Development of a depth controlling nanoindentation tester with subnanometer depth and submicro-newton load resolutions

A displacement controlling nanoindentation tester was developed. It adopts a zero-balance load detection technique for measuring the application load; and an ac-modulated optical fiber displacement sensor for measuring the relative displacement between the indenter and the sample surface. The indenter is actuated by a laminated piezoelectric actuator, and the, extension of the actuator is feedbacked by the relative displacement between the indenter and the sample surface. The depth controlling technique is extremely effective in suppressing the foundation-induced fluctuation and ensures 0.1 nm depth resolution iu ordinary laboratory circumstances. (C) 1997 American Institute of Physics.