for the first focal zone with beam centre
- Figure C.2 – x-axis scan at 4,4 cm depth for the second focal zone
- Table C.2 – Decibel beamwidth levels for determining midpoints
- Annex D (informative)Methods for determining the beam axisfor beams that are not well behaved [Go to Page]
- Figure D.1 – Asymmetric beam showing relative acoustic pressure versus sample number for the beamwidth midpoint method
- Annex E (informative)Uncertainties [Go to Page]
- E.1 General
- E.2 Overall (expanded) uncertainty
- E.3 Common sources of uncertainty
- Annex F (informative)Transducer and hydrophone positioning systems [Go to Page]
- Figure F.1 – Schematic diagram of the ultrasonic transducer andhydrophone degrees of freedom
- Annex G (informative)Planar scanning of a hydrophone to determine acoustic output power [Go to Page]
- G.1 Overview
- G.2 General principle
- G.3 Hydrophone scanning methodology [Go to Page]
- G.3.1 General methodology
- G.3.2 Particular considerations for implementation for HITU fields
- G.4 Corrections and sources of measurement uncertainty [Go to Page]
- G.4.1 Uncertainty in the hydrophone calibration
- G.4.2 Planar scanning
- G.4.3 Attenuation factor of water: unfocusing transducers
- G.4.4 Attenuation factor of water: focusing transducers
- G.4.5 Received hydrophone signal
- G.4.6 Integration
- G.4.7 Finite size of the hydrophone
- G.4.8 Partial extent of integration
- G.4.9 Non-linear propagation
- G.4.10 Directional response
- G.4.11 Noise
- G.4.12 Intensity approximated by derived intensity
- Annex H (informative)Properties of water [Go to Page]
- H.1 General
- Table H.1 – Speed of sound, c, and characteristic acoustic impedance, ρ c,as a function of temperature, for propagation in water
- H.2 Attenuation coefficient for propagation in water
- Bibliography [Go to Page]
