1 Small-footprint sector probes are used for transthoracie echocardiography as they facilitate ultrasonic access between the ribs. Consider a proposed linear phased array sector probe with the following characteristics: 64 elements with an element width W = 0.25 mm and elevation height h = 12 mm, kerfx = 80 pm, centre frequency f = 5 MHZ, 100% bandwidth. The proposed probe has a xed lens giving a focal length in the elevation plane E, = 10 cm. (a) All the elements are used to form an ultrasound beam focused at 15 em from the probe. (i) What is the minimum slice thickness? (ii) How can the probe design or driving parameters be changed to achieve a smaller minimum slice thickness? (iii) What are the advantages and disadvantages of a smaller minimum slice thickness? (iv) What is the focal width in the image plane