Microscope Basics(1)

Parts and focusing

Label the Compound Light Microscope

Ocular lens

Body TubeCoarse Adjustment KnobFine adjustment KnobRevolving nosepieceObjective lenses (4x, 10x, 40x)ArmStage Stage ClipsDiaphramLight source

Base

Focusing with a Microscope Plug in and turn on. Lower stage completely. Turn nosepiece to low objective. Raise stage with coarse objective until specimen

is seen. (Big knob) Fine focus the specimen. Centre specimen in the field of view. Rotate nosepiece to medium power objective. Refocus with fine adjustment. Re-centre the specimen. Refocus with fine adjustment. (Be careful not to

break the slide.) Adjust the condenser. (Light) Start over to look at another specimen. Carrying and storage instructions.

Microscope History and Development

Field of view and Magnification

Robert Hooke In 1665, the English physicist Robert

Hooke looked at a sliver of cork through a microscope lens and noticed some "pores" or "cells" in it.

Hooke was the first person to use the word "cell" to identify microscopic structures when he was describing cork.

Early Microscopes - Anton Van Leeuwenhoek

The father of microscopy, Anton Van Leeuwenhoek of Holland (1632-1723).

Anton Van Leeuwenhoek was the first to see and describe bacteria (1674), yeast plants, the teeming life in a drop of water, and the circulation of blood corpuscles in capillaries.

Antique microscopes (link)

Technological Advances in Microscopes

Compound Light Microscopes

Uses light Has two lenses Magnification limited to 2000x (400x

at LHHS)

Transmission Electron Microscope (TEM)

Uses beams of electrons Magnification of 2 000 000x Has two limitations:

Good only for thin specimens Only dead cells can be observed

Scanning Electron Microscope (SEM)

Electrons are reflected from the surface of the specimen

Produces a 3-d image Good for the thicker specimens Lacks the magnification and

resolution of the transmission electron microscope

Parts of the Compound Microscope

http://www.biologycorner.com/microquiz/#

Microscope Use http://www.youtube.com/watch?

v=scEhgAiazzU

Magnification

Magnification – how big an object appears under a microscope compared to it’s actual size.

Magnification = Objective lens X Ocular lens

(4x, 10x, 40x)(10x)

Calculating the size of a specimen

binder

Calculating the size of a specimen

Example under med. objectiveObject size = Size of field of view

Number of objects across field of view

Object size = 1.72 mm 14

Object size = 0.1 mm

Preparing a wet mount1. Obtain a clean slide, cover slip, and water

bottle.2. Place 1 drop of water in the middle of slide.3. Obtain specimen.4. Place specimen in the drop of water.5. Place the edge of the cover slip on one side

of the water drop.6. Slowly lower the cover slip on top of the

specimen.

Finished with your microscope?

Store microscope with the low objective lens in place.

Wrap cord around arm and cover microscope.

Wash slides/slips and return. Put back in the proper location. Arm always facing outward.