# Constraining the path of an infrared LED

Are there any specific infrared LED's that have a narrow "beam width" when emitting? If not, does anyone know of a way to constrain it? A lens perhaps?

I would like to control the beam width over a distance of about 2 ft. I might need to go with a laser emitter....

Any suggestions would help.

Thanks,

berkeman
Mentor
Maybe use a reflector element to focus the beam? Not sure about IR lenses. Did you google that?

mgb_phys
Homework Helper
For a typical 905nm (TV remote type) infrared led, most simple lenses will work pretty much the same as for a deep red led.
A B+W security camera is very useful for setup and focussing.

NoTime
Homework Helper
Using a short length of tubing will keep the beam fairly narrow over a couple feet.
The method you need to use depends on your exact requirements.

This all helps.

If I get any results, I'll try and post them on this thread.

Thanks again.

For a typical 905nm (TV remote type) infrared led, most simple lenses will work pretty much the same as for a deep red led.
A B+W security camera is very useful for setup and focussing.

I wouldn't know if my TV remote is IR or UV. Out of curiosity I tried my cell phone camera. It picks up the LED output, and displays it as pale blue.

Last edited:
NoTime
Homework Helper
Out of curiosity I tried my remote on a web cam.
It's definitely an IR remote, but it does indeed show blue.

Looks like the camera color processing folds redder than red back over into blue.
I wonder if a UV source would show up as red for the same reason.
I don't have a UV source to try this.

LURCH
The fiberoptics we used in labs at school had IR emitters that were encased in reflective material, so all the energy went into the fiber. BTW, have you thought of using an optical fiber to contain the beam?

Out of curiosity I tried my remote on a web cam.
It's definitely an IR remote, but it does indeed show blue.

Looks like the camera color processing folds redder than red back over into blue.
I wonder if a UV source would show up as red for the same reason.
I don't have a UV source to try this.

I don't have a web cam for comparison, so still using the cell camera.

I've been racking my brain for a UV source. It dawned on me, I had an old UV windowed eprom eraser. There's no filter over the tube. My samsung verizon cellphone camera picks up the light and displays it as saturated white surrounded by pale blue. The direct TV remote has a very dark red lense over the LEDs. On closer inspection, the LEDs are displayed as saturated white, and what I percieve as a surrounding pale red halo, itself surrounded with a pale blue halo.

I should add that I've been placing the camera too close to focus.

Last edited:
NoTime
Homework Helper
I've been racking my brain for a UV source. It dawned on me, I had an old UV windowed eprom eraser. There's no filter over the tube. My samsung verizon cellphone camera picks up the light and displays it as saturated white surrounded by pale blue. The direct TV remote has a very dark red lense over the LEDs. On closer inspection, the LEDs are displayed as saturated white, and what I percieve as a surrounding red halo, itself surrounded with a blue halo.

My IR shows saturated white to dark blue depending on how much I attenuate the beam.
Didn't notice any haloing effect that I can see. The image on the PC is fairly large compared to a cell phone.
I have a few UV sources, like your eprom eraser, but they all produce far to much visible light.

BTW, have you thought of using an optical fiber to contain the beam?

No, haven't thought about it at all...please give any suggestions that you may have.

I know the time from the past thread has been a little bit, but thought I would continue this...

Does anyone know of any low price suppliers of laser pointers? I googled them and got all kinds of stuff I wasn't looking for... I thought I remembered seeing nice single point lasers on the boardwalk for like $5....where'd they all go? Redbelly98 Staff Emeritus Science Advisor Homework Helper Can you explain more about what you are trying to do? I thought you were using IR ... laser pointers are generally visible light. What about a simple lens and an LED (IR or visible)? Anyway, I see laser pointers at my local Ace Hardware store for around$5 or \$10.