L1-L10 Foundation of Optics

what is the angle of incidence

where light is travelling from

where can angle of incidence travel from

infinity or a point source

what is angle of refraction

where light has travelled to

how does light travel in 90 degrees

undeviated

how does light bend from a lower to higher medium

deviate towards the normal

how does light deviate in a higher to lower medium

deviate away from the normal

what is a shadow

primitive image based on light blocked by an object

what is shadows based on

simple geometry

what is the formula for shadow size

d/x=h/y

what is an umbra

uniformly dark region of shadow (object blocks all regions of an extended source)

what is a prenumbra

region of shadow where light is partially blocked (gradually gets brighter towards edges)

how are objects seen through pinholes

equally in focus at all distances

name problems with pinholes

too small and not enough light will pass through, light bends slightly at edges, too large and pinhole acts as an extended source

what are pinhole occluders used for

check of a refractive correction and to rule out non refractive vision loss

what is refractive index

property of an optical medium equal to the velocity of light in a vacuum relative to the velocity in the medium

velocity of light in a vacuum

3 × 10^8

velocity in optical medium

V= c/n

what does snells law state

for a ray of light passing from one medium to a medium of a higher refractive index, the ratio of the sin of the angle of incidence to the sin of the angle of refraction is equal to the ratio of refractive indices of the two media

lateral displacement

perpendicular distance between the point where a ray of light enters a medium and the point where it exits the medium

critical angle meaning

the angle of incidence which gives rise to an angle of refraction of 90 degrees

what happens when the angle of incidence equals the critical angle

angle of refraction is 90 degrees

total internal reflection definition

when the angle of incidence exceeds the critical angle and light is reflected at the interface

what is a prism

piece of optical material whose surfaces are plane but not parallel

prims always change the ______ of light ________________

prisms always change the direction of light even when the indices on either side of the prism are the same

what 2 things does a prism have

base and an apex

the angle formed by the plane surface at the apex

apical angle

equation for angle of deviation

d= d1+d2

equation for d1

i1-i1’

equation for d2

i2’-i2

reflecting prisms are usually ?

silvered

when a prism is not silvered, the reflection occurs when?

i2’ > ic

opthalmic fresnel prisms

small rows of equally powered prisms

vergence

curvature of the wavefront

what is the vergence of the wavefront determined by

1. distance from point of interest to source

   1. refractive index of medium in which rays are travelling

-ve vergence = rays ______?

diverge

+ve vergence = rays ______?

converge

convex surfaces cause?

convergence

concave surfaces cause?

divergence

hyperbolic surfaces focus at?

single point

marginal rays are refracted more than those near the vertex, so light is focussed by?

spherical surfaces in a ‘caustic curve’

rays of spherical surfaces are assumed emerge as ?

spherical wavefronts that focus at a single point

if P is close to A, then ?

i and i’ are small angles

what is power classified as

amount of change in vergence that occurs at a refracting surface

refraction is assumed to occur?

in one plane

differences in refractive index for light of different frequencies are?

ignored

is F positive or negative in convex lenses

positive

simple lens

optical system with 2 refracting surfaces

thin lens

simple lens with a thickness that is negligible relative to the other distances involved

how can simple lenses be classified as

surface type and lens form

describe convex lens

positive + converging lenses, thicker in middle

describe concave lenses

negative + diverging

the image created by the first surface is the object for the ____ ______?

second surface

thin lens systems have at least?

2 lenses with negligible thickness BUT the separation between the lenses is significant

thick lenses/thick lens systems have at least?

2 optical surfaces that are seperated by a significant thickness

coaxial systems ?

al optical surfaces in the system share the same optical axis