Country: Sri Lanka
What device is used to measure light
I believe that when you said "light concentration", you meant "light
intensity", or simply, "brightness".
Light intensity is measured in units called "Lux", and measured using a
Lux meter. This does not measure the total amount of light being
emitted over a large area by a light source, but simply the intensity (or
brightness) at any selected point.
The so-called "light meter" that is often built into higher quality film
cameras, is a simplified Lux meter and measures the relative inensity
of light in order to allow you to set the correct exposure.
A photometer is used -- although "light concentration" is not a
standard scientific term. Typically intensity and flux are the terms
used. There are plenty of good resources on the Internet for more
Hope this helps,
This URL explains light measurement terminology and how the terms are
defined. The terms are candle-power, lumens, radiance and illuminance.
Light meters are used to measure the concentration of light. This is quite
a common tool for photographers so there are many light meters on the
I "Googled" "Lumen Meter" and you can find many products.
Here is a hand-held meter that reports out lux or foot candles:
Here is a cheaper version:
You can also find other meters, perhaps cheaper, by "Googling" "Light
You can find the Google search engine at http://www.google.com
So there you are. Good luck.
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Update: June 2012