CR2 ION reflector - how does it work?

liqht

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i know it has been discussed in other threads, but i've never seen a good explanation of how the reflector in the CR2 ION does what it does.

in my opinion, it is perfect, but i don't know how it can work. the reflector is narrow and deep (proportionally speaking), yet the beam is wide with almost no discernible hotspot. how can a narrow and deep reflector produce such a wide beam? i don't know anything about optics, but it seems counter-intuitive

here's one theory i've come up with: the focal point of the reflector is very short, about 1 inch from the light, which means the beam is amost 100% reflected light. am i anywhere close?

p.s. i would love to have a flood reflector for my newly acquired TnC AA 350 - does anyone know if the TnC reflector is swappable, and if so, what would be the appropriate reflector to create a pure-flood beam like the ION?
 

greenLED

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I think what we know about reflectors and beam patterns is completely different between Lux emitters and Cree LED's.
 

idleprocess

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It's a conic reflector:

(click for larger/better image).

The graphic just approximates the concept; it doesn't begin to simulate it with any accuracy. If emission from the light source is uniform, the center of the "beam" will be the brightest and intensity will drop off uniformly from the center until you reach the cutoff for spill due to the reflector/bezel. "Beam" angle will be very wide - about 90 degrees. All flood; arguably quite useful for a personal task light.

I say it's an approximation because I don't know the emission pattern for the xlamp LED used in the ION and I don't know the specifics of the reflector.

A narrower cone will simply narrow the flood and increase intensity in the "beam" but produce no hotspot like a conventional parabolic reflector.
 
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chevrofreak

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Not having a super shiny finish also helps to diffuse the beam further. If you want more throw you could try putting a mirror finish on it with some polishing compound. If you can get the light apart that is....
 

greenLED

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chevrofreak said:
If you can get the light apart that is....
:whistle:

The reason I mentioned the difference in emitters is because I compared the Ion to a Lux light I have (which also has a conical metal reflector, but is highly polished). The beam patterns are different - probably for more reasons that I can think of.
 

Planterz

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If you simply have a bare emitter sending light out the front of a tube (in other words, if you took the reflector out of your flashlight) you get a perfect circle of light, completely even throughout. Interesting beam, but dim because it's extremely ineffecient, with a lot of light lost because it's just dying inside the tube. A reflector, even the basic conical one in the Ion, bounces this otherwised unused light around until it leaves the front end of the tube. The larger the reflector, the more it can focus this light foreward. In the case of the Ion, the light is fairly evenly focused foreward, producing the flood. There is a bit of a hotspot in the center, but it's slight. The Ion's reflector probably isn't the most effecient, especially compared to the parabolic reflectors we usually see, in terms of lumens produced by the LED vs lumens going out the front end, but it works as the designer intended.
 

liqht

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those are some excellent insights, guys, thank you very much.
 

bwm

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idleprocess said:
It's a conic reflector:

(click for larger/better image).

The graphic just approximates the concept; it doesn't begin to simulate it with any accuracy.

Below is a (fuzzy, I know) edge on beamshot of a CR2 Ion.

cr2_ion_angle.jpg


My observations when taking the above photo is that there is a bright cone of light covering an arc of 60 degrees with a dimmer corona covering an additional 15 degrees to each side for a total of a 90 degree wide beam. When I shine it at a wall there is a discernable hotspot but the hotspot is not like the one made by a luxeon where the hotspot has a clearly defined border noticeable when the light is shined against the wall to see the beam pattern.

My MillerMods ARC-AAA has a clear hotspot covering a 30 degree central arc with a bright spill from 15 degrees from center to 55 degrees for a beam width to 110 degrees.

Brian
 
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