Optical microscopes use visible light and lenses (e.g., 10x, 20x, 40x, 100x) to magnify objects that are not visible to the naked eye.
Fluorescence occurs when matter absorbs light and then emits light at longer wavelengths. Microscopes that optically separate these colors are used to identify phytoplankton. Read more...
Scanning Electron Microscopes use electron beams with wavelengths thousands of times shorter than visible light, providing much greater magnification.