Lense Design Software - custom Lenses for use with LEDs - Page 1
Forum section: electronics / projects

author: mrpackethead
author_rank: Super Contributor
timestamp: November 02, 2016, 01:52:00 pm
content: Does anyone have any good suggestsions for design software for creating custom lenes for LEDS.

author: Fungus
author_rank: Super Contributor
timestamp: November 02, 2016, 02:26:16 pm
content: Quote from: mrpackethead on November 02, 2016, 01:52:00 pmCustom LEDs for LEDs? That's a tricky one.PS: What's special about LED lenses? They're just lenses.

author: singapol
author_rank: Frequent Contributor
timestamp: November 02, 2016, 02:28:24 pm
content: Can you be more clear, is it lens design software? If then what lens do you want to put in front of the LED for what purpose or use?

author: LaserSteve
author_rank: Super Contributor
timestamp: November 02, 2016, 03:03:54 pm
content: Fungus,Considering how the optical physics of high power LEDs works, you need to use Total Internal Reflection (TIR) in most lens designs. Plus your using TIR for maybe 60% of the light flux and classic optics for the rest of the ray bundle. That takes it well out of "simple lens design". As part of the design team for one of the first mass marketed led flashlights, I had to do it when the software model really didn't exist yet, so we had a programmer write us a model that could trace five rays at a time and display a graphic. That made things tedious. But the alternative was spending over 10K$ on commercial software, which did not yet have dedicated LED source models.If using a "direct" classic LED, with no phosphor, the index of refraction of the LED chip is far, far, higher then the encapsulation. This makes ray tracing very interesting. Coupling energy out of the die is difficult and often occurs at odd angles and less then useful patterns. Much of the emitted light can remain trapped at the die/encapsulation interface. Which results in things the manufacturer doesn't tell you, such as pyramid shapes being inscribed into the die surface to enhance transfer.Our way around this in the early days was to buy the LEDs in bulk, and regrind a new optical shape into the encapsulation. I'm often presently surprised when I walk into Big Box Mart and see modern molded variations of our patented design. Then we switched to Luxeon Star, which made life a bit easier. But not much. We convinced Luxeon to make a slight internal change in the second generation product which made life easier for flashlight designers.Now the software is nearing maturity. However the phosphor conversion coating in modern leds results in a "Fuzzy" source location, and you have to account for that. Its not a point source, and classical optics texts often assume a sharp point source for their models.If you want to dig into this, make sure there is a valid source optical model for the LED you wish to use, with a high ray count. Preferably the model is from a goniometer scan, and not just a theoretical model.Zemax and Photopia are pretty good... Others are Tracepro, ASAP, LightTools and Optis. Look at what the Cree and Lumileds web sites support.If your looking for good freeware, there isn't much out there, raytracing software is a niche product.If you just want to collimate a T1-3/4ths style package, that is not so hard. If you wish to design something very efficient for a modern high power led, that gets interesting fast. Especially if your injection molding the final product.My advice would be to find one of the ten or so independent "Bandit" consultants that already design these things. Then hire one.Steve

author: mrpackethead
author_rank: Super Contributor
timestamp: November 02, 2016, 03:29:50 pm
content: thanks steve, that was a very helpful and comprehensive answer.What i am wanting to do is create an optical system that has quite a few challenges.. tFirstly, i'm needing it to do a pretty good job of colour mixing.. I'll be Usign a multicolour LED.. Chances are that i'll proably need to use a mixing rod / light pipe to acheive this.. The dies are spread over a ~4x4mm space.Secondly, i'm needing to create a *very* narrow beam. probalby in the order of 2-3 degrees.I can buy an off the shelf optic set ( light pipe + lnese that will get be 7degrees..could i just put another standard lense in front of that and converge the beam further?I'll look up some of those softare packages.. Also any recommendations of indpendant folks to hire for a project?i wiill need to make around 10,000 lense sets for this project

author: LaserSteve
author_rank: Super Contributor
timestamp: November 02, 2016, 03:53:22 pm
content: Have you talked with my go-to favorites, Fraen and Carclo?Two to three degrees is approaching state of the art, and when you clean that up using a aperture and achromatic lens, you may be throwing away a large amount of flux... We looked at Optics for Hire, Inc. long ago... But two guys inventing in a former motorcycle repair shop, catering to Dorcy and trying to interest Maglite could barely afford the minimum "Buy in" to get the devices, let alone hire a good consultant. We did it with basic algebra and a little trig. You need something better then that.Best bet is to dig into LEDS MAGAZINE and look at the adverts, as I'm way out of date. But the physics does not change. If you were not using multiple sources I'd tell you to go reflective, like we did.Steve

author: Buriedcode
author_rank: Super Contributor
timestamp: November 04, 2016, 10:02:22 pm
content: I don't think you'll manage your '2-3' degrees divergence whilst also mixing colours from discrete LED's. Many have tried making 'pseudo-laser pens' back in the 90's using LED's and at best it was about 6 degree divergence - and didn't capture much light from the LED's.As you can probably tell from the replies, breaking it up into two parts, then perhaps trying to merge the two:- (efficiently) collecting light from discrete LED dies, and thoroughly mixing.- LED collimator to reducing the viewing angle.There are many *many* white papers on doing both, but they wont' play nice together: colour mixing, by its nature, scatters the light from each source in all directions, effectively 'randomising' the rays - this is why diffuse material is often used, so it can let *some* light though, but also reflects a lot at a seemingly random angle. The lightpipes used in small projects are often called 'mixing rods', and can be 25mm+example:https://optics.synopsys.com/images/lighttools/gallery/LEDS_mixingrod.jpgTrying to collimate the rays from that is tough to do efficiently (as in, capture > 30% of the light).In my spare time I designed some LED lamps in, of all things, POVray. Whilst its hardly the same as professional ray tracing software, and has a pretty steeep learning curve, one can play about with shapes, materials, and surface finishes with it and use photon count to keep track of the rays. As for dedicated software? I haven't found any that either isn't expensive, or lets you create your own shapes (rather than just move lens about for education).

author: branadic
author_rank: Super Contributor
timestamp: November 04, 2016, 10:40:10 pm
content: You can try Oslo:http://www.lambdares.com/oslo

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 05, 2016, 07:06:21 am
content: QuoteMost led lenses look nothing like conventional lenses. Not that you can't use conventional ones,but looking at what's on the market,there must be significant advantages in the different methods used. One difference is you actively don't want a coherent image,as you'd get a beam the shape of the die.Non diffused LED lenses in place of a camera lens can make some really funky images!Ledil is another big manufacturer.

author: m98
author_rank: Frequent Contributor
timestamp: November 05, 2016, 11:46:04 am
content: Might come in handy:http://www.opticalsoftware.net/index.php/how_to/lens_design_software/winlens3dbasic