meant by "focusing" in advertisements...

[sedstar]

I figured optics was the bst place for this n00b question... when llooking online at laser pointers, naturally the better ones brag they are "focusable"...

sellers dont really ELABORATE on the amount of "focus"... or, in MY case... the amount of DE-focus, lol

As i wnt to end up with a serviceable Laser IR illuminator... what amount of "focus" is in play here, typically?

as an example? with my LED flashlight, i fooled around with optical lenses, and got a small lens housing mounted onto the end of my UF 501B light... the light itself is nothing special at all... but with the LENS??

sure, up close, at my feet... theres just a super bright SQUARE of light... basically just a focus-ed "emitter"... but, the focus is pretty tight, lol... i can project a square of light onto a house 100 yards or more away...

jus kinda wondering wht amount of "focus" there typically IS with a higher powered laser pointer? I REALIZE you guys are ito focusing it TIGHT, i rather wanna go the OTHER way, naturally... to have a workable IR illuminator...

 

[Speedy78]

If anything removing the lens will get you that IR flood light for iluminating.

 

[sedstar]

quote"removing lens... get... the flood IR light"

answer: yes, i figure. I suppose i am not ALONE in that i end up somewhere like HERE, after seeing a "really cool project" someone made on the WEB, and had good documenttion and pictures of the "really cool project", eh?

in MY case, i ended up finding "Lucid science" project which was the guy wnted to hook a night tie security cam up to a rifle scope, and illuminate a house 200 feet away while filming it thru the rifle scope/securty cam setup.

for his project, he used a fiber optic coupled laser diode, but, he also demonstrated all of his project steps with a visible diode (so it was photographable). With the LENS off, it sprayed a wall of light across the room. REALLY, this reminded me of a LED flashlight with a LED emitter... with the reflector off, the light maakes a nice FLOOD with no "throw". Reflector size and design gives various flood vs. throw setups... but... to REALLY project a throw, you have to use a LENS.

which is what lucid science did, he played with lenses until he got one that "threw" his laser IR light a good distance.

I was THINKING i vould just power up a coupel hundred mA ir-laser diode, get the WALL SPRAY... and use a LENS to get the THROW i need... but i really dont know anything about lasers, and if i can "deal" with raw laser light in the same maner i can deal with bright LED emitter light.

really, on some basic level... when i look at a commercial IR laser illuminator? It APPEARS as if its just a laser diode, the housing is the power supply and battery power... and there is a thick LENS in front of it, with moveable focus...

....but, appearances can be deceiving, i know this... I just cant get over the idea that a commercial IR LASER ILLUMINATOR is a 50 to 100 dollar laser IR diode with a LENS and focusing mechanism similar to a projector or slide viewer... and the companies are charging 600 dollars for this rocket science.

the LUCID SCIENCE project really got me excited when i went and looked and found out i can buy a laser diode of impressive power (500 mA..) fairly cheap...

you mention taking the LENS off of a common laser pointer? Is the emission angle then, without lens, similar to a LED emitter? LIke 120 degrees or thereabouts?

 

[Speedy78]

Without the lens woukd be good for iluminating something up close. Depending on how far what you want to illuminate is from you a defocused or over focused diode woyld be better. I imagine the ones that are focusable online are designed to get a pin point a few centimeters from the lens for burning and what not. This will actually give you what you are probably looking for at a distance. The light would esentialy cross over itself and produce a tighter flood type thow than a bare diode. And if all else fauls ypu can build what you are looking for into a host of your liking.

 

[sedstar]

"crossing over"... yeah, you lwys in textbook explanations of cameras/lenses... the classical diagram is a long thin "x"... the x spot being a focal point, if memory serves (i'm no camera guy, lol) on a "classical" (spherical) lens, you have 2 of them... one in the "back" and one out in front.

in a camera, a LARGE area far away comes in at a shallow angle, crosses over just in front of the film (sensor nowadays). other lenses overcomplicate the system, but for the purposes of projecting light, are relativeky inconsequential. (i think anyways, lol)

I'm just doing it all in reverse... the "film" (or eye, if the diagram is a simple telescope) is the small bright light source, its thru a singoe lens (no image erection eyeiece needed) and playing with random lenses and random lights outside at night (god, my neighbors must TREASURE me, lol) I easily SAW the focal point, out in front of the lens (foggy night, lol)

different lenses hve different focal points, and i tried all i had. The BEST was a telescope with everything but the main objective lens out of it (tube was a good mount for lights)... and the most EFFICIENT was a eyepiece lens off of an old bbgun scope.

the bbgun scope lens, fits really well on the end of my ultrafire P60 flashlight, heh heh... it throws/projects the focused LED EMITTER image quite a distance quite well.

