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Perception > 9- Photometry > Flashcards

9- Photometry Flashcards

1
Q

Radiometry deals with

A

Power produced by a source of EM radiation

Does not take into account visibility of the source

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2
Q

Photometry deals with

A

Effect that radiation has on the visual system

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3
Q

Photopic luminosity curve describes

A

The sensitivity of the eye to different wavelengths

It is the difference between photometry and radiometry

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4
Q

Certain wavelengths are more efficient at stimulating the visual system then other wavelengths of light

A

Fact

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5
Q

Luminous power is

A

Total amount of light that emerges in ALL directions from the source

Lumen (lm)

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6
Q

Luminous intensity is

A

Light power produced in a GIVEN direction by poit source

Candela (cd)=1lm/str

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7
Q

Luminance is

A

The amount of light coming OFF a surface

Cd/m2, nit, apostilb

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8
Q

Illuminance is

A

The luminance power that falls ON a surface

Lm/m2, lux
Lm/ft2

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9
Q

Inverse square law states that

A

As a surface is moved away from from a point source, the number of lumens falling on it decreases with the square of the distance, decreasing the illumination

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10
Q

Inverse square law equation

A

E= I/d2

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11
Q

The amount of light relfected(brightness) is dependent on these 4 things

A
  1. How much light illuminates the source
  2. Distance from light source
  3. Reflectance of surface
  4. Tilt of the surface
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12
Q

Speculation reflector-

A

Reflects all the light in ONE direction

Surface looks shiny

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13
Q

Diffuse reflector

A

Scatters light in ALL directions

Surface looks matte or dull

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14
Q

Look at slides 18-20

A

Units

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15
Q

Retinal illumination is the

A

Amount of light falling on the retina

Trolands (Td)

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16
Q

Retinal illumination is directly proportional to these 2 things

A

Object luminance and pupil AREA

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17
Q

Retinal illuminance formula

A

Td= nits x mm2

=luminance of object area in nits x pupil area

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18
Q

As temperatures increases the peak wave ____

And the area under the curve(power) ____

A

Peak decreases

Power increases

19
Q

2,000 K sources appear yellow-white because

A

It has more energy in long wavelength region

20
Q

10,000 K source appears blue-white because

A

There is more energy in the short wavelength region

21
Q

The higher the color temperature (bluer color) the more_______

A

Light scatters and larger area of discomfort glare

22
Q

Higher color temperatures affects these 2 patients a lot

A

Presbyopia and cataract patients

23
Q

The peak luminance efficacy of photopic vision is

A

680 lu/W at 555

24
Q

The peak luminous efficacy of Scott pic vision is

A

1700 lu/W at 507 nm

25
Q

RGB cones peak response is at

A

555 nm

26
Q

Rods peak sensitivity is at

A

507 nm

27
Q

Colored filters do what

A

Absorb/reflect some wavelengths that are incident upon it

28
Q

Bandpass filters

A

Pass only a certain spectral band of light

29
Q

Narrowband filters

A

Pass only a narrow spectral band of light

30
Q

Broadband filters

A

Pass only a broader spectral band of light

31
Q

Long pass filters

A

Transmit long wavelengths of light, but not shorter wavelenghts

32
Q

Interference filters

A

Produce a very narrow band of light based on interference principle of light

33
Q

Subtractive color mixtures filter

A

Color filters subtract light

2 filter combination in sequence transmits less light than either one by itself

34
Q

Additive color mixtures filter

A

Light from different filters is added

Light is projected through 2 different color filters and combined on a screen

More light than either one by itself

35
Q

Neutral density filter

A

Transmits all wavelengths equally, and minimizing color distortion

36
Q

ND filters are specified by their

A

Optical density (OD)

37
Q

Optical density equation

A

OD= log(1/T)

T fraction transmittance of the filter

OD in log units

38
Q

What are ND filters used for

A

Sunglasses (block UV)

Minimize color distortion in patients with anomalous color vision

39
Q

Using a ND with high OD will do what to transmission and absorption

A

Lower transmission

Greater absorption of light

40
Q

An ND wth a low OD will do what to transmission and absorption

A

Higher transmission

Less absorption

41
Q

T/F ocular tissues are vulnerable to UV radiation

A

True

42
Q

Acute exposure to UVC can cause this in the eye

A

Solar keratitis

43
Q

Chronic UV exposure can play a role in development of these

A

Pinguecula
Pterygium
Cataracts
AMD

Perception (6 decks)

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