| 摘要 |
PURPOSE: To miniaturize an optical base and a dustproof cover by joining one pair of transparent tapered members to both parallel surface parts of a flat plate to make the tapered surfaces parallel to each other as occasion demands so as to compensate a shift of a light beam. CONSTITUTION: A tapered glass 22a to be fitted to the outer side of a fixed optical system is so bonded that its thin-wall side mark should be positioned on the upper side, while its thick-wall side mark on the lower side. By bonding in such a way, the three members consisting of the tapered glasses 22a and 22b and a cover glass become a transparent parallel-flat plate disposed in a deviated position from a vertical position to the light beam R as a whole. This dustproof cover is fitted to an upper surface part of the optical base 2a. Consequently, a hollow cylinder is not required as in the conventional manner, so that a space between a beam splitter 13 and the cover glass can be narrowed, and then the optical base 2a can be miniaturized while the dustproof cover can also be miniaturized. |
