I'm new to both electronics and programming and currently doing a very similar project for high speed flash photography.
All i have sorted at the moment is the laser circuit and the receiver circuit which uses a phototransistor.
I'm using 200k resistance with my photo transistor which triggers when the laser beam aligned with it is broken.
Here is my code with thanks to AWOL.
Play with trigger threshold and resistors to get the best response time for the flash.
//Light sensitive flash trigger using a phototransistor
//when sensor is momentarily blocked of light, analogue read
//increases which will output 5v to an optocoupler for 1 second
//then delays for 1 seconds.
//optocoupler + connected to digital pin 13
//phototransistor connected to analogue pin 0
#define optoPin 12
#define triggerPin A0
#define delayTime 0
#define triggerThreshold 300
#define triggerTime 1000
//initialize the digital pin 13 as an output.
int sensorValue = analogRead(A0);
while (analogRead (triggerPin) < triggerThreshold);
digitalWrite (optoPin, HIGH);
digitalWrite (optoPin, LOW);