Light Microscopy Modes

Light Microscope (LM)

passes visible light through a specimen

magnifies cellular structures through lenses

Brightfield (unstained specimen)

Unless cell is naturally pigmented or artificially stained, the image will have little contrast

Light passes directly through the specimen

Brightfield (stained specimen)

Staining with dyes enhances contrast

Most staining procedures requires the cell to be fixed, thereby killing them

Phase-contrast

Variations in density within the specimen are amplified to enhance contrast in unstained cells.

Useful for examining living, unpigmented cells

Differential Interference Contrast (Normaski)

Optical modifications are used to exaggerate differences in density

The image appears almost 3D

Fluorescence

The locations of specific molecules in the cell can be revealed by labeling the molecules with fluorescent dyes or antibodies

Fluorescent substances absorb ultraviolet radiation and emit visible light

Confocal

Using a laser

This "optical sectioning" technique eliminates out-of-focus light from a thick sample, creating a single plane of fluorescence in this image

Deconvolution

Using software

Reconstructed from many blurry images of cell at different planes

This process digitally removes out-of-focus light and reassigns it to its source, creating a much sharper 3-D image