The probing force is normally required to be less than 1 mN [16]. According to above parameter, the structure is analyzed and validated by FEA method, the probing sphere will remove 2.96 m along z direction and 44.2 m along x direction, respectively under vertical and horizontal probing force of 1 mN, The stiffness of probing system can be calculated as 22.62 N/min the X and Y directions, and 337.84 N/m in the z direction. And the first and the second order resonant frequency of the system is calculated by 810 Hz, so the frequency of probing force should be avoided around 810 Hz to keep the stability of system when probing force calibration is made. The finite-element analysis is shown in Fig. 4.