IR long distance detection

[ariakovo]

I want to make a ir photo sensor detector. The distance of the beam that detects any object in this field must be 6m or larger. If something cuts the beam the receiver reacts. Of cource i have to use a ir emitting diode and a photodiode or a phototransistor. But i can't fing a pair that achieves 6m distance. I have see these ir emiters :
http://optoelectronics.perkinelmer.com/catalog/Category.aspx?CategoryName=LPE+Process[/url]
But they achive only 4m. The sistance is d = sqrt(Ie / Ee). Have any ideas or knows any long distance components? Thank you in advance

 

[Nigel Goodwin]

Use an IR receiver IC from a TV (or similar) and modulate the IR LED at 38KHz, you will also need to add lower frequency modulation (encoding) to prevent the AGC turning the gain down. Check my PIC tutorials for examples of IR remote control using this technique.

It's easy to exceed 10m in this way.

 

[hazy842]

I would like to understand how I could extend the range of encripted IR data transmitions and where to start looking in to this. I have many questions. Thank you for your time Hazy