Radiometry/ Photometry Flashcards

1
Q

visual acuity testing is specified to have a minimum chart luminance of ______

A

85 cd/m^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is radiometry?

A

the science of the measurement of electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is photometry?

A

the science of the measurement of the eye’s response to (or perception of) electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the total power output of a light source measured in watts (joules/second)

A

radiant flux (aka radiant power)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

units of radiant flux (radiant power)

A

Watts (Joules/Second)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the power output of a point (light) source in a given direction (solid angle), measured in watts/steradian

A

Radiant Intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

units of radiant intensity

A

watts/steradian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

a sphere contains how many steradians

A

4 pi steradians

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the radiant intensity per unit projected area of an extended source, measured in watts/ square meter steradian

A

radiance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

units of radiance

A

watts / square meter steradian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the radiant flux incident on an object’s surface, measured in watts/ square meter

A

irradiance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

units of irradiance

A

watts/ square meter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the energy received per unit area of irradiated surface, measured in J/m^2

A

radiant exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

UV exposure limit

A

0.003 J/cm^2

in a day for cornea/skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

visible light exposure limit

A

3 J/cm^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

IR exposure limit

A

3000 J/cm^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the total power output of a light source, measured in lumens

A

luminous flux (luminous power)

18
Q

a ____ nm light is the ‘brightest’

19
Q

peak for scotopic conditions is _____ nm

20
Q

why is 555 nm light the ‘brightest’?

A

it has the most ‘luminosity’ or highest luminous efficiency for photopic conditions

21
Q

there are ___ lumens per watt at 555nm

A

683 lumens/watt

22
Q

for scotopic functions, ____ lumens/watt at 507nm

A

1700 lumens/watt

23
Q

what is the power output of a point light source in a given direction (solid angle), measured in lumens/steradian

A

luminous intensity

24
Q

units of luminous intensity

A

lumens/ steradian

candela, cd

25
what is the luminous intensity per unit projected area of an extended source, measured in candelas/ square meter
luminance
26
units of luminance
- candelas/ square meter - nit - foot-lambert (fL)
27
10^-6 to 10^-1 cd/m^2 is for ______ vision
scotopic
28
10^-1 to 10^1 cd/m^2 is for _______ vision
mesopic
29
10^1 to 10^7 cd/m^2 is for _______ vision
photopic
30
the eye operates over a tremendous range of light levels, about ___ log units
12 log units
31
what is luminous flux incident on an object's surface, measured in lumens/square meter (lux)
illuminance
32
units of illuminance
- lumens/ square meter - lux - lumens/ square foot (ft-cd)
33
1 fL = ___ cd/m^2
3.43
34
1 fc = _____ lux
10.76
35
_____ is defined (arbitrarily) as an amount of light getting into the eye
retinal illuminance
36
units of retinal illuminance
trolands (td)
37
formula for retinal illuminance calculations
trolands = luminance (cd/m^2) x pupil area (mm^2)
38
what is a special kind of surface whose luminance does not vary with the angle at which it is viewed
- lambertian diffuser | - cosine diffuser, perfect diffuser
39
how does luminous intensity change with distance?
it does not change with distance
40
how does luminance change with distance?
luminance does not change with distance
41
how does luminance of an extended source change with viewing distance?
it doesn't | brightness constancy
42
how does luminance of an extended source change with viewing distance? (for the same angular subtense of view)
the viewed area (projected area) of the stimulus decreases (linear dimensions) at sorted distances