Microscopes

History of the microscope The first compound microscope was created in the 1590’s. Anthony van Leeuwenhoek and Robert Hooke made improvements by working on the lenses

Robert Hooke Discovered the cell Hooke coined the term cell for describing biological organisms. He examined very thin slices of cork and saw a multitude of tiny pores that he remarked looked like the walled compartments of a honeycomb.

The compound light microscope Has two sets of lenses and allows light to pass through a specimen to form an image. It can produce clear images of objects at a magnification of 1000 times. Must have two characteristic to be useful: Magnification Resolution

Magnification Magnification is the enlarging of the image so it can be seen easier

Field of view The area you see through the microscope. Middle power The area you see through the microscope. The field of view gets smaller as you go from scanning power to high power. This is why you find the image under the lowest power first. Always center the object before you change to a higher power. High Power Lowest power (scanning lens)

Resolution good resolution poor resolution Resolution is the ability to distinguish between two points. Clear images are easier to see than blurry images.

Resolution

Parts of a microscope

Parts & functions Optical parts of the compound light microscope 1. Ocular lens/eye piece: Contains a magnifying lens, usually 10x or 15x. To look through.

Parts & functions 2. Objective lens: has three different magnifying lenses. On our microscopes A. Scanning lens: magnifies image 4X B. Low power: magnifies 10X C. High power: magnifies 40X

Total magnification How is total magnification of the microscope determine? Multiply the magnification of the eye piece lens by the magnification of the objective lens. For example if the eye piece is 10X and you use the low power objective lens which is also 10X, your total magnification is 100X.

Parts & functions 3. light source 4. diaphragm: regulates amount of light that passes up towards the eye piece. 5. Base: support microscope 6. Arm: supports body tube 7. Stage: supports slide to be observed.

Parts & functions 8. Body tube: keeps proper distance between eye piece and objectives. 9. Nosepiece: hold objectives, can be rotated. 10. Course Adjustment: moves body tube in order to focus the image. 11. Fine Adjustment: moves body tube slightly to sharpen image.

Bacteria

Blood cells

How to make a wet-mount slide 1. Get a clean slide and cover slip 2. Place one drop of water in the middle of the slide. 3. Place the edge of the cover slip on one side of the water drop. 4. Slowly lower to cover slip on top of the drop 5. Place the slide on the stage and first view with the scanning lens.