// ns_Pulser.ino
// Apply 62.5ns (@ 16MHz) pulses

int laser = 2;

void setup() {
  // setup:
  pinMode(laser, OUTPUT);
  noInterrupts();          // disable interrupts just in case
}

void loop() {
  // main loop: 
  PIND = B00000100;        // writing to the pin register toggles
  PIND = B00000100;        // output on AVR microcontrollers
  delayMicroseconds(100);
}