Instrument for measuring static and dynamic forces between surfaces in three dimensions

A device for measuring forces between two surfaces comprising:

• a first means for mounting an upper surface, said upper surface mounting means comprises a means to measure movement of said upper surface,
• a second means for mounting a lower surface in proximity to said upper surface, said lower surface mounting means also comprising a movement means to provide adjustable movement of said lower surface along a first axis, along a second axis orthogonal to said first axis, and along a third axis orthogonal to both said first and said second axes, said movement means is capable of providing said adjustable movement along said three axes simultaneously,
• a spring means coupled between said second mounting means and said adjustable movement means, said spring means deflects as a function of said forces between said upper and said lower surfaces, said spring means having a spring force constant;
• a light means to direct a beam of white light along said third axis through said upper and said lower surfaces to provide optical interference fringes when said white light passes through said upper and said lower surfaces, said interference fringes being a first measure of a distance between said upper and said lower surfaces;
• and wherein
• a distance between said upper and said lower surfaces as adjusted by said first movement means is a second measure of the distance between said upper and said lower surfaces, any difference between said first and second measures being a function of said forces between said upper and said lower surfaces and said spring force constant, said device is capable of measuring said adjustable movement along said three axes simultaneously.