lecture 4 photometry

Question 1

name the 2 ways one can quantify light

Answer 1

photometry and radiometry

Question 2

photometry is the measurement of _____ _____

Answer 2

visible light

Question 3

radiometry is the measurement of ____ _____ from ____ to ____

Answer 3

optical radiation, infrared to UV

Question 4

cd/m2 (or foot-lambert) are the units of…

Answer 4

luminance (Lv) aka nits (luminous intensity per unit projected area of an extended source)

Question 5

lm/m2 is the units of…

Answer 5

illuminance (Ev) aka lux (luminous power on a surface)

Question 6

a steradian is a ____ from a ____

Answer 6

cone, sphere

Question 7

radiometric equivalence of luminance (luminous intensity per unit projected area of an extended source) is…

Answer 7

radiance (W/sr/m2)

Question 8

radiometric equivalence of illuminance (luminous power on a surface) is…

Answer 8

irradiance (W/m2)

Question 9

a lumen is a unit of…

Answer 9

luminous power (lm)

Question 10

a candela is a unit of….

Answer 10

luminous intensity (lm/sr) or cd

Question 11

radiometric equivalence of luminous power (total light from a source) is….

Answer 11

radiant power (J/s) or W

Question 12

radiometric equivalence of luminous intensity (light produced in a solid angle by a point source) is…

Answer 12

radiant intensity (W/sr)

Question 13

lm/W is the unit for

Answer 13

luminous efficiency (how efficient our vision system is at detecting a source of a given luminous power

Question 14

____lm/W is the number of lumens per watt that is maximally absorbed by the photopic system

Answer 14

683 lm/W

Question 15

____lm/W is the number of lumens per watts that is maximally absorbed by the scotopic system

Answer 15

1700 lm/W

Question 16

on a graph of luminous effciency vs wavelength (nm) you are given 10 watts @500nm, 500nm corresponds with 0.4 on the luminous efficiency axis, what are lumens?

Answer 16

lumens=(lum eff)(683 lm/W)(W)….lumens = 0.4 x 683 x 10=2732 lumens

Question 17

What law describes adding all lumens from all wavelengths to get the total

Answer 17

Abneys law of additivity…. (scotopic and photopic can also add together)

Question 18

true or false: luminance is the same as brightness

Answer 18

false, brightness is percieved and can be percieved differently.

Question 19

true or false: an example of illuminance is the lit part of a table where a flashlight is shining

Answer 19

true

Question 20

true or false: an example of luminance is the light in motion moving away from its source

Answer 20

true

Question 21

which law describes: the energy twice as far from a source is spread over 4 times the area, reducing intensity by 4 times

Answer 21

the inverse square law..(also if you move 3 times as far the intensity reduces by 9 times)

Question 22

true or false: a troland (td) is is a unit of measurement equivalent to luminous intensity (cd) incident on the pupil

Answer 22

true

Question 23

in additive color mixing, blue + green + red make…

Answer 23

white

Question 24

in subtractive color mixing, cyan + magenta + yellow make….

Answer 24

black

Question 25

in subtractive color mixing, cyan + yellow=____, cyan + magenta =_____, magenta + yellow=____

Answer 25

green, blue, red

Question 26

in additive color mixing, red + blue=____, green + blue=___, red + green=____

Answer 26

magenta, cyan, yellow

Question 27

what kind of filter would I use if I wanted to isolate a light between 510nm and 530nm?

Answer 27

a bandpass filter

Question 28

What kind of filter would I use if I wanted to block 10% of light equally across the spectrum?

Answer 28

neutral density filter

Question 29

what kind of filter would I use if I wanted to filter out infrared light?

Answer 29

IR filter

Question 30

What kind of filter would I use if I wanted to allow everything below infrared to pass thru?

Answer 30

a cut filter

Question 31

what kind of filter would I use if I wanted to allow long wavelengths of light thru but not short wavelengths?

Answer 31

a longpass filter

Question 32

The cornea and lens work together to create what kind of filter?

Answer 32

a longpass filter to filter out UV