Diffusing LED Light

Check out lenses for the Luxeon range of LEDs, there may be something suitable

martin

Sand the acrylic tube

f

se

y

A) try wider angle LEDs, which may be sufficient

B) diffusing, when necessary, is generally done in 1 of 3 ways:

1) milky diffusing scattering media has high losses, since usuall less than 50% of emitted light is transmitted, and angular coverage is generally 180 degrees, which is often too wide 2) prismatic forward scattering uses transparent (not milky) material to scatter light and disorganize the LED chip image....usually the best option if you must diffuse...look for thin sheets of material with tiny pyramids on 1 or both surfaces 3) secondary condenser lens forms collimated beam with almost uniform brightness...highest performance alternative if you want relatively narrow angular coverage Paul Mathews

I suggest experimenting with the degree of diffusion you want, first. You can get artist's matte spray, which might be enough all by itself, but then again it might not, and then you have to get it off your plastic tube. Maybe try putting some Saran wrap over top before trying stuff.

Cheers,

Phil Hobbs

On the HomeBrew list, someone suggested sanding off the lenses of the LEDs to diffuse them.

Sanding is what worked for me. I sanded clear led's. I first cut one flat, but that was not needed.

greg

Try sanding the ends of the LEDs. Perhaps start by experimenting with one, rather than messing with your whole array. By altering the shape and surface polish of the epoxy "lens" you can do all sorts of things to the pattern of the light out.

Any diffuser (such as matte drafting film, which would be a good choice among that type of material) will cut down the light output as well as diffusing it, so if you can get a good result without doing that, you'll be better off.

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Cats, coffee, chocolate...vices to live by

f

If it's a thickwall tube (or maybe you can convert to a rod?) you can cement the LEDs to the ends and drive it as a light pipe.

Any flaw in the tube surface will glow; just apply sandpaper to get a uniform light output. You could also apply a milky paint coating to the tube's (inner or outer) surface.

snipped-for-privacy@zekfrivolous.com (GregS) wrote in news:fqmum8$aon$ snipped-for-privacy@usenet01.srv.cis.pitt.edu:

I'd use a rubbing compound,not sandpaper; you want just a translucent finish.

Maybe that 8000 grit SiC wet/dry paper would work,with water lube.

Inside the tube,you could push a swab coated with compound thru it,then rinse out. you could use the cleaning rod and swabs from a rifle cleaning kit.

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Jim Yanik
jyanik
at
kua.net

Use SMD LEDs instead. They do not have any "lens" projection effect, usually just the led chip in a sort of miniature bowl.

1/10" square experimenter PCB is very convenient to hand solder smt leds and / or resistors (0805 works best).

RGB SMD leds are getting cheaper too - mix the color to suit your mood :-)

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 - René

I have attemted to use the white semi-opaque plastic shheting that also has a rough surface and still had that problem. I wound up using that only putting a reflector on thesubject-side surface and used the light from the edges - "useable" is the best i can say for that idea. Probably steal an idea from photography and shine the light to a white umbrella (parabola or close approx) that reflects light to the object of interest.

Insufficent.

Insufficent.

It helps some, but the light is still "spotty" (brighter in front of each LED even at a few feet).

*That* is a much superior idea.

Perhaps turn the LEDs around so they point out the back and have the light reflect off the back of the tube, plus add your diffuser of choice if needed.

Dave.

I saw some one do this with "holographic diffusion film" - don't know who makes it or where it came from. Look at the LED line generator in an old fax machine - maybe some ideas there?

Maybe use edge lights like this

martin

These are available at:

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Regards,

John Popelish