I plan on mounting two pairs of photodiodes and LEDs six inches apart inside a PVC pipe.
One of the things I'm worried about as of now is how accurately I need to shoot in order to get a reading.
A lot also depends upon whether or not you can constrain the projectile path (inside a tube, e.g.), or whether you need to sense over a relatively large area (e.g., a firearm speed trap).
would I have to be directly in between them to get a reading?
Quotewould I have to be directly in between them to get a reading?Well how else would a signal be produced on the sensor?
I was thinking more of how large of a tolerance I'd have for the sensor to detect it;