1. Understanding Microscopes

2. Use of Microscope
To magnify objects that cannot be seen with the naked eye
Resolving power
Ability of microscope to distinguish objects as separate – measured in nm and the lower the number the smaller the object that can be distinguished

3. Types of Microscopes Stereo/dissecting microscope
3D images
Relies on light on top of image
Low magnification
Compound light microscope
Magnifies up to 2000 times
Resolving power – 500 nm

7. Compound Light Microscope

12. Other types of Microscopes
Electron Microscopes
Transmission electron microscope (TEM)
Magnify hundreds of thousands of times
Resolution as great as 0.2 nm
Scanning electron microscope
3D image
Lower magnification than TEM
Sample must be frozen or embedded on plastic – not living

13. Transmission Electron Microscope (TEM) 1: Electron cannon in the upper part of the column. 2 Electro-magnetic lenses to direct and focus the electron beam inside the column. 3: Vacuum pumps system. 4: Opening to insert a grid with samples into the high-vacuum chamber for observation. 5: Operation panels (left for alignment; right for magnification and focussing; arrows for positioning the object inside the chamber). 6: Screen for menu and image display. 7: Water supply to cool the instrument.

15. Scanning Electron Microscope (SEM) 1: Electron cannon in the upper part of the column (here a so-called field-emission source). 2 Electro-magnetic lenses to direct and focus the electron beam inside the column. 3: Vacuum pumps system. 4: Opening to insert the object into the high-vacuum observation chamber in conventional SEM mode. 5: Operation panel with focus, alignment and magnification tools and a joystick for positioning of the sample. 6: Screen for menu and image display. 7: Cryo-unit to prepare (break, coat and sublimate) frozen material before insertion in the observation chamber in Cryo-SEM mode. 8: Electronics stored in cupboards under the desk. 9: Technicians Mieke Wolters-Arts and Geert-Jan Janssen discussing a view

18. Compound Light Microscope
Ocular
Body tube
Revolving nosepiece
Arm
Low power objective
Medium power objective
Stage
High power objective
Coarse Adjustment
Stage clips
Diaphragm
Fine Adjustment
Light source
Base

19. Function of parts The tube that supports the eyepiece
The rotating device that holds the objectives
A small lens with low magnifying power
A medium lens with medium magnifying power
A large lens with high magnifying power

20. Function of parts 6. Metal clips that hold a slide onto the stage
7. An adjustable opening under the stage, allowing different amounts of light onto the stage
Directs light upwards onto the stage
A lens where you place your eye
Attaches the ocular and body tube to the base

21. Function of parts 11.The platform on which a slide is placed
12. A knob that makes large adjustments to the focus
13. A knob that makes small adjustments to the focus (it is often smaller than the coarse focus knob)
14. This supports the microscope

22. Measuring with a Microscope
Find diameter of field of view
Estimate the number of objects that will fit across the field of view
Divide this number into the diameter of field
Ex. Diameter = 1000 µm # across = 2.5
1000/2.5 = 400 µm

23. How do you work out the magnification of your microscope?
Ocular magnification X Objective magnification

24. Microscope Techniques
Making a wet slide
Add a drop of water to center of slide
Place object in water (do not let it get folded)
Use forceps to position coverslip (fingerprints will interfere)
Lower coverslip slowly to avoid air bubbles

25. A wet mount slide

26. Microscope Techniques
Staining or Adding Substances to Slide
Place drop of stain beside one edge of coverslip
Touch a small piece of paper towel to opposite edge of coverslip
Towel will absorb H2O and draw stain under coverslip

27. Staining Technique