Microscope types Flashcards
Bright Field
2D
unstained or stained
dark image against bright background
has several objective lenses
light beams at specimen, density differences of specimen form image
Dark Field
2D
living, unstained
bright image of the specimen on a dark background
hollow cone of light is refracted by specimen
Phase contrast
2D
living unstained specimen
hallow cone of light
light passes through specimen and some gets phased out onto phase plate
very dense= light waves slow and go out of phase
less dense= light passes and hits phase
Differential Interference Contrast
pseudo 3D
living, unstained
two beams of polarized light
detects differences in refractive index and thickness of specimen
Fluorescence
2D
dead, fluorescently stained (most cases)
bright image of specimen
Exposes specimen to high energy light
fluorescent makes specimen jump to higher energy level, when it comes back down it omits light
Confocal
3D
dead, stained
used to study biofilms
Laser beam, aperture to eliminate stray light, computer system
images specimen along multiple planes and puts together a composite image
Transmission Electron Microscope
2D
dead, stained, thinly sliced, chemically fixed
Electrons beamed at specimen by electromagnets
as electrons pass through specimen they form images
denser areas will scatter electrons
negative staining and shadowing
black and white
Vacuum
Scanning Electron Microscope
3D of surface features
dead, vacuum
can determine in situ location of environment niche
dry sample coated with thin metal film
electrons reflected from specimens surface
Scanning tunneling microscope
3D
magnification 100 million times
needle only 1 atom can fit on
steady current maintained by probe and specimen, as probe moves up and down constant current maintained to generate image
Atomic Force Microscope
3D
used for surfaces that do not conduct electricity well
laser
sharp probe moves over specimen at a constant distance
variation in density of specimen causes difference force on probe to generate image
