Answer
Brightfield microscopy provides a good basic view of a microorganic specimens' internal structures and pellicle. Darkfield microscopy only detects the light reflected by the specimen itself, providing a more isolated and accurate view of said specimen. This is handy for specimens which cannot be stained. Phase-contrast microscopy provides a very detailed view of the internal structures and pellicle of a specimen, which is achieved by a combination of direct light rays and reflected rays bringing the specimen into sharper focus. This can be used to study live microorganisms, which the other two types cannot.
Work Step by Step
1. The differing advantages of the types of microscopy depend on what the investigator requires.
2. All three types use compound microscopy - an objective lens and an oracular lens - but differ in terms of how light is used to display the specimens being investigated.
3. Brightfield microscopy is the type that is used in common light microscopes. It is the most basic type, showing the internal structures and pellicle of specimens. It is best used for a quick overview of a specimen structure which can be stained to bring it into focus.
4. Darkfield microscopy is a type that scatters light in a way that only the light reflected by the specimen itself is visible. The picture provided is of a light specimen on a dark background. This is useful for those specimens which cannot be stained for one reason or another.
5. Phase-contrast microscopy uses two sets of rays - diffracted (reflected) and undiffracted - which pass through the specimen at different speeds. The picture this presents highlights the specimen through different rays - blue indicates diffracted rays, red indicates undiffracted rays - and this highlights the internal structures and pellicle of the specimen.
6. What sets phase-contrast microscopy apart from the previous two types is that it can be used to study live microorganisms.
