How to specify/order aspheric lenses
How to specify/order aspheric lenses
(OP)
I want to order some aspherical lenses to use with focusing the light output from a single LED. I am not familiar with optics and I would like to know how to calculate the needed specifications so I can order from an optics supplier.
Is there some sort of formula that I can use?
Is there some sort of formula that I can use?





RE: How to specify/order aspheric lenses
Dan - Owner

http://www.Hi-TecDesigns.com
RE: How to specify/order aspheric lenses
This is a link to a paper on secondary optics design for LEDs and includes lenses (it comes up short of aspheres though):
C:\Documents and Settings\All Users\Documents\Reference Docs\LEDs & Lightpipes\Secondary Optics for SuperFlux LEDs.pdf
This is a link to anthother site that does cover aspheres although for use with Laser Diodes. It's not a big leap:
h
If you care to post the LED you are planning to use and what you are trying to do with it perhaps you will get more specific recommendations.
Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600
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RE: How to specify/order aspheric lenses
I'll try again:
http://www.philipslumileds.com/pdfs/AB20-5.PDF
Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600
www.lumenflow.com
RE: How to specify/order aspheric lenses
What I want to do is focus the light from a Cree XP-E LED
http://www.cree.com/products/pdf/XLampXP-E.pdf
Through a 12.7mm lens (11mm opening) mounted 2mm from the base of the LED. I want to produce approximately an 8 degree beam that does not project the square shape of the die. Something similar to the beam in the following picture.
http://www.expandku.com/smooth.jpg
I am looking for a thin assembly as opposed to a thicker reflector system. Perhaps a Fresnel lens.
Any help would be deeply appreciated.
RE: How to specify/order aspheric lenses
If you don't care about losing some lighting efficiency, there's h
Otherwise, see: http
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RE: How to specify/order aspheric lenses
RE: How to specify/order aspheric lenses
And the more efficient optics I believe, correct me if I am wrong, have to bonded directly to the die.
RE: How to specify/order aspheric lenses
There are a lot of low profile moderately efficient solutions and some larger very efficient solutions. I believe a search for RXI would turn up a decent optic. If you are interested in considering a different LED source, these people seem to have a line on a very efficient design (though I think the 94% they claim in the white paper comes with a disclaimer). Bigger than the Cree though.
http://ww
Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600
www.lumenflow.com
RE: How to specify/order aspheric lenses
The link you sent me looks interesting, but it's way too big.
RE: How to specify/order aspheric lenses
How thick is too thick? What about glass vs. plastic? When you say "a bunch" would that justify custom tooling? Is cost a factor (a coated lens will cost more than a plastic optic that operates on a TIR principle)? Is lighting a current area of expertise within your business (is there anyone there with the software to model this for you)?
Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600
www.lumenflow.com
RE: How to specify/order aspheric lenses
a lens mounted exactly 2mm from the PCB
The rest is right.
How thick is too thick? hum. A LISA XP lens adds about 5mm to the front of the LED assembly to produce the beam posted in the picture above. But I don't like it because it's plastic. So I would have to say 3mm would be the limit. Glass only, maybe even sapphire if the cost is not astronomical.
Yes, custom tooling would be justified. As for cost, I would like for each unit to come in under 25 USD and I am looking at ~200 units in the first run.
I am making high-end flashlights, but I deal mainly with the mechanical side so I do not have access to software that models light.
RE: How to specify/order aspheric lenses
I don't have anything solid to go on, but I think reducing the lens thickness by 40% isn't going to be solved by going to sapphire. Sapphire's index is only about 1.77, compared to 1.49 for PMMA.
Cubic zirconia, or Cleartran, perhaps; they both have indices >2.15. Cleartran (zinc sulphide) has an index around 2.3 in the visible.
However, in both cases, the index varies over the visible band, so there may be some limitations in color correction.
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RE: How to specify/order aspheric lenses
IRStuff is right as always. You will need a higher index glass if you want the optic to be that thin. I have the Cree in my library so I stuck a couple lenses in front of it and changed the curves and material and didn't come close to 8 degrees (assuming 2 theta 1/2) until the radii were really small and the index was approaching 2.0. I didn't do a "design" so take it for what it's worth.
I would suggest you contract with an optical engineer who can do the modeling for you. If you are going to spend money on tooling it will save you money in the long run. An internet search or a search in the Photonics Spectra Buyers Guide should turn up a bunch of capable contractors. Local is nice but Gotomeeting works fine too. Lens venders might have referals though many don't like to play favorites.
The other problem you might have is getting to your price point given your volume. If you use a molded glass optic you will need to have it molded here in the states. 200 is considered a sample run overseas. 2M is production. That is not so much the case state-side. If you go with a ground glass lens then the curves might be a cost driver. With the high index and steep radii I don't know if you'll get around using an asphere for the color correction IRStuff refers to. You don't want a bright rainbow maker. Again, I'd suggest you hire an expert.
Harold
SW2009 SP4.0 OPW2009 SP2 Win XP Pro 2002 SP3
Dell 690, Xeon 5160 @3.00GHz, 3.25GB RAM
nVidia Quadro FX4600
www.lumenflow.com
RE: How to specify/order aspheric lenses
It's more or less a retrofit. The original electronics are being moved to a new shell. 2mm is the distance between the rim of the pill (tube containing the LED, driver, MCU) and the LED's base. And the shorter the distance to the lens, the less light I lose.
Seems like there isn't going to be a single thin lens that will beat what I get from the LISA XP. I'll probably just go with that one then. Thanks for all the help.
RE: How to specify/order aspheric lenses
As for thickness, I think you're mistaken. PMMA's visible light transmission is quite high.
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RE: How to specify/order aspheric lenses
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