Dedoming XR-E R2 in aspheric Solarforce L2 for more throw?

[bshanahan14rulz]

Yes you will have a more narrow beam.
But I don't see why it would result in higher candela.

I meant widening the beam, which would reduce the lux but also reduce divergence, right?

Mentioned experiences tell otherwise then your binoculars suggestion, unless you found 100% optical efficiency, which would be a doubtful claim at least.

You would have higher 'perceived throw' only if you express throw as a ratio between candela and divergence.

This is why "throw" pisses me off. Nobody says what it is, it's some subjective term that can mean lots of different things to different people. To me, it is a laymans term for low divergence.

With 'correcting for abberations by additional lenses' you can't get more efficiency from your your system as the weakest link.
Not from emperical, theoretical nor holistic point of view.

Too many big words for me, but I think you are saying that adding lenses will reduce the efficiency of the overall system. Yep, I agree. I'm saying sacrifice some optical efficiency and beam diameter to decrease divergence. Also, binoculars aren't meant to be super efficient, just to be accurate, so the comment above about my owning some fancy 100+%

[Walterk]

binoculars aren't meant to be super efficient, just to be accurate

Binoculairs can only be as accurate as your eye can interpret what the lenses brings you.
Light gathering is the most important to deliver contrast, so you distinguish shapes and colours.
The bino's and telescopes with highest magnification ( read smallest beam angle) have the lowest lightgathering.
Just like flashlights, entry and exit apertures determine lightgathering / lux.
Bigger diameter exit lens give higher lightgather / lux, higher magnification / narrow beam comes from smaller oculair / led-die.

Huygens used only 2 lenses in some of his telescopes, and he got plenty magnification. So don't overdo with lenses.

I agree that efficiency is no argument as long as the beam is satisfying.

[fyrstormer]

How could removing the pre-collimator lense on an XR-E possibly improve throw? It will let more light go to waste. I understand that throw is affected by the size of the die image facing the outermost lense, and de-doming the XR-E will reduce the die image. However, throw is also affected by the amount of light exiting the flashlight, and de-doming the XR-E it will also cause more light to be lost against the inside walls of the focusing chamber. The size of the beam might be smaller without a dome, but it will also be dimmer, given the same power consumption. I don't see how there can be any significant improvement one way or the other. The only significant difference I can think of is the size of the beam, and I would think a wider beam from a dome-intact XR-E would be more useful for seeing distant objects, since distant objects tend to be kinda small due to perspective.

[bshanahan14rulz]

Walterk: Thanks for those examples of real-world multi-lens optics. I understand now why binoculars are summarized by their collecting lens size and magnification. So, to have a good contrast and high magnification, you'd need very unwieldy, large lenses at the end and big space between the large lens and the eye lens. So I guess the main reason they use more than two lenses is to sacrifice overall efficiency for a more compact handheld device, since with each added lens more losses are introduced into the system from absorption and reflection?

In the laser hobby, the most widely used lens system is a galilean beam expander, due to its simplicity. The main drawback to these are that to achieve lower and lower far field divergence, you have to use larger and larger lenses, and/or larger gap between the two lenses. I can barely ray-trace a single lens, not to even mention 3 or 4, but I would guess that if compactness were an issue, there should be ways to add lenses to reduce the length of the system while increasing losses in the lenses?

Thanks for the insight, trying to learn optics hands-on without having any known optics to play with, maybe my next project should be classifying and measuring my lenses.

fyrstormer:
I think that is the meat of the question here. Dedoming the LED will provide a smaller source, and we can better collimate it. However, the loss in lumens from both a more lossy light extraction from LED package AND a larger "cone" of light exiting from the LED would both contribute to a lower overall output has the potential to cancel out the benefits of dedoming for a smaller source.

[fyrstormer]

So I'm inclined to say, if de-doming lets you move the main lense closer to the emitter surface, then it might be an improvement; otherwise, it's not likely to make any difference.

[DIWdiver]

If you want to increase throw, dump that piece of c---- DX aspheric and put in an Ahorton. It will gather vastly more light. The focus is a few millimeters from the lens, instead of tens of millimeters. Having tried both personally, I can say the difference is stunning.

And before you ask, no, I didn't take beamshots. I took one look, dropped the DX in a box and haven't picked it up since. I dove my light with Ahorton aspheric and XML the last two weekends. Awesome!

[Walterk]

@bshananan: Well you brought the binos up . Have you tested it yet?
Google binoculars at laserpointerforum and you'll read some experiences: decreases throw, decreases divergence.

Awaiting my shipping from Trout for the Ahorton's lens but he must be busy cycling or something...