These three components are all mounted on the now invisible tripod base and they all move together.
The laser shoots a beam of light at the back of the cantilever’s tip.
The reflected laser beam then bounces up to strike the photodetector. This special photodetector can tell where, front to back, the laser is striking its surface.
The cantilever assembly is very precisely mounted so that, when it is not in contact with a sample, the reflected laser beam actually strikes the photodetector near its front edge (in front of the yellow arrow we have inserted).
