in the vertical direction between two adjacent interference rings is half wavelength. By

taking the diameters of interference rings measured by moving reading microscope as

horizontal coordinates，and taking the air layer thickness differences de- termined by the order

difference of interference rings as longitudinal coordinates，the large circle equation of

the planoconvex lens sphere in Newton’s ring device can be fitted and used to obtain the

curvature radius of the plano- convex lens sphere. The experimental results show that the

new experimental data processing method needs less measuring points，the process is simple and

the results are reliable.