Notes

First century AD

The glass has been invented. The Romans discovered a clear glass that was thick in the middle and thin on the edges. They called this clear glass lens, derived from the Latin term lentil because it resembled the shape of lentil bean.


Circa 1284

Italian, Salvino D'Armate is credited with inventing the first wearable eye glasses


1590

Two Dutch eye glass makers, Zaccharias Janssen and brother Hans Janssen experimented with multiple lenses placed in a tube. The Janssen’s observed that viewed objects in front of the tube appeared greatly enlarged, creating both the forerunner of the compound microscope and the telescope

1665

English physicist, Robert Hooke looked at a sliver of cork through a microscope lens and noticed some "pores" or "cells" in it.

1632- 1723

Anton van Leeuwenhoek built a simple microscope with only one lens to examine blood, yeast, insects and many other tiny objects. Leeuwenhoek was the first person to describe bacteria, and he invented new methods for grinding and polishing microscope lenses that allowed for curvatures providing magnifications of up to 270 diameters, the best available lenses at that time.

Types of Microscopes

• Compound Microscope
• Dissection Microscope
• Scanning Electron Microscope (SEM)
• Transmission Electron Microscope (TEM)

Simple Microscopes are composed of one lens and provide relatively low magnifying power (5x). Example is magnifying glass.

Compound Microscopes are composed of two or more lenses that provide powerful magnification.






Three Categories of a Compound Light Microscope



1. Illuminating Parts are the parts that provide light. Light is important for the object/specimen to be seen. They may come from two sources: natural source, reflected sunlight; artificial source, light bulb.
Mirror
Reflects the light from the source to the specimen
Diaphragm
Regulates the amount of light from the source to the specimen
Ocular/Eyepiece
Focuses light to the eye; where the observer peeps through.
objective lenses
they gather light

2. Magnifying Parts are the parts that enlarge the object or specimen
Ocular Lens
Enlarges the object six times (6x) or ten times (10x).
Aside from gathering light, they magnify the image. Most often, a CLM has three objectives
Low Power Objective (LPO)
Locates and enlarges the specimen 10x
High Power Objective ( HPO)
It enlarges the specimen 40x, 43x, or 45x.
Oil immersion Objective ( OIO)
that enlarges the object 100x

3. Mechanical Parts are the parts of the microscope that support, adjust, connect, and move other parts.
Base
It supports the entire weight of the microscope
Arm
Supports the body tube and the part that is held when the microscope is carried from one place to another.
Body tube
Connects the lenses of the objectives and the ocular.
Stage
It is the flat platform where you place your slides
Stage clips
It holds the slide in place. If your microscope has a mechanical stage, you will be able to move the slide around by turning two knobs. One moves it left and right, the other moves it up and down.
Adjustment knobs/screws
This helps move the objectives to bring the specimen into focus.
Coarse adjustment knob/screw
It is the large knob that moves the body tube faster to focus the specimen.
Fine adjustment knob
Is the smallest knob that is used to get a sharp focus of the specimen being viewed.
Revolving nosepiece
The rotating disc that holds the different objectives and allows for the shifting from one objective to the next.

Microscope Care

• Always carry with 2 hands

• Never touch the lenses with your fingers.

• Only use lens paper for cleaning

• Keep objects clear of desk and cords

• When you are finished with your "scope", rotate the nosepiece so that it's on the low power objective, roll the stage down to the lowest level, rubber band the cord, then replace the dust cover.