right if you have a camera embedded in a piece of tissue this is what you would see in general yeah you got bright spots everywhere there there are actually a lot of photons down there even when it's deep but they're all spread all over the place so using this optical focus we can actually collect a lot of the bright spots and concentrate them onto this ultrasound focal spot if we were to use an your higher-order effect we catch you coalesce all of them into a single spot so this can be extremely powerful right