That's because the alpha channel object doesn't have fine collisions so the circles are destroyed when they hit the bounding box (which is way out in diagonal directions). Use of the collision condition instead of overlap condition sometimes allows the circles to go through the laser too. Not bad for displaying a laser though.
the link doesnt work ! And I was looking for some lazer 360 effect ! Can someone post a new one? Or repair the link, or send me a copy of this. Pleease! This looksreally nice