# Need fine engineering help please! desperate (thank you)



## eatkabab (Aug 5, 2010)

*Newcomers, please skip to post #87 on page 3 - Thank you*
https://www.candlepowerforums.com/threads/286288&page=3

The following is a lamp I have developed for medical/surgery use. I'm just about finished creating it, but in testing, have realized that it must be about 15% brighter to be as useful as possible.

I cannot increase the package size, and have no idea what else to do to increase brightness. Lenses and machining are all custom work.

I will be eternally grateful to whoever can help me out. I would even go so far as to giving whoever helps me out one of these lights when completed.

Thank you to everyone on this forum and all your infinite wisdoms.







Edit:
Options that have been brought up (more discussion on any is more than welcome):
- TIR lens: might be a solution, but unlikely as these lenses do not provide sharp focus
- Lens coatings: a partial solution
- Having just one proper lens: I'm attempting to produce this
- Using a different LED: SST-50-W or OSRAM: New LED being used is the XRE
- Polish the bore from the LED to the first lens: possible gain, but will likely result in sloppy focus.
- Increasing current to LED: the complete casing cannot be increased in size and cannot get any hotter than it already does at 1amp
- Add heat-sinking fins and such: Do little or nothing due to small size requirement.

What has been established:
- A lot of light is lost with the current focusing strategy.
- For the application, there must be a very sharp delineation between light/dark at the edge of the ~13.5 degree focus beam (hence all the black on the inside)


Best possible solution so far:
Replace the XPG LED for an XRE LED. The XRE may provide less light, but its illuminated field is 90deg rather than the XPG's 125deg. The result should be more light down the center where its needed. Use a highly specific short focal length lens.


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## kingofwylietx (Aug 5, 2010)

Depending on the led's angle of emittance, you may be able to pick up 10-15% by coating the internal bore between the LED and lens 1 with a reflective substance. This would be easy to test using reflective aluminum tape. If it works, you can improve on that with a more reflective substance or by chroming it. Try that (if that doesn't improve it enough, can you fit a reflector in there)?


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## LV426 (Aug 5, 2010)

I'll guess the driver is located externally, you'll ''just'' have to beef it up to 1.2-1.5A...


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## eatkabab (Aug 5, 2010)

kingofwylietx said:


> Depending on the led's angle of emittance, you may be able to pick up 10-15% by coating the internal bore between the LED and lens 1 with a reflective substance. This would be easy to test using reflective aluminum tape. If it works, you can improve on that with a more reflective substance or by chroming it. Try that (if that doesn't improve it enough, can you fit a reflector in there)?



I've tried numerous reflectors and have found that they don't work well with lenses. Doing the math, reflectors + lenses = a mess. That seems to be the case in reality as well.

I haven't tried chroming the bore, but I assume it will cause the same problems as a reflector. Of course I will try anyways.

Unfortuantely, I can't crank the amps up above 1A due to heat problems. Its only about 25mm long and 18mm diameter. I can't get any more heatsinking outta it.


*I've read in other forums that the SST-90 LED may be more efficient at 1A. Is this true? Thank you for your advice*


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## entoptics (Aug 5, 2010)

Perhaps you could expand the external diameter by a couple mm, then mill the exterior with circumferential rings to increase the surface area? Essentially creating miniature cooling fins?

If you did this at the back, you could make it a little bit bigger still at the rear most portion around the LED and make the "fins" a bit taller, then step the diameter down to near original size towards the front?

Just an idea. Might get you enough heat sinking to step up your current enough for the brightness you need, without significantly increasing the size of the light.


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## KuKu427 (Aug 5, 2010)

Replacing the lens assembly with a TIR should help.
Or get coated lenses.


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## Connor (Aug 5, 2010)

Like the others said, coated lenses will help. There's a 4% loss at each glass/air border.

One more thing: It seems the inside of your light is mostly black? Spray-painting it with a high gloss silver should yield a few more lumens as well. Especially your "black spacer" will eat up quite some photons. 

-Connor


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## IMSabbel (Aug 5, 2010)

If the diagram is at the right scale, you are wasting >75% of the lumens. The lens only fills a small solid angle from the led, while the XP-G is near lambertian.

Would a TIR optic not be better suited if brightness is a requirement?


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## bigchelis (Aug 5, 2010)

The easiest is to put a TIR Optic...maybe the Surefire L1 type will fit.

You would gain as much as 50% more light just from that alone.


Then you could get a 1.4A driver from shinningbeam.com



bigC


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## eatkabab (Aug 5, 2010)

Thank you very much for your responses. Something I failed to explain is that the light needs to have a very sharp focus. When you look directly at the light, it must be as dark as possible until your eye moves into the actual beam. This is the reason for the matte black outter ring and the black spacer. In my experience with this, using even a mirror spacer doesn't seem to increase the central beam brightness and only adds to the bright halo around the center.

Connor and KuKu427 said something about lens coatings to increase optical efficiency. What kind of a coating are you referring to? I'm actually using high grade plastic lenses.


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## eatkabab (Aug 5, 2010)

IMSabbel said:


> If the diagram is at the right scale, you are wasting >75% of the lumens. The lens only fills a small solid angle from the led, while the XP-G is near lambertian.
> 
> Would a TIR optic not be better suited if brightness is a requirement?



I've realized this as well. We haven't looked into using TIR lenses. Can a TIR be used on the LED die and then also the lenses as well to provide the proper focus? Producing these lenses are extremely expensive. Do you know of any manufacturers that may already produce one that small?

Another option is using a different LED all together. Possibly an SST-50 @1a or OSLON OSRAM?


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## Connor (Aug 5, 2010)

eatkabab said:


> Connor and KuKu427 said something about lens coatings to increase optical efficiency. What kind of a coating are you referring to? I'm actually using high grade plastic lenses.



The 4% loss I mentioned is for *each* glass/air border. Plastic/air borders will have a (slightly) different loss.

Optical grade coatings are usually made of several layers of metal vapor deposits, at least that's what they use on things like photographic lenses etc.
Those vapor deposits are applied in vacuum chambers, which is a costly process. There may be cheaper/different processes available for plastic lenses - maybe you can get them readily made from your current supplier.

-Connor


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## UberLumens (Aug 5, 2010)

You could try changing the material to copper, especially directly under the led the more heat u can pull away the better.


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## eatkabab (Aug 5, 2010)

UberLumens said:


> You could try changing the material to copper, especially directly under the led the more heat u can pull away the better.



There is a very small bit of copper directly behind the LED chip. The heat pull from the LED is very good. The heat-sinking is also adequate, the problem is that the light must be very small and light weight, therefore it gets very hot and can burn someone during handling (It will be handled while on). I cannot increase the size at all and we've tried adding all sorts of fins. They don't do anything significant but increase manufacturing cost and difficulty.

