3. Wave Properties

TAMU BMEN 311 - Imaging Living Systems [Wave Properties]

imaging techniques use

interactions between waves (notably EM or sound waves) and matter (such as glass and tissue)

logitudinal waves

left to right

• sound waves

transverse waves

up to down (cosine waves)

• x-ray & CT

absorption

energy transerred into medium

emission

“Fluorescence” / glowing

transmission

light passes through medium or into a new medium

reflection

light bounces or changes direction when reaching a barrier

specular reflection

diffuse or scattering reflection

refraction

lights bends when passing from one medium to another

due to change in speed of wave

constructive wave interference

waves add thogether

destructive wave interference

waves subtract

Refractive index

how much path is bent or “refracted”

snell’s law

n₁sin0₁=n₂sin0₂

or

sin0₁/sin0₂ = v₁/v₂

Diffraction

bending and spreading of wave as it passes through an opening or around barrier in its path

small diffraction

wide gap

large diffraction

narrow gap