The laser beam is focused by a lens into a small spot. The first thing the operator must do is align the laser so that it strikes the back of the very end of cantilever. To do this, a TV camera looks from the left at an image bounced off a partially transparent mirror on the tilted end of the piezoelectric tube (invisible in this scene). This allows the operator to look down on the cantilever with an image like that inset at the lower right.
By adjusting the knobs at the top, the laser can then be aimed at the back of the cantilever.
