Long ago in a place called Cheaper Than Dirt, there used to exist cheap IR filters. I bought one from them about 4 years ago for my 6p. It was a simple rubber thing that slipped over the bezel with a small retaining ring - it didn't cost more than 4 or 5 bucks.
Does anyone sell or even manufacture these things anymore??
zmoz - This material is basically a bandpass filter that allows only (mostly) the IR range through.
I know where to get the filter plastic in 12" square sections. I was just wondering if anyone has seen a cheaper supplier for either the bulk sheets or the slip-on filters themselves. The science and lab supply stores seem to all think pretty highly of the stuff and tend to charge a lot.
I should have bought the whole truckload when Cheaper Than Dirt had them. They had a bunch of different sizes for SF's and Mag's.
I took colored "gels" used for stage lighting and cut them to size and use them in the lens of my 3 D maglite. Works for me. I go to a local music store [Sam Ash] to get them. Used red, blue green, orange. Looking thru my cheap Russian monoc, it gives just about the same effect, if not a little less, of the flashlight in regular use with the naked eye.
Use developed unexposed E6 transparency film, it's nearly visible-opaque and IR-transparent. I have a roll of it here (120 sized, so about 2.5" wide) and can send you a piece if you want it.
Edmund (Scientific) Optical has some sizes of plastic filter now, a 2-inch diameter (mag-lite bezel) is $7.30 and their shipping isn't real cheap,,, but I got tired of searching for other options online that people said "hey, this works pretty well". So if you want to know how well it works, then you have to buy it from somewhere specifically selling it as such, and who gives transmission specs for it, and Edmund does. Look in (edmundoptics.com) online catalog/optics/filters and diffusers/longpass/ for "optical cast plastic".
...The glass filters work better but cost way more (anywhere), and are much more difficult to cut to size.
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Well nuts--the Edmund filters appear brown over a mag-lite and shine a beam that is a deep red--but I have since been informed that you can actually see up to 1000+ nm, if it's bright and it's the only light there is.
So my dream of a flashlight invisible to the naked eye but visible to gen-1 NV is dashed.
(sob)
However, regarding the lighting gels that webley445 mentioned--I looked for these and did find a source for the Lee filter gels near me. These are thin plastic colored sheets used for stage lighting, they cost about $6 for a 20 x 24-inch sheet, and you can cut them into any size or shape you want with regular scissors. The fellow on this page: http://www.amasci.com/amateur/irgoggl.html mentions using Primary Red and Congo Blue--but there are better ones for longer IR filtering. The colors that you really want for IR-pass are #027 Medium Red and either #713 J. Winter Blue or #735 Velvet Green. One layer each of the red and either of the others looks BLACK in daylight on a sunny day--you can only really see the sun's disc through them, they are too dark to use for that guy's "$10 infared goggles", but a gen-1 NV scope can see right through them easily.
---The guy I got them from handed me a little designer swatch book as I was leaving, almost as an afterthought--and it has a little transmission chart for most of the colored filters that goes all the way up to 800 nm, so you can pick combinations with the transmissions you want. The reds have a transmission "hump" only on the long end of course, and the green/blues have a hump near 400-550 nm, and all also have an IR hump. The two combinations above are about the only two where the red transmission doesn't reach all the way down into the blue-green transmission--however, the light from both of these combinations *does* look blue-green, so there is some bleeding going on, but it was the best I could find going through all the colors. The website has the transmission charts as well, but online they end at 700 nm.
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I am pretty sure that my eyes cannot see anything close to 1000nm, but there might be exceptions out there. I was always under the impression that even 880 nm was considered invisible. A lot of filters are passing a wider distribution of light than the particular wavelenght center. Your best bet is to try to buy some IR LEDs, as they tend to be almost monochromatic.
The problem with trying to use LED's is that a single one isn't bright enough, and multiples cannot be focused well. I tried it already. 840nm LED's you can see the die glow red in the dark, but 940's I couldn't see at all if they were off or on.
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Single LED is quite bright to a Gen 2 or 3 night vision device.
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--->Well maybe, but then if you had a gen-2 or 3, you probably wouldn't need a light anyway.
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I emailed Astraproducts for a couple prices.....
By the by, I have found that the astraproducts site ( http://www.astraproducts.com ) will not display in any Mozilla browser on my Win98 machine, and also will not display on Mozilla 1.6 on another separate computer running Fedora/Linux. It will only show up in Internet Explorer.
Does anyone else have this same problem?
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Naw, in a very dark room indoors there isn't much light to amplify... it's pretty dark even to my good G2 tube. Outdoors, there's always been enough light, but indoors the IR illuminator comes in handy.
Even on a very dark night, no moon or stars because of clouds, or in dense woods, a Gen 2 and even a Gen 3 pair of nvgs needs some sort of extra light. An IR LED is great for reading, or doing close up work, looking at guages for instance. A higher power IR light is great when looking into shadows with even GEN 3 nvg's. It can really make looking into vehicles, or bunkers easy.
With GEN 1, I'd definately want some sort of additional light source, since even GEN 2 looks kind of dark to me these days, unless it's a full moon.
