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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
RGB cones peak response is at
555 nm
26
Rods peak sensitivity is at
507 nm
27
Colored filters do what
Absorb/reflect some wavelengths that are incident upon it
28
Bandpass filters
Pass only a certain spectral band of light
29
Narrowband filters
Pass only a narrow spectral band of light
30
Broadband filters
Pass only a broader spectral band of light
31
Long pass filters
Transmit long wavelengths of light, but not shorter wavelenghts
32
Interference filters
Produce a very narrow band of light based on interference principle of light
33
Subtractive color mixtures filter
Color filters subtract light 2 filter combination in sequence transmits less light than either one by itself
34
Additive color mixtures filter
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
Neutral density filter
Transmits all wavelengths equally, and minimizing color distortion
36
ND filters are specified by their
Optical density (OD)
37
Optical density equation
OD= log(1/T) T fraction transmittance of the filter OD in log units
38
What are ND filters used for
Sunglasses (block UV) Minimize color distortion in patients with anomalous color vision
39
Using a ND with high OD will do what to transmission and absorption
Lower transmission | Greater absorption of light
40
An ND wth a low OD will do what to transmission and absorption
Higher transmission | Less absorption
41
T/F ocular tissues are vulnerable to UV radiation
True
42
Acute exposure to UVC can cause this in the eye
Solar keratitis
43
Chronic UV exposure can play a role in development of these
Pinguecula Pterygium Cataracts AMD

Perception (6 decks)

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