Long pulses _____ axial resolution.

Long pulses _____ axial resolution.

• A. Degrade
• B. Improve
• C. Has Little Effect
• D. Depends On Frequency

Answer: (A)

Axial resolution is determined by the spatial length of the emitted pulse. The spatial pulse length is the distance the pulse travels during one cycle, essentially number of cycles in the pulse times the wavelength. When the pulse is long, it contains more cycles, leading to a longer spatial pulse length. A longer spatial pulse length means two reflectors that are close along the beam axis can’t be distinguished, so axial resolution gets worse. So long pulses degrade axial resolution. Shorter pulses, with fewer cycles or shorter wavelengths, shorten the spatial pulse length and improve axial resolution. The other statements don’t fit this direct relationship.

Axial resolution is determined by the spatial length of the emitted pulse. The spatial pulse length is the distance the pulse travels during one cycle, essentially number of cycles in the pulse times the wavelength. When the pulse is long, it contains more cycles, leading to a longer spatial pulse length. A longer spatial pulse length means two reflectors that are close along the beam axis can’t be distinguished, so axial resolution gets worse. So long pulses degrade axial resolution. Shorter pulses, with fewer cycles or shorter wavelengths, shorten the spatial pulse length and improve axial resolution. The other statements don’t fit this direct relationship.