Our journey begins here.

Simple to Complex – Life’s Levels of Organization

Introduction to the MicroscopeTypesCarePartsFocusing

Stereoscope

• This microscope allows for binocular (two eyes) viewing of larger specimens.

Simple Microscope vs. Compound Light Microscope

Similar to a magnifying glass and has only one lense.

Lets light pass through an object and then through two or more lenses.

Which kind do we use?

Stereoscope & Light Microscopes

Light MicroscopeLight Microscopelight as source light as source of of

illuminationilluminationglass lensesglass lenseslimited limited resolution resolution (loses (loses resolving power resolving power at at magnifications magnifications above 2000X)above 2000X)

Comparison of Microscopic Techniques for Visualizing a Living, Unstained Cell

Bright field

Phase-contrast

Florescent Stained Cell –shows the skeleton (green) and nucleus (purple) of the cell, etc.

Higher Resolution Is Achieved by Viewing Sections of Fixed, Stained, and Embedded Samples

A microtome cutting sections of an embedded sample.

What can you see with a microscope?

Electron Microscope

Uses a magnetic field to bend beams of electrons;– greater magnification

& resolving power than light microscope

The two types are: Scanning and Transmission

Electron Microscopy

A wavelength of electron beam is much shorter than light, resulting in much higher resolution

Scanning Electron Microscope (SEM)

• Allow scientists to view a universe too small to be seen with a light microscope.

• SEMs scan the surface of a specimen to magnify 3-D objects up to 150,000x

• Invented in 1965, see the 3-D surface of a specimen.

Scanning Electron Microscopy (SEM) Visualizes Surface Features

Specimen Preparation

Specimens are coated with metals to deflect electrons from a beam scanned across the sample.

SEM of Stereocilia Projecting from a Cochlear (inner ear) Hair Cell

SEM Photos!

Transmission Electron Microscope (TEM)

• Electrons are passed through very thin specimens to see what is inside!

• Invented in1933 • Magnification is

500,000x

A TEM of an Onion Root Tip Cell

Confocal Scanning Laser Microscope

• confocal microscopy and scanning probe microscopy

• have extremely high resolution

• can be used to observe individual atoms about 2,000,000x magnification

Confocal Scanning Laser Microscope

More images!

Optical sections of a pollen grain

Scanning confocal microscopy allows reconstructing a 3D image by stacking optical sections.

Stacked sections

Scanning Tunneling Microscope

The scanning tunneling microscope (STM) is a non-optical microscope that scans an electrical probe over a surface to be imaged to detect a weak electric current flowing between the tip and the surface.

Can find the position of individual atoms and molecules on the surface

Scanning Tunneling Microscope

Scanning tunneling microscope (STM) invented in 1981, is widely used in both industrial & fundamental research to obtain atomic-scale images of metal surfaces. It provides a three-dimensional profile of the surface.

Light Compound Microscope

Eyepiece

Body Tube

Revolving NosepieceArm

Objective Lens

StageStage Clips

Coarse Focus

Fine Focus

Base

Diaphragm

Light

• Always carry with 2 hands.• Only use lens paper for

cleaning.• Do not force knobs.• Always store covered• Keep objects clear of desk

and cords.

• Place the Slide on the Microscope• Use Stage Clips • Click Nosepiece to the lowest setting (shortest objective lens)• Look into the Eyepiece• Use the Coarse Adjustment Knob to focus

first then use the fine knob.• Total Magnification= ocular (eyepiece) X objective lens

What Are Some Characteristics What Are Some Characteristics of Microscope Viewing?of Microscope Viewing?

Characteristic Low power

High power

MagnificationObjective lens X Eyepiece lens

Field of viewLight intensityDepth of field*layers or levels penetrated

More

Greater

Dimmer

Smaller

Less

Less

Larger

Brighter

1. Use pencil - you can erase and shade areas.

2. All drawings should include clear and accurate labels (and be large enough to view details), with the specimen name (usually on slide) and magnification.

3. Labels should be written on the outside of the circle. The circle indicates the viewing field as seen through the eyepiece, specimens should be drawn to scale – i.e. if your specimen takes up the whole viewing field, make sure your drawing reflects that. All arrows should end with the point touching the object to be labeled! last does not exist in certain plant cells).

Tips on Good Drawings of Specimens

Tips on Good Drawings of Specimens

100 X 400 X

• Follow steps to focus using low power

• Click the nosepiece to the longest high objective

• Do NOT use the Coarse Focusing Knob

• Use the Fine Focus Knob to bring the slide

What can you find on your slide?

Which is the most powerful kind of microscope?

• Use this animation for slide show for light, optics: lenses color etc.