A system (100) uses a pyroelectric membrane (122) and an ultrasound absorber (123) to measure the amount of ultrasonic energy received from a transmitter (105) through a sample (110). The thermal response of the pyroelectric membrane (122) is sensitive to ultrasound time-averaged intensity but is insensitive to the phase of the ultrasound. A waveform (200) shows rising (210), peak (220) and decaying (230) portions of a signal from the pyroelectric membrane (122) in response to on/off transitions of the transmitter (105). A system (300) uses a peak detector (333) to automatically turn the transmitter (105) on/off. A system (400) has background removal circuitry (444) to remove unwanted accelerometer-induced noise or electrical noise. A multi-element ultrasonic sensor (520) has cavities (555) so that a dummy sensor (521 b) can be used to compensate for unwanted accelerometer sensitivity of a sensor element (521 a). A sensor (620) has ultrasound absorbing (or reflective) regions (660) to compensate for unwanted accelerometer sensitivity. A system (900) has a low frequency path (909) sensitive to the pyroelectric effect, and a high frequency path (919) sensitive to the acoustic pressure amplitude, of a signal from a sensor (920). A sensor (1020) uses a pyroelectric material (1022) with poled regions (1099) separated by a non-poled region (1098).Linvention concerne un système (100) utilisant une membrane pyroélectrique (122) et un absorbeur dultrasons (123) pour mesurer la quantité dénergie ultrasonore reçue depuis un émetteur (105) dans un échantillon (110). La réponse thermique de la membrane pyroélectrique (122) est sensible à la moyenne temporelle de lintensité ultrasonore mais insensible à la phase de lultrason. Une forme donde (200) représente des parties croissante (210), de crête (220) et décroissante (230) dun signal provenant de la membrane pyroélectrique (122) en réponse à des transitions marche/arrêt de lémetteur (105). Un système (300) utilise un détecteur d
