Computing total illumination from an LED

[Ken]

How does one convert from "brightness", size of LED and viewing angle
to total illumination?

For example, one white LED is 3mm, has a "luminous intensity" of 700
mcd and a viewing angle of 40 degrees.

Another white LED is 5mm, has a luminous intensity of 10,000 MCD and a
viewing angle of 10 degrees.

They both have forward voltage of 3.2-3.6 volts and draw 20 ma.

How do they compare as far as total light emitted?


Ken
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[Dr Engelbert Buxbaum]

Ken wrote:

How does one convert from "brightness", size of LED and viewing angle
to total illumination?

For example, one white LED is 3mm, has a "luminous intensity" of 700
mcd and a viewing angle of 40 degrees.

Another white LED is 5mm, has a luminous intensity of 10,000 MCD and a
viewing angle of 10 degrees.

They both have forward voltage of 3.2-3.6 volts and draw 20 ma.

How do they compare as far as total light emitted?

There was a paper on that subject in Elector, October 2003, page 18-23