Multiple ultrasound image generation based on tuned alignment of amplitude hologram over spatially non-uniform...

In this study, a method for readily and inexpensively generating intense midair ultrasound fields that are reconfigurable in real-time is proposed for applications of midair nonlinear acoustic effects. To generate such ultrasound fields, specifically designed ultrasound sources or phased arrays of ultrasound transducers are conventionally used. The former can be more readily fabricated but cannot drastically reconfigure the generated ultrasound field, and the latter can create electronically controllable ultrasound fields but is much more expensive and difficult to implement. The proposed method utilizes a planar ultrasound source with a fixed surface vibration pattern and a newly designed amplitude mask, which partially covers source emission to form a predetermined ultrasound field with a corresponding specific spatial pattern when placed at a specific position. This new mask allows for switching of the generated fields among several presets by changing the mask's position on the source. The proposed technique requires only slight mechanical translation of the mask over the source to instantly reconfigure the resulting midair ultrasound field. This method enables the creation of a reconfigurable ultrasound field with a large source aperture in a significantly inexpensive, practical setup, potentially extending the workspace of current midair ultrasound applications to a whole-room scale.