I am in a undergrad Vison Science class where the professor recently talked about LASIK surgery. In the surgery, a special type of laser that could heat up a specific point (a sphere actually) and nothing else. According to how much he knew, there were two beams of what I assume are electromagnetic waves that intersect and heat only that point of intersection and nothing else (with emphasis on not heating any other point in the paths of the beams).
I become very interested in this laser and searched about it on the internet. However, my knowledge in light and lasers is primitive, and I could not understand most of the vocab. Can someone explain how this works in language that a high school graduate can understand? Also, it may be possible that this property is only due to the nature of the tissue. In that case, what is this property called?
Is there a law that could help us predict the maximum precision of this heated point (the minimum radius of the sphere)?