This uses a simple IR LED and IR Receiver, it works very well at high speed in the Dubai sunshine.http://rcarduino.blogspot.ae/2012/09/lap-timer-build-along-part-3-timer.html
The key to getting this working was -
1) Spray paint the inside of the receiver enclosure with 'ultra flat' non reflective camouflage paint
2) Fix the received so that it is an inch back from the small opening in the enclosure
This ensures that only direct light is able to reach receiver, all indirect light is absorbed by the non reflective pain before it can reach the detector.
You can find details of all the components etc by following the other posts in the build along.