This chapter could be called “Practical Microscopy,” “The Microscope,” or simply “Microscopy,” but I chose to call it Köhler Illumination to emphasize the role of this essential—yet still not widely known more than a century after its introduction—technique of getting the best performance from a microscope. I have tried to provide in this chapter common, practical microscopy issues that don’t require a deep understanding of optical theory, ray diagrams, and the like. As will be seen, Köhler illumination provides a systematic approach to adjusting the illumination system without guessing how best to adjust the field diaphragm, substage condenser height, and opening of the substage condenser aperture diaphragm. In addition to optimizing optical resolution, Köhler illumination is fundamental to quality photomicrography and digital imaging.
KeywordsDust Particle Substage Condenser Lens Surface Aperture Diaphragm Blue Filter
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