optics

Question 1

Fermat’s Principle

Answer 1

basic rules of geometric optics (straight-line propagation of light in homogeneous media, the law of refraction, and Snell’s law)

observation that the path of a light ray between 2 fixed points is the path that takes the least time.

Thus, in a homo- geneous medium, where the shortest path between the 2 points obviously corresponds to the path that takes the least time, it follows that light travels in straight lines.

Question 2

Coherence

Answer 2

ability of light to produce interference phenomena.

Question 3

Diffraction

Answer 3

light “spreading out beyond the edges” of a small aperture

the absence of aberrations, takes the form of alternating bright and dark rings surrounding a bright central spot, the Airy disc, rather than a point.

Question 4

Laser

Answer 4

Light Amplification by Stimulated Emission of Radiation.

Question 5

Rayleigh scattering

Answer 5

Wavelength-dependent scattering that occurs when light interacts with particles much smaller than the wavelength of the light.

The blue appearance of the sky during daytime and its reddish appearance during sunrise or sunset is due to Rayleigh scattering by atmospheric gas molecules

Question 7

3 regimes of light scattering

Answer 7

Rayleigh scattering, Mie scattering, and geometric scattering

Question 8

Tyndall effect,

Answer 8

for scattering of light by colloidal suspensions, does not describe a separate scattering regime, but rather the effect of the light beam becoming visible.

Question 9

Rayleigh scattering

Answer 9

occurs when light interacts with particles much smaller than the wave­ length of the light

The degree of this form of scattering varies strongly with wavelength,inversely to its fourth power.

probability that light will scat­ ter is much higher for shorter wavelengths (higher frequencies), such as blue light, than for longer wavelengths (lower frequencies), such as red light.

Question 10

Mie scattering

Answer 10

particles whose size is the same order of magnitude as the wavelength of incident light.

does not vary strongly with wavelength and tends to be stronger in the forward direc­ tion

eg white appearance of clouds

cataract formation-whitish ap­pearance of the lens under slit­lamp examination.
strong forward, but less wavelength­ dependent

increase in forward scattering is what results in decreased contrast of the patient’s retinal image, and hence increased glare sensitivity.

microvacuoles is responsible for degraded visual quality associated with the formation of glistenings in intraocular lenses.

Question 11

Geometric scattering

Answer 11

particle size is much larger than the wavelength of incident light

Question 12

raindrops

Answer 12

raindrops are larger than water droplets in clouds
refracting and reflecting the white sunlight from their surfaces.

Question 13

Maxwell’s classical theory of electromagnetic waves.

Answer 13

light as transverse electromagnetic wave whose oscillating electric and magnetic fields are perpendicular both to each other as well as to the direction that the light travels

Question 14

define state of polarization

Answer 14

elec­tric field oscillates perpendicularly to the direction of propagation

Question 15

Partial polarization,

Answer 15

mixture of unpolarized and polarized light (linear, circular, or elliptical).

Question 16

Fresnel showed

Answer 16

polarized component of reflected light tends to be linear, parallel to the interface.

Question 17

Reflected light is completely polarized if the angle of incidence equals

Answer 17

the Brewster angle

At the Brewster angle, all the reflected light is linearly polarized, but not all the linearly incident light is reflected.

Question 19

Visual acuity

Answer 19

cone photoreceptor has the ability to discriminate two objects in space subtended by an angle of 1 minute of arc at the nodal point of the eye