Breaking the beam

I am new to Arduino and electronics in general and would like to have a sensor detect a beam breaking.

Basically I am creating a rig to trigger a camera flash when a drop of liquid breaks the beam.

I have no idea what I need for the sensor, I have the rest of my setup all sorted.

I know I will need some form of light source and some sort of receiver but that's as much as I know.

Any advice would be great.

Thanks.

Phil

Look at SFE, they have a board too.

Perfect.

Thanks.

Phil