Reflector Dimensions vs Beam Shape?

[kosPap]

hello all!

this things is bugging me for a while now...

1. What is the effect of a reflector that is larger in diameter than another one,when both have the same depth?
2. What is the effect of a reflector that is deeper than another one,when both have the same diameter?

My understanding is that a wider produces a more tight hotspot while a deeper one puts more of the corona/spill on the hotspot whatever the hotspot's size size.

I would really like to explain me the way the Ultarfire C2 (a rather wide shallow one) and the MiniMaglED (a narrow but DEEP one) work....

thanks a bunch, Kostas

 

[yaesumofo]

As a guess I would say the net effect is about the same. a tighter beam.


Another thing to considder is the emitter's location relative to the focal point of the reflector.
If you look at a MAG flashlight you can adjust the place ment of the emitter the beam goes from wide to tight back and forth as the emitter passes through the focal point of the reflector.
In the end the MAG reflector produces a very tight beam.
if you were to create a wider reflector of the same shape you would get a tighter beam. if you create a deeper reflector I beleive you get a tighter beam as well.
if you make a shallow reflector it will be a wider beam. if you make a wider and shallower reflector it will be wider as well.

This is off the top of my head using examples of lights which are patterned in my brain.
I am not sitting here with a five mega elephant and an aleph a19 cree.
my point is that I could easily be WRONG so please to be too harsh if I am. there ideas are just a starting place for discussion.
The Guy to ask is McGizmo. He is as close to an expert on the topic as we have here I beleive. He has designed many reflectors.


Yaesumofo

 

[joema]

1. What is the effect of a reflector that is larger in diameter than another one,when both have the same depth?
2. What is the effect of a reflector that is deeper than another one,when both have the same diameter?...

This is an excellent question. I have asked it myself many times, and never gotten a definitive answer.

Observationally, the beam angle seems related to the ratio of reflector diameter to emitter size. E.g, a Surefire U2 with a large Luxeon V emitter requires a larger diameter reflector to achieve the same beam angle as a Fenix P3D with a smaller CREE XR-E Q5 emitter.

A large WWII searchlight could produce a tiny beam angle of 1.5 degrees, but the reflector was about 1 meter diameter.

The reflector depth (or focal ratio) is also related, but I don't know how. In parabolic telescope mirrors a deeper mirror (lower f/ratio) produces a wider field of view. A parabolic flashlight mirror is like a reflecting telescope in reverse.

This implies a deep-dish flashlight reflector would produce a wider beam, but I don't think it works that way. A deeper reflector might limit the spillbeam angle.

 

[LukeA]

Hope this helps

 

[Crenshaw]

but the mag plunger had a massive diameter reflector, and it was a thrower...


the hotspot on the C2 is insanely small...

Crenshaw

 

[LukeA]

but the mag plunger had a massive diameter reflector, and it was a thrower...


the hotspot on the C2 is insanely small...

Crenshaw

With a larger diameter reflector, a light will throw further than one with a smaller diameter reflector, regardless of depth. This is bacause the emission source appears closer to the ideal point source in a larger reflector than it does in a smaller reflector.

 

[kosPap]

Observationally, the beam angle seems related to the ratio of reflector diameter to emitter size. E.g, a Surefire U2 with a large Luxeon V emitter requires a larger diameter reflector to achieve the same beam angle as a Fenix P3D with a smaller CREE XR-E Q5 emitter.

I have heard it before in this forum, that time regarding the incan bulbs filaments being horizontal or poerpedicular. Doesn't this describe the L4 spill abd puts more points in Luxeon Rebels?

Also I think I know how the Ultrafire C2 reflector works. It is a big one and redirects the side part of the LED beam inwards toward the hotspot. but since the reflector is also shallow, the mediddle part of the LED beam escapes....Am I assuming correctly?

cheers Kostas