If you look at a drop of pond water through a microscope, you may notice that it is not always easy to see all the structures and detail. Using special staining techniques, scientists can highlight certain parts of organisms they are viewing so they are much more visible under a high-power microscope. A number of other techniques involving light correction, background enhancement, and variation in microscope types help scientists view images of organisms.

Contrast: Manipulating the light source or adding a coloring agent can improve the contrast and image of the cell that is being observed. The images on the right show how changing the contrast can improve how well the cell can be seen.

Pages 253-254

Magnification is how much you enlarge an image. You can magnify objects using high-power lenses. However, if the image becomes blurry then increasing the magnification is of no value.

The ability of a light microscope to maintain a clear image with increasing magnification is the resolution of the microscope. With modern lens technology, the resolution of high-quality microscopes is limited by the wavelength of light.

Pages 255-256

Special enhancement techniques have allowed light microscopes to reveal detail that would not even be considered possible when light microscopes were invented. However, the wavelength of light is a limiting factor on how much detail can be seen. In the latter half of the twentieth century, various types of electron microscopes have been developed. Because electrons are used to illuminate the specimens, the resolution of electron microscopes is about 2.5 nm (nanometres), which is over 100 times better than that of a light microscope.

Read pages 258 to 260 of the textbook to learn about “Electron Microscopy.”- You will study various types of electron microscopes.