Patent ID: 7084384

Claim:
In an atomic force microscope having a moveable cantilever, an optical position detector comprising: a light source; an adjustable diffractive optical element positioned to receive a light beam emitted by the light source and transmit a first light beam in a first direction when the adjustable diffractive optical element is in a first configuration and in other directions when the adjustable diffractive optical element is in other configurations; a focusing assembly to focus the first light beam emerging in the first direction or the other directions onto the moveable cantilever, wherein the first light beam emerging in the first direction is focused on the cantilever when the cantilever is in a first position, and the first light beam emerging in other directions is focused on the cantilever when the cantilever is in other positions; and a position sensitive detector to collect a light beam reflected from the cantilever in the first and other positions, with the output of the position sensitive detector varying as a deflection of the cantilever changes.