| Zugriffsnummer | 11265 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Broadband amplitude and phase calibration of hydrophones and impulse deconvolution within diagnostic ultrasound exposimetry |
| Autor(in); Institution |
Wilkens, Volker; 1.6, Schall, PTB-Braunschweig
Koch, Christian; 1.6, Schall, PTB-Braunschweig
|
| Quelle/Jahr | Proceedings of the Joint Congress CFA/DAGA '04, Strasbourg, March 22 - 25, 2004 : [7ème Congrès Français d'Acoustique, 30. Deutsche Jahrestagung für Akustik, Salon Européen de l'Acoustique]:(2004) |
| Availability | [CD-ROM] ; file name: cd1\\articles\\000148.pdf |
| Herausgeber(in) |
Cassereau, Didier
|
| ISBN | 2-9521105-2-2 (Vol 2) ; 2-9521105-3-0 (CD-ROM) |
| Verlag | Paris: Societe Francais d'Acoustique |
| Konferenzangaben | CFA/DAGA '04, Strasbourg, 22-25, March, 2004, France |
| Freie Schlagworte | Ultrasound Exposimetry ; Hydrophone Measurements ; Impulse Deconvolution |
| Zusammenfassung | Reliable measurement of ultrasonic pressure fields requires hydrophones calibrated in a broad frequency range. A secondary hydrophone calibration technique using an optical multilayer hydrophone as the reference is described. The optical hydrophones offers high lateral resolution and a constand frequency response in a remarkably broad frequency range (1 - 75 MHz). By measurement of broadband ultrasound pulses with the optical hydrophone, and in a second step with the hydrophone to be calibrated, the complex-valued frequency response is obtained in a very fast, simple, and efficient way in a broad frequency range with high frequency resolution. The technique is applied to calibrate both a piezoelectric membrane and a needle-type hydrophone. The calibration data obtained can be applied to significantly improve hydrophone measurement results. This is demonstrated by exposure measurements on a typical diagnostic ultrasound machine. The standard pulse parameters such a spositive peak pressure p+ and rarefactional peak pressure p- obtained by the commonly applied evaluation method using the voltage to pressure transfer factor at the acoustic working frequency M(f awf) are compared transfer function M(f). The membrane hydrophone is shown to systematically overestimate p+, underestimate p-, and overestimate the pulse intensity integral PII if no broadband conversion is applied. Using a deficient needle-type hydrophone all pulse parameters were dramatically overestimated due to strong variations of the frequency response, but the results could be improved to a large extent using the broadband conversion method made possible by the pulse calibration data. |
