| 摘要 |
An illuminating device with a diffused, radiating, surface light source (3) and an aperture system positioned between the light source and the object is provided. The aperture system is formed by two optically complementary aperture screens (4, 5) which are disposed in series, and are spaced apart. The first aperture screen (4) thereby consists of a large number of transparent circular discs (8), positioned at intervals on an opaque base, and a second aperture screen (5) consists of a large number of opaque circular discs (9), positioned at intervals on a transparent base. The diameter of the opaque circular discs (9) is larger than that of the transparent circular discs (8), so that the circular discs of the two aperture screens (4, 5) overlap in the projection. The microbiological structures used generally have a large number of almost circular areas which are positioned in a regular surface pattern on a transparent base or round one or some relatively large circular transparent areas on a light-dispersing base. With the illuminating device according to the principle of the complementary aperture screens, the contrast of such microbiological structures in relation to the base could be substantially improved.
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