Hi everyone,
I’m stuck on the same problem from few days. So I’m asking for your help…
The aim is to calculate the theorical irradiance distribution of a UV led on surface at a typical distance form this UV source.
(Unfortunately UV LED are not an isotropic source)

For example, let say:
- Radiant Flux Φe=20mW
- Viewing Angle θ1/2=60°
With the following radiation Characteristics


At a distance “d” from this source, how can I calculate the irradiance of a surface defined by the radius “r” ?


Then, with different radius, it gonna be easy to show the distribution, like the following on for example:



thank you !

 

From your picture, i think that for angles less than 30 degree (or -30) most part of all radiation that leaved the diode is now distributed in the shadowed circle or radius r you draw. From the graph, i would say that the rectangular region of 6x10 squares contains radiation emitted under those angles. At the sides of it, i see two 5x10 left and right triangle areas, that add another 2x(5x10/2) = 50 squares.
If you had 20mW for all directions, i think 20x( 60/(50+60)) = 11mW go to the circle for which radius r and distance d relate in such a form that: tan 30° = r/d = 0.57.
As a rough stimation, now you can divide 11mW by pi*r^2 to obtain mW/m2 on it.
But in fact...you should weight that at each point by a cosine angle that vary on the circle surface and sum on each angle...ie,an integral.