As far as I can tell (and some of you have realized as well), I am wasting a lot of light and need a more efficient light gathering strategy. If I could find a TIR lens that was cheap and fit perfectly, I'd be all over it (looking...). Another obvious option would be to find an LED chip thats a similar size but more efficient at 1amp... (still looking but not hopeful)


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## bshanahan14rulz (Aug 5, 2010)

With a TIR, you'd be able to move the LED forward more, leaving more room for extra thermal mass. While the border between light and dark won't be as sharp, you'll have more lumens going forward. 

May I ask what these are going to be used for?
Edit: oh, read in another thread, headlight for medical professionals.

You might also try out a few different tints of LED. If you have a few prototypes that you will be loaning to medical professionals for field testing, they might want something that makes the warmer colors pop out too, not simply more light. And I bet a TIR would work great for you.

Here's some manufacturers. After you find a lens you like, check with typical distributors to see if they have any. Cutter offers quite a few, and you can get some carclo stuff from newark and futureelectronics.

some links for your browsing fun

Carclo optics products page:
http://www.carclo-optics.com/opticselect/

Fraen products:
http://www.fraensrl.com/prodinfo.html

Ledil products:
http://www.ledil.fi/index.php?page=xp-g

khatod:
http://www.khatod.com/cms/general_led_lighting___home_page-1237430.html


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## KuKu427 (Aug 5, 2010)

If you need a sharp delineation between lit and unlit areas then a TIR probably won't do.
You should try to get coated glass or sapphire lenses.
http://www.edmundoptics.com/onlinecatalog/browse.cfm?categoryid=11

Please note that a 15% increase in overall lumen will not equal a perceived 15% increase in brightness.
Have you tried a single large lens placed closer to the LED? Might be more efficient than the two lens system you have now.


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## Whineyweim (Aug 5, 2010)

Beg Cree for an S3?


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## eatkabab (Aug 5, 2010)

bshanahan14rulz said:


> With a TIR, you'd be able to move the LED forward more, leaving more room for extra thermal mass. While the border between light and dark won't be as sharp, you'll have more lumens going forward.
> 
> May I ask what these are going to be used for?
> Edit: oh, read in another thread, headlight for medical professionals.
> ...



Yes this is a dental surgery headlamp. The goal is to produce a super cheap dental headlamp for the students at UCSF since the current ones on the market are ridiculously expensive.

To be honest, I believe that if we had one proper lens it would do the trick. Unfortunately, the manufacturer we're using doesn't understand anything I've told them and has produced maybe five terrible lenses. We've sunk plenty of money into this and don't really have much more to develop more lenses.

I believe someone talked about TIR lenses and brought a few to show us, but we quickly rejected them due to their inability to function as intended. Its just very difficult to get TOTAL internal reflection and if I remember correctly, the result is sloppy light that is difficult to focus further.


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## the.Mtn.Man (Aug 5, 2010)

eatkabab said:


> To be honest, I believe that if we had one proper lens it would do the trick. Unfortunately, the manufacturer we're using doesn't understand anything I've told them and has produced maybe five terrible lenses.


Sounds like you need to find a new manufacturer.


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## eatkabab (Aug 5, 2010)

the.Mtn.Man said:


> Sounds like you need to find a new manufacturer.



I wish! But we have little money left...


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## CampingLED (Aug 5, 2010)

Work on the optics. If I would do dental work I do not want to get closer to 30cm and no mouth is 14cm wide. :thinking:


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## znomit (Aug 5, 2010)

Replace the XPG with an XPE. You'll get a brighter smaller spot.


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## Mockingbird (Aug 5, 2010)

I'm just a layman, but it seems to me that in your quest for a pretty beam you have prevented some of the side spill light from getting out the front by using that black spacer.


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## eatkabab (Aug 5, 2010)

znomit said:


> Replace the XPG with an XPE. You'll get a brighter smaller spot.



The XPE is rated at a lower efficiency 122lm/350ma vs (XPG) 139lm/350ma. Are you saying that at 1amp, the XPE is more efficient than the XPG?

Edit:
From what I can tell, it seems as if the XPE just has a physically smaller light emitting die.


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## znomit (Aug 5, 2010)

eatkabab said:


> The XPE is rated at a lower efficiency 122lm/350ma vs (XPG) 139lm/350ma. Are you saying that at 1amp, the XPE is more efficient than the XPG?


 
The XPE has a 1x1mm die. The XPG is 1.4x1.4.
The XPG projects a spot 1.4x the diameter of the XPE, so its light is spread out over twice the area.

2*122/139 = 1.75 (actually I think 139 should be 145 but you get the idea). This is a noticable bump in brightness.

You might want to look into aspheric optics too (I think dealextreme.com or cutter.com.au do 12 or 14mm ones).


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## eatkabab (Aug 5, 2010)

CampingLED said:


> Work on the optics. If I would do dental work I do not want to get closer to 30cm and no mouth is 14cm wide. :thinking:



I'm sorry my number was off. The beam is ~2 degrees. That 30cm was supposed to be 75cm


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## jimmy1970 (Aug 5, 2010)

Due to the fact that the internal surfaces of the light body are a non reflective black, you need to consider an emitter that produces most of it's light in a forward pattern as opposed to a side ways pattern.

The older Cree XR-E R2 emitter does just this. An XR-E with a single aspheric lens will provide a sharp focused beam in a square beam the shape of the emitter. Take a look at the Tri-V from Cool Fall for details (here at CPF under custom builders)


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## mudman cj (Aug 5, 2010)

I second the aspheric optics used with an XR-E!


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## eatkabab (Aug 5, 2010)

znomit said:


> The XPE has a 1x1mm die. The XPG is 1.4x1.4.
> The XPG projects a spot 1.4x the diameter of the XPE, so its light is spread out over twice the area.
> 
> 2*122/139 = 1.75 (actually I think 139 should be 145 but you get the idea). This is a noticable bump in brightness.
> ...




We wanted an aspheric lens, but apparently the lens maker didn't understand that...

While your calculations make sense, the documentation does not reflect the same.

I'm looking at the XR Q5 LED now. It claims to do 107lm/350ma over a 90deg spread. This is technically more light at the center (where its needed) than the XPG's 140lm/350ma over a 180deg spread. Is this correct?


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## znomit (Aug 5, 2010)

mudman cj said:


> I second the aspheric optics used with an XR-E!


 
I third it (who was suggesting XPE?  )


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## eatkabab (Aug 5, 2010)

znomit said:


> Replace the XPG with an XPE. You'll get a brighter smaller spot.



