METHOD FOR MEASURING ANGLE ERROR OF ROTARY POLYGON MIRROR AND MEASURING DEVICE USED FOR IT

摘要

PURPOSE: To measure the error of the slant angle of a rotary polygonal mirror accurately by measuring the angle of the horizontal direction of the first reflecting mirror with an autocollimator. ;CONSTITUTION: A secondary rotary stage is rotated. The bisector of the angle formed of first and second reflecting mirror surfaces 11 and 12 of a rotary polygon mirror 10, which are neighboring to each other, is made to agree with the normal line of a main rotary stage 30. Thus, the reflecting mirror surface 11 is set at a measuring position. When the position of the polygon mirror 10 is determined in this way, at first, a horizontal direction angle θ₁ and a vertical direction angle ω₁ are read with respect to the reflecting mirror surface 11, which is captured in the field of view of an autocollimator 40. When the reading is finished, the stage 30 is rotated by 180 degrees, and the horizontal direction angle θ₂ and the vertical direction angle ω₂ are read with respect to the reflecting mirror surface 12. The sum of the horizontal direction angles, which are a read with respect to the respective reflecting mirror surfaces 11 and 12, i.e., θ₁+θ₂, is the slant angle error β₁₂ of the reflecting mirror surface 11 and the reflecting mirror surface 12.;COPYRIGHT: (C)1995,JPO