Where are all the Fresnel lenses?

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zerodish
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Where are all the Fresnel lenses?

This has been brought up before but I think it is time to bring it up again because of the invention of COB. The bigger emitter you have the harder it is to focus. The problem has been addressed before. Scientists who were trying to focus the suns light into a smaller spot to produce more heat ran into this problem. They solved the problem by designing a lens that did this but the sun was no longer in focus. This is a problem if you are trying to view sun spots but not if you are trying to produce a smaller spot. I will never be able to find the original article which was likely in Science News. So we know the problem can be solved. I’m not trying to make a laser out of COBs I just want a light that has a good throw at high power. The Fresnel lens would have to be close to the emitter. It would then have to pass through other lenses to collimate it.

alpg88
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Fresnel is no different than regular lens optical wise, it’s only advantage is its size.

Edmund optics has them as well as amazon and ebay. focusing large cob is not an easy task, nor it makes sense, since you can do it a lot easier with small die led, that is why you do not see it used a lot. ledil seanna lens uses Fresnel, it can do 1* with xp size led, but it wont work with cob.

Unheard
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But to answer the question: One of them is in front of a TrustFire MC1.

Smile, you cannot kill them all.

Scotty321
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I think the AB L18 also uses a fresnel lens… but the L19 has more throw, and neither uses a COB.

Unheard
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Yeah, as alpg88 pointed out, it is just a space saving lens. No advantage for large emitters.

The MC1 has an interesting cone shaped spot profile. Not sure why that is. Not bad, just unusual.

Smile, you cannot kill them all.

warzi1975
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Alonefire X40 has also a fresnel lens.

Robert

MascaratumB
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Brinyte T28 Artemis! (zoomable flashlight)

dthrckt
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MascaratumB wrote:
Brinyte T28 Artemis! (zoomable flashlight)

I had never heard of this. Just watched some reviews. If I didn’t have a maxtoch la60 coming this week I would definitely buy one. So unique!

warzi1975
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HaikeLite HT08 is also a fresnel zoomie.

Robert