pimeäkenttamikroskopia

Pimeäkenttamikroskopia, also known as dark-field microscopy, is a technique used in microscopy to enhance the contrast of unstained, transparent samples. Instead of illuminating the sample directly with light, the illumination path is modified so that only light scattered by the sample enters the objective lens. This results in the sample appearing bright against a dark background, making it highly visible even if it has low intrinsic contrast.

The key to pimeäkenttamikroskopia is a specialized condenser that blocks the direct light path from the illumination source. This condenser has an opaque disk in its center, creating a hollow cone of light. Only the light that is diffracted or scattered by the specimen at the edges of this cone can be captured by the objective lens. Consequently, the light that would normally pass straight through the sample and into the objective is prevented from doing so, rendering the field of view dark.

This technique is particularly useful for observing live microorganisms, such as bacteria and protozoa, as well as small particles, fine details in cells, and crystals. Because it does not require staining, which can kill or alter the specimen, pimeäkenttamikroskopia is ideal for studying dynamic processes in living cells or for observing samples that are sensitive to chemical fixation. The increased contrast allows for easier visualization of structures that might otherwise be invisible under standard bright-field microscopy.