Dark Field Microscope
This is used for examining live microorganisms which are invisible in light microscope and cannot be stained by standard methods. It can be used to study samples which can get distorted by staining and cannot be identified further. The distinct feature is the dark field condenser that contains an opaque disc.
The disc blocks direct entry of light to the objective lens. The light rays reflected off the specimen enter the objective lens and in the absence of direct background light, the specimen appears light against a dark background (Figure 2.9). The microbes are visualized as halos of bright light against the darkness, as stars are observed against the night sky (Figure 2.10).
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