Infrared or laser?

I am making a project with 2 parallel beams which form a directional tripwire of sorts. I have been looking for suitable components for a while on sparkfun.com and I was wondering if you guys could suggest whether I go for infrared light or maybe a modified laser pointer or something along those lines. All they need to do is be long enough to reach the width of a regular doorway.

I'm completely new to the hardware scene so any suggestions you guys have I'd /really/ appreciate :slight_smile:

Cheers

tech

Either will work but the IR will not be so obvious.

are there any certain components other than a transmitter or receiver needed or do I need them to be certain componenets, directional or anything like that?

thanks

There is an IR beam and detector in this project:-
http://www.thebox.myzen.co.uk/Hardware/Sneak_Thief.html
If you want to look at the electronics.

how directional are these IR emitters? Would you be able to have them parallel to each other and not have them interfere (i.e have the light from the first picked up by the second receiver?) The problem is telling the direction that the person passing through the beam is traveling. I was thinking that a laser pointer would be more directional than the IR emitters but I'd like to use IR if at all possible.

Ideas anyone?

Not too directional but put the receiver of the first one and the transmitter of the second one on the same side of the door. Then they don't interfere too much. Also put them in a tube about 3 or 4cm long to remove any sideways spread.

edit: I just realised what you meant,

t1 --------------- r1
r2 --------------- t2

I see what you mean yeah, thats a great solution, thanks