A shot-noise- and diffraction-limited Michelson interferometer and two optical beam deflection configurations are compared for application in an atomic force microscope. The results show that under optimal conditions the optical beam deflection method is just as sensitive as the interferometer. This remarkable result is explained by indicating the physical equivalence of both methods.
Putman, C. A. J., de Grooth, B. G., van Hulst, N. F., & Greve, J. (1992). A theoretical comparison between interferometric and optical beam deflection technique for the measurement of cantilever displacement in AFM. Ultramicroscopy, 42(44), 1509-1513. https://doi.org/10.1016/0304-3991(92)90474-X