phyrev ch.5 - Dynamic aperture a form of electronic...

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Dynamic aperture – a form of electronic receive, electronic focusing, allows the receive beam to be as narrow as possible at all depths and optimizes lateral resolution at all depths. - size of the group of elements energized to produce one pulse Ch. 12 Contrast, Spatial, and Temporal Resolution Improved temporal resolution (high Frame Rate) Diminished Temporal resolution (low Frame Rate) Shallow imaging Deep imaging Single focus Multi – focusing (improves lateral resolution) Narrow sector Wide sector Minimize line density High line density (improves spatial resolution Factors that shorten the time required to make each frame increases frame rate and improve temporal res. FR vs image quality - as temporal res. improves (higher FR), image quality degrade - as temporal res. degrades (low FR), image quality improves - increasing line density degrades temp res. but improves spatial res. - turning on multi-focusing degrades temp res. but improves lateral res. HIGH TEMPORAL RESOLUTION LOW TEMPORAL RESOLUTION High frame rate Low frame rate Shallow Deep Fewer pulses per image More pulses per image Single focusing Multi-focusing Narrow sector Wide sector Low line density High line density Associated with better movie, but low quality image Assoc. with poor quality movie, but higher quality image Contrast Resolution
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phyrev ch.5 - Dynamic aperture a form of electronic...

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