The Microscope

Module 5: Tools and Techniques of Biologists

The Microscope

The Microscope

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Parts of a microscope

Types of microscopes

Proper Handling of a Microscope

parts of a microscope

parts of a microscope

Click on the magnifying glass to start!

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Click on the icons to read more on microscope parts, or click on the image to try them out yourself !

MICROSCOPE PARTS: ILLUMINATING MAGNIFYING MECHANICAL

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How to's of handling and using a microscope

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MAGNIFYING PARTS

1. Eyepiece - Contains the ocular lens and is where you peek through to observe a specimen. The eyepiece is labelled with the magnification power. A magnification “10x” means that the image is enlarged by a factor of 10. 2. objective lenses - Called as such because they are closest to the object being viewed. Microscopes vary in the number of lenses they have. The degree of magnification for each objective lens is indicated on its side and the tube length is directly proportional to the ability its able to magnify a specimen.

I. scanner objective – Called as such because its used to scan and locate the specimen before viewing at a higher magnification. This objective magnifies the image by a factor of 4. Some microscopes do not have this objective, in which case you can begin with the 10x objective. II. low power objective (LPO) – This objective magnifies the image by a factor of 10 and is used to get an overview of the specimen. III. high power objective (HPO) – This objective magnifies the image by a factor of 40 and is used view the very fine details of the specimen.

Click on any of the objecttives to see them in action!

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Plant cell cross-section sample

1.

scanner objective

2.

low power objective

3.

high power objective

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ILLUMINATING PARTS

1. light source - This may be a mirror or a bulb that projects light upward to illuminate the specimen. 2. condenser – This contains lenses that captures and focuses light from the light source below onto the slide mounted on the stage. 3. iris diaphragm – The diaphragm allows you to regulate the amount of light by adjusting the diaphragm lever. Most of the time, it is all the way open to allow the maximum passage of light. It may be adjusted to reduce the amount of light passing through the specimen should the image be too bright or dim, and to increase the contrast to allow you to see the specimen more easily against the background.

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MECHANICAL PARTS

1. base - The base bears the weight of the microscope. 2. arm – The arm is the vertical framework ascending from the base along the back of the microscope. 3. revolving nosepiece – This is a circular metallic structure attached below the body tube. It holds objectives that can be rotated to change the to the magnification required to examine the specimen. 4. stage – The stage is the flat surface upon which you will place the slide you will examine. 5. aperture - This is the hole in the stage. 6. stage clips – The stage clips that can be used to secure or fasten the slide on the stage. They should snugly hold the slide in position.

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MECHANICAL PARTS

7. stage control knobs - These knobs move the slide right or left. For microscopes without the stage screws, the slide is manually moved. 8. coarse adjustment knob – For a specimen on a slide to be in focus, the distance between the specimen and the objective lens must be precise. The coarse knob moves the objectives up and down quickly and quite visibly, altering the distance between them. It is important to note that the coarse focus knob is only used with the scanner or low power objective, otherwise the microscope or objective lenses could be damaged. 9. fine adjustment knob – The fine focus moves the objectives in very minute amounts that it is hardly noticeable to the naked eye, for a more precise adjustment. This is the knob used to get the perfect distance to bring the image into focus at high magnification using the high power objective.

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stage, fine and coarse

adjustment knobs

Video excerpt from https://www.youtube.com/watch?v=tVcEEw6qbBQ&t=355s

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vs.

compound light stereo microscope

click on a microscope to start!

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compound light microscope

• Able to provide high power magnifications up to 400x

• Used to view specimens that are not visible to the naked eye such as cells, bacteria, etc.

• provides 2-dimensional images of a chosen specimen

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stereo microscope

• as the term "stereo" suggests, this microscope has two seperate ocular lenses to provide a 3-dimensional image of a specimen

• Used for observing specimens in low magnifications (2-100x)

• Ideal for studying the surface and depth of relatively large specimens such as bugs, organs, etc.

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What kind of microscope was used to view the different specimens?

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