Fundamentals of Microbiology

2.1.4 Dark field Microscopy

Dark field microscope is used for examining live microorganisms which are invisible in the ordinary light microscope or that cannot be stained (some organisms are distorted by staining). Dark field microscope uses a dark field condenser that contains an opaque disc. The disc blocks light that would enter the objective directly. Only the light that is reflected off the specimen reaches the objective lens. The specimen appears bright against a black background.

 

                                                 Dark field                                                                                           Phase contrast