National Physical Laboratory

Calibration of Ultrasound Hydrophones

Ultrasonic hydrophones

This suite of calibration services provides calibrations of the free-field sensitivity of miniature hydrophones of the type used to characterise medical ultrasonic fields. The services cover the frequency range 0.1 MHz to 60 MHz.

Calibration of a hydrophone over the frequency range 1 MHz to 40 MHz

The service uses a multiple frequency technique based on non-linear distortion of an initially sinusoidal acoustic tone burst.

A comparison method is used where the response of the test hydrophone is compared against a reference transfer standard hydrophone, the calibration of which is traceable back to the NPL Primary Standard laser interferometer. Hydrophone sensitivities are derived in the frequency range 1 MHz to 40 MHz in integer frequency steps. Optimum sensitivity for the test hydrophones are in the range of 10nV/Pa to 1000nV/Pa, although calibrations can be carried out down to 5 nV/Pa but with expanded uncertainties which may be degraded significantly.

Best overall measurement uncertainties for hydrophones of typical response (i.e. sensitivities of greater than 20 nV/Pa from 1 MHz to 40 MHz) are 6% for 1 MHz to 8 MHz; 7% for 9 MHz to 12 MHz; 8% for 13 MHz to 16 MHz; 11% for 17 MHz to 20 MHz; 12% for 21 MHz to 30 MHz; and 15% for 31 MHz to 40 MHz.

Full range of hydrophone calibrations

The following calibrations are available:

  • Magnitude calibration of a hydrophone over the frequency range 1 MHz to 40 MHz in 1 MHz increments; UKAS accredited
  • Relative phase response calibration of a hydrophone over the frequency range 1 MHz to 40 MHz in 1 MHz increments
  • High frequency hydrophone calibration (Magnitude only) up to 60 MHz
  • Fine frequency calibration (Magnitude only) between 0.1 MHz and 20 MHz in increments of ≥10 kHz; UKAS accredited from 1 MHz to 20 MHz
  • Matching and calibration of a hydrophone/amplifier combination

Average turnaround time for calibrations: 3 weeks


Customer Service tel: +44 20 8943 8631

Last Updated: 19 Mar 2013
Created: 5 Jun 2009


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