| 摘要 |
An aperture wheel having a circular base assembly which is adapted to be mounted for rotation about its central axis and a circular disc assembly which is removably and concentrically mounted on the base assembly is disclosed. The base assembly includes a circular frame having a central aperture and plurality of circumaxially spaced openings. A plurality of indexing pins are fixedly mounted on the frame for indexing the angular position of the frame, each indexing pin being associated with and precisely located relative to one of the circumaxially spaced openings. The disc assembly includes a circular plate having a central aperture and a plurality of circumaxially spaced openings, the openings being arranged so that they can be brought into registration with the openings on the frame when the disc assembly is mounted thereto. Means are provided for fixing the plate on the frame at either one of two angular positions and means are provided for holding the disc assembly so that it can be placed onto the frame and/or removed from the frame. In using the aperture wheel, a plurality of aperture plates and/or filter plates are mounted on the plate over the spaced openings using the two mounting pins located at each opening and secured in place by fasteners which are fastened onto the mounting pins. The loaded disc assembly is then placed on the frame and rotated to the desired angular position. Preferably, a plurality of discs assemblies may be provided, each loaded with a plurality of aperture plates and/or filter plates and each used separately as required with a single base assembly.
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