Are LEDs inherently directional?

No. One way for a manufacturer to boost the luminous intensity spec (usually given in candelas or millicandelas) is to focus the beam more tightly. The same light flux, focused into a tighter beam, will give a higher luminous intensity spec. So indicator LEDs with 10 degree beam width are popular now, in part because they have higher specs compared to the same LED packaged to have a 30 or 70 degree beam width. It’s more common to see illumination-grade LEDs rated in lumens, which doesn’t take into account the focusing of the beam.

Arrays built from narrowly focused LEDs will be narrowly focused; arrays built from other beam distributions will exhibit the beam distribution of their component LEDs. Narrow-beam LEDs and arrays can lose apparent impact when viewed slightly off-axis.


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