The Microscope

Types of Microscopes• Compound light microscope• Electron microscope• Scanning Electron Microscope

Compound Light Microscope History Zacharias Janssen was a Dutch lens-maker

who invented the first compound microscope in 1595 (a compound microscope is one which has more than one lens).

His microscope consisted of two tubes that slid within one another, and had a lens at each end. The microscope was focused by sliding the tubes. This advanced microscope had a 3 to 9 times power of magnification.

The lens in the eyepiece was bi-convex (bulging outwards on both sides), and the lens of the far end (the objective lens) was mono-convex (flat on one side and bulging outwards on the other side).

Compound Light Microscope

Compound Light Microscopes show the viewer an image by passing a light through the specimen. Total magnification is the Eyepiece (Ocular Lens) magnification multiplied with the objective lens magnification.

Example: Eyepiece 5X Objective 40X Total Magnification 200X

Compound Light Microscope Labeling

Eyepiece

Body Tube

Revolving Nosepiece

Low Power Objective

High Power Objective

Stage

Diaphragm

Light Source

Course Adjustment Knob

Fine Adjustment Knob

Grasping Arm

Stage Clips

Inclination Joint

Base

Electron MicroscopesWhere did Electron Microscopes Come From?

Electron Microscopes were developed due to the limitations of Light Microscopes which are limited by the physics of light to 500x or 1000x magnification and a resolution of 0.2 micrometers. In the early 1930's this theoretical limit had been reached and there was a scientific desire to see the fine details of the interior structures of organic cells (nucleus, mitochondria...etc.). This required 10,000x plus magnification which was just not possible using Light Microscopes.

Electron Microscopes What are Electron Microscopes?

Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale.

This examination can yield the following information• Topography

– The surface features of an object or "how it looks", its texture; direct relation between these features and materials properties (hardness, reflectivity...etc.)

• Morphology – The shape and size of the particles making up the object; direct

relation between these structures and materials properties (ductility, strength, reactivity...etc.)

• Composition – The elements and compounds that the object is composed of and

the relative amounts of them; direct relationship between composition and materials properties (melting point, reactivity, hardness...etc.)

• Crystallographic Information – How the atoms are arranged in the object; direct relation between

these arrangements and materials properties (conductivity, electrical properties, strength...etc.)

Scanning Electron Microscopes

• The first Scanning Electron Microscope (SEM) debuted in 1942 with the first commercial instruments around 1965. Its late development was due to the electronics involved in "scanning" the beam of electrons across the sample

Microscope Review1. What are the three types of microscopes?

The Compound light microscopeThe electron microscope

The scanning electron microscope

2. Who invented the first compound light microscope?

Zacharius Janssen

3. What is the formula to finding total magnification?

Eyepiece Magnification multiplied by objective lens magnification.

Microscope Review4. How does a scanning electron microscope

function?The microscope concentrates a highly energetic beam of electrons to closely

examine an image, and then project an image of the specimen on a monitor.

Microscope Review

Eyepiece

Body Tube

Revolving Nosepiece

Low Power Objective

High Power Objective

Stage

Diaphragm

Light Source

Course Adjustment Knob

Fine Adjustment Knob

Grasping Arm

Stage Clips

Inclination Joint

Base

5. Label this microscope ?

The Microscope

The End Thank you for paying

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