SOMEONE on here in a different thread discussing lenses an optics? Gave me a bright idea (pun intended, lol) to use PVC pipe of differing outside diamaters fitted inside one another to move back aand forth for aa crudely centered focusing mechanism.

I aalso wanted a different lens, and found a 10 dollar pocket telescope thingy for hunters... gutted it for the main objective lens... wrapping thin static foam around the lens holder tight made it stick squarely in the end of the BIG tube, and my p60 flashlight fits okay in the smaller tube, and they move in and out pretty well...

the shorter FOCAL LENGTH of the pocket telescope objective lens was great, less movement for focusing... this worked best so far practicing with a LED emitter flashlight amyways... before, i was getting a 1" square "LED EMITTER" focused image really bright, focused on the wall a coupel several feet awy... 20 feet awy t was a couple inches big.

THIS setup, with the 10x main objective short focal length lens? from a couple feet away, its REALLY TINY (and bright!) and from the 20 feet across a room and a half i use to focus up farther? Its QUITE noticably smaller (but perfectly foused) image of the LED emitter.

smaller image at same distance? should mean my "projected LED emitter image" at longer distance will be smaller too. Smaller projected light image = same amount of light but in a smaller area = "brighter"

I'm only playing with visible light LED p60 flashlights, for a couple reasons...

1) the LED itself is quite small of a point light source... approximates the tiny "source" aperature laser light will come out of, i figure.

2) visible light is easier to fiddle with to get lenses and focusing set up with.

3) visible light from a LED emitter is not nearly as dangerous as messing with IR laser diode output, LMAO

4) LED emitters produce a narrow band of light frequency, as do lasers... i FIGURE what "works" raactically with a visible LED emitter, should more or less work with a Laser diode.
=============================================================

i am *thinking* that using a p60 LED emitter flashlight, with the reflector removed, will be substantially similar to using a laser diode, IE, super-wide angle "flood" no throw... its my hope anyways. Th way this setup is working? I still have to TEST it (it is getting dark now, lol) but i am confident the smaller image at same distance is better for longer distance.... i figure i just replace the PVC 2 pipes with 2 metal tubes, one threaded inside the other, for infinite focusing... i suppose if i choose my LSER DIODE corrctly, it should mount up in a p60 flashlight decent...

makign going from mock up to test unit pretty straightforward. switching over to threaded metal tubes will also be better for HEAT conduction, lol.

==============================================================

my only main concerns right now are...

1) last time i replaced a visible LED flashlight with a IR LED p60 drop in? I could "focus up" the LED EMITTER in IR, and got an image on the wall with my camera, but, it was VERY faint and dim... actually the IR emitter was supposed to be hotter than the visible LED 960 stock unit.

2) I get "some" chromatic errors when i lens-project vivible LED light... the crisp white light from my p60 flashlight? after being tightly focused, there is bands of pale yellow thru the image projected... no big deal with a vivible light throwing project, but, that "shift" from a cheap lens from crisp white to some pale yellow... i dont wanna "color shift" the IR light, as the band from 800 to 900nm is fairly slim.

PS - this is going swimmingly well, for now... i am REALLY GLAD i found this place... just someone mentioning the PVC tubes for focusing?? made this whole thing a LOT easier... it worked with a BONUS...

when i moved past "focus point" and over focused? I got a fairly bright circle of light for "close in" illumination, and moving back and forth at the post/pre focus point, made the circle of light smaller and larger, heh heh

(this will be important when using the laser diode, as they are so dang BRIGHT, it will prevent blooming in the image for night vision at close range)

until i get done playing with VISBLE LIGHT after dark? My neighbors are gonna HATE me, hee hee...

