Microscopes

compound microscope

a type of microscope where light is passed through two sets of lenses

simple microscope

a type of microscope where light is passed through one lens

monocular

having a single eyepiece

binocular

having two eyepieces

ocular lens

contained in an eyepiece, and magnifies images 10x

objective lenses

sets of lenses on a rotating nosepiece, magnifies images from 4x to 100x

total magnification

ocular magnification x objective magnification

specimen

item being viewed

stage

a platform which the specimen is placed on

x-y mechanical stage knobs

moves the slide on the surface of the stage, but does not raise or lower the stage

coarse focusing knob

used for large-scale movements, with 4x or 10x objective lenses

fine focusing knob

used for small-scale movements, with 40x or 100x objective lenses

illuminator

a high-intensity bulb below the stage

condenser lens

a lens below the stage which focuses all of the light rays on the specimen to maximize illumination

diaphragm

this can be opened or closed to adjust the amount of light

rheostat

a dimmer switch that controls the intensity of the illuminator

chromophores

pigments that absorb and reflect particular wavelengths of light

oil immersion lens

a special lens designed to be used with immersion oils

destructive interference

out of phase wavelengths with wave troughs that will cancel out wave peaks

fluorochromes

capable of absorbing energy from a light source then emitting this energy as visible light

immunofluorescence

used to identify certain disease-causing microbes by observing whether antibodies bind to them

light microscopes

uses visible light or ultraviolet light to produce an image; up to about 1000x

brightfield, darkfield, phase contrast, differential interference contrast (DIC), fluorescence, confocal, two-photon

types of light microscopes

brightfield microscope

a type of light microscope; produces an image on a bright background; most commonly used in labs as standard microscope

darkfield microscope

a type of light microscope; increases contrast without staining by producing a bright image on a darker background; useful for viewing live specimens

phase contrast microscope

a type of light microscope; uses refraction and interference caused by structures in the specimen to create high-contrast, high-resolution images without staining; useful for viewing live specimens and structures (i.e. endospores and organelles)

differential interference contrast (DIC) microscope

a type of light microscope; uses interference patterns to enhance contrast between different features of a specimen to create high-contrast images of living organisms with a three-dimensional appearance; useful for viewing detailed structures within live, unstained cells

fluorescence microscope

a type of brightfield microscope; uses fluorescent stains to produce an image; useful for identifying pathogens, finding particular species, distinguishing living from dead cells, finding locations of particular molecules within a cell, and immunofluorescence

confocal microscope

a type of light microscope; uses a laser to scan multiple z-planes successively to produce numerous 2D high-resolution images at various depths, which can be turned into 3D with a computer; useful for examining thick specimens such as biofilms

two-photon microscope

a type of light microscope; uses a scanning technique, fluorochromes, and long-wavelength light to penetrate deep into thick specimens such as biofilms

electron microscopes

uses electron beams focused with magnets to produce an image; 20-100,000x or more

transmission (TEM), scanning (SEM)

types of electron microscopes

transmission (TEM) microscope

a type of EM; uses electron beams that pass through a specimen to visualize small images; useful for observing small, thin specimens (i.e. tissue sections and subcellular structures)

scanning (SEM) microscope

a type of EM; uses electron beams to visualize surfaces; useful for observing 3D surface details of specimens

scanning probe microscopes

uses very short probes that are passed over the surface of the specimen and interact with it directly; atomic level observation; 100-100,000,000x or more

scanning tunneling (STM), atomic force (AFM)

types of scanning probe microscopes

scanning tunneling microscope (STM)

uses a probe passed horizontally at a constant distance just above the specimen while the intensity of the current is measured; maps structure of surfaces; works best on conducting materials but can also be used to examine organic materials if fixed on a surface

atomic force microscope (AFM)

a type of EM; can be used to map a 3d structure of surface by pushing the tip of the probe onto it repeatedly at a constant current; more easily used with nonconducting samples