a better throw idea..

Flashlight Modding and DIY Parts
1

Hi again,

a couple of moths ago, i was doing some sketches and was thinking about some ideas I have in my mind. when I see my drawing i think maybe could work but when i experiment some times later it was pretty much a fail. now i was thinking what i am missing and what is wrong and since I lack qualification for optical systems I am sharing it here hoping some of the knowledge member around here could help me finding why it can not be done.
I think that part of the fail is the visualization of light as a straight ray or as a simple line and not as a waive( what actually it is) ?

so here is my drawing and schematics, and pardon me for the poor quality, to lazy to make an new one from scratch:

my idea back than was to make the ultimate thrower and to achieve this i was trying to make something that was able to capture all the light emitted from the source and after capture, compress it in one small area (till this part I know it can be done its relatively easy as u see in the picture) and after compress the ray of light continue in parallel so like some sort of white laser. well after some experiments with lens it looks like it is impossible to comperes and achieve parallel light in the same time. what I am missing here?

reflector, lens 1. and 2. just work ok, what is failing is at diverging lens 3. at leas that it what i see in my experiments.

2

Is the unconnected postimage link necessary?

3

oh this image posting in here are killing me slowly :stuck_out_tongue: lol what i have done now :bigsmile:

4

Well your text (previously the link wasnt hidden in the text, like is now) is just a link to an image host, that has no relevance to the thread. Its simply SPAM for the site you choose to link with. The picture is fine, the image host that image is hosted on is fine, the link hidden in the text is for what purpose though?

5

listen the way u tould me to insert as direct link simply do not work, i do not tell that before just to not sound rude. when i use direct link do not show picture but just a link in here, and I do like to show picture. with direct link this is what i get :

I find that using “Hotlink for Website” just work but some time it ad that row below that seems to bother you. any way to get rid of that, for example what can I delete in the code of the link to erase that row?

edit: finally direct link is working! from what i see it need “!!” to work as it should.

6

(tekst under the image is still one big link to the picture-host site)

The idea you have for compressing the light will work for a 'point source', when the led size is infinitely small. unfortunately a led is not like that, so every lens element you put in the light path will produce an image instead of a point, the rays will not be all parallel and there starts trouble with the idea.

Please draw the same schematics, but with a real size led and rays starting at two distant points on the led die, and see where they end up..

7

There ya go. :wink:

8

yes finally

back on topic, I just made an quick drawing following the advise of djozz :

from there it seems that not only my original idea will not work but also from a single point it will not work ?

9

Try this optics simulator, there's more of them on the internet and perhaps better ones, this one is nice and simple:

http://physics.bu.edu/~duffy/java/Opticsa1.html

10

I am part of a DIY night vision building site… thats how i got into flashlights…

on that site, we make INFRARED ILLUMINATORS for our night vision.

the basic plan everyone ELSE uses on that site? a single lens, everyone says it has to be aspherical.

all the “new builds” all the members try? its basically just trying a differrent aspherical lens.

I wanted to try something DIFFERENT??

I build my IR illuminators, with 2,3 and 4 lenses… the first lens? its down INSIDE a p60 reflector, lol… the second lens? just outide the reflector… the 3rd and (sometimes) 4th lens? further out.

on my screen? I have taken pictures of my “well focused emitter” at up to and including over 800 yards… its DIM by that far? but, if i move the light and keep the scope still, i can SEE the light move.

mind you, this is with a 3-watt IR emitter… not some 15 watt super-duper modded job.

=

I had to solve the equations for 2 lenses, to get the focal length of the resultant lens assembly… to add a 3rd lens? i run the same equation, with the FIRST SET of lenses treated as one lens… and add the 3rd les as the second lens.

when i go “four lenses”… i treat the first 2 lenses as lens 1, and the second 2 lenses as lens 2.

also? my “last main lens” is the biggest diameter lens, and its smalled diameter than every other build (thy tend to go with ONE BIG ASPHERICAL)

none of my lenses are asphericals, lol… i came to the conclusion, that there is no compelling reason to use an aspherical. You can just as well use a plano-cpnvex lens(es) instead.

==

i broke a number of “rules” or “guidelines” with my design…

1) asphericals are not magical… i tend to use biconvex or plano convex. Diameter and focal length of the lens are the key specifications to a lens… not shape or type.

2) you cant use a lens with a reflector?? I do… i put the first (small) lens down INSIDE the p60 reflector.

3) you have to “black out” the reflector or inside of the head, or it ruins the beam… i found that the reflected light that goes into that FIRST lens down INSDE the smooth reflector? made the image brighter (can see further)

it was 6 to 9 month project… and i havent seen any other pictures or videos, or even a claim that anyone has seen their emitter focused up further away than mine.

I am slowly saving up for a metal lathe, because no one wants a IR ILLUMINATOR made out of plastic, lol… they want “all metal” in the field…lol

11

djozz is right you should be thinking in terms of magnification of an object. magnfication is completely dependent on the focal length of the lens or reflector surface incidence.
lens 1: similar to a TIR path. the problem is the distance of the aspheric to the source is so short, it will reduce the spill but not help the spot much.
lens 2, 3: are you trying to make a thrower or a laser? the initial profile of the beam is not going to be detectable at 100m let alone 10, again it’s the magnification at distances longer than the focal length which counts, so this adds nothing

i really like this presentation of flashlight optics here

12

Any thoughts on a freshnel lens

This one might fit into a Convoy S series

This one with a little bit of work might fit a 26.5mm P60 dropin

13

djozz, sedstar, islisis, WarHawk-AVG thank you for your input.

enjoyed pretty much the slides I know the major info before, but still its lot of information well putted and pretty much cover every thing, the data on nits even if little outdated are very informative.
and a good TIR looks like the first part of my system. interesting bit sound to me the dielectric coating reflector, what is that our ordinary cheap plastic reflectors? first time I hear about that high efficiency in reflector.

the simulator is lot of fun too, played a little today and it seems very useful. it save you a lot of time. I have downloaded some simple simulators for optics in my phone before, but seems difficult to operate. in contrast this is very easy and clean.

@sedstar, nice to hear you achieved good result. I am still learning and experimenting in this hobby of mine. but i have to say one thing, as far as i know u can skip aspherical in your night vision device and will not lose much because you use monochromatic light, but we in flashlight use white light most of the time and a spherical lens gave more precise focus if I am not mistaken. also a curbed surface reflect more light than a flat one near the source so it capture less light than an aspherical with the flat surface toward the source.

need some more time to experiment with simulator now cya

14

For compensating chromatic abberations, you don't need an aspheric, but an achromat (two lenses of different diffractive index glued together, compensating for different diffraction of different wavelengths), aspherics solve the focussing problem of spheric lenses that rays going via the side of the lens are focussed in another plane than rays going through the middle of the lens, you need an array of lenses to solve that without aspherics.

15

Nice one!
Anybody got a clue about their shipping costs (to Europe)?

16

member jspeybro (he's from Belgium) had some fresnel lenses for sale, he may still have some:

17

yes you are completely right, my mistake. I know it was to give a better focus but did nit geave enough importance the reasons behind. now that I read your coment, it make perfect sense.

18

Sorry to hijack some of your topic, but:

I came across that thread earlier.
You bought one, I believe.
But the one in the link seems to have (reatively) shorter focal length, i.e. larger diameter with F=15mm.

Shipping ruins it at $13.— :frowning:

19

link to the diy nv illuminator building forum? and link to your project?

20

How about a flashlight made with this fresnel lens?

giant fresnel lens 0:)