Prepared By: Ms. Carolyn R. Magat The MICROPSCOPE Prepared By: Ms. Carolyn R. Magat

Objectives: Determine the parts and function of the microscope. Identify scientist who first worked with the aid of the microscope.

What is a microscope? an optical instrument having a magnifying lens or a combination of lenses for inspecting objects too small to be seen or too small to be seen distinctly and in detail by the unaided eye.

Types of Microscope Compound Microscope Compound microscopes are light illuminated. The image seen with this type of microscope is two dimensional. This microscope is the most commonly used. You can view individual cells, even living ones. It has high magnification. However, it has a low resolution.

Types of Microscope Dissection Microscope A dissection microscope is light illuminated. The image that appears is three dimensional. It is used for dissection to get a better look at the larger specimen. You cannot see individual cells because it has a low magnification.

Types of Microscope Confocal Microscope This microscope uses a laser light. This light is used because of the wavelength. Laser light scan across the specimen with the aid of scanning mirrors. Then image is then placed on a digital computer screen for analyzing.

Types of Microscope Scanning Electron Microscope SEM use electron illumination. The image is seen in 3-D. It has high magnification and high resolution. The specimen is coated in gold and the electrons bounce off to give you and exterior view of the specimen. The pictures are in black and white. Q: what is the difference between SEM and Confocal: Medium SEM Electron Confocal: laser light

Types of Microscope Transmission Electron Microscope TEM is electron illuminated. This gives a 2-D view. Thin slices of specimen are obtained. The electron beams pass through this. It has high magnification and high resolution. Q: what is the difference between SEM and Confocal: Medium SEM Electron Confocal: laser light

Parts of the Compound Light Microscope

Microscope Parts and Functions B C D E F M L K H G J I B. Arm: supports tube & connects it to the base C. Stage Clip: holds microscope slide in place D. Coarse adjustment: raises / lowers stage to bring image into focus E. Fine adjustment: brings image into sharp focus F. Base: Supports microscope G. Illuminator: Light source A. Eyepiece: Holds ocular lens; lens that you look through; magnified image of objective lens

Microscope Parts and Functions B C D E F M L K H G J I I. Stage: platform that holds the slide J. Microscope slide: holds the specimen K. Objective lenses: magnifies the specimen Shortest lens has least magnification Longest lens has greatest magnification H. Diaphragm: Controls the amount of light that passes through a specimen

Microscope Parts and Functions B C D E F M L K H G J I L. Revolving nosepiece: holds 2 or more objective lenses M. Body tube: Connects eyepiece to objective lens

How to Calculate Magnification Magnification of eyepiece X magnification of objective lens If eyepiece is 10 x and objective lens is 4x, then what is the total magnification? 10x X 4x = 40X

How a Light Microscope Works Use lenses to make small objects appear larger Compound light microscope: Two lenses separated by a tube Lenses magnify an object by bending the light that passes through the lens Magnification: ability to make things appear larger than they are Resolution: fineness of detail that can be seen in an image Go to Section:

Microscope Safety 1. Always use 2 hands to carry a microscope; one on the arm and one hand supporting the base 2. Only use lens tissue to clean lenses 3. When focusing, always look to the side to watch and make sure the objective lens doesn’t hit the slide 4. Always use the lowest power (shortest) objective lens for bringing specimen into focus Bring specimen into focus by first using coarse adjustment, then use fine adjustment Never use a microscope with a frayed cord Because we have running water in our lab area, NEVER turn on the water when using a microscope

How to Prepare a Slide 1. Place slide on a flat surface. 2. Place a drop of water on the slide. Add the specimen to the drop of water (at times, you may want to have the specimen already on the slide before adding the water). 3. Hold the coverslip by its sides and lay its bottom edge on the slide close to the specimen. Holding the coverslip at a 45° angle helps. 4. Slowly lower the coverslip so that it spreads the water out. If you get air bubbles (looking like little black doughnuts), gently press on the coverslip to move them to the edge. If there are dry areas under the coverslip, add a little more water at the edge of the coverslip. Too much water can be dabbed off with a piece of paper towel

How to Prepare a Slide The diagram below shows how a cover-slip should be lowered onto some single-celled organisms during the preparation of a wet mount. Why is this a preferred procedure? A The cover-slip will prevent the slide from breaking. B The organisms will be more evenly distributed. C The possibility of breaking the cover-slip is reduced. D The possibility of trapping air bubbles is reduced.