Apptech <apptech@paradise.net.nz> wrote:
> The "Batwing" LED radiation pattern has lobes either side of centre with
> increasing light intensity with angle, up to a limit, whereafter it falls
> off sharply.
> 
> I find this light distribution pattern extremely useful for certain
> applications, and it is not uncommon for lens makers to make lenses which
> provide a tight beam, using this pattern as input. But, it is inobvious
> what the motivation was for designing this pattern initially.
> 
> Can anyone provide an authoritative comment on this or, failing that,
> hazard any half likely guesses.

Even illumination of a flat surface -- in particular, backlighting?

I seem to recall that bare LED chips prefer to emit light from their edges
anyway, so creating a reflective cup in which to mount them that fine-tunes
this pattern is probably relatively easy.

-- Dave Tweed
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