What happens to axial resolution when pulse duration shortens?

What happens to axial resolution when pulse duration shortens?

• A. Worsens
• B. No change
• C. Improves
• D. Becomes undefined

Answer: (C)

Axial resolution is governed by spatial pulse length—the physical length of the emitted pulse along the beam. Spatial pulse length depends on how long the pulse lasts (and the wavelength it contains): shorter pulse duration means fewer cycles and a shorter spatial pulse length. With a shorter spatial pulse length, echoes from two interfaces that are close together along the beam axis overlap less, so they can be distinguished as separate reflections. That is why shortening the pulse duration improves axial resolution.

Axial resolution is governed by spatial pulse length—the physical length of the emitted pulse along the beam. Spatial pulse length depends on how long the pulse lasts (and the wavelength it contains): shorter pulse duration means fewer cycles and a shorter spatial pulse length. With a shorter spatial pulse length, echoes from two interfaces that are close together along the beam axis overlap less, so they can be distinguished as separate reflections. That is why shortening the pulse duration improves axial resolution.