Types of Microscopes 0.1 mm is the smallest object that is seen with the human eye. When we view with a microscope, we are either viewing in micrometer (um 1/1,000) or nanometers (nm 1/1,000,000). Compound Light Microscope Specimen is mounted on a glass slide and is illuminated with a beam of light (Bulb) from below. a. Uses light that passes through the specimen to magnify the object. b. Make sure object is thin enough for light to pass through. c. Can view living cells; this is good if you want to study the movement of an organism. d. Does not have as high resolution (magnification gives a clearer image at higher powers) e. Can view objects as small as a cell.

Types of Microscopes a. Uses beam of electrons to magnify the object. 2. Electron Microscope a. Uses beam of electrons to magnify the object. b. Objects have to be dead; (can’t study movement, and the image is in black and white) c. Good resolution. d. Can view objects as small as a DNA.

Types of Microscopes Two types of Electron Microscopes: Transmission Electron Microscope cuts specimen in half and stains with metal ions. 2. Scanning Electron Microscope stain entire specimen with metal ions and produces 3D images.

Types of Microscopes 3. Scanning Tunneling Microscope uses a needle-like probe to measure differences in voltage to see image. Used to study LIVING ORGANISMS.

Parts of the Microscope A. Eyepiece (ocular lens): Magnifies image usually 10X. 1. Use the eyepiece of the compound light microscope to find total magnification by multiplying the objective by the ocular lens. 2. Ex: If I have an objective of 10X, my total magnification is 100X because the eyepiece is 10X multiplied by the objective, which is 10X, and 10X and 10X multiplied together equals 100X total magnification. 3. What is the total magnification if my objective is 4X? 40X 100X? 1,000X B. Arm: supports the base. C. Stage : Supports the slide.

Parts of the Microscope D. Stage Opening: This is where light enters the slide/specimen. E. Fine Adjustment Knob: Moves the stage in small increments and brings the image in sharp focus; use on any objective. F. Coarse Adjustment Knob: Moves the stage in large increments; focuses the microscope; use only on low power. G. Base : Supports the entire microscope. H. Light or Mirror: illuminates or reflects light. I. Diaphragm : Adjusts the amount of light J. Diaphragm lever: adjusts the diaphragm K. Stage Clips: Holds the slide in place

Parts of the Microscope L. High power objective: Small field of view, 10-43X; advantage seeing up close, disadvantage, see less of the specimen M. Low Power Magnification: (objective) Large field of view, 4X; advantage-see more of the object, disadvantage-Not as magnified. N. Revolving Nosepiece: Holds the objectives and can be turned from one objective to the next. O. Body Tube: Allows light to pass and provides distance between the eyepiece and objective lenses.

Proper Handling and Use of the Compound Microscope

Proper handing and use of the compound Microscope Carry the microscope with a hand on the base and a hand holding the arm. Make sure the cord is wrapped around the microscope and is not dangling. Hold it close to your body. Clean the objective lenses and eyepiece with lens paper. ALWAYS start with low power. Turn on the light source. NEVER use sunlight as a light source, as it could blind you. Put the slide on the stage and secure it with stage clips. Move the coarse adjustment until the image is in focus. Do not put the stage touching the slide. (only use low power) Adjust the fine adjustment until the image is in sharp focus. Turn to the next higher power. Adjust the fine adjustment… NEVER use the coarse adjustment on high power. When finished, turn the microscope off and put the objective back at the low power. When storing the microscope, cover it to protect it from dust.

SLIDES: (making a wet mount)

Procedure for making a wet mount Clean the slide and coverslip with lens paper. Put the specimen in the center of the slide (make sure it is thin, so light can pass through. Using a medicine dropper, place one drop of water on the specimen. Position the coverslip at a 45 degree angle along the drop of water and lower it slowly.

Procedure for making a wet mount cont. If you trap air bubbles, tap the coverslip with a pencil eraser. (Don’t lift up; you could lose your specimen and have to start over. If you have excess water, hold a paper towel at the edge of the coverslip.