Lecture 12

Question 1

Sound can ____/______

Answer 1

Converge/diverge

Question 2

Sound is _______ and is not ______ 0r _______

Answer 2

A mechanical wave

Is not ionizing radiation

Is not electromagnetic

Question 3

Transducer assembly aka _____ or______

Answer 3

Probe

Scan head

Question 4

Probe made of (4)

Answer 4

Element, damping material, matching layers, and case

Question 5

What does transduce mean

Answer 5

Convert one form of energy into another

Question 6

Converse piezoelectric effect

Answer 6

Turning pulse/echo into voltage

Question 7

Reverse piezoelectric effect

Answer 7

Turning voltage into pulse/echo

Question 8

Piezo-electric element aka

Answer 8

Crystale

Question 9

Adding a voltage causes thickness of ____ to change. This creates a ____

Answer 9

Element

Mechanical wave

Question 10

1 cycle of alternating voltage —>

Answer 10

2/3 cycles of pulse

Question 11

Longer alternating voltage ==

Answer 11

Longer pulse (doppler )

Question 12

Returning echo affects the _____ and this creates a ______

Answer 12

Element

Voltage

Question 13

What is one of the first natural piezoelectric crystals

Answer 13

Quartz

Question 14

We now make synthetic crystals with which types of ceramics

Answer 14

Lead
Zirconate
Titanate
Barium

Question 15

Electric elements are usually made of _____

Answer 15

Lead zirconate titanate

Question 16

Lead zirconate titanate is aka

Answer 16

PZT

Question 17

We make PZT piezo electric my

Answer 17

Placing it in a strong magnetic feild at a high temp (350) which realigns its molecular dipoles

Question 18

When piezo electric elements are heated, what happens

Answer 18

The molecules spread out

Question 19

When piezo electric elements are polarized, what happens

Answer 19

The dipoles align

Question 20

piezo electric elements are cooled while in

Answer 20

Magnetic field

Question 21

What is the curie point

Answer 21

The temp in which the magnetic properties of a solid can be changed

Question 22

The curies point of PZT is

Answer 22

350 degrees

Question 23

piezo electric element has a ________ frequency

Answer 23

Natural vibrational frequency

Question 24

The natural frequency of piezo electric element can also be called (3)

Answer 24

Fundamental freq
Operational freq
Resonance freq

Question 25

Operating frequency depends on ____

Answer 25

Element

Question 26

Propogation speed of PZT element

Answer 26

4 mm/us

Question 27

Thickness of element

Answer 27

Th

0.2-1 mm

Question 28

2 x th = ______

Answer 28

Wavelength

Question 29

To get different frequencies we would have to

Answer 29

Change crystals/transducers

Question 30

In present day systems, they are bit more complex and can uses the _________ to adjust the transducer frequency

Answer 30

Voltage frequency

Question 31

With pulsed wave we are dealing wiht a ______

Answer 31

Bandwidth

Question 32

2 or 3 freq on the same element =

Answer 32

Multihertz operation

Question 33

PRF of voltage also affects PRF of

Answer 33

Pulse

Question 34

Piezo-electric element is inversely proportional to

Answer 34

Depth

Question 35

If you need to go farther down you must _______ PRF

Answer 35

Decrease

Question 36

If PRF is not decrease when trying to go deeper you get

Answer 36

Range ambiguity / echo misplacement

Question 37

For 2d ultrasound ______ automatically accomodates

Answer 37

Depth