I found a new in package surefire IR filter for $29 on ebay a while back. I thought I got an awesome deal at the time, till I read about the cheaper ways above. I don't know whay I bought it, I don't even have any IR goggles or scopes. Just had to have it when I saw it though.
Lasernerd...
What models \ brands od CD players have you seen IR Laser LEDS in?
I have been inside many and I always find the visible 632nM variety.
I used to repair them and have never seen a IR Laser in a consumer unit..
It would be cool if you could alsave these from old players.
Every audio CD player I know of uses a 780nm near-IR laser diode. This is generally visible as a dim, dull, deep cherry red color; not quite invisible to most people.
The brands I have seen this type of laser in are JVC, Sony, and perhaps Kenwood.
DVD and video disc players use what I believe is a 635nm visible red laser diode.
[ QUOTE ] The_LED_Museum said:
Every audio CD player I know of uses a 780nm near-IR laser diode. This is generally visible as a dim, dull, deep cherry red color; not quite invisible to most people.
The brands I have seen this type of laser in are JVC, Sony, and perhaps Kenwood.
DVD and video disc players use what I believe is a 635nm visible red laser diode.
[/ QUOTE ]
Yes, DVD players need the shorter wavelength of the 635nm diodes. I winder if it's just cheaper to mass produce the 635nm units and use them in everything now? This would probably make sense in terms of reducing the manufacturer's inventory of different LDs, and I'm guessing that it also works better with burned CDs as well as the stamped ones.
A lot of laser printers use the Sharp LTO22 series of NIR LDs. These also operate at 780nm, that deep cheery-red glow. They're pretty readily available on the surplus market, either individually or buried within a salvaged collimator housing.
These are pretty rugged little diodes from an electrical standpoint. While I've blown out several 635nm units, I have yet to damage one of the LTO22s from the occasional electrical abuse.
[ QUOTE ] flashlightlens.com said:
Wow. I was sure this thread was long gone. I've emailed Astra also to see just how highly they think of their filters.
Hi Guys, I'm new to this forum. I read this thread and would like to offer my findings on IR illumination...Dead cheap [img]/ubbthreads/images/graemlins/wink.gif[/img]
Like many here, I've messed with IR Leds etc, there are only a few that can cut it, the best I found were some german multi-chip beasties, which are not bad, but about £10 each, so these were discounted.
I have 2 russian nightsights, a 1st and 2nd gen, the later cost about £2K I believe, it's 14 inches long with the 'Big' zoom lense & light hood. I have a 6 Volt lantern type lamp, which has good power, (note.. modded for sealed lead acid batt) I researched certain dedicated IR filters, obtaining some samples of the Lee IR 87 filters, light transmission above 730nm etc. These worked ok with my 2D mag-lite. Noting that all things that appear black are not always, I have a 'black' glass ashtray, that is indeed 'Not' black its actually dark red. It actually worked as a crude IR filter when hitting it with lots of light, the drawback being the glass is unnecesarily too thick and heavy. Baring these thoughts in mind, I applied the same to plastics. I obtained some ICI Persex, black of course, this also is indeed dark red. I cut a new lense for the 6V torch, replacing the original. An optical comparison between the Lee IR filter and the Perspex one appeared to have the same dull red glow etc. Tests with the Night sight were good, I could illuminate stuff at about 80 metres, (limited by the distance I could get from my garden). This same cheapy method should work for video cams. Perspex looks usefull..
Webley445's method will stand a lot heat, by the nature of the material etc.. But I'm curious, The E6 transparency film, how does that standup to heat? in say a 35 Watt Halogen spotlight?? methinks melt-down??
[ QUOTE ] Lasernerd said:
The infrared Laser Diode in a CD player can really light things up!
[/ QUOTE ]Yo Lasernerd [img]/ubbthreads/images/graemlins/smile.gif[/img] this is indeed an interesting thought. My Gen 2 nightsight has a 50mW IR laser, focusable from 5 to 200 metres. Sadly when I acquired this sight, the previous owner had blown the laser, by replacing the 2x AA carrier with a PP3 [img]/ubbthreads/images/graemlins/crazy.gif[/img] I examined this unit very closely, the photodiode feedback was 'Not' used in there design (which was crap) it was being driven in some weird pulse mode, on a pcb that looked hand drawn. The rest of the unit lense & mechanics are nice. It maybe worth hanging an 'Ex' CD player IR laser in this unit, as I have a couple here. A interesting point on the original Laser, the window of the diode had a small piece of some opaque crystal glued over it? presumably to diffuse the beam (make safe?) On top of that, the back of the focusing lense had a piece of polythene bag stuck to it, more safety?? The sight can be seen here, if the link works? http://uk.f2.pg.photos.yahoo.com/ph/snc1@btinternet.com/detail?.dir=/f6cb&.dnm=223b.jpg
Any ideas as to the typical power of an IR laser in a CD player?? I doubt if I'm gonna find a 50mW job [img]/ubbthreads/images/graemlins/wink.gif[/img]
Cheap IR Filters??
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