I don’t know if this is possible and thus the question but is it possible to mount 3 XR-E’s on a concave surface all pointed at the same spot to increase surface brightness over that of one emitter? It would be an additive effect as far as I know.
Put a small collimator lens at that spot and then have a large aspheric at the end of the head in the usual manner.
The portion of the beam from the three emitters that intersect should be much brighter than just one.
The beams (other than the middle one) wouldn’t be pointed straight out but they would hit the collimator lens so the question is would that straighten (collimate) the beam and would the 3 beams intersection be brighter in reality (rather than in theory) than one?
Maybe Dr. Jones will comment on this (along with anyone else).
The build would be more complicated obvious (and beyond my abilities).
If this kind of thing works it would result in a thrower that could be much brighter in a smaller size than the current fare.
The fact that Saabuster hasn’t done it tells me that there is probably a flaw in my logic 
I think the beams will cross at given distance, but they will spread again according to the angle given to them.
I do not think it will work, I think it would be better to use three lenses one for each, as they are very close you can adjust the distance from them to the lenses to concentrate the light on a single point, someone here already did that with three XR-E on 44mm aspheric lenses and it did work quite well.
Did they post a thread here regarding their light? Do you have a link? Were they able to get a higher lux reading than one emitter would provide?
Thanks.
Here you got it:
Thanks. I don’t know how I missed seeing that thread. It’s an interesting approach. It does make for a large light. Due to the inefficiencies of having to grind part of the lenses off it would be interesting to be able to compare a single XR-E R2 at 1.5A behind a 88mmaspheric (if there is such a thing) and this approach.
I’d still like to hear from Dr. Jones if he reads this thread. Yavi, you may be right regarding the beams not being collimated in my scenario but it seems to me that’s what the collimating lens would do.
That’s what the aspheric does in effect as well. It focuses rays coming in at different angles.
Indeed it won't work. The crucial part in your proposal is the collimator in the focus. You want it to redirect light from three separate beams into one beam - such a thing doesn't exist (unless they have separate spectra). A usual collimator lens can redirect light from different directions into the same direction, but at different positions of the lens, so each part of the lens redirects light from one direction forward.
The 88mm aspheric should out-throw that interesting 3*44m light - if that 88mm-lens has a better quality than those 44mm lenses, which might prove difficult. Would be quite heavy, too.
Thanks for the explanation of why the collimator lens in my scenario wouldn’t work.
I can understand how one good 88mm aspheric lens could out throw 3 44mm lenses just based on the lenses.
Why wouldn’t that (3 aspheric) light throw further than a single emitter and 88mm lens just based on the fact that with the 3 aspheric light you also have three emitters rather than one all focusing at the same spot?
Thanks.
because a larger optic could concentrate more light - ie give a higher lux
the 3 lens light might be a whole lot more useful (at least to me) since it would have ~3x the overall output.
a huge lens on a single XRE would be fun, but at that point you're almost better off w/ a defocused laser lol (aside from the color...)
That’s my point however (I’m missing something I’m sure) if the light has 3x the output and that output is directed at the same point then the lux should be 3x higher.
With the one large lens the lux is higher due to the larger lens but the output should be lower(that’s my question I guess) with only one emitter than with three.
So, when you say that you’d rather have 3x the output what does that do for you if the lenses are all focused on one spot if not greater throw?
There are several factors at play in your scenario.
One factor is the manner in which light is collimated. I have the feeling that you are equating focus with collimation.
Focusing is akin to the 'burning the ant,' where the light is gathered into a single point. This is highly distance-dependent. Imagine the light exiting the lens at an acute angle WRT the centerline, converging on a single point
Collimation gathers and sends the light out in a fairly parallel arrangement, and is far less distance-dependent. Imagine the light exiting the lens parallel to the centerline, and continuing in that manner.
Since our collective experience is much more inline with the magnifying glass scenario, it's a normal mistake to make.
Yeah, I now get why the collimator lens at the focus point in my scenario doesn’t work. No one has really addressed the other part of my question though (I don’t think) regarding why 3 emitters focused at one point wouldn’t result in higher lux than one emitter (even with a larger diameter lens).
I don't want to flow into the discussion deeply, because my english is limited. My theory was, that this lens has quite short focal lenght ,and owing to this the the projected die picture will be large. I had good experience with this lens with a single xr-e, and that's the reason why I used this lens for the triple xr-e light. Triple lux value with a relative large spot size.
I don't know what kind of single xr-e+lens combination can produce similar spot intensity and size.
They would, but only at the distance where the beams converge - aka the point of focus.
I thought that was adjustable as well. I guess the adjustment was just to get the beams converged at one fixed point?
If that’s the case then I would think that the one fixed point could be infinity which would still greatly increase the throw.
If focused for infinity, the beams won't converge. Lux remains the same.
If they converge, the do so only at a single distance, diverging before and after.
Why can’t that single distance be infinity?
It can, but the beams won't converge. No increase in lux. I don't know how else to explain it, besides that the beams remain parallel.
EDIT: OK, so the beams are focused for infinity. From where do you calculate lux? There is no point along the beam's pathway where the beams converge, therefore no increase in lux - only a larger spot of the same intensity.
Why can’t the beams be collimated…all rays going straight but they are mounted on a curved surface so they are going straight from the curved surface and they are all focused at infinity so after 100 feet (100 meters or whatever infinity is for those lens) then all emitters are pointing to and focused at the same spot.
You say that there is a spot at which they all converge so why can’t that be infinity? If it is the beams will be overlapping and the lux will be increased.
The three beams can converge into one spot, in that 3*44mm light they already do. And indeed: The spot brightness of the three beams add and result in a three times brighter spot - compared to a single 44mm lens.
The single 88mm lens however has four times the area (again compared to the single 44mm lens) and thus 4 times the spot brightness, since spot brightness is proportional to apparent lens area.
All of the above supposing equivalent light sources and the absence of losses and imperfections.
But at a given surface area, at a certain distance from the source of light there are more (rays) of light passing through than a simple collimated beam (parallel) at the same distance and surface area. Hence the intensity is greater. The difference increases the farther you measure lux.