PURPOSE: To cut an optical member into an elliptic shape by fixing a cutter to a rotary shaft, and by inclining the principal axis of the optical member to be cut to an angle with which the optical member is cut into a desired elliptical shape, with respect to a fixed axis.
CONSTITUTION: A principal axis passing through the center of a polygon mirror 15 is set at a desired inclined angle of Xdeg. with respect to the rotary axis of a cutter 20. A drive means 22 is operated to rotate the cutter in the direction of the arrow P so that the polygon mirror 15 is fed in the direction W by a feed and rotational angle indexing device 40, and accordingly a first surface 30 is at first formed by a cutting tool 23. Then, the polygon mirror 15 is indexed to an angle of 72deg. by the feed and rotational angle indexing device 40 so as to form a second surface 30 in a similar manner. Thus, first to fifth surfaces 18 are formed so that a polygon mirror 15 having a substantially pentahedron can be formed.
IMAFUKU FUMIO
OKADA KOICHI
