Herzog, T.T.HerzogHeuer, H.H.Heuer2022-03-082022-03-082011https://publica.fraunhofer.de/handle/publica/309522An ultrasonic sensor for detecting and/or scanning an object includes a substrate and a piezoelectric sensor unit arranged on or at this substrate and/or connected to this substrate. The rear side of the substrate facing away from the piezoelectric sensor unit has a surface structure including a plurality of elevated portions and recesses, with this surface structure being configured so that a diffuse scattering of ultrasonic waves incident on the rear side from the direction of the sensor unit takes place by it; and/or in that its elevated portions and/or recesses have a mean lateral extent in the range of 0.05 [mu]m to 1 mm, preferably from 0.1 [mu]m to 200 [mu]m, preferably from 0.2 [mu]m to 20 [mu]m, and/or a mean lateral extent which is smaller than or equal to the wavelength of an ultrasonic wave which can be produced by the piezoelectric sensor unit.en620patent20100000489