"I can micromachine spots how small?"

When micromachining with ultrafast laser pulses, the threshold becomes extremely accurate. That is, you get the same results shot-after-shot. Now, imagine that you focus the beam to the smallest spot you can (say about one micron diameter). The intensity of light will be higher in the center of the focal spot, and fall off as you move away from the center. If now you arrange the light intensity so that only the center of the spot is above threshold, you can remove material in an area that is smaller than the spot itself. In this manner it is possible to remove material in areas as small as 50 nm (0.000002 inch). Of course, larger spot sizes are also possible.

Photo Courtesy of the University of Michigan