A medical imaging system must clearly resolve two closely spaced points inside soft tissue. The minimum required axial resolution is 0.25mm. The speed of sound in the tissue may be taken as 1540ms−1.
(i) State the relationship between the minimum resolvable axial distance and the wavelength of the ultrasound pulse.
(ii) Calculate the minimum operating frequency that the ultrasound transducer should have to achieve the stated resolution.
(iii) Determine the time period of the sound wave at the frequency found in part (ii).