But it isn't focused on a
single small spot; it has to scan across
multiple small spots in order to form a recognisable 2d image. If it were just focused on a single small spot the entire time, all you'd see is a dot.
That means one of two things must be true. Either a) the beam is way brighter than other light entering your eye, such that it delivers in a single focused beam the same amount of energy that would otherwise be distributed evenly across the surface of your retina if you were viewing natural light. (Thus the questions I posed in my previous comment.) Or b) the beam is the same brightness as other light entering your eye, meaning the amount of energy in any individual pixel is far _less_ than what your eye receives from natural light. (I imagine this would make the image appear very dim.)
