Microscope Anatomy — the brightfield microscope
The brightfield microscope is the most commonly used microscope: a compound microscope with two or more lenses that produce a dark image on a bright background. Every part has a job — click any glowing point on the diagram, or take the guided tour.
Magnification Lab — how big, and how sharp?
Total magnification is the product of the ocular lens (10×) and the objective lens. Switch objectives, focus the image, and see why the 100× lens needs a drop of immersion oil — and why viruses stay invisible at any magnification.
Seeing Techniques — one specimen, six kinds of light microscopy
The same slide looks completely different depending on the microscope technique. Switch between brightfield, darkfield, phase-contrast, DIC, fluorescence and confocal microscopy — and for confocal, move through the specimen’s depth.
Electron Microscopy — TEM vs SEM
Light microscopes stop near 1000× because visible light runs out of resolution. Electron microscopes use electron beams with wavelengths of 0.005 nm instead — reaching up to 100,000× (some, 2,000,000×). Two designs, two different views.
Slide Preparation — wet mounts and fixed smears
Before anything can be observed, the specimen must be prepared. Walk through the two basic preparations used with light microscopes: the wet mount (fast, keeps cells alive) and the fixed smear (attaches and preserves cells for staining).
Staining Bench — making the invisible visible
Stains (dyes) are salts: the colored ion is the chromophore. Basic dyes (crystal violet, methylene blue, safranin, malachite green) carry positive chromophores that stick to negatively charged cell walls — positive stains. Acidic dyes (eosin, acid fuchsin, rose bengal) are repelled by cell walls — negative stains that color the background. A simple stain uses one dye; differential staining uses several to tell organisms apart. Step through the classic protocols below.
Chapter Quiz — Microscopy
Twenty-two questions covering the whole chapter: the brightfield microscope and its parts, the light microscopy techniques, electron microscopy, specimen preparation and staining.