The Microscope. The History. How a Microscope Works. How a Microscope Works 4/28/16. The History. The History. Mr.

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1 The Microscope The History Many people experimented with making microscopes Was the microscope originally made by accident? (Most people were creating telescopes) The first microscope was 6 feet long!!! Mr. Schmidt Science 9 The Greeks & Romans used lenses to magnify objects over 1000 years ago. The History Hans and Zacharias Janssen of Holland in the 1590 s created the first compound microscope Anthony van Leeuwenhoek and Robert Hooke made improvements by working on the lenses The History Anthony van Leeuwenhoek Hooke Microscope Robert Hooke Zacharias Jansen The First Microscope How a Microscope Works How a Microscope Works Convex Lenses are curved glass used to make microscopes (and glasses etc.) Ocular Lens (Magnifies Image) Body Tube (Image Focuses) Objective Lens (Gathers Light, Magnifies And Focuses Image Inside Body Tube) Convex Lenses bend light and focus it in one spot. Bending Light: The objective (bottom) convex lens magnifies and focuses (bends) the image inside the body tube and the ocular convex (top) lens of a microscope magnifies it (again). 1

2 Simple Microscope Simple Compound Stereoscopic Electron Similar to a magnifying glass and has only one lens. Compound Microscope Lets light pass through an object and then through two or more lenses. Stereoscopic Microscope Gives a three dimensional view of an object. (Examples: insects and leaves) Electron Microscope Uses a magnetic field to bend beams of electrons; instead of using lenses to bend beams of light. A Lens Enlarges an image and bends the light toward your eye. 2

3 Eyepiece Lens The Parts of a Microscope Usually has a power of 10 x Body Tube Ocular Lens Nose Piece Objective Lenses Stage Clips Diaphragm Light Source Arm Stage Coarse Adj. Fine Adjustment Base connects the eyepiece to the objective lenses body tube the part that holds two or more objective lenses revolving nosepiece and can be rotated to easily change power Adds to the magnification Usually you will find 3 or 4 objective lenses on a microscope. objective lens 3

4 They almost always consist of 4X, 10X, 40X and 100X powers when coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X, 400X and 1000X. objective lenses The high power objective lenses are retractable (i.e. 40XR). This means that if they hit a slide, the end of the lens will objective lenses push in (spring loaded) thereby protecting the lens and the slide. Stage clips hold the slides in place. If your microscope has a mechanical stage, you will be able to move the slide around by turning two knobs. One moves it left and right, the other moves it up and down. stage clips controls the amount of light going through the specimen Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and is used to vary the intensity and diaphragm size of the cone of light that is projected upward into the slide. There is no set rule regarding which setting to use for a particular power. Rather, the setting is a function of the transparency of the specimen, the degree of contrast you desire and the particular objective lens in use. diaphragm makes the specimen easier to see light 4

5 Occular lens magnifies; where you look through to see the image of your specimen. They are usually 10X or 15X power. Our microscopes have an ocular lens power of 10x. arm supports the tube and connects it to the base the flat platform where you place your slides Moves stage (or body tube) up and down stage coarse adjustment knob small, round knob on the side of the microscope used to fine-tune the focus of your specimen fine adjustment knob after using the coarse adjustment knob base the bottom of the microscope, used for support 5

6 4/28/16 Objective Lenses Objective Lenses Low Power = 4 x Medium Power = 10 x High Power = 40 x Comparing Powers of Magnification What s my power? To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective. What are the powers of magnification for each of the objectives we have on our microscopes? We can see better details with higher the powers of magnification, but we cannot see as much of the image. Which of these images would be viewed at a higher power of magnification? Microscope Care & Usage Caring for a Microscope Clean only with a soft cloth/tissue Make sure it s on a flat surface Don t bang it Carry it with 2 HANDS one on the arm and the other on the base 6

7 Carry a Microscope Correctly Using a Microscope 1. Start on the lowest magnification 2. Don t use the coarse adjustment knob on high magnification you ll break the slide!!! 3. Place slide on stage and lock clips 4. Adjust light source (if it s a mirror don t stand in front of it!) 5. Use fine adjustment to focus Quiz Time!! 7