 

[phoenix77]

I would THINK that the type of lens that you'll be needing would look like a round glass marble, that was sliced into 2 even pcs. I have a 'SIPIK' flashlight that has the lens mounted on a sliding, focusing shaft. The closer the lens is to the 'light emitting filament', the larger the 'SPOT' that is thrown. As I slide the lens AWAY from the 'light emitting filament, the emitter projects a mirror image of itself. This is at the FARTHEST distance of travel allowed by the flashlight, but I imagine that if the shaft that the lens travels on was long enough, the same thing would happen, but in reverse. If the shaft was REALLY LONG then you would be able to project a spot as large as you would like, provided that the shaft was loooong enough. Then you would have your 'IR ILLUMINATING FLOODLIGHT' you want. That's been MY experience with lenses that will ''throw'' a flashlights beam from a concentrated 'spot' to a wide angle 'flood'. Don't know if this helped or not, but I tried with the info. & experience I've had................... phoenix77/rob
PS, There's a part inside the projectors that laserists have been cannibalizing for their diodes, that contains some lenses (which can be changed) that are mounted on a sliding focusing assembly that you MIGHT be able to use for focusing your IR light source however you would like. It has a very nice, smooth action to it.

 

[sedstar]

wow... it mght actually be "too" efficient, LMAO... (although... with a laser diode.... its not like there wont be abundant illumination, lol)

this new lens, would be GREAT for very long range... the other lens i was using on the flashlight, woul be best for up to 100 yards...

Hm. if i can just "kick over" to a laser diode, and everything worls like it does with visible LED emitters, my project prototype ould be done. (but, life is never so simple, is it?)

I have, actually, exactly NO IDEA how lenses are measured and quantified. (to order one, lol) I can tell you the diameter, i can tell you the thickness at the edge and the center only cos i have a fairly accurate digital caliper.

my best hunch is that the best lens is likely somewhere's inbetween these two lenses i am using. *shrugs* I couldnt tell you x-power, focal length, nothing. (the engineer in me, *hates* flying blind and trial and error, with a passion, believe me, ha ha)

I vaguely realize i might have to purchase some special laser lens that does optically whatever these lenses are doing, either for keeping the wavelengths of emissed light within "band", or, simply because some part of me thinks laser light even unfocused might melt them, lol...

its looking like i just need to order a pair of the special goggles s i dont go blind, and what? mebbe a half watt laser diode module? Well, the ENGINEER in me says "you know, 400ma is MORE than enough, judging by commercial examples, if your design is sound!"

on the other shoulder? LMAO... the redneck in me is saying:

1) go BIG or go home
2) bigger is always better
3) why have ENOUGH light when you can have TOO MUCH light?
4) melting a lens would actually be sorta cool

FORTUNATELY, and not coincidentally, my ACCOUNTANT is thinking somewhere inbetween the engineer and the redneck... big enough to not worry about design losses, cheap lenses, and losses from chromatic aberrations... but, not ridiculous from a portable power source point of view... be nice to go "all night" on a motorcycle battery and all...

 

[sedstar]

big 10-4 on the "sipik" light, lol (you on candlepower forums, and/or budget lights? Thats where i STARTED out on this project, lol)

seen pictures of the sipik and clones, they are little "throwers" by reputation.

theres ALSO a thingy called an "Ahorton lens", its an aspherical lens (kinda like a globe cut in half, lol) thats noted for its "throw" and emitter-focusing nature.

there are other lenses that perform substantially the same function, and have more or less same/similar shapes... its just the Ahorton is supposed to work so WELL at its job.

yah, the focusing on a projector?? that crossed my mind too, lol... i'm old enough i remember film on REELS for a real film projector in gradeschool classrooms, lol... by the time i hit junir high, it was all VCR taapes on TVs they would wheel in... i suppose today its all DVD to show kids instructional movies.

i'm trying to keep this all down in weight and size, as its intended to mount on a gun platform... i cant think of anything simpler than a tube threaded inside of another tube wth mating threads, you simply turn it to focus and de-focus it... the 2 PVC tubes are about as long as my forearm now, although about half that is just for the length of the thin flashlights that i play with for now...

i could mount the batteries in a smaller short tube, located outSIDE the main business tube, to ge it even shorter, and just use the head of the light inside... guessing 6 or 8 inches long when done, if the batteries are in another tube. Diameter is a little over outside dimensions of an Ultrafire cheapie.

if the laser diode module doesnt "mind" the glass lens, i *might* be in business...

 

[Speedy78]

here

 

[sedstar]

bad link?