laser-phototransistor throughbeam detector

[archmichael]

i am currently working on a project that requires an digital 1 output from a phototransistor when a laser beam falls on it and a zero when the beam is broken. however the problem is the setup needs to work indoors or outdoors. any ideas on how i can get around the ambient light difference to give a reliable signal??

 

[3v0]

Place the phototransistor inside a tube and point it at the laser. This has the effect of making it very directional.

Paint the inside of the tube black to absorb light.

 

[crutschow]

You can also use an optical filter that only allows the color of the laser through it. That will block most ambient light.