# Acrylic ball lens for tight even beam



## McGizmo (Jun 11, 2002)

A simple mod I did using a Techass PR2 shows the effect of an acryllic ball used as a lens:







The PR2 unaltered beam is shown below:





A 1" clear acrylic ball is held up to the light with the distance to paper being the same:





A similar but less dramatic effect is possible holding the ball up to an Arc AAA. By adjusting the distance of the ball from from the LED a very small bright beam can be obtained.

It may be for a single LED light to function as both a wide angle "candle" as well as a narrow bright spot a focusing lens applied to a wide angle LED could perform better than a narrow beam LED with a difussing lens. Certainly with the ball mounted in a sliding tube, an adjustable beam would be available.

The PR2 appears to have a shortened head. This seems to be necessary for the ball to get close enough to the die and to allow for an adjustable focus of the light beam. It would be very interesting IMHO if one of you with good light measuring equipment could experiment with this. The acrylic balls are pretty cheap at places like Tap Plastics and I assume that the LED's can be shaved and re-polished.

The beam resulting from the ball lens is very even in brightness to the naked eye.

Junior science project 1B completed....


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## McGizmo (Jun 18, 2002)

Since this was such a popular post with wide spread comments



I decided to add additional photos:





Above and below, a Luxeon emitter is placed against the 1" acrylic ball.






And below, an Arc SLS on the left and ball lens on the right.






(since I don't have brass ones, I play with my plastic ones



)


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## McGizmo (Jun 18, 2002)

Hey don,
Cool pics! Thanks for sharing them! BTW, I think I know you!


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## Darell (Jun 18, 2002)

Careful there, Don #2. Don #1 is a bit touchy about his mods...

I just have one question: Does the thing bounce when you drop it face-first?


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## McGizmo (Jun 18, 2002)

Excellent rebound, especially on concrete!

Why thank you for asking


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## **DONOTDELETE** (Jun 18, 2002)

Counting the already-manufactured-in optics of the original LED, in effect isn't this a light beam passed through _two_ lenses?

No point being made here, just an observation...


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## Graham (Jun 18, 2002)

Ooh ooh! I was going to post to this on the weekend, but got distracted.

Anyway, while out shopping I found some little 15mm acrylic balls, and remembering Don's post, thought I'd try it. So at home I found some plastic tubing with about a 12mm inner diameter. I jammed one of the balls into a small bit of tubing, and then stuck that on the end of a white Arc AAA, with the ball sitting right up against the LED.

Bingo! A nice even beam circle similar to what you get with the PT Impact.

It sits on the end of an Arc AAA quite well - there is just enough tubing to hold it onto the bezel, but leaving enough space to turn it on and off.

I took a couple of photos but don't have them here at work. I'll post them tonight when I get home.

Graham


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## McGizmo (Jun 18, 2002)

Mr. Bulk, I think you are correct. Or in the terms of say camera types you could call it a lens of two elements. The collimator used on the LS might also be considered a lens so a LS with optics I believe could also loosely be considered a lens of two elements. 

I would however like to point out that my balls bounce much better than the collimater ( I have intentionally spelled collumator three different ways and probably still didn't get it right)


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## bucken (Jun 19, 2002)

I was playing around with an Arc LE and some different lenses a while back. The best combination I came up with was holding a globe-shaped map magnifier in front of the Arc LE.

I was easily able to light up a target backstop in the back yard (after dark, of course) which is about 55 yards away from the back of the house. This was also while shining the light through some heavy glass sliding doors (I was inside the house). The amount of light didn't have near the same authority as say a Surefire E2 would but, nonetheless, it was still quite impressive.

On the negative side, the map magnifier is about 4" diameter, and you had to hold it about 4" away from the front of the Arc LE to get the best beam. The beam could almost be described as a huge laser beam, with no light spillage outside of the beam at all.

I have some small, clear marbles but to get the tightest beam, they still have to be held slightly in front of the Arc. Does anyone know what might happen if maybe a third of the marble was ground off and polished. Would that make it focus the light better while being held (hopefully attached) to the front of an Arc?

I don't think that any lense small enough to attach to an Arc LE could possibly duplicate the power that you can get from a much larger lense but, if we put our heads together, maybe we might come up with something practical.

