| 摘要 |
PROBLEM TO BE SOLVED: To easily execute the inclination regulation of an optical axis with high accuracy by forming a sloping part which has a critical angle with the optical axis and has a sloping surface of a plane or curved surface in the position where is off the effective region (off the effective diameter of an objective lens, etc.), of optical parts allowing the transmission of a beam or reflecting the same and at where the peripheral part of the beam arrives. SOLUTION: The objective lens 1 is integrally molded wit the ring band-shaped sloping part in the peripheral part which is off the effective diameter (off the effective region of the other optical parts) of the objective lens 1 together with the lens part. The inclination at the cross section of the sloping part is so formed that the angle formed by the normal of the face of the sloping part and the objective lens optical axis of the objective lens 1 forms the critical angle. When the objective lens 1 inclines, the peripheral light 9 refracts even at the reference plane 6 of the objective lens 1. The incident angle of the beam refracted by the reference plane 6 to the sloping part, however, is larger than the critical angle in the sloping part 4a on the side where the edge of the objective lens 1 falls. The incident angle is smaller than the critical angle in the sloping part 4b on the side where the edge of the objective lens 1 rises. |
