Microscopy

Introduction: Welcome to the microscope section of the compendium review. You are about to see slides from an online microscope simulator that can be found at www.udel.edu/biology/ketcham/microscope/. There is an excellent tutorial and video clip to get you started. The most commonly used microscope, the compound microscope, is the one that is going to be discussed.

A Brief History

This website www.southwestschools.org/jsfaculty/Microscopes/ind... has a great page where you can see a pictorial evolutionary history of the microscope. Zacharias Janssen is given credit for the first compound microscope. It was as simple thing of a tube with a lens at either end. Many believe it was actually his father who invented it, considering Zacharias’ age at the time. This invention came to being around 1590. From there, Robert Hooke, in 1660, improved it by research and publishing “Micrographia,” coining the word cell. Later, a man with no wealth or formal education, Anton van Leeuwenhoek was known as the best microscope maker for the time period (early 1700s).

Things to Know

Things to know about a compound microscope:

-Most commonly used

-Light illuminated

-2-D image

-View individual cells (even while the cells are still living)

- High magnification and low resolution

-Uses glass slides

-Focuses mechanically

-Uses glass lenses

How Parts Work

Ocular Lens: The piece at the very top that magnifies the image of the specimen formed by the objectives.

Body Tube: Supports the eyepiece and the oculars.

Revolving Nosepiece: Allows one to move the objectives to different magnification powers.

Arm: Supports the body tube.

Objectives: This is the microscope. Objectives are the tiny lenses that produce the image seen through the ocular lens. The powers labeled on the objectives (e.g. 4) are multiplied by ten because that is what the ocular lens is set at. For example, if you were using the 10 objective, you would be seeing the image magnified by 100.

Stage: What holds the slide as well as h

aving an opening where light can come through.

Stage Clips: Holds the slide in place.

Iris: Determines how much light is let through. It works like the iris of your eye, the more light, the wider the opening and vice versa.

Coarse Adjustment Knob: Moves the stage up and down.

Fine Adjustment Knob: Sharply focuses the image.

Light Source: Where the light comes from.

Base: Holds the microscope.

• Here are some pointers from www.udel.edu/biology/ketcham/microscope/. and www.southwestschools.org/jsfaculty/Microscopes/ind... for instructions on how to use the microscope.

Before looking into the microscope

1. After placing the slide on the stage, make sure the lowest objective is in place and the stage is either all the way up or all the way down.

2. To move the slide around, use the XY controls. Be careful, if you are looking through the oculars, the slide may move opposite of the way you are turning the knob.

3. Turn the light on and open the slide to center your specimen.

4. Ensure the iris is closed after slide is centered to avoid blinding yourself when you first look through the oculars

Now look into the microscope

1. Look into the microscope with both eyes open.

2. Adjust the oculars so there is one circle and keep your face a slight distance from the oculars.

3. Depending on if you started with you stage all t

he way down or up will determine which way to move your coarse adjustments. This should also be the only time you use the coarse adjustment. This moves the stage up and down. Move it very slowly until you can see your specimen.

4. You may need to adjust the iris.

5. Once you have found your specimen, use the fine focus knobs to make the image clear.

6. Remember to use the XY controls to move the slide.

7. Place the desired part of the specimen in your field of view before you increase the magnification.

8. Adjust the iris accordingly once further magnified.

9. When you are finished, lower the stage all the way and rem

ove the slide.

Some very important tips

*When carrying a microscope, grasp the arm and use your other hand to support the base.

*Only use lens paper to clean the glass, paper towels and other like items will scratch it! NEVER TOUCH THE LENSES WITH YOUR FINGERS.

*When finished, make sure the base is all the way down and the lowest objective is in place.

Microscope Slides

Now is your chance to see some slides from the online microscope simulator.

This image is while looking through the microscope. What you are looking at is a cheek cell sample at magnified times forty. It may be hard to tell on this picture, but it is in focus with the iris at the right level.

Try as I might, this image did not want to get any bigger. Here you are looking at the same slide, but magnified times 100. In order to get this, I had to adjust the fine focus knob and open the iris a little bit. Again, this picture is (believe it or not) in focus with the correct amount of light.

Last but not least, here is the same cheek cell. Now you are seeing it up close and personal magnified four-hundred times! As the picture is not that large, this one is a little better to see that is is focused. Again, I had to adjust the fine focus and iris, but did not touch the coarse focus. That only happened when working with the 4 objective.

Conclusion: After browsing through this section, you found information on a compound microscope. You saw images, got written directions, as well as a brief history. Now that you hav

e the basics of science under yourbelt, it is time to move on. We are about to work our way up to the workings of a cell. We will begin by discussing the characteristics of life and move on from there. In the next section, you will learn that all life shares the same seven characteristics. You will also see how life is organized.