Okay so I believe znomit intended to say XRE as I have found a similar conclusion. I'm going to see if the casing can be modified to accept the larger LED.

Continued responses are MORE than welcome!
*THANK YOU ALL! I cannot tell you how much I appreciate this.*


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## Jash (Aug 5, 2010)

Have you thought about removing the dome off the led? 

I did this to my headlamp (rebel 100 using an optic) and the extra throw and brightness were amzing. It also sharpened up the hotspot a LOT. Only makes 100ish lumens but out-throws my XP-E Quark 2AA Tactical now.


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## guiri (Aug 5, 2010)

Also, instead of sinking money (too late unfortunately but for the future) into manufacturers, I'm thinking you should be able to find most of your stuff ready made. After all, these days, there is lots of stuff out there.

George


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## John_Galt (Aug 5, 2010)

Yes, that, plus the smaller die size of an XR-E v. an XP-G (1mm^2 v 2mm^2) will result in more light projecting forward, thus increasing the intensity of the spot.

Maybe you've covered this, but are you thinking of using a neutral or warm white LED? Yes, they are less efficient in terms of lumens/watt of energy, but they have a higher CRI rating, and many comment that they make colors appear more natural and shapes appear more "3-D" as opposed to flat.

The increased "naturality" of the output would probably make up for the loss in output.


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## znomit (Aug 5, 2010)

eatkabab said:


> Okay so I believe znomit intended to say XRE as I have found a similar conclusion. I'm going to see if the casing can be modified to accept the larger LED.
> 
> Continued responses are MORE than welcome!
> *THANK YOU ALL! I cannot tell you how much I appreciate this.*


 
Actually you'll see a significant bump with just replacing the XPG with XPE and no need to mod anything else. Next step is XRE and then XRE + aspheric.


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## jimmy1970 (Aug 5, 2010)

jimmy1970 said:


> Due to the fact that the internal surfaces of the light body are a non reflective black, you need to consider an emitter that produces most of it's light in a forward pattern as opposed to a side ways pattern.
> 
> The older Cree XR-E R2 emitter does just this. An XR-E with a single aspheric lens will provide a sharp focused beam in a square beam the shape of the emitter. Take a look at the Tri-V from Cool Fall for details (here at CPF under custom builders)



Just to add to my previous post, the 'spacer disc' would be blocking a huge amount of light before it has a chance to get anywhere near the optics!

The 'can' of the XR-E will protect the emittered light from being lost.

The Q5 is slightly less efficient bin than R2.

This would actually be a pretty simple project I would think for one of the very talented modders on this site. 

Your lens designer has to have a very thorough knowledge of the focusing requirements of the chosen emitter before they have any chance of being able to design a lens system to suit.

James


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## eatkabab (Aug 5, 2010)

jimmy1970 said:


> Just to add to my previous post, the 'spacer disc' would be blocking a huge amount of light before it has a chance to get anywhere near the optics!
> 
> The 'can' of the XR-E will protect the emittered light from being lost.
> 
> ...



The spacer disk is about .1mm thick around the actual LED. Its not blocking any part of the plastic bulbous part.

I don't quite understand how just using the XPE will give me more brightness down the center. The data sheet of the XPE is identical to the XPG but just less intensity. It doesn't reflect any more focus or light down the center.

When you say "the Q5 is less efficient than the R2" you mean the XRE Q5 is less efficient than the XPG R2 right? Although in my application, the XRE will hopefully work better.

I can't find if the XRE light emitting square is the same size or larger than the XPG. Would anyone happen to know the measurements?


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## vtunderground (Aug 5, 2010)

To be honest, I think the only way to increase output that much would be to ditch the dual lenses and use a TIR optic. You may have enough room in that body to recess the optic slightly, blocking any dim spill beam you might have, and achieving the narrow cutoff that you're looking for.

I'd buy one of every "narrow" XP-G optic on Cutter's website, and hope that one of them would produce a suitable beam.


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## csshih (Aug 5, 2010)

a XR-E has a 90 degree viewing angle compared to a 125 degree of a xpg.. so I'll agree with everyone else's suggestion of using it.
check out my emitter guide:
http://www.lumensreview.com/emitter_index/emitter index.htm

https://www.candlepowerforums.com/threads/270419
for more emitter info.

with a relatively low current draw, I would suggest you acquire a EZ900 die'd one.


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## eatkabab (Aug 5, 2010)

So a possible solution that has been developed is to use an XRE LED rather than the XPG. The XRE delivers less lumins, but it does it over a 90deg spread rather than a 180deg spread like the XPG.

A TIR lens won't give me the proper focus I need unfortunately. They focus the light well, but provide very sloppy scatter around the edges. the result is not something necessarily brighter sadly. :-/


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## eatkabab (Aug 5, 2010)

csshih said:


> a XR-E has a 90 degree viewing angle compared to a 125 degree of a xpg.. so I'll agree with everyone else's suggestion of using it.
> check out my emitter guide:
> http://www.lumensreview.com/emitter_index/emitter index.htm
> 
> ...



This is AMAZING. I wish I had found this earlier. Your link says that the XRE has an even smaller emitting die (0.9mm). Is that correct? That would be excellent if so.


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## jimmy1970 (Aug 5, 2010)

eatkabab said:


> The spacer disk is about .1mm thick around the actual LED. Its not blocking any part of the plastic bulbous part.
> 
> I don't quite understand how just using the XPE will give me more brightness down the center. The data sheet of the XPE is identical to the XPG but just less intensity. It doesn't reflect any more focus or light down the center.
> 
> ...


:thinking: When you say XPE, I think you mean XR-E. The XR-E R2 is more efficient than the Q5 bin. 

Technology progression: XR-E Q5, XR-E R2, XP-E R2, XP-GR5. The emitter surface has been increasing in size slightly with each emitter upgrade - more total lumens but a slight decrease in surface brightness.

James....

*EDIT: The smaller the ratio between surface area and surface brightness, the better for a highly focused application. Please consider the fact that slight changes with this ratio can make a huge difference to the end result - consider that few of the previous optics designed for the XR-E emitter work successfully with the newer cree emitters!!*

*As the OP said, the EZ900 as the ultimate in small surface area emitter development - an even smaller emitter surface area again with better efficiency.*


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## DM51 (Aug 5, 2010)

Very interesting project!

However, you have posted it in two places, which is a contravention of Rule 9. I'm merging the threads and moving the combined thread to H&M.


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## eatkabab (Aug 5, 2010)

DM51 said:


> Very interesting project!
> 
> However, you have posted it in two places, which is a contravention of Rule 9. I'm merging the threads and moving the combined thread to H&M.