-bucken-


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## McGizmo (Jun 19, 2002)

Bucken,

I think that you will find that a hemisphere, 1/2 of the ball will will also work but give a sliightly different beam angle (wider). The farther you are from the LED, the larger the diameter of the lens needs to be to catch all of the light from the LED and redirect it. With the chopped head of the Techass PR2, the ball lense seems to be able to get on the other side of the focal point of the inherent lens in the LED itself. This allows for the external lense to be adjusted in relative position and vary the beam angle. What impressed me the most is the evenness of light distribution with in the circular beam pattern as well as the abrupt cut off from light to no light. ANyone with a luxeon star w/o optics can see that an external lens can be brought close to the LED and a very impressive beam pattern can be obtained. These plastic houses also sell hemispheres of acrylic to be used as legs on acrylic boxes.
The curvature of the surface of the lense and refractive index of the material dictate how much the light is bent as I recall from HS physics (many years ago). With this simple ball, much of its mass is unnecessary for the same beam result. A M&M shaped lens where you would take the two curved surfaces and bring them closer together would also work. I suspect that a freznel maginfying glass could also provide an interesting beam. 

With an incandesent light source that is sending out light at all angles, A parabolic reflector is required with the light source at the focal point to catch all light and re direct it in a beam. The LED's already have the light directed in a more defined beam and therefore I think a lens can effectively be used for further re-direction.

Note: the above information is speculation based on impaired reasoning and understanding.


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## Darell (Jun 19, 2002)

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by McGizmo:
*
Note: the above information is speculation based on impaired reasoning and understanding.



*<HR></BLOCKQUOTE>
Damn. It sure was a lot of words though. I was *really* impressed right up until the discaimer.


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## McGizmo (Jun 19, 2002)

Leo,
I don't have any of the hemi-spheres but I have chucked a ball in the lathe and turned a flat and shoulder in a ball to get it to sit into one of my Tri-clusters. It worked fine but since there are 3 LED, I got three distinct round dots of light on the wall. Too narow of a beam for the application. You can use these lenses to see the ugly die pattern in the LED if you set the focus wrong. I am confident that a flat surface against the LED will allow for more ligght transfer through the lens. If the angle of incidence is too great ( Angle of light hitting the lens surface) the light will bounce off the lense instead of going through it. I suspect that if the ball were drilled to mate to the LE as the collimater does, the maximum amount of light would go through the lens. 

As I've suggested above, these ideas should be tested with good light reading equipment to see what loss in light occurs. As we have discussed off forum, Design around the emitter instead of a star allows for more options in the design of the mating surface and configuration of the "host" structure of the emitter. The existing collimator or other type of lens could be added to the emitter as desired.

I really like the idea of a glass lens as it would serve to filter out damaging UV from the ambient as well as provide a long lasting, non yellowing lens for the light. If we are going to be messing with this stuff, why not mess with the directivity of the photons as well as the number produced. ( yes, I'm refering to the particles D)

- Don


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## hotfoot (Jun 20, 2002)

I really need some acrylic balls now...

Don, any chance you've got beam pics using the acrylic hemispheres you were talking about earlier? Another thing to consider is the transmission losses thru the acrylic itself. Even the standard PMMA NX-05 optics that come with the LS/O doesn't have that great a performance. How would a large mass of acrylic like that fare efficiency wise?


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## bucken (Jun 21, 2002)

FWIW... I have learned that a small fresnel lense works nearly as well as the much larger globe-shaped map magnifier! The fresnel lense is thinner than a credit card and about the same size (in fact, I carry it in my wallet where I almost forgot about it).

On the downside, however, I have to hold it about 8 inches away in front of the Arc LE to get the most powerful beam. Hmmm... That's also about the same distance that I have to hold it away from a page of small print in order to read it the best. I think I remember seeing some fresnel lenses somewhere that just lays flat on a map and everything looks bigger without having to hold it away from the page. Wonder if something like that might be better?



Does anyone have a different fresnel lense they could try?

-bucken-


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## Saaby (Jun 21, 2002)

Just a little history lesson, thats because the fresnel lens was invented to replace roundish lenses. The round lenses (globe I guess, round implies flat I guess, mathmatically anyway) were large, heavy, and broke easily, that is the reason for all the consentric circles in the fresnel lenses...

Since we're on the subject of lenses I'll talk for a moment about stage lighting, maybe if we all put our heads together (ouch!) we'll be able to get something practical out of it.

