hi Pepe,
If you are using this project only as laser beam break detection barrier, the simple Digital detector you have built should be OK for raising a MCU Interrupt.

What is the laser barrier being used for.? ie: what is causing the laser beam break.?

E

 

The photodiode will work in 2 ways:
-Analog for detecting littles changes in light (detect lightnings for example)
-Digital for detecting fast moving objects breaking the laser barrier.

In digital mode I need to detect an air gun bullet. It travels at 1000f/s aprox. So the bullet moves 1mm every 3,3us. The bullet is 5mm diameter. We have 5*3,3 = 16,5us to detect it (this is the time the bullet breaks the barrier).

I'm going to start to test if the previous circuit works well.