Re: how to get a crisp circle of light

On Mar 28, 4:39 pm, "Boxman" <box...@xxxxxxxxxxx> wrote:
On Mar 28, 12:36 pm, "Helpful person" <rrl...@xxxxxxxxx> wrote:

I understand the concept. In my experience designing these systems,
when you collimate the LED initially as suggested, the distribution of
light at the aperture plane will still be quite inhomogenous and when
you re-image the aperture you are imaging that inhomogenous
distribution. Generally if one wants to image an aperture plane and
get a very smooth distribution, the LED needs to be brought to a
"blurry" focus that removes the spatial structure of the LED. This
requires a more specialized surface than a traditional collimating
lens.


If the condensor lens is not a single element asphere but designed to
image a field the size of the source then then there should be very
little variation in illumination. However, this is often difficult to
do while collecting the full NA.

The best advice to the poster might be to buy an old projector on
Ebay, take it apart and copy the condenser / projector system.

Please visit my web site at www.richardfisher.com

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