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Team:Cambridge/References/ProjectBioluminescence/LightLevel
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Revision as of 10:27, 23 July 2010
Light Output
Increasing Light Emission
- [http://www.ncbi.nlm.nih.gov/pubmed/12234677 Paper on isolation of G-LRE and H-LRE, which lists previous attempts to improve light production]
- [http://www.ncbi.nlm.nih.gov/pubmed/10036167 Intensified light emission in presence of low ATP concentration by PPDK]
- [http://www.ncbi.nlm.nih.gov/pubmed/1332531 Enhanced luciferase activity through cytodine nucleotides]
- [http://www.ncbi.nlm.nih.gov/pubmed/12044905 Gene chimerisation to improve practical usefulness of firefly luciferase]
- [http://www.ncbi.nlm.nih.gov/pubmed/17540326 Genetically modified firefly luciferase - the EPIC luciferase]
Relevant Physics
- 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.
- The [http://en.wikipedia.org/wiki/Lumen_%28unit%29 lumen] is simply cd*sr. It is thus the analogue to the Watt
- 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
- The luminance of an object is how much light is emitted from it. This is also measured in Lux, but it is different contextually.
- A table of ambient illuminances. For our glowing bacteria to be seen from a given distance, they must be at least 1/20th of this value.
| Illuminance | Example |
|---|---|
| 10−5 lux | Light from Sirius, the brightest star in the night sky |
| 10−4 lux | Total starlight, overcast sky |
| 0.002 lux | Moonless clear night sky with airglow |
| 0.01 lux | Quarter moon |
| 0.27 lux | Full moon on a clear night |
| 1 lux | Full moon overhead at tropical latitude |
| 3.4 lux | Dark limit of civil twilight under a clear sky |
| 50 lux | Family living room |
| 80 lux | Hallway/toilet |
| 100 lux | Very dark overcast day |
| 320–500 lux | Office lighting |
| 400 lux | Sunrise or sunset on a clear day. |
| 1,000 lux | Overcast day |
| 10,000–25,000 lux | Full daylight (not direct sun) |
| 32,000–130,000 lux | Direct sunlight |
- A brief [http://en.wikipedia.org/wiki/Candela#SI_photometric_light_units summary] of the different luminous measures
- A [http://cvision.ucsd.edu/lumindex.htm site] containing luminosity functions
- To summarise, the luminosity function allows one to convert between radiant energy and luminous (i.e., visible) energy.
Human Vision
