In a four-ring annular array, how many focal depths are typically utilized per scan line?

In a four-ring annular array, how many focal depths are typically utilized per scan line?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (D)

Focusing in an annular array is achieved by applying delays to each concentric ring so their beams converge at a chosen depth. Each ring acts as its own focal aperture, so the number of distinct focal zones you can form along a single scan line equals the number of rings. With a four-ring array, you can create four separate focal depths per scan line, improving resolution at multiple depths. Thus, four focal depths per line.

Focusing in an annular array is achieved by applying delays to each concentric ring so their beams converge at a chosen depth. Each ring acts as its own focal aperture, so the number of distinct focal zones you can form along a single scan line equals the number of rings. With a four-ring array, you can create four separate focal depths per scan line, improving resolution at multiple depths. Thus, four focal depths per line.