| 摘要 |
The invention relates to an objective system (39) which is suitable for use in an optical scanning device (15). The lens system (39) comprises a first lens, or objective lens (45), and a second lens, or auxiliary lens (47), which are mounted in fixed positions in a lens holder (61). The objective lens comprises more than one half of a first spherical lens body (67) having a first diameter (D1) and the auxiliary lens comprises more than one half of a second spherical lens body (69) having a second diameter (D2) which is smaller than the first diameter. The objective lens and the auxiliary lens are surrounded by a first circular-cylindrical inner wall (83) and a second circular-cylindrical inner wall (85), respectively, of the lens holder, having a diameter which is substantially equal to the first and the second diameter, respectively. Said inner walls can be provided in the lens holder in very accurate coaxial positions by means of conventional tools. In this manner, a very accurate centering of the objective lens and the auxiliary lens in the lens holder is achieved in a comparatively simple manner.
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