LED surface brightness vs tungsten and HID

[LightForce]

Hi guys, What is the real LED surface brightness?

I don't really know how many cd/cm2 these modern LEDs die have in opposite of HID and halogen filament.

This parameter plays crucial role in throw values...
How to calculate it?

For example, XR-E LED which have 1x1mm die and 250 lm @ 1000mA.

Cheers!

 

[IMSabbel]

Basically, 1 candela means a radiation of one lumen per radian.
A point source with 1 candela would have 4Pi lumen thus.

Approximate a led as an lambertian radiator, and you would get something like 4-5 lumens per candela (very ballpark, there have to be some values somewhere for this case without integrating over the cosine angular dependence).

So lets assume 1mm^2 die area. and about 50 candela from the 200-250 lumens, this would mean about 50 million CD /m^2, which seems a bit on the high side.

But on the other hand, some TVs have up to 1000 cd/m^2, while a single die hurt your eyes to look at, so it might be right...

Ah, noticed that those values in your graphs are per cm^2. Thus the led would be at about 5000.

 

[LightForce]

Thanks for explanation! I wonder what is the exact candela/lumen figure for lambertian light source.