Basic Intrumentation Flashcards
The Reverse _______ Effect is US
Piezoelectric
CW US has essentially one frequency called the
RESONANCE frequency
The preferred wavelength for US is what
Based off crystal thickness. The crystal thickness = 1/2 the wavelength
Different thickness of crystals =
Transducers with different frequencies
What is the matching layer? How thick is it?
It protects the active element; it is 1/4 the wavelength thick
Low Q value, if damping is heavy…
Transducer will have a low Q value… or a short ring down time.
If damping is lighter, than there will be a high Q value
Damping material reduces what exactly
Reduces:
Ringing, lowers intensity of output signal
Shortens pulse length
Reduces pulse duration
Improves axial resolution
Bandwidth, whats the difference between CW and PW
CW has a narrower bandwidth, higher frequencies (high Q-factor)
PW has a broad bandwidth, with more frequencies (low Q-factor)
Q-factor is directly related to _________
Bandwidth
Q-factor describes a few things…
Describes the purity of the PZT crystal
A higher Q-factor rings for a long period, produces long pulse length
No units, UNITLESS
Shorter pulse = lower Q factor
Higher pulse = higher Q factor
If bandwidth decreases… what increases?
Q-factor
Wavelength equation
Wavelength = c / f
Period equation
Period = 1 / f
