Focusing Flashlight Beam?

[ApexProxy]

I love how as you guys argue about the point once in a while someone pops in and says "you are both right and why are you arguing?".

IMHO, I do not think the whole argument about the speed of light matters in relation to the main reason that you cannot focus a source such as an LED. Isn't the emitter size like 99%+ of the reason you cannot focus the beam into a tight laser style beam, thus rendering the light speed argument nearly irrelevant?

 

[BShanahan14rulz]

Stop trying to threadjack this thread, Apex. This thread is about the speed of light as it propagates through different materials, not about focusing light from an LED in a flashlight. Learn to read!!! ;-)

But yeah. Main reason is that LEDs are massive. Although if you had a lens that was just as massive, you could attain some pretty low divergence, albeit at the cost of a rather large diameter beam

 

[ApexProxy]

I would like to some day make a giant reflector so I could make a small C6 with an XM-L T6 project a wicked beam.

 

[sedstar]

from a brief period (newbie at flashaholic too, lol) on candlepower forums and budget light forum lurking both places...

an "Ahorton" lens is highly thought of as a means of making a LED flashlight throw a really tight beam a long distance.

I achieved a "similar" effect, by using a eyepiece off of a 6 dollar BBGUN SCOPE... if you have an old 20mm 4x "TASCO bbgun" scope laying around? or you can get one for like 6 bux brand new at walmart...

anyways, the eyepiece unscrews easily... it is slightly tapered, you can use either end to focus the beam larger and smaller. I liked it SO MUCH, i stuck it on the end of one of my flashlights. I USED to have to use a SPOTLIGHT (like a cop does...) to see house numbers when delivering after dark. NOW??? I just use my handheld flashlight.

really, its pretty "neato". I now use it to "spot" deer with, no need to brek out the big cumbersome spotlight for out to 100 yards. This is just a stock over the counter 100-120 lumens flashlight?? it would be even MORE dramatic with a "real" flashlight, lol...

it focuses the "LED DIE" perfectly on the wall, or at distance. Its only a couple degrees "projection".

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even BETTER? TASCO makes a 10 dollar "monocular" fixed 10x power... its for hunters, basically "half" a cheap prism binonular you can toss in a hunting jacket pocket; they are handy.

for ten bucks? I bought one and tore out the "main objective" lens... THAT puppy focuses the LED flashlight when you get the focal length right even SMALLER... and it throws it further and tighter.

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but, still... an "Ahorton" lens is the gold stndard, sort of... but, other lenses when you play with them? Can have DRAMATIC results with a LED flashlight...

your looking for something with a short focal length... if you have anything laying around thats a SHORT optical device, thats usually a good indication. Example, the MONOCULAR i mentioned? its a couple inches long, hence, a short fcal length... a TELESCOPE worls the same, but, it has a l-o-n-g focal langth.

 

[ApexProxy]

I was thinking of doing the same thing for use as a tactical light on my rifle. I found that instead I can use a 660nm single mode laser and break its focus a little so that at range the dot expands and fills my scope's view with red light at hundreds of meters. Its also doesn't break my night vision as bad as white light. I may look for a way to have both now though. It would be nice to have one of each as long as I make them both small and light enough. I used a WF-602C for the laser and I will likely use the same host for the flashlight if I can find optics that will fit into it.

 

[sedstar]

Apex ?!?!

what you describe with the visible RED laser is exactly wht i want to do with an IR laser.

Grrr!

any chance you could PM me any details of what your using? will a generic laser pointer or module with "focus-adjustable" get me several degrees of "spread" like a 'scope degree field of view??

i look at 500 dollar IR ilaser illuminators, and i think "i'm not paying 300 to 400 extra dollars just cause its got a weaver mount on it"...

I have been thinking 2 to 13 degrees of spread/divergece was about right... what are you using? I need details... lol...

 

[ApexProxy]

Got IR I would say the divergence from the diode alone even after optics would have quite a spread. Then adjusting focus as needed I am certain it would work. My laser setup is just using a standard 3-element lens for focus and with it its not hard to expand the beam as needed. Careful about how generic you go with the laser because if you go too cheap the duty cycle may lack as well as longevity. I would even suggest making one custom because then you can make it to your own specs.