Yes, I'm so sorry. I posted it to the proper place, then realized that it wasn't getting any attention. I'm very sorry. I was desperate and I cannot thank everyone on this forum enough.

This is truly a wonderful place.


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## ama230 (Aug 5, 2010)

You are on the right path but with dual optics like you have it is basically fighting themselves. As well as the black on the inside of the casing is also taking about 10% of the light and wasting it.

You would first take a reflector or make the inside of the casing shinny. This would help diffuse the light instead of trapping or soaking the photons. Black is a very good color to absorb heat or trap it and what you want to do is emit or dispose of it. 

If you wanted a great solution on the cheap is to take the led and move it to the first lense location and then use a tir. Then if you wanted and this is optional is to coat the inside to help as to get the absolute most. But with a tir it will give the same two outer rings with a great center beam for identification and sorts.

here's a diagram to show a little of whats going on and could go on.





As in the diagram above the beam is also bouncing again before the first optic and then losing some more light and its scattering and getting less light out.

Also try looking into a frosted like tir from a osram emitter as this gives a great soft but strong beam. It would take the three rings above and mesh them together nicely.


It will probably work better with a xr-e as the xp-g as discussed above has a very wide viewing angle and may not be sufficient for you app but who knows as nobody I think has tried a xp-g with a tir, they generally use a reflector instead of an optic.

Hope this helps to give you a basic idea.
Eric


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## Linger (Aug 5, 2010)

ama230, great diagrams!
OP, if you want it tighter then that (your continued quest 'it must focus properly) then worry about the extra spill light afterwards.
E.G., use the Tir, and if you only want the hotspot and not the spill to the side, then you can extend a little sheild around the bezel (the very end of the light) and use that to shave off the excess light. (I get the impression you're trying to keep the spill from going into the patients eye, yes?)

Use an emitter with a tighter emittence pattern (XRE is the type of emitter, R2 is the flux bin, the efficiency or brightness of it, so XRE R2 and then you'll select the tint, like 3B which is about a standard incandecent bulb, so a Cree XRE R2 3B).

You may want to add a finned outside to the casing, increase surface area to improve heat dissipation of the light head.

Sorry but that initial design wastes the majority of the lumens produced. The first pictures is a very inefficient application.


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## Kestrel (Aug 5, 2010)

IIRC there is a thread with various *graphs* showing light intensity as a function of the viewing angle from various LEDs, and IIRC^2 the XP-G was considerably wider than the older XR-E's (which has also been posted above). Anyway, this definitely isn't my specialty, but perhaps others here are more familiar with those graphs and could dig them up and forward a link to the OP?

Edit: I thought it might have been from jtr1962, but I was wrong. I tried searching but didn't come up with the thread I was looking for. I know it's somewhere in the /LED/ (emitter) subforum though...:thinking:


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## eatkabab (Aug 5, 2010)

ama230 said:


> You are on the right path but with dual optics like you have it is basically fighting themselves. As well as the black on the inside of the casing is also taking about 10% of the light and wasting it.
> 
> You would first take a reflector or make the inside of the casing shinny. This would help diffuse the light instead of trapping or soaking the photons. Black is a very good color to absorb heat or trap it and what you want to do is emit or dispose of it.
> 
> ...



I just found the box of TIR's we were originally testing. After going through a couple dozen, I haven't found a single one that comes close to the focus necessary. Additionally putting a lens in front of the TIR causes a mess of light at any distance. I will continue to try various combinations, but am doubtful.

The black internals are to reduce the spread of light all over the place in order to keep it out of the patients eyes (as someone stated above). I'm going to try to polish the first part of the barrel from the LED to the first lens, but am almost sure that won't result in anything brighter and will only add to scatter.

I realize that there is a very narrow range of the flux that is being 'used.' From everyones response here, it seems as if just replacing the XPG with an XRE should solve nearly all my problems. I'm looking for roughly 15% more brightness with the same super sharp ~2deg focus.

Because the diode of the XRE is smaller, I will however need to rearrange the lenses a bit, but I may even end up with an even smaller package which would be even better.

The other question I have is weather just using an XPE will increase brightness. Some say it will, but the data sheets reflect otherwise. The calculation of a smaller spot running the same current makes sense to make more direct light, but I don't know without trying.

I also realize that the dual lens system is not optimal, but I haven't been able to find a better off the shelf solution and unfortunately we wasted our development money on a retarded (for lack of a better word) lens manufacturer. The diameter is 19mm. Can't find any aspheric lenses in that size that are less than about $40.

Please let me know what you think about just replacing the XPG with an XRE.
Thank you immensely


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## mudman cj (Aug 5, 2010)

Placed at the focal point of a lens, a light source having a higher surface brightness will produce a brighter spot. Despite the lower overall lumens output of the XP-E, its much smaller die area results in a higher surface brightness at 1 Amp. Still, due to the viewing angle difference, the XR-E will be better still for use with lenses such as you are doing.


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## csshih (Aug 5, 2010)

eatkabab said:


> This is AMAZING. I wish I had found this earlier. Your link says that the XRE has an even smaller emitting die (0.9mm). Is that correct? That would be excellent if so.


thanks!

correct! :huh: the XRE has a even smaller die than the xpg.. but unfortunately has a large package. I think the large optics help a bit in this situation!


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## Tekno_Cowboy (Aug 5, 2010)

ThorLabs makes some nice ashperic lenses on the cheap. You also don't need to use one that is 19mm wide. You could go with one 10-15mm wide just as easily, which would also reduce the focal length, giving you more room for heatsinking and possibly finning. This would also allow you to drive the LED at a slightly higher current for more output.

This reminds me quite a bit of this mod I did.


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## Linger (Aug 5, 2010)

Look, *shine a light down a card board tube* - you can isolate a good usable hotspot, no spill. Forget complex optics and focal lengths.
I understand you're probably tried reverse engineering, working backward from some high priced production unit: well dental headlamps don't have a wide market because they aren't that good.
As long as you try to take care of everything inside, you're buggered for efficiency.
Cheapest/best is to go for tightest focused beam and put an Xmm wide appature in place of a lens at the end.


eatkabab said:


> The black internals are to reduce the spread of light all over the place in order to keep it out of the patients eyes (as someone stated above).
> You've got this backwards.
> Put the Emitter
> 
> ...


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## MikeAusC (Aug 5, 2010)

*Even a $1.00 lens can produce a smaller beam !*

Your Optics manufacturer obviously knows far less than the people on CPF.

