Microscopy illumination methods

Microscopy illumination methods available are critical illumination and Koehler illumination. The latter is used more often because it avoids flares and ghosting. Therefore, it is essential for activities such as microscope photography.
There are two types of Koehler illumination, one method in which light is transmitted through the specimen (transmitted) and one method where it is reflected from the specimen (incident). Transmitted Koehler illumination is used for transparent or semi-transparent specimens, while incident Koehler illumination is useful for objects such as metal, which do not transmit light.

• Critical illumination
• Koehler illumination