Microscopy

History of the Microscope

Hans and Zacharias Janssen- (1595) Eyeglass crafters- Magnify object 3-10x

Robert Hooke- (1655) Observed pores on corks and called them "cells"

History of the Microscope

Anton van Leeuwenhoek- (1673) First to see microscopic organisms in pond water. His microscope lead the way to the microscopes we use today.

Carl Zeiss- (1850s) Refined the microscope by adjusting the lenses to improve optical quality. His company is still manufacturing microscopes today.

Microscope Vocabulary

Magnification: increase of an object's apparent size

Resolution: power to show details clearly

*Both are needed to see a clear image

Types of Microscopes

Compound microscope:

First type of microscope and most widely used

Light passes through 2 lenses

Magnify up to 2000x

Optical Microscopes

Types of Microscopes

Dissecting Microscope (stereo microscope):

Provide 3 dimensional view of object

Magnify up to 100x

Useful for observing opaque objects

Types of Microscopes

Confocal Laser Scanning Microscope:

Able to also scan an object in depth

Computer is able to assemble the object as a 3D image

Types of Microscopes

Electron Microscope:

Used to view very small objects: viruses, DNA, parts of a cell

Uses beams of electrons rather than light

Much more powerful

Types of Microscopes

Transmission Electron Microscope (TEM):

Can magnify up to 250,000x

Beam of electrons is transmitted through an ultra-thin specimen and interacts with the specimen as it passes through

Types of Microscopes

Scanning Electron Microscope (SEM):

Can magnify up to 500,000x

Produces images of a sample by scanning it with a focused beam of electrons. The elctrons interact with the atoms in the sample.

Types of Microscopes

X-Ray Microscope:

Uses a beam of x-rays to create an image

Due to small wavelength, image resolution is higher than with compound microscopes

Used to view living cells

Caring for Your Microscope

Parts of the Microscope

What does the Base do? supports the microscope

What does the arm do? it is used to carry the microscope

What is the stage? platform where the slide with the specimen is placed

What do the stage clips do? they hold the slide in place on the stage

What does the eyepiece do? magnifies the image for the viewer

What are the objective lenses? low-power and high-power lenses that magnify the specimen

What is a Coarse adjustment? large knob used for focusing the image under low-power

What is a fine adjustment? smaller knob used for focusing the image with the high-power objective

What does a diaphragm do? controls the amount of light that passes through the specimen

What does the light source do? provides light for viewing the specimen

Parts Functions

Magnification

Your microscope has 3 magnifications: Scanning, Low and High. Each objective has magnification on it In addition to this, the ocular lens (eyepiece) has a magnification. The total magnification is the ocular x objective

Always start with the scanning objective

Carry the base with one hand and the arm with the other

Microscope should be stored with scanning objective clicked into place

Plug in your microscope

Use the coarse knob to focus and the fine adjustment until object is clear

Once focused, switch to low power and use the coarse knob to refocus and the fine adjustment to make image clear

Now you can switch to high power (not if thick slide or no cover slip) and only use fine adjustment to focus image

Recap1.  Scanning --> use coarse and fine knob 2.  Low power --> use coarse and fine knob3.  High power --> use fine knob only

TroubleshootingOccasionally you may have trouble with working your microscope.Here are some common problems and solutions.

1. Image is too dark!Adjust the diaphragm, make sure your light is on.

2. There's a spot in my viewing field, even when I move the slide the spot stays in the same place!Your lens is dirty. Use lens paper, and only lens paper to carefully clean the objective and ocular lens. The ocular lens can be removed to clean the inside.  The spot is probably a spec of dust.

3. I can't see anything under high power!Remember the steps, if you can't focus under scanning and then low power, you won't be able to focus anything under high power.  Start at scanning and walk through the steps again. 

4. Only half of my viewing field is lit, it looks like there's a half-moon in there!You probably don't have your objective fully clicked into place..

Troubleshooting

5. Eyestrain and HeadachesAdjust interpupillary distanceAdjust eyepiece diopter settingUse matched eyepieces

Storage of Microscopes

Clean using lens paper only

Store with scanning objective in place

Power off microscope

Wrap cord around base

Using both hands, store in microscope cabinet with dust cover on