Dynamic phased arrays and ultrasound modulators

The acoustic hologram has made it possible to shape ultrasound waves and project complex pressure patterns in 2D and in 3D, as we have also recently shown. The hologram contains tens of thousands of elements which can be used to form sophisticated pressure patterns by setting the phase and/or amplitude across the wavefront of a sound wave. It thereby offers more degrees of freedom than conventional phased array transducers (PATs). However, the hologram is generally static, whereas PATs are dynamic. PATs do not only have fewer elements, but they are also more difficult to fabricate and require complex electronics. In this talk, I will describe our efforts to combine the best of both worlds. For this, we are exploring the use of light waves as a means to control ultrasound waves. I will describe direct and indirect approaches that can be used to control and modulate holographic ultrasound fields.