MicroscopesMicroscopes

Biology 11

The History

Many people experimented with making microscopes

Was the microscope originally made by accident? (Most people were creating telescopes)

The first microscope was 6 feet long!!!

The Greeks & Romans used “lenses” to magnify objects over 1000 years ago.

The History Hans and Zacharias Janssen of Holland in

the 1590’s created the “first” compound microscope

Anthony van Leeuwenhoek and Robert Hooke made improvements by working on the lenses

Anthony van Leeuwenhoek1632-1723

Robert Hooke 1635-1703

Hooke Microscope

The History

Zacharias Jansen1588-1631

The “First” Microscope

How a Microscope Works

Convex Lenses arecurved glass used to make microscopes(and glasses etc.)

Convex lenses bendlight and focus it inone spot.

How a Microscope Works

Ocular Lens(Magnifies Image)

Objective Lens(Gathers Light, Magnifies And Focuses Image Inside Body Tube)Body Tube

(Image Focuses)

•Bending Light: The objective (bottom) convex lens magnifies and focuses (bends) the image inside the body tube and the ocular convex (top) lens of a microscope magnifies it (again).

The Parts of a Microscope:

Body Tube

Nose Piece

ObjectiveLenses

Stage Clips

Diaphragm

Light Source

Ocular Lens

Arm

Stage

Coarse Adj.

Fine Adjustment

Base

Body Tube

The body tube holds the objective lenses and the ocular lens at the proper distance

Diagram

Nose Piece

The Nose Piece holds the objective lenses and can be turned to increase the magnification

Diagram

Objective Lenses

The Objective Lenses increase magnification (usually from 10x to 40x)

Diagram

Stage Clips

These 2 clips hold the slide/specimen in place on the stage.

Diagram

Diaphragm

The Diaphragm controls the amount of light on the slide/specimen

Turn to let more light in or tomake dimmer.

Diagram

Light Source

Projects light upwards through the diaphragm, the specimen and the lenses

Some have lights, others have mirrors where you must move the mirror to reflect light

Diagram

Ocular Lens/Eyepiece

Magnifies the specimen image

Diagram

Arm

Used to support the microscope when carried. Holds the body tube, nose piece and objective lenses

Diagram

Stage

Supports the slide/specimen

Diagram

Coarse Adjustment Knob

Moves the stage up and down (quickly) for focusing your image

Diagram

Fine Adjustment Knob

This knob moves the stage SLIGHTLY to sharpen the image

Diagram

Base

Supports the microscope

Diagram

Caring for a Microscope

Clean only with a soft cloth/tissue

Make sure it’s on a flat surface

Don’t bang it

Carry it with 2 HANDS…one on the arm and the other on the base

Carry a Microscope Correctly

Using a Microscope

Start on the lowest magnification Don’t use the coarse adjustment knob on high

magnification…you’ll break the slide!!! Place slide on stage and lock clips Adjust light source (if it’s a mirror…don’t

stand in front of it!) Use fine adjustment to focus

Simple MicroscopeSimple Microscope

Anton van Leewenhoek was the first to use the single lens microscope for biological purposes.

Consisted of 1 lens used today for quick

observations specimens may be alive for

examination.

Compound Light MicroscopeCompound Light Microscope

Consists of two lenses objective and eyepiece

both of which magnify the image

these two lenses form the optical system.

Structural parts that hold the specimen and the lenses is called the mechanical system

Stereo microscope (dissection)

Contains an ocular and an objective for each eye

allows the scientist to view images as 3-D

used primarily for viewing external structures

specimens may be kept alive for examination.

Phase Contrast (lens) MicroscopePhase Contrast (lens) Microscope

Changes the way light passes through a living specimen so that you may see cellular parts not usually visible under a compound microscope.

Under the compound microscope the tissue would have to be dead, now it may be living.

Frits (Frederik) Zernike won the Nobel prize 1953 for the development of this microscope.

Transmission Electron MicroscopeTransmission Electron Microscope

Specimens are dead an image can be magnified

as large as 250, 000x. Electron beam is sent

through a vacuum chamber.

Electromagnets focus the image on a screen

denser materials appear darker than less dense material.

Also know as the TEM

Scanning Electron MicroscopeScanning Electron Microscope

Like the TEM, this microscope uses electrons to focus an image and is able to view things much smaller than the light microscope.

Unlike the TEM, the SEM allows the viewing of 3D images.

However, the specimens are dead.

Also known as the SEM

MagnificationMagnification

The ability to increase the size of an image of a specimen.

The magnification of an image on a compound microscope is found by multiplying the power of the eye piece by the power of the objective.

The larger the magnification the less area you are able to see.

ResolutionResolution

The ability to show two points that are close together

in order for the increased magnification of a microscope to be of use, its resolution must also be increased

resolution is dependant on the quality of the lens.

Microscope Calculations: