IEC 61161:2013

Overview

IEC 61161:2013 is an international standard developed by the International Electrotechnical Commission (IEC) that defines procedures and performance requirements for measuring the total emitted acoustic power of ultrasonic transducers using radiation force balances. This third edition expands on previous editions by addressing both circular and rectangular transducers and updating calibration methods and measurement considerations.

This standard applies particularly to ultrasonic power measurements:

• Up to 1 W in the frequency range of 0.5 MHz to 25 MHz
• Up to 20 W in the frequency range of 0.75 MHz to 5 MHz

It covers the use of radiation force balances of gravimetric and force feedback types for different ultrasonic fields including well-collimated, diverging, and focused beams.

Key Topics

Radiation Force Balance Principles

• Measurement based on the force exerted by ultrasonic waves on a target suspended in a medium.
• Targets can be absorbing or reflecting, each with specific characteristics impacting measurements.
• Considerations include target geometry, positioning, and coupling to ensure accurate force detection.

Transducer Types and Configurations

• Includes both circular and rectangular ultrasonic transducers.
• Addresses focused ultrasonic beams and how scanning influences power measurements.
• Describes the significance of lateral target positioning and transducer-target separation.

Calibration and Measurement Uncertainties

• Calibration methods differ based on whether the system is used as a primary or secondary measurement tool.
• Measurement uncertainties are systematically assessed considering factors such as:
  • Balance system resolution and linearity
  • Environmental conditions including temperature and water quality
  • Target and transducer alignment
  • Ultrasonic attenuation, cavitation, and acoustic streaming effects

Limitations and Correction Methods

• Discusses limitations due to cavitation and temperature rise affecting radiation force measurements.
• Provides guidance on estimating acoustic power in diverging or focused beams.
• Annexes provide foundational formulae, buoyancy change methods, alternative measurement techniques, and specifics on propagation media.

Applications

IEC 61161:2013 supports several practical applications where precise ultrasonic power measurement is critical:

• Medical ultrasound transducer testing to ensure safety and performance in diagnostic devices.
• Industrial ultrasonic cleaning equipment calibration for optimized cleaning power and efficiency.
• Non-destructive testing (NDT) where beam power influences inspection reliability.
• Research and development of advanced ultrasonic devices involving various transducer shapes and beam focuses.
• Compliance with IEC 61161 assures consistency and reproducibility in ultrasonic power measurement worldwide, facilitating regulatory approval and quality assurance.

Related Standards

• IEC 62555 – Future standard that includes details on buoyancy change methods linked from IEC 61161.
• Other standards for ultrasonic power measurement and application-specific guidelines may complement IEC 61161:
  • IEC technical committee 87 publications on ultrasonics
  • ISO/IEC directives guiding standard preparation and verification processes

Keywords: IEC 61161, ultrasonic power measurement, radiation force balance, ultrasonic transducers, acoustic power, ultrasonic beam calibration, ultrasonic measurement uncertainty, focused ultrasonic beams, circular transducers, rectangular transducers, cavitation effects, ultrasonic testing standards.