To get a narrow focussed beam with a sharp cutoff, you want to focus the image of the LED sharply - and your beamshot shows clearly that the silly two-lens arrangement predictably goes nowhere near that.

Here's a test I just did using an XRE and a DX4584 lens - this lens costs $1.00 and is 22mm in diameter !!!!
www.dealextreme.com/details.dx/sku.4584

At 75cm the die-image is 6cm wide and of course has very sharp cutoff.

Since the light is focussed in a square of 6cmx6cm, it will obviously be much brighter than the 14cm diameter illuminated by your very expensive tailor-made optics.

It would take me a while to post a photo, but it would look just the same as the many images posted already on CPF of a focussed die iimage.


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## MikeAusC (Aug 6, 2010)

*Improving Thermal Design*

There seems to be as much room for improving the Thermal Design as the optics.

1. With a single lens, the internal space only requires a cone shape going from LED to lens - ribs painted matt black will prevent light spill outside the target area.
You can now machine grooves going down to the cone, for better heat transfer to air.
The grooves will reduce thermal mass, but for a light that's going to be on a for a long time it's more important to have ways of getting rid of the heat, than to soak it up internally.

2. The Mounting Clamp is a useful part of getting rid of heat - don't machine it down for barely-adequate mechanical strength - leave as much metal as possible to conduct the heat away to the support and to the air.

3. If it's still too hot to touch safely, put a shield over it. Use a perforated metal shield like you see around truck exhausts or use a more open wire frame. These still allow air-circulation.


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## ama230 (Aug 6, 2010)

Linger said:


> ama230, great diagrams!
> OP, if you want it tighter then that (your continued quest 'it must focus properly) then worry about the extra spill light afterwards.
> E.G., use the Tir, and if you only want the hotspot and not the spill to the side, then you can extend a little sheild around the bezel (the very end of the light) and use that to shave off the excess light. (I get the impression you're trying to keep the spill from going into the patients eye, yes?)
> 
> ...


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## MikeAusC (Aug 6, 2010)

*15% Brightness increase*

Torches that have multiple brightness levels usually have steps that are 2x or 3x change in current drive, because people have trouble noticing brightness change until it's at least 50%.

I assume the extra 15% you need is to achieve some measured Lux specification.

Although with the improved single-lens optics I suggested above, you'll have no trouble exceeding 15%.


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## MikeAusC (Aug 6, 2010)

*Lens + Reflector*

If you want a sharp image wth minimal spill, then there's only one option if the main optic is a lens.

Use the spherical internal-reflector with a window as explained painfully in this thread -
https://www.candlepowerforums.com/threads/269598

Although it has been patented now !

All the other suggestions just result in a lot of light outside the main beam.


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## stinky (Aug 7, 2010)

You may also want to contact Surplus Shed for lens alternatives:

http://www.surplusshed.com/lens.cfm

They may have nicer alternatives than DX, but using pyrex glass and/or coated yet still pretty cheap.


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## eatkabab (Aug 7, 2010)

stinky said:


> You may also want to contact Surplus Shed for lens alternatives:
> 
> http://www.surplusshed.com/lens.cfm
> 
> They may have nicer alternatives than DX, but using pyrex glass and/or coated yet still pretty cheap.




I actually already ordered a slew of lenses from Surplus Shed. Also talking to them for a minute, I learned how great of people they really are. Wonderful customer service.

So my current setup that will be arriving soon is the XRE R2 with a 12mm focal length lens.

On the XPG that I have, it seems a 15mm focal length is perfect, and a 10mm focal length is about 4X the necessary size. Since the XRE die is exactly half the size, a 12.5-13mm focal length should give me the 10deg viewing angle I desire.


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## wquiles (Aug 7, 2010)

eatkabab said:


>



In that photo where you are holding the lens about 14mm from the LED, what is a good estimate of the % light lost that never reaches the target due to the very wide dispersion angle of the LED?

Is it here where a pre-colimator lens could "capture" some of this wasted light?


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## saabluster (Aug 7, 2010)

eatkabab said:


> I actually already ordered a slew of lenses from Surplus Shed. Also talking to them for a minute, I learned how great of people they really are. Wonderful customer service.
> 
> So my current setup that will be arriving soon is the XRE R2 with a 12mm focal length lens.
> 
> On the XPG that I have, it seems a 15mm focal length is perfect, and a 10mm focal length is about 4X the necessary size. Since the XRE die is exactly half the size, a 12.5-13mm focal length should give me the 10deg viewing angle I desire.


I would be very wary of using Surplus Shed if you have very many of these to make. 

You should know that although the XR-E will give you the best performance as far as brightness is concerned it will also come with a built-in halo. My suggestion is to use the R3 bin XP-E assuming CRI is no concern for this project. If you would like to talk about your setup just send me a PM with your phone# and I will give you a call. 



wquiles said:


> In that photo where you are holding the lens about 14mm from the LED, what is a good estimate of the % light lost that never reaches the target due to the very wide dispersion angle of the LED?
> 
> Is it here where a pre-colimator lens could "capture" some of this wasted light?


Judging from his remarks it seems he is going for lux not throughput so the pre-collimator is unlikely to help with his setup. That said it depends on the quality of the lenses he is using.


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## eatkabab (Aug 7, 2010)

wquiles said:


> In that photo where you are holding the lens about 14mm from the LED, what is a good estimate of the % light lost that never reaches the target due to the very wide dispersion angle of the LED?
> 
> Is it here where a pre-colimator lens could "capture" some of this wasted light?



While using the pre-collimator would definitely help in that sense, it also introduces so many new angles of the light that cannot be focused. There must be a very sharp delineation of bright/dark (the focus must be very sharp). In my experience, lenses are designed for and work best with point lights rather than light coming in at all directions...


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## saabluster (Aug 7, 2010)

eatkabab said:


> While using the pre-collimator would definitely help in that sense, it also introduces so many new angles of the light that cannot be focused.



It doesn't affect how well it can focus. It just allows you to gather up more light and send it out. Focusability is the same or better. However even though more light gets out the intensity will be about the same.


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## ama230 (Aug 7, 2010)

Here is a site with cheap prices on optics and there are many for the xp series including your xp-g and there is all types of finishes and coats to the plastic to get the diffusion right.

http://www.cutter.com.au/products.php?cat=30&pg=2

just type in xp optics in search as they have tons...


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## eatkabab (Aug 7, 2010)

ama230 said:


> Here is a site with cheap prices on optics and there are many for the xp series including your xp-g and there is all types of finishes and coats to the plastic to get the diffusion right.
> 
> http://www.cutter.com.au/products.php?cat=30&pg=2
> 
> just type in xp optics in search as they have tons...



