Shorter pulse duration has what effect on axial resolution?

Shorter pulse duration has what effect on axial resolution?

• A. Worse
• B. No change
• C. Better
• D. Uncertain

Answer: (C)

Shorter pulse duration reduces the spatial length of the emitted pulse along the beam, which lowers the spatial pulse length. Axial resolution—the ability to distinguish two reflectors that lie along the beam path—improves as spatial pulse length gets shorter. Since axial resolution is roughly half of the SPL, making the pulse shorter directly enhances the ability to separate echoes that are close together along the axis. SPL depends on the number of cycles in the pulse and the wavelength, so a shorter duration effectively means fewer cycles or a higher frequency, both of which shorten SPL and sharpen axial detail.

Shorter pulse duration reduces the spatial length of the emitted pulse along the beam, which lowers the spatial pulse length. Axial resolution—the ability to distinguish two reflectors that lie along the beam path—improves as spatial pulse length gets shorter. Since axial resolution is roughly half of the SPL, making the pulse shorter directly enhances the ability to separate echoes that are close together along the axis. SPL depends on the number of cycles in the pulse and the wavelength, so a shorter duration effectively means fewer cycles or a higher frequency, both of which shorten SPL and sharpen axial detail.