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3 is the identification number indicating that this is a form error specification. 3 isthe coarse form error or power,ie ,the difference in the radius of curvarurc of the surface and a reference surface.This number is the maximum allowable number of fringes. 0.2 refer to the regular form errors.these are asymemerrical form errors(astigmatic,cylindrical) and are defined by the maximum allowable diffrence between the number of observed frings in orthogonaal directions. 5 is the identification number signifitying that this is a cosmetic surface specification. 3 is the maximum number of permitted surface imperfection(digs,pits). 0.063specifies the size of these imperfections ,Eachimperfection is approximarel to a square,and the number 0.063 is the length of the side of the square,in mm. |