I've actually tried every variation of these TIR lenses made just for the rebels and XPG's. They don't perform as advertised (or I might just not be understanding the advertised specifics). They may be good for crude applications, but unfortunately not for mine.


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## eatkabab (Aug 7, 2010)

saabluster said:


> My suggestion is to use the R3 bin XP-E assuming CRI is no concern for this project. If you would like to talk about your setup just send me a PM with your phone# and I will give you a call.



Thank you so much for your extremely generous offer. I messaged you but I'm not sure if it went through since I cannot find a "sent PM" folder in this sites forum system...


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## saabluster (Aug 7, 2010)

eatkabab said:


> Thank you so much for your extremely generous offer. I messaged you but I'm not sure if it went through since I cannot find a "sent PM" folder in this sites forum system...


hmm.. no PM is showing. Try shooting an email to omglumens at gmail dot com.


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## MikeAusC (Aug 7, 2010)

eatkabab said:


> On the XPG that I have, it seems a 15mm focal length is perfect, and a 10mm focal length is about 4X the necessary size. Since the XRE die is exactly half the size, a 12.5-13mm focal length should give me the 10deg viewing angle I desire.


 
I've tried using the SAME lens in front of an XPG and an XRE and I found that the image size projected at 75cm is virtually the same.

Both LEDs come with lenses mounted directly on the emitter, so Die Size is academic - unless you're going to remove the lens.


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## MikeAusC (Aug 7, 2010)

*What Beamwidth do you need ?*



CampingLED said:


> Work on the optics. If I would do dental work I do not want to get closer to 30cm and no mouth is 14cm wide.





eatkabab said:


> I'm sorry my number was off. The beam is ~2 degrees. That 30cm was supposed to be 75cm


 
When you talked about wanting a 2 degree beamwidth, I pointed out that you can get a 5 degree beamwidth using a $1 lens within the size limits of your existing housing - 5 degrees is 6.5cm at 75cm. 2 degrees is 2.6cm at 75cm and if you really want that within your existing case size, you will need to use 2 lenses.


　



eatkabab said:


> On the XPG that I have, it seems a 15mm focal length is perfect, and a 10mm focal length is about 4X the necessary size. Since the XRE die is exactly half the size, a 12.5-13mm focal length should give me the 10deg viewing angle I desire.


 
10 degrees is 14cm at 75cm - is this the beam size you actually want ?


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## HarryN (Aug 7, 2010)

BTW - I don't think your lens designer is that bad - what you are trying to do is very difficult. That being said, if you are not using a high CRI led in your application, it might still fail, as the standard LEDs are really poor for medical use. They typically just don't provide sufficient red delination.


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## eatkabab (Aug 9, 2010)

*Re: What Beamwidth do you need ?*



MikeAusC said:


> 10 degrees is 14cm at 75cm - is this the beam size you actually want ?



Yes you are correct. I intended to type "~12" degrees but didn't realize the "1" didn't come out. The ideal viewing angle is 13.5degrees (after slightly diffusing the light by setting the focal length to a little less than the lens focal length).

In testing, I too just realized that I cannot use the diode size for my measurements since both the XRE and XPG have lenses over the diode. You said that both the XRE and XPG ultimately produce the same size spot if all extra-LED lens/distance variables are constant. I have yet to receive my XRE samples, so do you mind me asking how close in size they were?

This information would be very helpful. Thank you very much for catching that.


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## MikeAusC (Aug 9, 2010)

*Re: What Beamwidth do you need ?*



eatkabab said:


> how close in size they were? Was the XRE only about 1cm smaller from that distance?


 
I've just done another test where I tried to make the focussed image as small as possible - the results at 75 cm using a DX4584 22mm dia lens are - 

4.5cm - XRE Q4 (EDIT - older one with the larger die)
5.0cm - XPG R4
6.5cm - SSC-P7 (but big cross through it)
10.0cm - SST50
11.5cm - SST90

Hopefully this helps - let me know if more tests are needed.


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## Walterk (Aug 9, 2010)

Here is a thread about calculating on Led's combined with Aspheric lenses.

Here is a thread about the apparant die-size, it might explain someting about the size of the die of the diode, and the dome on top of it.
It also has some information about TIR on the end.

For how to calculate the angle of the spotsize:
It's best to try in real life as you want a specific beampattern.
Instead of calculating I find it easier to use drafting software.

Two notes:
1 - The sketch is using the die, but that is wrong, you should use the 'apparant-die-size' as it is perceived by your eye, projected on the dome.
2 - The optical center of the lens is not at the first plane, but somewhere in the middle of the glass mass, towards the curved side.

So the sketch mainly shows how you can derive an indication for the beamangle. 








Edit: My suggestions FWIW; 
Use one lens, thats easier and still you can shape the beam as desired.
The Led does not need to be at the focal length, overfocussing, closer to the lens still can give a sharp cut-off.
Dont use a lens with very short focal length, it gives a wider beam and usually more distortion.
Longer focal length gives more narrow beam.

Edit2: Corrected link to thread about 'apparent die-size'.


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## eatkabab (Aug 9, 2010)

In order to choose the correct lens with the 9.5deg sharp viewing angle I need, it appears I must know the 'apparent size' of the XR-E diode. I've yet to receive my XR-E's but I did the following test to measure the apparent size of an XPG.

so using a 33mm focal length lens, I measured a sharp focus angle of 3.29deg.
Plugging that number into the following formula, I derived for "d" the diode size: (which is I'm assuming the apparent size of the diode)

View angle = 2 Arctan(d/2f) - http://en.wikipedia.org/wiki/Angle_of_view
d = 1.898mm

Using this new d, I derived that an f=12mm lens will give me a 9.04deg viewing angle. Is this correct?


With this information and MikeAusC's note that the XRE and XPG LED's have almost the same apparent size, can I assume that an f=12mm lens will give me the same 9.04deg angle? (But I would assume that the XRE's apparent size is slightly smaller and go with an f=11.8mm)

Is that also correct?


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## MikeAusC (Aug 9, 2010)

Just to complicate things, the original XREs (EDIT-corrected from XPE) use 1.0mm die, whereas newer ones use a 0.9mm die.

So if you were designing for production, it would neeed to be based on the 0.9mm die.

I'm not sure if there's an easy way to determine if mine or your XRE has a 1.0 or 0.9 die.


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## eatkabab (Aug 9, 2010)

MikeAusC said:


> Just to complicate things, the original XPEs use 1.0mm die, whereas newer ones use a 0.9mm die.
> 
> So if you were designing for production, it would neeed to be based on the 0.9mm die.
> 
> I'm not sure if there's an easy way to determine if mine or your XRE has a 1.0 or 0.9 die.



