Microscopes

Microscopes
Microscopes: are devices that produce magnified images of structures that are too small to see with the unaided eye.
? Types of Microscope
1- Light Microscope
• Confocal Microscope
• Fluorescence Microscope
2- Electron Microscope
- scanning EM
- Transmission EM
? Light Microscopes
The most commonly used microscope is the light microscope Compound light microscopes allow light to pass through the specimen and use two lenses to form an image.

Magnification:
The increase of an object s apparent size.
Magnification Your microscope has 3 magnifications: Scanning, Low and High .Each objective will have written the magnification .In addition to this, the ocular lens (eyepiece) has a magnification . The total magnification is the ocular x objective
magnification ocular lens total magnification
Scanning 4x 10x 40x
Low power 10x 10x 100x
High power 40x 10x 400x

Field of view: the area visible through the microscope lenses. Field of view decreases as magnificaiton increases.
Resolution: the ability to show details clearly. Resolution allows the viewer to see two objects that are very close together as two objects rather than as one.
Resolution is determined by the quality of the microscope lenses - the better the lenses, the better the resolution .
• Compound microscopes
Compound microscopes use multiple lenses to produce an increase in magnification. If the eyepiece lens enlarges by a factor of 10 (10X) and the objective lens enlarges by a factor of 40 (40X), the total magnification is the product of the two - 400X.



Parts of a Compound Light Microscope
• Eyepiece (Ocular): Usually contains a 10X lens.
• Arm: contains the housing for the fine and coarse adjustments and connects the base of the microscope to the nosepiece and ocular.
• Nosepiece: A rotating head that has the objective lenses attached to it. The lens to be used should "click" into position when the wheel is gently turned so that it is directly over the speciman slide.
• Objective lenses: may have (scanner ,low ,high ,oil immersion objectives ) and is used use to increase the magnification of the spacemen.
Stage: The speciman slides rests on this part of the microscope.
• Stage clips : hold the slide in place

• Coarse adjustment knobs: The larger of two sets of knobs located on either side of the arm, just above the base. This adjustment is used to make large adjustments in focusing by moving the lenses up and down. Never use this adjustment when using the 40X objective.
• Fine adjustment knobs: The smaller of two sets of knobs located on either side of the arm. This adjustment is used to make small adjustments in focusing. It has a limited amount of movement and is most efficiently used after focusing with the 4X objective and coarse focus, then increasing magnification and making final adjustments with the fine focus knob.
• Light source: Located directly under the stage.
• Adjustable diaphragm: This rotating wheel on the underside of the stage allows the user to adjust the amount of light that passes through the specimen. As a general rule, the lowest intensity of light that allows you to resolve the structure of the object you are viewing should be used.
Care and Handling of the Lab Microscopes
• A microscope is a delicate piece of equipment and should be treated with care.
• Use two hands when carrying the microscope. Place one hand around the arm of the microscope and the other under the base for support.
• Carry the microscope upright and close to the body.
• Place the microscope flat on the table, but not too near the edge where it might be knocked off.
• DO NOT slide the microscope back and forth on the lab table.
• If it becomes necessary to clean the lenses on the microscope, ask your facilitator for a piece of lens paper. Other materials, such as paper towel, can scratch the surface of the lens.
• Cleanup:
• Unless otherwise instructed, wipe the sample and coverslip off the slide with a paper towel when finished.
• Throw the paper towel and its contents away.
• Return the microscope slide to its container.
• Return the microscope to storage.