Posts that relate to the Keyword: illuminatioin

Increasing Contrast using Optical Methods

Many microscopic specimens are either very thin or transparent or lack color. They lack contrast and can not be easily seen in bright microscope light. In many cases it is not possible or desirable to chemically stain the specimens. In this case, optical techniques become necessary to enhance contrast.

Sand from the Kalahari Desert

Sand from the Kalahari desert under the microscope. Dark field illumination.

Oblique Illumination

Oblique illumination is a contrast enhancing technique which can be realized with the use of home-made filters (patch stops) placed into the filter holder of the microscope condenser.

Adjusting Koehler Illumination

Koehler illumination ensures that the specimen receives a bright uniform light. Only those areas actually seen are illuminated.

Advantages of Koehler Illumination

Koehler illumination offers a range of advantages over “critical illumination”. Illumination is more uniform, specimen heating is reduced as well as light reflections for photographic work.