There are 3 main types of lighting instruments, PAR cans, Fresnels, and Elipsoidal Reflector Spots, hereforto known as ERC.

Par cans are just that, a can that you stick a large parabolic bulb in, you can use the same bulbs as you use in outdoor flood lights. No focus, most LED lites seem to be running on this concept.

Next is the Fresnel, it's a little more advanced, they have a frenel lens in front of the bulb (hence the name...) and then there is a large cleap bulb inside the lamp on a mount that can be moved towards the back of the lamp or towards the front, there is also a parabolic reflector in the back of the light housing...moving the lamp away from the lens causes more of a spot, moving it closer to the lens gives it more of a flood.


The most advanced type (And therefore the most expensive...) is the ERS. This uses a huge reflector and lots of lenses to give you a highly focused beam of light. You can make the spot larger or smaller but it stays a beam. You can use shutters to cut out the beam on the edges among other things...these are an electricians best friend.


Some sort of fresnel lens would make a great flashlight lens, you can get a highly focused beam, or a nice flood. You would need a way to move either the LED or the lens, fortunatly many lights (Think Mini-Mag and I'm not even bashing it) have a mechanism like this already. How about a tiny precision engineered fresnel lens made out of Lexan? That would be sweet!


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## McGizmo (Jun 21, 2002)

Some related thoughts/ comments. It has been mentioned in another hot running thread that dimpled reflectors are more effective than highly polished reflectors. They are more effective in bluring the imperfections and inconsistancies in the light source. 

Mag's reflectors deliver a very efficient level of their light to target but mirror the imperfection of the light source as well. Hence, BU beam that is criticized relentlessly here in CPF. 

I think the dimpled reflector is akin to the nylon over the lens of a camera to soften the picture. In fact, has anyone tried shooting a flashlight through a fine mesh, like some nylons? "Pantyhose beam shaper warms colors to fall fashion"





Any way, whether the light is redirected via reflection or refraction, loss will occur to the extent that the material used isn't perfect. From what little I can gather with only visual evaluation of photon re-direction, I think shaving and re-polishing the head of an LED coupled with an optics qualiity glass lens has the best chance of yielding an evenly defined and dispersed beam of light from a single LED.

With the LS, I think a bare emitter coupled to a glass lense could yield a directed beam of light similar in intensity to the collimator. For mods and durability, A glass lens might be easier to inccoporate into the flashlight head and would not be as prone to scratches and wouldn't yellow over time. 

I have a fresnel magnifying glass as well but the magnifying glasses of either format are not powerful enough to effectively 
redirect the light in the fashion we are after. I've been meaning to test a jewelers loop but keep forgetting to. There are some inexpensive glass loops of high power magnification that might provide a viable lens.


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## Saaby (Jun 21, 2002)

I've got it...a glass lens of some sort (Perhaps fresnel but whatever) or maybe Lexon, since it's nearly indestructable but I don't know how well a lens it would make, anyway..in a housing like on flashlights where you could turn something (In this case the head) and have the lens move closer or further away from the bulb. The lens would be set back enough that it would be more or less protected from most scratches and such.

Another way to describe it is a combination of binoculars and a telephoto lens...get it now? If not go expose the film in your telephoto camera and watch the lens go out and in from the inside of the camera...


**EDIT**

Ok tried it witn some 20x-125x Bincoculars and it kinda worked...I had to use my non-led Noric with the headcap still on it which affected performance a little I'm sure

I tried a few different configurations and the one that finally worked was shining the light backwards through the binoculars which made the light cast a very nice very even "beam" of light on the wall, when I moved the zoom thing the light got more spread out...wasn't very bright but that could've been for many reasons.


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## McGizmo (Jun 21, 2002)

In conjunction with some experimenting on Luxeon Emitters, I took some shots and some light readings of a LE with the collimator as well as a 1" ball lens. You can see some info and images HERE

To determine relative efficiencies of various lenses and reflectors would require a system like Craig has as well as a more controlled light positioning mechanisim. 

The more I have played with the Luxeon LED's the more I can appreciate the challange faced by anyone making drivers for them. Inconsistancies in color and and working volt/current relationships from one LED to the next would make it tough, IMHO, to predict the results of a random selected Luxeon coupled with a designed circuit. I am in way over my head on the electronics side but it looks like you have to have a circuit that will give you a specified current while the voltage may vary.

