JPS6428611A - Optical device capable of magnification conversion - Google Patents

Abstract

PURPOSE:To prevent measurement accuracy from decreasing owing to an optical axis shift even by magnification conversion by providing an objective, an optical path branching member, an optical path composing member, etc. CONSTITUTION:Images of different magnification which are formed on the same plane through 1st and 2nd optical paths are formed by switching optical path shield members S1 and S2 arranged on the optical paths alternately by insertion and extraction. The optical axes of the optical paths are aligned with each other by the optical path composing member 3, so the centers of the images of different magnification meet each other at all times and the possibility of the optical axis shift in the magnification conversion by the switching of the optical paths is eliminated. Further, a relay lens 6 on the 2nd optical path further enlarges and forms the image by the objective 1, the optical path branching member 2 branches light more to the 2nd optical path than to the 1st optical path, and the member 3 composes light more from the 2nd optical path than from the 1st optical path. Therefore, an image of high magnification which is apt to become dark can be made bright relatively and the difference in brightness from an image of low magnification is reduced.