The Study of Microbial Structure: Microscopy and Specimen Preparation contd...

2. Dark Field Microscope
        In the dark field microscope the background remains dark & specimen is illuminated. It contains a special condenser lens mounted  under the stage which don't permit light to be transmitted directly to specimen & into objective lens. The dark field condenser lens focus light on the specimen at an oblique angle such that light that don't reflect of an object doesn't enter  the objective lens. Therefore, only light that reflects  off specimen will be seen & the light simply passing via slide will not enter the objective lens. So the microorganism  bright on the dark background. Dark field microscope  diagnosis  of syphilis  by detecting the causative agent  Treponema palladium  which don't stain well. It is also important  to study motility life of  procaryotic & eucaryotic cells.


   

fig: Dark field microscope 

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