In soft tissue tow interfaces that generate ultrasound refle

In soft tissue, tow interfaces that generate ultrasound reflections are separated by d =1.0 mm along the direction of the beam. The criterion for resolution is that the two interfaces be at least half the pulse length apart, and that pulses must be at lease one wavelength long. What is the minimum frequency that will resolve these interfaces?

Solution

The minimum frequency is

f = c/d= 3*10^8 /1*10^-3 = 3*10^11 Hz