An important role in microscopy is how the sample is illuminated. Illumination methods are broadly classified into transmitted illumination and incident illumination. The appropriate method needs to be selected according to your specimen and purpose.

Types of illumination PDF

A light diffusing plate placed on the reflector enables uniform illumination, but passing through the plate makes the light slightly less bright.

Types of illumination in slit lamp

When using transmitted illumination with an optical microscope equipped with a condenser lens, there are three types of lighting: Koehler illumination, diffuse illumination, and critical illumination.

Illumination lighting meaning

Illuminates the back surface of the sample. This method is suitable for biological observation, such as colourless, transparent cells, and is used by general biological microscopes. There are two types of transmitted illumination: brightfield and darkfield:

Gathers light at the surface of a sample. This method generates bright illumination, but has a higher chance of being unevenly distributed.

What is illumination in the Bible

Illuminates the front surface of a sample. This method is useful when observing 3D objects, such as materials and other industrial samples, as well as opaque samples. Stereoscopic microscopes generally utilise this type of lighting.

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Gathers light to the backside of the objective lens. This is the most commonly used method for transmitted illumination and features bright and less-varied illumination. This method is indispensable for observation at high magnification.

The light source can differ depending on the microscope being used. It is necessary to select an appropriate light source based on an understanding of the characteristics of each light source.