Tight beam: How??

Could someone provide (or point me to) some details about exactly what configuration of bulb and reflector results in a really tight flashlight beam?

Thanks.

Pelican SuperDuperMityLite 2AA

Same with the Pelican Super Sabrelight (3 alkaline C) and Stealthlight (4 alkaline AA).

These lights have very bright tight hotspots for their battery configurations, but very little useable corona. I'd really like to see higher current alternative L/A's for these lights for use with NiMH's.

In comparison to my favorite long throw light, My 9P with 3" Turbo head, the super mitylight has
a more diffuse hotspot and the Stealthlight has a more concentrated hot spot. (I can't find my Super Sabrelight at the moment. Hmmmm.....)

My Big Beam sealed beams and my Coleman 4D combination fluorescent / incandescent lantern each also have tighter hotspots than the Surefire 3". The Coleman, by the way, has a very nice long throw with rechargeables and a Carley #807 4.8 V 1.6 A 7.7W 166 Lumen Xenon lamp potted into a PR base.

The Stealthlight has a MR11 sized, 1 3/8" diameter. This inclines me to want to experiment with a W/A 12.0 V 1.17 A 289 Lu MR11 bulb with a 6 degree beam. I think this assembly might plug in directly to a parallel DB8AA with 5@ CR123's and a 34mm dummy in each barrel and have a run time of 2 hours. I would probably have to grind down the bulb retaining ring on the socket.

This same MR11 lamp assembly intrigues me for project lights using 2@ 6.2 V NiMH A battery packs.

2, 3, or 4 cell C or D Mag-Lite with single Nichia LED PR drop in replacement bulb. This is from my personal experience. The Versalux is by far the brightest of the bunch (2 Cell alkaline only). It is so tight, that it hardly widens with distance.

In the SureFire range, the T1, T2, T3, T4 & T5 Classic 3" diameter reflectors produce very good tight round beams. I'd pick the T2 & T3 as favourites.

The SRTH (2.5" diameter) SureFire TurboHead (from LPS) produces a mean tight beam from a variety of lamps - the N1 & N2 especially.

Al

The best filament bulbed torch I have with an incedibly good tight beam when focussed is a Chinese torch "Tiger Head" Brand, model FT200.
It is incredibly well made and has a bright MES bulb in it. Powered by 2 Duracells it has managed to light up car numberplates and the like from 3/4 a mile away!
I'm not normally a fan of filament torches since being introduced to the delights of LED, bt thiss torch will probably never be modded except to test a screw-in MES LED.
The key to a good focus is to have either an axial filament (*** found in some pencilbeam automotive spotlights, or to have as small a filament as possible right at the focal point of the reflector.
In terms of LEDs there are some incredibly bright and tight-beamed dvices out there with very high mcd figures and 1 or 2 degree beam angles which is almost laser-like. However, although these devices can project an incredibly tight beam, you are left with a small dot of light, which admittedly can be projected long distances but will not illuminate objects that well!
A good compromise is a beam angle of about 8 degrees such as in my Toshiba LED equipped torches. The orange BT2 I built and tested on mmny night walks enabled me to illuminate distant objects such as signposts and render them readable with a small amount of lightspill providing nearfield illumination. THe bst of both worlds was achieved in a single torch.

If I could just refine my original question a bit--what I'm looking for is more like simplified and concise theory about the constructional elements that contribute to tightly focussed flashlight beams. In other words, how do you produce it?

Thanks.

You design a parabolic reflector that takes into consideration the light's illumination source and how this deviates from a single point source. The smallest and deepest parabolic reflector that still will satisfactorily accomodate the source of light will give you the tightest beam. The deeper the reflector, the more of the light produced will be redirected in the reflected beam as opposed to the direct beam out of the flashlight. A secondary reflector in front of the light source can bounce that much more light off the parabolic surface.

- Don

Don: This is excellent (and I enjoyed seeing your website). So, if I may paraphrase and extrapolate, potentially a tube extension with a reflectorized inner surface could be adapted to the front of an existing flashlight to further tighten a beam. Is this correct, or is there a point of diminishing returns where the tube length destroys the parabolic reflector effect?

Finally, can you (or others) recommend a resource (web or otherwise) for introductory material on parabolic reflector design?

Sotto,

Think of the photons as billiard balls and the rule that the angle of incidense is equal to the angle of reflection (no english ) A straight tube will likely tighten the direct beam as more and more photons are likely to contact the reflector as opposed to making it out of the reflector without any contact but once the photon hits the straight wall, it will deflect at a particular angle and regardless of the length of the tube, it will continue to bounce back and forth at this same angle (in theory) until it exits the tube at again the same angle. It will never "straighten" out. In reality, the more times this photon hits, the more likely it will be absorbed by the reflector and not get out at all.

I am not familiar with any resources on parabolic reflector designs but no doubt they are out there. Most cad and solid design software can draw a simple parabola for you. These are based mathematically on a single focal point. I would think the secret is then knowing how to possibly tweak this for a non single point light source.

Once you have a design, you will need someone with a CNC machine to render the part.

- Don

Don:
If I could also ask you to clarify a general principal for me: given a parabolic reflector and a point lightsource mounted on some sort of track running axially from the base of the parabola out through the open end, will the tightest beam occur with the pointsource at the base and the widest beam at the opening of the parabola?

Thanks.

Originally posted by EMPOWERTORCH:
The best filament bulbed torch I have with an incedibly good tight beam when focussed is a Chinese torch "Tiger Head" Brand, model FT200.

Click to expand...

<font size="2" face="Verdana, Arial">have you any pictures of this light ?

Hi Artar,

Tigerhead
It is the second light from the right.

From here.

Thanks bart for producing the picture. Have you got any of these torches?

Thanks Max for the very instructional link on simplified reflector function. It's just what I needed and a good starting place for some experimentation.

I don't know beans about design.

I have some Coleman lights 2D and 3D with big heads that produce some of the tightest beams I know of. The reflectors are rather shallow for their diameter.

Most Mags are ringy and artifacty but go get a 2C,2D,3C,or 3D and put a new Mag Xenon bulb in it. Do whatever you must (I tweak the PR base mostly) to get it perfectly centered. And throw a VERY tight VERY hot spot with a usable Corona.

Ditto get an Eveready 4D Waterproof Lantern and do nothing else but put fresh alkys. Hot spot and nice Corona.

If I could design a reflector I still wouldn't know what to do then!