| 摘要 |
The light reflected or scattered from the object (54) is projected on to the mirror surface of the optical element (51), deflected to the sensor and evaluated. The passage opening (52) of the optical element (51) is arranged concentrically to its mirror surface (53) and with the scanning and the passage of the object (54) through the opening, the light source (44,44') illuminates the object around its periphery in the region of the passage opening. The light (48) reflected or scattered from the periphery of the object falls on the mirror surface of theoptical element (51), so that, in the direction of the main axis (42) of the optical element (51), a second mirror (50) is positioned within its opening angle (14), over the passage opening, with a mirror surface (60) inclined to the main axis of the optical element (51) which transmits the reflected or scattered light to optics (26) for a sensor (57) detecting a circumferential stirp (58) from this light that corresponds to a circumferential region (55) of a specified width of the object.
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