The Microscope

What structure in an animal’s body is this?

Where are these found?

How do biologists study cells?

A microscope is an instrument that produces magnified images of tiny structures.

Early Microscope

Early Microscope

Modern Microscopes

Compound Light Microscope

contains more than one lens magnification: up to 1000x useful for studying many

kinds of cells and small organisms

Electron Microscope

in the 1920s, a German physicist discovered a way to use magnets to focus beam of electrons

uses a beam of electrons instead of light to examine a sample

magnification: as much as 1000x larger than a light microscope

Electron Microscope

Two Kinds:Transmission Electron Microscope (TEM)

Scanning Electron Microscope (SEM)

TEM

gives a 2 - D view works much like a

slide projector specimen must be

cut into very thin slices so that the electron beam can pass through

SEM

gives a 3 - D view uses a thin beam

of electrons to scan a sample’s surface

does not reveal the internal structure of a sample

Images produced by light and electron microscope

Terms to remember:

Magnification – ability of the microscope to magnify or enlarge an object (example: 5x, 10x, 45x)

Total Magnification: magnification of the eyepiece x magnification of the objective

Resolution = sharpness of an image

Parts of the Microscope

Parts of the Microscope

Three main parts:A. Optical PartsB. Illuminating PartsC.Mechanical Parts

A. Optical Parts

- used for magnification of the image

1. Ocular / eyepiece 2. Objectives

A. Optical Parts

Objectives – tubes attached to the revolving nosepiece

A. SPO (4x) – gives an overview of the specimen

B. LPO (10x) – used for locating parts of the specimen

C. HPO (40x) – use to view small details of the specimen

B. Illuminating Parts

- used to focus or direct light

1. Mirror - used to reflect light - plane, convex2. Diaphragm - regulates the amount of light reflected

C. Mechanical Parts

- necessary for movement and support

1. Base – allows the microscope to stand2. Pillar – supports the stage3. Stage – where glass slide is placed4. Arm – curved part grasped when carrying the microscope

C. Mechanical Parts

5. Revolving nosepiece – where the objectives are attached6. Draw tube – holds the eyepiece7. Coarse adjustment knob – raises or lowers the body tube to bring image into focus8. Fine adjustment knob – focuses image further

C. Mechanical Parts

9. Inclination joint – allows tilting of the microscope10. Mirror rack – holds mirror in place11. Stage clip – holds specimen in place on the stage