Code for determining the location of a ball thrown through a laser sensing grid.
Phototransistor from Mouser
512-QSD123 QSD123 4mA PHOTO TRANS Rise/Fall time = 7 Microseconds (should be fast enough...)
Takes about 100 microseconds to read, plus whatever processing we have to do with information. This will likely be the issue, if done once per sensor, this is 7.2 ms even once per shift register is 900 microseconds, which only leaves 100 microseconds for the rest of the processing. Which actually might be possible.