Laser trigger for chronograph

I finished this laser wall trigger for my HIGH RESOLUTION AND ACCURACY CHRONOGRAPH. The purpose of this device is to generate the trigger start and stop impulses for my chronograph as soon as an object disrupts any of the laser beams. So if I have two laser walls (with one or more laser beams on each of the walls) and they are placed at a given distance from each other, as soon as an object crosses the first laser beams a start impulse will be generated and the chronograph will start counting. Then as soon as the object crosses the second laser beams a new impulse will be generated and the chronograph will stop counting.”

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