Using LEDs with parabolic reflectors...

alpg88

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he was not asking for hard documentation, just some more information on why would TIRs be better than reflectors. that thread has that information.
 

louieatienza

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Silent Thunder Ordinance has a couple flashlights that use TIRs... I suppose you have to like the particular beam pattern they produce...
 

alpg88

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Silent Thunder Ordinance has a couple flashlights that use TIRs... I suppose you have to like the particular beam pattern they produce...

beam profile is something that can be very different in same lights between 2 different reflectors, as well as between 2 different tirs.

yes tirs capture and use more light emitted by led than a reflector, but a good reflector will still be better than a bad tir. in everyday use vast majority of people will not notice a difference, it is when you start building something special, it may matter a bit. we have seen great examples build with reflectors, and lenses. usually lamp reflectors are not that good with leds, but there are exceptions.
in reality there aren't many good large trowing reflectors available for leds. if any. (there are few large ones at kd or dx, i tried 2 different, made for leds, but they were not true spot, narrow flood at best) ledil seanna tir lens is one of the few optics available for leds with an angle like that.
 
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louieatienza

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All the TIRs I've seen are some molded plastic so I'm not so sure of their overall efficiency as to a high end reflector. Also I don't know of any available in larger (over 60mm dia.) so there's a distance limit as well.

I can't see why a catadioptric reflector system wouldn't be more efficient since there is no material but air for light to pass through. The problem is not with the reflector but the throw angle of the LED emitter, which RLT collars try to address.
 

Agpp

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Silent Thunder Ordinance has a couple flashlights that use TIRs... I suppose you have to like the particular beam pattern they produce...

Which ones? I don't see any on their site.

Thank you. Frankly, initially I was disappointed with this thread as I view it as both incomplete and unorganized. But it did contain a single gem: a link to a custom TIR created by Ra:
http://www.candlepowerforums.com/vb/showthread.php?283513-Homemade-67mm-glass-based-TIR-optic!
Too bad the pics are dead. Anyway, it contained some actual numbers (though few of them), his experiments showed TIR to throw 3-5% less than aspheric. Furthermore, my personal pet peeve have been AR coated TIR lenses.
Some people speculate about them. Theory at my basic level shows no problems with implementing them. I searched for them, a lot. I failed to find a single specimen.
Now Ra is a person with enough knowledge to craft a working TIR, that's something. He doesn't say it clearly, but his statement seems to indicate that he has created a coated TIR. And makes it clear that he views it as a thing. This is the most reliable account I've seen so far.
 

alpg88

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All the TIRs I've seen are some molded plastic so I'm not so sure of their overall efficiency as to a high end reflector. .

yes optically clear polycarbonate, pmma and silicone, they are more efficient, since they capture all light from led, not so with reflectors, thou difference in efficiency is not night and day. there are different quality tir, as well as different quality of reflectors.
a clear uncoated glass will block more light than a coated one. but it would seems like coating should be blocking light, not help more to go thru.
 
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Agpp

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yes optically clear polycarbonate, pmma and silicone, they are more efficient, since they capture all light from led, not so with reflectors, thou difference in efficiency is not night and day. there are different quality tir, as well as different quality of reflectors.
a clear uncoated glass will block more light than a coated one. but it would seems like coating should be blocking light, not help more to go thru.
Efficiency = light_out/light_in
TIRs are normally quite inefficient, largely because being uncoated costs them about 8%, with further losses leading to overall ~85-90% efficiency. Note that lights that put a glass lens ahead of the TIR to protect it lose another ~3%.
Cheap alu reflectors have efficiency of about 85% and capture (this differs a lot) 65% of light leading to overall efficiency of ~90% before the light hits the lens and - as long as the lens is AR coated - a total of ~87%.
Overall - they are quite similar when it comes to efficiency.