I have seen it stated here that " Your mileage may vary"....... It might be more appropriate to state: "Your illumination may vary"....


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## McGizmo (Jun 21, 2002)

I forgot to mention here on the post that the ball lens provided a 50% brighter reading than the standard Luxeon collimator; 4890 Fc VS 3090 Fc at beam center. This is primarily due to the tighter beam. I tried a glass jewelers loop and it also tightens and cleans the beam; not as much as the collimator or ball.


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## Graham (Jun 22, 2002)

Ok, I had said I would post the pics of what I did with the acrylic ball and an Arc AAA, here they are:





Just a 15mm acrylic ball attached to the end with some narrower plastic tubing





Slightly blurred close up





The resulting beam, at a distance of about 1 foot or so - the beam is actually quite visible at a distance, has a better 'toss' than an unadorned LED..
I kind of like it..

Graham


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## JonSidneyB (Jun 22, 2002)

hmmm, very very interesting thread.


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## JonSidneyB (Jun 22, 2002)

Hey McGizmo, What the heck is that brass thingy you got there? I need one of those.


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## Al (Jun 22, 2002)

Thought I'd plug in this link to Edmund optics. They offer both glass & sapphire ball lenses. Half-ball lenses (collimating) available too. Curiously, the sapphire variety seem to be the more inexpensive.
http://www.edmundoptics.com/Find/Find.cfm?query=ball+lens&col=IOD_ProductSearch 

Light transmission characteristics will probably be better than acrylic material?


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## Graham (Jun 22, 2002)

Interesting link, but I think I'll stick with my acrylic balls. They only cost about $0.50 each..

Graham


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## Al (Jun 22, 2002)

*Interesting link, but I think I'll stick with my acrylic balls. They only cost about $0.50 each..*

From where?


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## Graham (Jun 22, 2002)

From a DIY/handycraft store here in Tokyo. They sell all sorts of stuff, including acrylic in various shapes and sizes. Matter of fact, I'm so impressed with my Arc AAA one, I'm going to see if I can get some bigger ones tomorrow to try with my Arc LS..

Graham


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## McGizmo (Jun 22, 2002)

Graham,
Nice photos of the Arc AAA. Don't bother with a larger ball lens on the Arc LS; you will get a very strange, unusable beam. The ball lens needs to be close to the LED itself. The collimator won't allow that.

Jon,
What brass thingy are you refferring to?

Al,
Nice resource on Edmund optics; thanks!

I see that ElektroLumens has started a new thread where he is using a lens(es) for an adjustable beam on a LE. Cool!


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## Graham (Jun 22, 2002)

Thanks for the tip, Don. 

I was playing with my Arc AAA w/b last night, and it definitely gives a much better beam with a nice useable field of light at a distance, better than without. Its an eerie sort of searchlight effect.

Anyway, I think this is a very useful little add-on.

Graham


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## dat2zip (Jul 30, 2002)

I read this topic a while back and I finally got over to the store and picked up some balls. One size dropped right into my Luxeon minimag and produces a nice tight beam. I don't have a beam shot yet, but, here is a picture of the flashlight.







Here is a beam shot. Excuse the camera tilt.
The ball is 0.75" in diameter.






It is shot with a -2 exposure. There is a large fringe on the standard Luxeon and NX-05 optics.

Another picture at -.5 exposure setting.





-WayneY


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## McGizmo (Jul 31, 2002)

Wayne,
Nice photos. Judging by the washed out lines, It would appear that the ball actually provides a wider beam of high enough illumination to washout more of an area? Have you measured the center hot sopt with a meter? We need to make a polished countersunk can that fits down on the emitter base and grabs the light shooting out sideways and hopefully directs that as well into the ball. I believe I'm echoing JR here 

- Don


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## dat2zip (Jul 31, 2002)

Don1 or Don2??,

I did some light measurements with a half used set of batteries. The regular mod'd flashlight measured in around 205CD and with the acrylic ball it measured 350 at the hot spot. I did not measure all around the center area, just looked for the peak reading.

Hmmm, wonder if it would be blinding bright with a new set of batteries. 

Better stuff some fresh batteries in my pocket.


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## JollyRoger (Aug 1, 2002)

Nice pics, Wayne! I really like that effect....must try it....


