For increased speeds, I recommend the TLP117, that has an inverted logic output but requires a 5V source around the output facet. I’ve gotten 10 microsecond pulses out of the a person, that needs to be in the position to let you know some thing about its velocity! FAB-EPM material https://vibration-isolator-spring15791.ltfblog.com/28086245/5-simple-techniques-for-what-is-isolator-and-its-function