Well either way, if you can tell me with high likelihood that the apparent sizes of the XPG and XRE are the same, it would prove very very useful to me. the .1mm can make a difference, but I'll consider that to be why I choose a 11.8mm focal length rather than 12mm


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## MikeAusC (Aug 9, 2010)

eatkabab said:


> if you can tell me with high likelihood that the apparent sizes of the XPG and XRE are the same, it would prove very very useful to me.


 
Don't the test results in my Msg 72 above give you that ?


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## eatkabab (Aug 9, 2010)

MikeAusC said:


> Don't the test results in my Msg 72 above give you that ?



oooo sorry, must have missed that one. Thanks


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## saabluster (Aug 10, 2010)

MikeAusC said:


> Just to complicate things, the original XPEs use 1.0mm die, whereas newer ones use a 0.9mm die.
> 
> So if you were designing for production, it would neeed to be based on the 0.9mm die.
> 
> I'm not sure if there's an easy way to determine if mine or your XRE has a 1.0 or 0.9 die.



I am assuming you meant to say X*R*-E and not X*P*-E. There is no evidence as yet that the XP-E uses the ez900 die. The XR-E does however use both. It is very easy to tell the difference as the ez900 has a copper colored band around the die.


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## MikeAusC (Aug 10, 2010)

saabluster said:


> I am assuming you meant to say X*R*-E and not X*P*-E.


 
aarrrgghhh - thanks, now corrected to XR-E.





saabluster said:


> The XR-E does however use both. It is very easy to tell the difference as the ez900 has a copper colored band around the die.


 
Thanks - that makes it clear that my XR-E Q4 5C from Cutter is the 1.0mm die.


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## Crimepays (Aug 10, 2010)

Hey check this out. It looks alot like what you have made. It is slightly larger in diameter though. 

http://www.thorlabs.us/NewGroupPage9.cfm?ObjectGroup_ID=2692
http://www.thorlabs.us/NewGroupPage9.cfm?ObjectGroup_ID=3307

It might give you some ideas. It has nice heat sinking.


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## eatkabab (Aug 12, 2010)

My LED supplier tells me that the XRE R2 has a viewing angle of 115deg and the Q3 has a viewing angle of 90deg. (despite whats written in the datasheet)

Is this correct? Does anyone know the viewing angle of the Q5? The supplier only has the specifics on the R2 and Q3.


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## John_Galt (Aug 12, 2010)

Q5/R3, etc have nothing to do with the viewing angle.

The XR-E has a 90* viewing angle.

The XP-E/XP-G has a 115* viewing angle. 

Your supplier is talking about two different types of LED's.


Q5/R2/R5 just refer to the BIN of the LED. A bin is the group of LED's with similar efficiencies. Theoretically, you could have a super efficient R5 XR-E, with the EZ-900 die, and a very poor Q3 efficiency XP-G. But either is not likely to happen...


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## Chrontius (Aug 14, 2010)

I think what is called for here is a TIROS optic - a TIR with an integral aspheric at the business end.

Inova used them in flashlights for a good long while, and they produced some _fantastically_ well collimated beams, lacking badly in the spill, with just some ringy wasted light from odd interactions. Can you afford to buy an old TIROS inova to play with?

I have *no* idea if this image is accurate to the angles involved, but you can see how the TIR lens and the aspheric are cast as one piece here: 










There are rings and ridges (not sure how to describe it) on this generation TIROS optic; they seem to be there to moderate the laser-like focus of a typical aspheric into a nice round spot, instead of the typical aspheric image of the die. Later (current) TIROS revisions removed the aspheric portion entirely, however.

Also - what about including a heat pipe or two in the light to pump heat to the outside of the case?


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## MikeAusC (Aug 15, 2010)

*Double your light output with no extra heat*

So how have our suggestions helped ?

In another thread I've done some calculations, based on analysis done by bbb74. 
https://www.candlepowerforums.com/posts/3490781#post3490781

If you increase lens size so it captures +/-50 degrees instead of +/-40 degrees AND switch from an XP-G to an XR-E, the percentage of light captured from the LED increases from 44% to 94%.

Seems an easy way to achieve your goal in the original post, of 15% increase. 

btw you never answered my question about the +15% goal. A person would have great difficulty detecting a 15% increase - is there some minimum lighting level you need to achieve to comply with an industry standard, or is it to match a competing product.


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## Dr.Jones (Aug 23, 2010)

The apparent die size of an XR-E EZ900 is quite less than that of an XP-G, the XR-E EZ1000 is somewhere in between. 

You could use an XR-E R2 EZ900 LED, as others already said. The spot will be smaller, but brighter, since that LED still has the highest surface brightness around, about 40% more than an [email protected]
The smaller viewing angle doesn't really help for spot brightness though.



> If you increase lens size so it captures +/-50 degrees instead of +/-40 degrees


A strong aspheric lens usually can capture +/-35°, so 40° or even 50° is quite a lot...

If heat sinking is good enough for 0.85-1.0A, it might be good enough for 1.1A, too?


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## eatkabab (Aug 23, 2010)

*Re: Double your light output with no extra heat*



MikeAusC said:


> So how have our suggestions helped ?
> 
> In another thread I've done some calculations, based on analysis done by bbb74.
> https://www.candlepowerforums.com/posts/3490781#post3490781
> ...




The 15% increase that is needed isn't necessarily exactly 15%, its just my estimation. Basically brighter is better, thats all. The current model needs to be a bit brighter in order to be useful. Its currently bright enough in the center of the spot, but dies off at the edges enough to loose its functionality.

I've taken everyones help into consideration and am now testing prototypes with the XRE R2 with biconvex and plano-convex lenses. So far tests have indicated that this is exactly what needed to be done. I cannot thank everyone on this forum enough. I hope to find a way to return the favor.

With the XRE, I've got 2 lenses that almost work perfectly:
Biconvex 14mm diameter focal length =12mm
Plano-convex 15mm diameter, focal length = 18mm (coated)

Both can produce the correct sized spot and at the correct brightness. Ideally the biconvex focal length should be between 10.5-11mm and the plano-convex somewhere between 12-15mm focal length. (both in 15mm diameter-largest apatite as Dr.Jones also indicated. Indiana Jones?:thumbsup *I cannot correctly calculate the perfect focal length though. I've tried all forms of calculations and have come up with little more than estimations.*

*I cannot for the life of me understand why first of all the plano-convex produces a much cleaner spot, and second, why a longer focal length plano-convex can produce the correct focus when compared to a shorter focal length biconvex.* Clarification on this would greatly help.

The following is a picture of current tests and the lenses to be made. I greatly appreciate any input.

