An IR Filter For LED Lights?

Hello, Im wondering if anyone makes an IR filter lense adapter for fenix LED Lights, specifically for the P1D CE or The L1P?

I'd like to be able to convert them into an invisible IR floodlight by attaching an IR filter lense cap to them.

I'd also be willing to build one myself.

Any reccomendations or suggestions?

If I build one what material should I use for the filter? I am told filtering led light is different from filtering say a xeon light so the lense material may have to be different.

led's used in visible light lights put out no IR.

As far as i know, no led emits light in the ir-part of the spectrum.

Well that kinda ruins my plans for an LED IR Lense Filter.


I guess the solution is to buy and LED IR flashlight then.

Thanks

IR filters are usually for incandescent lights. You will need a light with an IR LED if you want enough IR from an LED.

Incandescent lights, by their nature, emit light in many wavelengths, including IR. This makes it easy to put a filter over the bulb that blocks all but one wavelength, giving you a somewhat dimmer, but still useable colored light. You can use a pass filter for any color that the bulb emits, including IR.

LEDs, by their nature, emit a very pure light. A red one makes only red light, a blue one only blue, etc. If you put a filter over them to pass a particular color light, you will find that it's just not making all that much light other than its intended color, and you don't really get anything useful. White LEDs are an exception to this. They are actually blue LEDs that have been jiggered around by adding some yellow. You may be able to filter a white LED to get blue, but it's just not making much IR, so it is unlikely that you could use it for an IR light.

You can use this to your advantage by getting something with IR LEDs. To the naked eye it will look like it isn't doing anything, and it will convert electricity to IR light more efficiently than an ordinary incan. bulb.

so....if i want an ir flashlight.....i'll be better off using an ir led flashlight than using an incan with an ir filter? did i understand that right?

If your thinking of building a IR flood then the 5 watt IR LED, Anyone use them? thread from the Night Vision forum will be of interest.

The person who started that thread built one for use with a motion detecting video camera that had IR capabilities.

The thread contains info on high power IR LEDs, optics, and electronic drivers to properly power the IR LEDs. There is also a link to a good IR video of something that triggered the cam/IR floodlight.

XtreMe_G said:

so....if i want an ir flashlight.....i'll be better off using an ir led flashlight than using an incan with an ir filter? did i understand that right?

Click to expand...

Most of the output of an incandescent is technically IR (too long a wavelength to be visible) but it's a broad spectrum IR -- only a portion of it is "near-IR" (close to visible range) that is detectable by cameras. However, incan is a MUCH more efficient of IR than visible light. An incan with an IR filter is probably going to be the cheapest way to go, especially if you want high output. If you only need low output IR then I'd go for LED (LED are better for low output in general, as incandescent must get very hot to work well).

One thing that I think would be useful would be a flashlight/LED with 5 separate dies: IR, Red, Green, Blue, UV that could each be switched on and off separately. IR only could be used for use with an IR camera. UV-only mode could be used to check for fluorescent strips in money etc. RGB could be used together for white output. Red-only could be used to preserve night vision, and so on.

By using a filter, you are essentially throwing away everything except the wavelengths you want, all the time. With LEDs you have the option of only using IR output, or a single-colored output when you need it. Note that "White" LEDs won't be able to do this (blue plus a yellow/green phosphor), only LEDs with separate red green and blue output.

There are a lot of flashlights out there that use a high power white LED, surrounded by several small 5mm red LEDs (for night vision preservation). Replacing those red with IR LEDs would give you an optional IR projection mode for use with an IR camera. It also gives you the advantage of turning the IR output off when you don't need it -- incandescent throws IR all the time.