Scattering Flashcards by Sade Kehinde | Brainscape

Q

Scattering of light is caused due to the in-homogeneities in a medium
in-homogeneities = _______

A

particles

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Two MAIN types of scattering

A

Incoherent

Coherent

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

CONDITIONS for Incoherent Scattering:
1
2

A

white light

particles far apart

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Incoherent scattering depends on :

A

size of particles

distance btw particles

strenght of interaction:- refractive index
absorption strength

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

particle size > wavelength of light

A

M

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

particle size = wavelength of light

A

T

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

particle size < wavelength of light

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

• reflection & refraction
causes scattering

A

M

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

Example: halos seen through
a fogged up car window

A

T

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

• forward direction scattering

A

M

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

dipole re-radiation causes
scattering

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

stronger dependence at
shorter wavelength (blue)
than on the longer
wavelength

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

spread light out in more
direction

A

T

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

wavelength independent

A

M

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

• interior wave effects causes
scattering (diffraction)

A

T

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

Examples: Blueness of the sky

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

wavelength dependent

A

T

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

Example: whiteness of the
clouds

A

M

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering, Tyndale scattering, or Rayleigh scattering?

isotropic in direction (all)
scattering profile shows forward and backward scatter

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

_________Scattering is an elastic scattering,
as the scattered photons’ energy do not
change

A

Rayleigh

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Inelastic scattering of particles is called

______ Scattering.

A

Raman

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

________ Scattering theory applies for particles both absorb and scatter.

A

Mie

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Techniques based on scattering theory are used in several studies in the understanding of optical
properties of biological tissues like skin, brain, breast, bone, other soft tissues, other fibrous tissues and
fatty tissues, and even blood cell

A

Mie

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

The bluer the light the more the light_______
and the larger the area of
________

A

scatters

glare

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Mie scattering produces ______ scattered light

A

unpolarized

Q

Rayleigh : when reflected and transmitted light are perpendicular , get strong _________

A

polarization

Q

In 1882, _________published Le Rayon Verte – the Green Ray – in which he
dreamed up an old Scottish legend that says
anyone who sees a green flash will never
again make a misstep in matters of the heart.

A

Jules Verne

Q

Coherent scattering: When the particles are
___________
than the coherence length of the light,
________and _______interference occurs
between the waves scattered from different
particles

A

much closer together

constructive and destructive

Q

Coherent scattering:

Particles much_____ than the wavelength of the light

• Each particles acts as a ________ for the coherent
scattered waves
• Scattered waves propagate ______ and overlap.
• Acts as ‘diffraction ______

A

smaller

source

outward

grating

Q

Many coherent scattered waves interfere…
______ in most directions

•________ in two directions
• _____to incident light (forwardscatter)
• Refract _______ to incident wave
(phase shifted)

A

• Destructively

Constructively

Parallel

relative

Q

Intraocular Light scatter: leads to deleterious visual effects, like
• Glare while \_\_\_\_\_\_\_\_\_\_
• Hindrance from \_\_\_\_\_\_\_ during daytime
• \_\_\_\_\_\_\_recognition problems
• \_\_\_\_\_\_\_of vision
• Color and contrast \_\_\_\_\_

A

night driving

low sun

Facial

Haziness

loss

Q

Light going into the

eye?

A

• Forward scatter (FWS) –

Q

Light reflecting

back from the fundus?

A

• Backward scatter (BWS) – Light reflecting

back from the fundus

Q

Small protein particles (α-crystallin) and rough
surface reflectance dominate ________light
scattering
• Whereas, large sized protein particles
dominate________ scattering.

A

backward

forward

Q

____________consists of Collagen Fibrils (parallel
bundles) which are less than wavelength of the light.
• Incomplete destructive interference causes about 10%
scattering in cornea.
• Corneal scattering helps in slit-lamp examination of the
cornea.

A

Corneal stroma

Q

The Collagen fibers (random order) in _____have larger
spacing than the wavelength of light.
• Due to large particle incoherent forward scattering, ________
appears whitish.

A

sclera

sclera

Q

Case: ________ Fibers get smaller and sclera takes

on a bluish due to Rayleigh-type scattering.

A

Scleral thinning.

Q

:
• Yellow pigments in the lens scatter more light (forward
scatter).
• Cataract is formed when protein in the lens clumps
together forming fluid pools causing additional
scattering.
• Cataract formation degrades vision by scattering. The
amount of scatter increases with the cataract growth.

