Light modulated detection system for atomic force microscopes

Claim 1

A scanning force microscope device comprising in combination: a. a sensing probe having a reflective surface on one side and a scanning tip on the opposite side, said tip adapted to be positioned adjacent a surface to be scanned; b. illuminating means for generating a radiant energy beam and for applying said beam to said reflective surface; c. modulating means for periodically changing said radiant energy beam in a predetermined fashion to produce a modulated energy beam; d. position control means for moving said scanning tip in a predetermined pattern to follow the contours of a surface to be scanned; e. detector means in the path of the portion of said modulated energy beam returned from said reflective surface and operable in response to changes in the energy beam position caused by tip movement in a predetermined direction to produce a motion signal representative of tip movement corresponding to the contours of the scanned surface; and f. demodulating means for recovering the information contained in the modulated signal produced by said detector means, whereby tip motion in a direction orthogonal to scanning motion results in motion of said modulated radiant energy beam which is demodulated to produce an electrical signal corresponding to and representative of the surface contour of a scanned surface.