Ultrasound is routinely used in many medical applications. Concern for the safety of subjects undergoing investigations has led to the development of systems to quantify the acoustic output of such devices. One system, the NPL ultrasound beam calibrator, uses a multi-element hydrophone to determine rapidly the temporal and spatial characteristics of the acoustic output. When investigating pulsed systems it is necessary to synchronise data acquisition with the launch of the acoustic pulse, a procedure that currently can be both time consuming and difficult. This article examines the feasibility of using an alternative, optical approach, generating a trigger signal in response to the changes in refractive index associated with propagation of the acoustic pulse.
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