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 | | From: | Alain Riaud | | Subject: | Very Basic Question | | Date: | Sat, 8 Jan 2005 08:16:49 +0100 |
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 | Hi All of you,
I'm looking for a page explaining clearly the relationship betweem optical
mw,lumen, candela, lux, steradian, in order to compare the "light flux"
hitting a plane lit by different brands of LEDS.
Depending on manufacturers light power is measured in mcd, lumen,mw, angles.
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| | From: | Ian Stirling | | Subject: | Re: Very Basic Question | | Date: | 08 Jan 2005 15:03:57 GMT |
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| Alain Riaud wrote:
> Hi All of you,
>
> I'm looking for a page explaining clearly the relationship betweem optical
> mw,lumen, candela, lux, steradian, in order to compare the "light flux"
> hitting a plane lit by different brands of LEDS.
>
> Depending on manufacturers light power is measured in mcd, lumen,mw, angles.
Radiometry and photometry in astronomy
http://www.stjarnhimlen.se/comp/radfaq.html
May be of some use.
In short.
mW is actual power out.
Lux is a lumen per square meter.
There are a variable (500 green, 100 red, 300 blue (ROUGHLY!)) numeber of
lumens per watt, depending on how visible it is. Two lights of different colour
and the same number of lumens appear as bright.
A steradian is a beam of light covering 1/4pi of a sphere.
A candela is a unit of brightness, 1 lumen per steradian.
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