1. A system for optically and non-invasively characterizing an acoustic beam, said system comprising: a container having an immersant disposed therein, said immersant comprising an immersion medium seeded with a plurality of seed particles; at least one optical transmitter that illuminates at least some of said plurality of seed particles; at least one optical receptor to track at least one optically-detectable parameter of at least some of said illuminated seed particles, thereby generating at least one immersant parameter map; and a processor that determines one or more characteristics of the acoustic beam from said at least one immersant parameter map and one or more known properties of said immersant.