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Light microscopy techniques

Many biological microscopic objects are very small and translucent. In bright field microscopy, contrast is adjusted with an iris located within the condenser. In addition, contrast enhancement can also be achieved by optical contrast techniques described below. Alternatively staining of various cellular structures is obtained by organelle specific dyes.

> Chapter "Hellfeld" in "Lichtmikroskopie online" (in German)

> can be done with all CIUS microscopes

Phase contrast

Phase contrast is the most common light microscopic technique to enhance contrast. It requires special phase contrast objectives and a corresponding phase ring in the condenser. Again, density differences within the sample are transformed to yield higher contrast. However, this method requires a very powerful light source and is thus not very often used in microscopes that are equipped with halogen lamps.

> Chapter "Phasenkontrast" in "Lichtmikroskopie online" (in German)

> can be done with all CIUS microscopes except Zeiss UV microscope

Differential interference contrast (DIC)

In Differential interference contrast (DIC) objects give crisp images with threedimensional effect. This contrast is produced by two Wollaston prisms within the beampath, the polarizer and the analyzer. Hence small density changes within the object are displayed.

> Chapter "Interferenzkontrast" in "Lichtmikroskopie online" (in German)

> Leica CLSM 1 and 2, Leitz Fluovert, Reichert UnivaR

Dark field

Dark field yields highest possible contrast. Direct light is blocked in the condenser and only light that is refracted by structures of the sample can enter the objective; they shine brightly on a dark background. Hence even structures below the resolution of the light microscope can be observed, e.g. cilia of bacteria.

> Chapter "Dunkelfeld" in "Lichtmikroskopie online" (in German)

> can be done with all CIUS microscopes except Zeiss UV microscope

Polarization microscopy

Some biological objects contain highly organized, almost crystalline structures. They show special and characteristic diffraction patterns in polarized light. Using polarizing filters within the light path of the microscope, analysis of these structures is possible. Similar to the dark field method, only light that has been diffracted by the sample can enter the objective. This method can also be applied to measure density and weight of intracellular structures.

> Chapter "Polarisation" in "Lichtmikroskopie online" (in German)

> can be done with all CIUS microscopes except Zeiss UV microscope

  

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Lastupdate: 04.04.2016 - 13:38