Diffraction 1 (10-11)

Question 1

A diffraction grating made of _______slits

Answer 1

‘circular

Question 2

• An optical device that blocks alternate zones is called

a

Answer 2

‘Zone Plate’

Question 3

A diffraction grating that creates inwardly bending

‘spherical’ diffracted wave forms a ._______

Answer 3

‘point image’

Question 4

For a ___________source of light incident on a zone plate:
• Central order (0th) goes through
• First order (1st) forms point image at___
.
• Second order forms point image at ____
• Third order forms point image at _____

Answer 4

monochromatic

straight.

f2

f2/2.

f2/3

Question 5

___________ blocks wave that contribute to
destructive interference at the diffraction maximum,
making the image formation much__________

Answer 5

Fresnel zone plate

‘dimmer’.

Question 6

Phase Plate:

Instead of blocking these waves, they are phase shifted
by _______

Then, the phase shifted waves would be________with the axial wave, and would contribute to the
_________ interference at the diffraction maximum,
making the image much________

Answer 6

180°.

in phase

constructive

‘brighter’.

Question 7

Ways to make ‘Phase Plate’ by adjusting -

1. No. of _______
2. Depth of the____ d)
3. Refractive ______μ)
4. __________

Answer 7

grooves

groove (

Index (

Wavelength(λ)

Question 8

A zone plate with kinoform shaped grooves

is referred to as a _______

Answer 8

diffractive lens.

Question 9

: A single
refractive lens with a
phase plate imbedded on
one side of its surfaces.

Answer 9

Hybrid lens

Question 10

A Fresnel lens with equal zone widths. A Fresnel

lens is always a ______lens.

Answer 10

mono-focal

Question 11

Diffractive Lens Design Details:

Local grating ______determines ray direction (add power).

Spacing gets progressively smaller from____ to its
______.

Answer 11

spacing

center to its edge.

Question 12

Diffractive Lens Design Details:

Local Step______determines ‘diffraction efficiency’ of light.
[determines how much light put into the add portion]

Answer 12

height

Question 13

Allocation of energy into each diffraction order
When m= ____focal length of 0th order is infinite (zero
power).
The base power of the lens provides all the power at
this order. At this power, ______ vision is corrected.
When m=_____ energy is distributed to the 1
st order.

Answer 13

=0,
distant
=1,

Question 14

Unwanted patterns onto the retina
which affect the visual performance by
obscuring relevant retinal image.

Answer 14

Dysphotopsia

Question 15

Bright artifacts onto the retina.

Ex. Arcs, rings, streaks, halos & glare

Answer 15

Positive Dysphotopsia:

Question 16

Blockage of light onto the retina.

Ex. Shadows, dark spots.

Answer 16

Negative Dysphotopsia:

Question 17

Fresnel’s lens increases the luminosity of the

lighthouse lamp by a factor of ______

Answer 17

4.

Question 18

\_\_\_\_\_\_\_\_Lighhouse in Waimanalu,
Hawaii. The lighthouse
has a hyper-radiant
Fresnel lens with a 1.3-m
focal length, one of the
largest in the world.

Answer 18

Makapuu

Question 19

Delivers color by absorption at
certain wavelength and reflects at
others)

Answer 19

chemistry

and pigment coloration

Question 20

Delivers color due to Interference,

diffraction & Scattering.

Answer 20

physics and structural patteren

Question 21

A component found on the insect

exoskeletons. RI, n = 1.53 – 1.56.

Answer 21

chitin

Question 22

_______________causes ‘iridescence’ color.

Answer 22

Overlap of several orders of diffraction

Question 23

• Strength of the Iridescence depends on the__________ and ___________

Answer 23

‘groove density’ and

the ‘surface quality’.

Question 24

0th order is very _____

3rd-8th order is ______

Answer 24

intense

iridescence

Question 25

Holography: Developed by__________ in 1948. Had to wait until the invention of Lasers (Coherent source) to record a hologram. In _______received Noble prize in physics

Answer 25

Dennis Gabor | 1971

Question 26

Requirements of Holography : _______ Light Maintain ‘_______ of 2 waves constant all through out Extremely complicated ______________

Answer 26

Coherent phase relationship’ Interference

Question 27

Unlike conventional imaging, in_________imaging ‘Light from each point on the object will reach all points on the film’

Answer 27

holographic

Question 28

holography: _________causes Interference pattern to be formed producing an image with 3D information.

Answer 28

Phase-difference

Question 29

Requires a_________Source to view the holographic image recording

Answer 29

Coherent

Question 30

__________ in 1969 invented ‘rainbow’ hologram | – a second generation holography.

Answer 30

Stephen Benton

Question 31

________ viewed – You will see ‘3D image’ _________viewed – You will see ‘different colors’ Types of Holograms: ____________ Real Image formed (m=+1) are not normal viewed Virtual Image formed (m=-1) behind the film are viewed

Answer 31

Horizontally Vertically Transmission and Reflection

Question 32

For the eye, only a section passes through the pupil; the iris is an obstruction that diffracts the light. This diffraction blurs the image. For a system limited only by diffraction (no optical aberrations), the image radius for a point object =__________

Answer 32

1.22 λ f/d meters.

Question 33

Pupil size controls impact of ___________ and ___________on retinal image quality (emmetrope)

Answer 33

ocular aberrations diffraction

Question 34

collagen: A fibril spacing (d) ______than the wavelength of light (λ) will make the fibrils transparent as light passes through undeviated.

Answer 34

smaller

Question 35

If d < λ then θ > 90 deg for all m > 0. Therefore, no diffraction orders exist except _____ Under this condition, the fibrils diffract no light and appear transparent.

Answer 35

m = 0.

Question 36

WHAT IS THIS TALKING ABOUT? Light entering the eye is diffracted by small particles in the eye. Each particle causes a circular diffraction pattern on the retina tens of degrees across. Interference of overlapping diffraction patterns for white light is easily observed by viewing a small, bright, white light source. We perceive a very fine pattern of innumerable needles of light, fanning out from the point object over several degrees.

Answer 36

The ciliary corona is an entoptic diffraction phenomeno