A

Crystalline lens

Q

• With the coalescing of ‘collagen fibers’ in _______due to
aging causes fluid packets and thereby developing a
localized scattering.
• This causes patients to see floating specks and threads.

A

Vitreous humor

Q

________ scatters light as much as cornea.
• When blood circulation/supply is interrupted, the ______
integrity is damaged, and edema fluid starts collecting in
the nerve fiber layer. This increases______light scattering
turning the area into milky gray (cotton wool spots).

A

retina

retinal
retinal

Q

Sources of Ocular scattering:

5:

A

Sources of Ocular scattering:

Cornea
Sclera and Iris
Lens
Vitreous humor
Retina

Q

\_\_\_\_\_\_\_\_\_\_
scattering is identical
for all healthy eyes,
and for all ages.
(Constant)+

A

Corneal light

Q

__________ wearers experience a significantly higher light scatter.*

A

Contact lens

Q

Corneal light scatter may increase after _____________

A

laser refractive surgery

Q

surgery type?
– Mean stray light increase by a factor of 1.4 in eyes with 4 mm
pupil and a factor of 2 (0.3 log units) for 8mm pupil.

A

Radial Keratotomy (RK)*

Q

surgery type? –corneal backscattering of light, which correlates with
visible haze, is significantly stronger after _____
•

A

• Photorefractive keratotomy (PRK)*

Q

surgery type?– Epithelial ingrowth after ________can cause an
increase in straylight.
•

A

Laser-assisted in situ keratomileusis (LASIK)*

Q

surgery type? - Reported decreased

scatter in the follow ups.

A

Corneal Refractive Therapy (Orthokeratology or Corneal reshaping)*

Q

The amount of scattering/stray light in the eye depends also on the pigmentation in the
_________

A

fundus.

Q

• Sclera and iris are not totally opaque.They diffusely transmit long wavelengths due to the________ in the scleral
wall and iris.

A

color of the pigments

Q

For a light-blue eye effective transmission of the iris was___%for red and ___% for green
light. Also the eyewall around the iris transmits a significant amount of light.

A

1%

0.2

Q

Fundus has stronger reflectance of ____ wavelength ____ due to the pigments, and
also the blood.
• Blue eyes, blue-green eyes causes greater________ of light from fundus and
more light transmission through the eye walls.

A

longer

red

back scattering

Q

For the dark-brown eyes of pigmented individuals transmission is lower by____orders
of magnitude.*

Dark brown eye has abundant melanin pigments which absorbs strongest at ______
wavelength.#

A

two

shorter

Q

For natural pupils (between
2 and 7 mm diameter),
scatter _______depends on
pupil diameter

A

weakly

Q

Light scatter by
\_\_\_\_\_\_\_\_\_\_\_\_\_
increases significantly
with age and much
more higher for
cataract eyes

A

crystalline lens

Q

___________ are the result of water absorption and
subsequent phase separation within the IOL matrix and
are clinically observed in almost all types of IOL material,
including hydrophobic and hydrophilic acrylics,
silicone, and PMMA.

A

Glistenings

Q

:
Radiation of sharp needles of light that is
perceived subjectively around a bright point light
source.
• Originates from light scattering by small particles.

A

Ciliary Corona

Q

• The ________ is a colored band, much like the rainbow,
perceived surrounding a bright spot of light at a mean
distance of 3° radius.
• it originates from the fibrous structure of the eye lens.
• the lens fibers form a diffraction grating, arranged in a
circular fashion, much like the spokes of a wagon wheel.
• the_______ appears only for______pupil sizes,
depending on the subject

A

lenticular halo

lenticular halo

larger

Q

: are introduced
IOLs to reduce the amount of blue
light transmission in the eye (Natural
Chromophore).

A

blue light blocker*

Q

blue light blocker benefits

A

Drastically reduces the light
scatter (see below)
• Blocks Blue light harmful to retina
• Reduce the effect of chromatic
aberrations of the eye.
• Do not affect VA, CS, &amp; Color
vision

Q

blue light blocker side effects

A

Potential side effects of a reduction in blue-light
transmission include color-vision disturbance,
decreased scotopic sensitivity (which can lead
to poorer performance in dim lighting conditions),
and sleep–wake timing disruption.