use one laser and let it make a zig zag pattern to the detector by placing the laser under a small angle and you will get a dozen or more "trip wires"
LASER)/////////(very fast pulse detector)
The pulse detector must be able to switch in the period the beam is broken.
Light travels 300.000KM/sec =300.000.000.000 mm
in one nanosecond it travels 30 centimeter.
if your ball is 10 cm in diameter and it flies at 72KM/hour that is 72000 meter /3600 seconds = 2000 cm per second.
The maximum disruption of the laser beam will be 10 cm == 1/200 second
so the signal pulse disruption will be in the order of 1..5 milliseconds.
should be doable with Arduino but you need a fast (on/off) light sensor