Team:Cambridge/References/ProjectBioluminescence/LightLevel

From 2010.igem.org

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==Relevant Physics==
==Relevant Physics==
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*The [http://en.wikipedia.org/wiki/Candela Candela] measures how much light is being emitted by a source of radiation. It is related to [http://en.wikipedia.org/wiki/Radient_intensity Radient intensity] (which is measured in watts per steradian) but has been weighted by a [http://en.wikipedia.org/wiki/Luminosity_function Luminosity function]. This alters the power output so that it is proportional to the sensitivity of the human eye.
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*The [http://en.wikipedia.org/wiki/Candela Candela] measures how much light perceivable to the human eye is being emitted by a source of radiation, the Luminous Intensity (or luminous flux. It is related to [http://en.wikipedia.org/wiki/Radient_intensity Radiant intensity] (or radiant flux) (which is measured in watts per steradian) but has been weighted by a [http://en.wikipedia.org/wiki/Luminosity_function Luminosity function]. This alters the power output so that it is proportional to the sensitivity of the human eye: [http://en.wikipedia.or/wiki/Candela#Explanation Definition] of the candela with respect to Radiant intensity. Therefore, an object which is black may be emitting a lot of radiation (measured in watts per steradian) but since it is not perceivable to the human eye it is emitting 0cd of radiation.
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*The [http://en.wikipedia.org/wiki/Lumen_%28unit%29 lumen] is simply cd*sr. It is thus the analogue to the Watt
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*The [http://en.wikipedia.org/wiki/Lux Lux] measures how much light is incident on a suface, the Illuminance. It is related to irradiance (measured in Watts per m^2) but has been weighted again by the luminosity function. 1lux=1cd/m^2
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*The luminance of an object is how much light is emitted from it. This is also measured in Lux, but it is different contextually.
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{| class="wikitable"
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!Illuminance!!Example
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|-
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|10<sup>−5</sup> lux ||Light from [[Sirius]], the brightest star in the night sky
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|-
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|10<sup>−4</sup> lux||Total [[star#Radiation|starlight]], overcast sky
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|-
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|0.002 lux||Moonless clear night sky with [[airglow]]
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|-
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|0.01 lux||Quarter moon
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|-
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|0.27 lux||Full moon on a clear night
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|-
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|1 lux||Full moon overhead at tropical [[latitude]]
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|-
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|3.4 lux|| Dark limit of civil [[twilight]] under a clear sky
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|-
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|50 lux||Family living room
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|-
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|80 lux||Hallway/toilet
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|-
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|100 lux ||Very dark overcast day
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|-
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|320–500 lux || Office lighting
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|-
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|400 lux ||[[Sunrise]] or [[sunset]] on a clear day.
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|-
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|1,000 lux||Overcast day
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|-
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|10,000–25,000 lux ||Full [[daylight]] (not direct sun)
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|-
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|32,000–130,000 lux||Direct [[sunlight]]
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|}
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==Human Vision==
==Human Vision==

Revision as of 16:17, 22 July 2010

Contents

Light Output

Increasing Light Emission

Relevant Physics

  • The Candela measures how much light perceivable to the human eye is being emitted by a source of radiation, the Luminous Intensity (or luminous flux. It is related to Radiant intensity (or radiant flux) (which is measured in watts per steradian) but has been weighted by a Luminosity function. This alters the power output so that it is proportional to the sensitivity of the human eye: Definition of the candela with respect to Radiant intensity. Therefore, an object which is black may be emitting a lot of radiation (measured in watts per steradian) but since it is not perceivable to the human eye it is emitting 0cd of radiation.
  • The lumen is simply cd*sr. It is thus the analogue to the Watt
  • The Lux measures how much light is incident on a suface, the Illuminance. It is related to irradiance (measured in Watts per m^2) but has been weighted again by the luminosity function. 1lux=1cd/m^2
  • The luminance of an object is how much light is emitted from it. This is also measured in Lux, but it is different contextually.


IlluminanceExample
10−5 lux Light from Sirius, the brightest star in the night sky
10−4 luxTotal starlight, overcast sky
0.002 luxMoonless clear night sky with airglow
0.01 luxQuarter moon
0.27 luxFull moon on a clear night
1 luxFull moon overhead at tropical latitude
3.4 lux Dark limit of civil twilight under a clear sky
50 luxFamily living room
80 luxHallway/toilet
100 lux Very dark overcast day
320–500 lux Office lighting
400 lux Sunrise or sunset on a clear day.
1,000 luxOvercast day
10,000–25,000 lux Full daylight (not direct sun)
32,000–130,000 luxDirect sunlight



Human Vision

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