Transmission, Reflection, and Absorption of Light

Question 1

what is a filter

Answer 1

an optical element that alters the intensity and or the spectral distribution of light passing through it
intensity

Question 2

where does reflection and absorption take place at of the filter

Answer 2

reflection takes place at the surface of the filter
absoroption takes place in the body of the filter (can occur at the surface if it is coated w/ an electrically conductive material such as metal)

Question 3

how does absorption happen w/in glass and plastic

are they thickness dependent?

Answer 3

glass: absorber distributed throughout the body of the filter resulting in thickness dependence
plastic: absorber while still inside the material is confined to a thing layer near the surface and is not dependent on thickness

Question 4

when is thickness important to a filter

Answer 4

when the filter is bulk tinted

-tint distributed throughout the body

Question 5

what are surface tinted lenses

Answer 5

plastic lenses for ex that deposits tint in a thin layer near the surface which is independent of the thickness of the lens

Question 6

what is T12 a property of

Answer 6

surface only, doesn’t change w/ thickness

Question 7

what are photochromatic lenses

how do they work

Answer 7

lenses whose color changes in response to light exposure

• lenses darken by a change in bulk transmittance in response to UV light
• surface transmittance NOT affected

Question 8

how is bulk transmittance affected when photochromatic lesnes darken? lighten?

Answer 8

when leneses darken bulk transmisttace decreases and then increaes when the lesnes fade

Question 9

for plus lenses, where is the tint the darkest

Answer 9

darkest at the center

Question 10

how is tint affected in glass photochrom lesnes

Answer 10

since tint is distributed throughout the body, the tint is darker where the lens is thicker

Question 11

what is the optical density the unit to speificy for

Answer 11

external transmittance of filters when 2 or more are to be used in serioes

Question 12

when filters are in series, how are their densities changed

Answer 12

their densities add

Question 13

what are optical fibers, when are they used

Answer 13

optical fibers are long glass strands that are used in transmission of info over great distances
-very thick filter which has an extrememly high TB

Question 14

what is an optical fiber system that brings you tv and internet

Answer 14

verizon FIOS

Question 15

what is disability glare and discomfort glare

Answer 15

disability glare: stray light falling on the retina that may come from an external source or arise by scattering w/in the eye
ex. snow, sky overcast w/ thin clouds, catarct
discomfort glare: bright source in the line of sight like driving

Question 16

what does sunglass’s amoutn of reduction depend on

Answer 16

1. the ambient light intensity

2. age

Question 17

who needs darker sunlgasses, who needs lighter ones

Answer 17

darker: people on snow, esp at high altitudes
lighter: ppl w/ cataracts and reitnal compromise

Question 18

what do polarized sunglasses do

Answer 18

discriminate light that is reflected from horiz surfaces
like roads and water, NOT snow
-brings down overall transmittance to 15%, can’t be made w/ transmittance greater than 50%

Question 19

what are some examples of LED displays

Answer 19

aircraft instrumentation
bicycle instruments
instruments in cars

Question 20

what do yellow filters do

what do blue blockers do

Answer 20

yellow filters darken the sky, useful for aircraft pilots and sport shotting

blue blocker reduces blue light
-doesnt change color values, darkens sky, reduce haze