# Constraining the path of an infrared LED

1. Jun 10, 2008

### dingpud

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,

2. Jun 10, 2008

### Staff: Mentor

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

3. Jun 10, 2008

### mgb_phys

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.

4. Jun 10, 2008

### NoTime

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.

5. Jun 11, 2008

### zeitghost

6. Jun 11, 2008

### dingpud

This all helps.

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

Thanks again.

7. Jun 12, 2008

### Phrak

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: Jun 12, 2008
8. Jun 13, 2008

### NoTime

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.

9. Jun 13, 2008

### 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?

10. Jun 13, 2008

### Phrak

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: Jun 13, 2008
11. Jun 13, 2008

### NoTime

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.

12. Jul 8, 2008

### dingpud

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

13. Oct 23, 2008

### dingpud

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