(Note: Diffuse focus because this is how it will be used. Spot on right has correct sized spot but too dark at edges.)
Plano-convex spot does not appear to be darker than the biconvex in real life.















There is a TON more information I've learned, but its too much for one post. For example, aspheric lenses are good, but have so many weird angles going on that they end up producing a good center spot, but the edges are significantly fuzzed at best. Also, why do smaller aperture biconvex lenses have a radius of curvature less than their focal length sometimes(this seems to be for very short focal lengths)? Why do plano-convex lenses act so differently when you place them outside their designed focal length when compared to biconvex? - all things that make it more difficult to even estimate the proper focal length. Basically I don't know if these new lenses will have too short of a focal length or now and have no idea how to judge.


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## Walterk (Aug 23, 2010)

Nice set up, and interesting questions !


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## eatkabab (Aug 23, 2010)

Walterk said:


> Nice set up, and interesting questions !



Thank you, but I also have one more dilemma I just realized and would like someone to confirm for me if possible...

The products on this page can be used as reference (PDF CAD views):
http://www.thorlabs.us/NewGroupPage9.cfm?ObjectGroup_ID=125


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## Dr.Jones (Aug 23, 2010)

Focal lengths are only easy to use for thin lenses, i.e. lens thickness is negligible compared to the focal length, which is not the case here. With thick lenses, things get more complicated: the effective focal length is measured from somewhere within the lens, and that spot actually is different for the two different lens orientations (with plano convex lenses).
That's one reason why there are two focal lengths given for the plano-convex lens: The back focal length is measured from the plane side to make positioning easier.

About plano-convex vs. biconvex: You have a strongly divergent beam on one side and a collimated beam on the other, and it may sound plausible that an asymmetric lens is better suited for such an asymmetric ray setup. (A better explanation might be that you try to split the required total refraction as evenly as possible between the two refractive surfaces to minimize aberrations.)

I think an aspheric would do an even better job at that relatively low f/#.

About your last post: Maybe it uses a different kind of glass with a higher refractive index?


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## MikeAusC (Aug 24, 2010)

*Re: Double your light output with no extra heat*



eatkabab said:


> *I cannot for the life of me understand why first of all the plano-convex produces a much cleaner spot,*.


 
I think it's mainly due to low angle-of-incidence where the light in air strikes the glass at sharp angle. This is what happens on the outer parts of the lens when we have the lens so close to the LED.

Any imperfections in the surface of the lens will cause great deviation from the ideal raypath when this angle is very low. In a bi-convex lens this angle will always be much lower than a plano-convex lens. 

The ideal to avoid low angles would be a Concave-Convex lens, but I've never had one that I could use to test this out. I do have a Plano-Concave lens that came out of a Video Projector that I may try. 

Although I do have two similar Plano-Convex lenses - one produces a bright sharp image, the other a dimmer softer image ????


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## Dr.Jones (Aug 25, 2010)

Yes, that's what I meant.

However, a concave-convex lens is not the best thing to have in general, but so-called 'best form' lenses are - as long as you stick to spherical singlet lenses: Thorlabs best-form lenses




> Although I do have two similar Plano-Convex lenses - one produces a bright sharp image, the other a dimmer softer image ????


I don't know what those lenses really are, but maybe one is an aspheric? There's a thread on good and bad aspherics with pictures: Another aspheric lens question


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## MikeAusC (Aug 25, 2010)

Dr.Jones said:


> Yes, that's what I meant.
> 
> However, a concave-convex lens is not the best thing to have in general, but so-called 'best form' lenses are - as long as you stick to spherical singlet lenses: Thorlabs best-form lenses


 
I can't see a lot of these appearing in torches - 
- They're $80 even with no AR coating
- They have an Aperture of F1.6 (40/25) - the really bright torch lenses are generally F0.8. 
- These are only collecting a narrow angle of light.
- With shortest focal length of 40mm for a 25mm lens, they make for big torches
- Because the lenses aren't close to the LED, they won't have the low incident angle problem of F0.8 lenses.


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## Dr.Jones (Aug 25, 2010)

That's why you use aspherics for low f/# lenses.
I just wanted to point out that those best-form lenses are the best *spherical* singlet lenses.
Spherical lenses are much more easy to produce in high optical quality than aspheric ones, which is why they still have their use (compared to aspherics).


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## UCLAHutchinson (Sep 20, 2010)

Hi Eatkabab,

It looks like we've been working on very similar projects. I've struggled with the same optics problem and may have a solution for you, or at least some fresh perspective. Please drop me a line at r dot c dot hutchinson at gmail dot com.


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## hazlewob (Oct 19, 2011)

Did you ever finish this project? I might be interested in buying one, depending on the final price.


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## eatkabab (Oct 20, 2011)

I sent you a PM but I'm not sure you got it. There doesn't seem to be a working "sent items" folder on this forum...


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## hazlewob (Nov 12, 2011)

Got it, thanks. I sent you a PM too but I also don't know if you got it and it didn't show in my sent box(I think there is a box we are supposed to check to have it appear there). My DIY light is nearly complete, I will post a few pics and specs when it is finished. It will probably not look as nice as yours because I have just been ordering different pieces and parts trying to make things work trial and error style. My last obstacle is finding a universal mount, I have one for "through the lens" but not for "flip-ups".


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## eatkabab (Nov 13, 2011)

really poor message system on this forum. I sent you a reply...


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## saabluster (Nov 13, 2011)

eatkabab said:


> I sent you a PM but I'm not sure you got it. There doesn't seem to be a working "sent items" folder on this forum...


It's there. When I'm reviewing my messages it is on the top left just under the button for "inbox".


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## Valex (Nov 13, 2014)

Old thread but really interesting!


I'm trying to mod a Maglite 6D with a Cree led and an aspheric lens.


I already bought a CREE XM-L2 emitter module with reflector but I must wait 20-30 days for have it in my hands.
It is write that the reflector length is 30 mm (diameter is 52 mm like the original Maglite glass).
From the picture I can suppose that the led will be 25-26 mm from the edge of the reflector (the lens will touch this edge).
I found two lens with two different Focal length (26 mm and 40 mm) but I'm not sure witch one to buy. These are the specs:
Lens 1:
Outer diameter
52mm
Inner diameter
49mm
Height
24.8mm
Edge thickness
2.5mm
Light transmittance
97%
Optical refractive index
1.474
Focal length
26mm


Lens 2:
Outer diameter
52mm
Inner diameter
46.9mm
Height
19.8mm
Edge thickness
2.6mm
Light transmittance
99%
Optical refractive index
1.474
Focal length
40mm

Could you please help me to chose one?


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