Being able to capture more light results in optics designer having more control over the beam shape.
 

alpg88

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Efficiency = light_out/light_in
TIRs are normally quite inefficient, largely because being uncoated costs them about 8%, with further losses leading to overall ~85-90% efficiency. Note that lights that put a glass lens ahead of the TIR to protect it lose another ~3%.
Cheap alu reflectors have efficiency of about 85% and capture (this differs a lot) 65% of light leading to overall efficiency of ~90% before the light hits the lens and - as long as the lens is AR coated - a total of ~87%.
Overall - they are quite similar when it comes to efficiency.

Being able to capture more light results in optics designer having more control over the beam shape.

silicone tir 94%
acrilic tir 90%
pc tir 87-89%

reflector 90%



all from same manufacturer ledil, as you see material matters, same with reflectors, reflective coatings are not all same.

i do agree, in normal everyday use, no real difference, but this thread is not really about what is generally more efficient, the guy want to build a spotlight, and as far as availability goes, ledil seanna is the best for that, there is no reflector on the market that will be better for such use. i'm not talking about exotic reflectors, that may or may not work. sure some apparently pretty good, but not easy to get.
 
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louieatienza

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silicone tir 94%
acrilic tir 90%
pc tir 87-89%

reflector 90%



all from same manufacturer ledil, as you see material matters, same with reflectors, reflective coatings are not all same.

i do agree, in normal everyday use, no real difference, but this thread is not really about what is generally more efficient, the guy want to build a spotlight, and as far as availability goes, ledil seanna is the best for that, there is no reflector on the market that will be better for such use. i'm not talking about exotic reflectors, that may or may not work. sure some apparently pretty good, but not easy to get.

Update: CDI sent me an email saying that the Ledil Seanna assemblies I ordered will ship on 12/4... Not bad considering the 6 week quoted lead time.

Efficiency aside, it's a pre-made, engineered product, making it relatively easy to implement. Not exactly DIY but we'll see how good it is in actual use.

Maybe parabolic reflectors are not as efficient, but currently they handle higher powered and larger light sources, something the Seanna line currently cannot do (they only have one size in their line.)

The idea had already been done by at least a couple folks...

http://budgetlightforum.com/node/41545

http://budgetlightforum.com/node/47242
 

louieatienza

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I have a few projects in the works... I started out toying with Fresnel lenses; fun for cheap. I do have an AceBean X80 for wide flood, and a BLF GT70 for some long throw fun. It's great to see people's reactions when I pull it out of the bag!

In the works - an aspheric lens thrower similar to Enderman's OptiForce, a small searchlight wth a retro-firing LED (have some nice parabolic reflectors already), and a light bar for my boy's Jeep for off-roading.

I loved Enderman's SyniosBeam thread and always wanted to build something like it. Have a few LEDs to choose from...
 

louieatienza

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that seems too vague of answer, so i called them, they are not ordering to keep them in stock, this item is not popular, someone placed an order for 2 pc, but they have no eta on that yet. so unless people order, they will not reorder just to keep in stock, as they do with more popular items. can't blame them thou, i used to work in retail, if items sit on the shelfs too long they get lost, misplaced... etc so no surprises businesses do not stock items that do not move fast.

if you need one, 50 bucks may not be that terrible, but if you need several, might worth ordering from cdi and wait.

Just to update, I have received both Seanna fixtures... and as a quick and dirty test I did a makeshift setup with a Black Flat and one 18650 cell. It looks almost like a thin laser beam shooting out of the lens! I do have some White Flats coming in, in both 1mm^2 and 2mm^2. I think the 2mm^2 should have better throw than the XHP35 HI. I do have some XHP35 HI, but have to still set up my test platform (buck/boost driver and 3S LiPo) before I can see what they do.
 

louieatienza

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Which ones? I don't see any on their site.

Storm of Ra - TIR + aspheric lens... Big throw with HUGE sharply demarcated hot spot. I think the best of both worlds, though the beam pattern would take getting used to.
 

Agpp

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Thanks for the info, I haven't seen the TIR mentioned before.
 
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