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## moraino (Aug 6, 2002)

> Originally posted by dat2zip:
> [QB]I read this topic a while back and I finally got over to the store and picked up some balls. One size dropped right into my Luxeon minimag and produces a nice tight beam. I don't have a beam shot yet, but, here is a picture of the flashlight.
> 
> Wayne,
> ...


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## Wingerr (Aug 6, 2002)

For a less-than-portable lens, try shining your lights through the Watercolors crystal ball; it puts all the light into a tight beam for the same Dorcy Cool Blue/ Turtlelite I effect.


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## dat2zip (Aug 7, 2002)

moraino,

Correct, You remove the collimator, and the front bezel lens. The ball just sits in there like it was made for that flashlight.

-WayneY


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## hank (Aug 8, 2002)

>polished countersunk

That makes sense -- drill halfway into the ball for the LED, then turn that back half of the sphere into a parabola so it acts as a reflector?

Maybe simpler to stick half a sphere on top of the normal plastic reflector in a MiniMag.

Who has spheres or half-spheres the right diameter to drop into the various small maglights? Tap plastics?


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## McGizmo (Aug 8, 2002)

Hank,

Wayne and I have purchased acrylic balls from Tap. I believe they also have hemispheres as well but have not been to a Tap store in some time. The 3/4' ball is what Wayne has used on the mag AA. I have also messed with 1/2" as well as 1". The larger the diameter, the tighter the beam.

- Don


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## ElektroLumens (Aug 28, 2002)

> Originally posted by McGizmo:
> *Ball Lens: Beam Shot Bump................... ( seems to be new interest)*


<font size="2" face="Verdana, Arial">Yep, they're totally cool! I call them 'crystal optics' !





Wayne J.
www.elektrolumens.com


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## hank (Aug 28, 2002)

>the larger the diameter the tighter the beam ...

Are you able to cut a slice off one of those larger diameter balls to make a, um, whatsit, half-convex? flat side and convex side -- leaving a piece with that radius curve on the front and a 3/4" diameter flat side? I'm wondering if you need the whole larger diameter ball, or just a lens with that radius curve.

Or maybe you need a biconvex lens with that radius curve but not the middle of the larger sphere; just itching to get these into use.

I guess it's time to look into the optically clear glue used to assemble compound lenses -- balsam-something? And see if it can take the heat of a close up LED.

Someone must have access to a computer set up for optical design; I've read that the reason cheap cameras take good pictures nowadays is that lens design has become much cheaper due to computation.


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## McGizmo (Aug 28, 2002)

Hank,

As soon as you flatten one side, the beam angle increases. These balls are incredibly inefficient as you can see side light spilling out and yet the beams get higher readings than the collimators. As I stated in an earlier thread than this, I think some well designed optics and or reflectors will give us beams from the luxeons that we can only imagine at this point. The big guns are working on these things now. I spoke with an old aquaintance on the phone yesterday whose company is currently focussing on the transportation industry with 1 and 5 W luxeon lights. They have optical engineers working on photon management with sophisticated computer aided equipment. For an idea of their size, when ramped up, he says they will be going through 20K luxeons per week!

- Don


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## McGizmo (Aug 29, 2002)

Ball Lens: Beam Shot Bump................... ( seems to be new interest)


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## ElektroLumens (Aug 29, 2002)

> Originally posted by McGizmo:
> *Hank,
> 
> As soon as you flatten one side, the beam angle increases. These balls are incredibly inefficient as you can see side light spilling out and yet the beams get higher readings than the collimators. As I stated in an earlier thread than this, I think some well designed optics and or reflectors will give us beams from the luxeons that we can only imagine at this point. The big guns are working on these things now. I spoke with an old aquaintance on the phone yesterday whose company is currently focussing on the transportation industry with 1 and 5 W luxeon lights. They have optical engineers working on photon management with sophisticated computer aided equipment. For an idea of their size, when ramped up, he says they will be going through 20K luxeons per week!
> ...


<font size="2" face="Verdana, Arial">So, these new Luxeon Star LED's are the 'Light Wave' of the future? 

I have heard that the current Luxeon Star optics lose about 15% of the light. I have also heard the a reflector will lose about 10%. The more glass or plastic to pass through, the more the loss. Also, light is lost as it reflects off the surface instead of passing through.

Considering these are simply spheres, it is amazing they do what they do.






Wayne J.
www.elektrolumens.com


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