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B9 PERCEPTION > Photometry Radiometry > Flashcards

Photometry Radiometry Flashcards

1
Q

Radiometry:

A

Power produced by source of EM radiation (Objective)

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2
Q

Photometry:

A

Effect that the radiation has on the visual system (Subjective)

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3
Q

Luminous power:

A

total amount of light that emerges in all directions from the source (unit: lumen lm)

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4
Q

Luminous intensity

A

light power produced in a given direction by a point source (unit Candela (cd)= 1 lumen/steradian)

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5
Q

Luminance

A

amt of light coming off a surface in a specific direction (Candela/m^2 or nit or apostalib) (e.g. TV)

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6
Q

Illuminance:

A

luminous power that falls on a surface. (lumens/m^2 or lux) (e.g. Projector screen)

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7
Q

Specular reflector:

A

reflects all light in one direction (e.g. mirror)

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8
Q

Diffuse reflector:

A

scatters reflected light in all directions (e.g. matte paint)

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9
Q

Black body:

White body:

A

absorbs all light

reflects all energy

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10
Q

Bandpass filter:

A

filter that passes only a certain specified spectral band of light

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11
Q

Narrowband filters:

A

A filter that passes only a narrow spectral band of light

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12
Q

Broadband filters:

A

A filter that passes only a broader spectral band of light

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13
Q

Long-pass filters:

A

filter that transmits long wavelengths of light, but not shorter wavelengths.

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14
Q

Interference filters:

A

very narrow band of light based on interference principle of light

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15
Q

4 criterions for luminous intensity with diff surfaces:

A 
DIRT
Distance from light source
Illuminates the surface (how much light)
Reflectance of the surface
Tilt of the surface relative to your line of sight
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16
Q

100% lambertian surface:

A

1 lux on gives 1/π nits (0.318) off
1 lux on 1 apostilb off
1 apostilb= 1/π candelas/m^2= 1/π nits

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17
Q

Grey lambertian surface=

A

reflects 50% of light

1 lux on 0.5 apostilb off

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18
Q

Retinal illuminance=

A

trolands (Td) is proportional to object luminance and pupil area (not diameter)

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19
Q

Optimal light sensitivity for photopic conditions: ???
Peak luminous efficiency of photopic vision is: ???
Optimal light sensitivity for scotopic conditions: ????
Peak luminous efficiency of scotopic vision is: ????

A

Optimal light sensitivity for photopic conditions: 555 nm
Peak luminous efficiency of photopic vision is: 680 lu/W
Optimal light sensitivity for scotopic conditions: 507 nm
Peak luminous efficiency of scotopic vision is: 1700 lu/W

20
Q

UVC:

A

UV cornea pain, solar keratitis

21
Q

Luminous efficiency equation

A

Luminous efficiency= luminous eff680Watts

22
Q

Inverse square law

A

E=I/d^2 (E=illumination, I=intensity of point source, d= distance from point source to surface)

23
Q

Td

A

Td= (luminance of object in nits) * (pupil area in mm^2)

24
Q

Area of circle=

A

Area of circle= πr^2

25
Q

Eye is more sensitive to what color light?

A

Green 550 nm

26
Q

What is the luminous efficiency at 400 nm? given a graph

A

=0 (get from graph given)* (680/W)* 10W

=0 lumens

27
Q

What is the luminous efficiency at 600 nm?

A

= 0.62 (get from graph given)* (680/W)*10W

=4216 lumens

28
Q

Luminous efficiency:

A

how many lumens a certain light source produces per Watt

29
Q

We see better or worse with LEDs at night? what is a disadvantage of LEDs

A

Better
Disadvantage: 3 times more scattering at 465 nm than at 600 nm
(decreased wavelength increases rayleigh scattering) which causes discomfort glare for presbyopes and cataract pts

30
Q

RGB cones respond from ________nm with peak response at ____nm.

A

400-700nm

peak: 555nm

31
Q

Rods respond from _______nm, with peak sensitivity at _____nm.

A

400-600nm

peak: 507nm

32
Q

Peak luminous efficacy of photopic vision is _______ at peak response of _____nm.

A

680 lu/W

555nm

33
Q

Peak luminous efficacy of Scotopic vision is __________ at peak response of _____nm

A

1700 lu/W

507nm

34
Q

A _____________ filter transmits all wavelengths equally, and minimizes color distortion.

A

Neutral density (ND)

35
Q

Optical density equation

A

OD= log(1/T)
or
OD=log10(1/T)

36
Q 
TP
A source of which of the following color temperatures will appear most red?
A. 2000K
B. 3000K
C. 5000K
D. 10000K
A

A. 2000K

37
Q

TP

The color temp of an incandescent bulb is 3300K. This means that:

A

The bulb’s spectral distribution matches that of a blackbody radiator whose temp is 3300 K.

38
Q

TP
A ND filter transmits 50% of 450nm light that is incident upon it. If 40 W of 550 nm are incident on the filter, how many watts are transmitted?

A

20 W

39
Q

TP

Which of the following light sources has more energy concentrated in the blue region of the spectrum?

A

LEDs

40
Q

TP
A stimulus consisting of 10W (power) of 400nm produces zero lumens of light, whereas a 10-W stimulus of 600nm produces 4216 lumens.

A

Radiometrically Equal and Photometrically Unequal

41
Q

TP

One candela is equal to:

A

1 lumen/ m^2

42
Q

TP

Appropriate units for luminous power, illuminance, and luminance are:

A

Lumens, candelas/m^2, lumens/m^2

43
Q

TP
You are asked to determine if the lighting conditions in the classroom are adequate. The lighting conditions are specified in which units?

A

Candelas/m^2

44
Q

TP
When measured at an angle of 10 degrees to its surface a matte surface has a luminance of 50 foot lamberts. What is the luminance when measured 20 degrees from the surface?

A

50 foot-lamberts

45
Q

TP:

As a surface is moved away from a light source, the illumination of the surface:

A

Decreases

46
Q

TP

As the object in view moves farther from the eye, the retinal illuminance:

A

Remains constant

B9 PERCEPTION (4 decks)

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