Microscopes

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.


How it works:


A microscope uses the same trick as a refracting telescope — light waves being bent as they travel through glass. In a telescope, the idea is to bend parallel light from very faraway objects into a small focus at the eye. In a microscope, the idea is to bend spreading-out light into a parallel path, then bend that light into a small focus at the eye.



First, we have to light up the object. A mirror mounted under the microscope stand does the job. Light bounces off the mirror, passes through and around our object(mounted firmly to a microscope slide), and into the objective lenses. These lenses bend some of the spread-out light beams from the object into straight line paths that travel through the microscope tube. Next, the light beams reach the eyepiece lenses. These lenses bend the light back into your eye, so you can see the object up close and personal.



The power of the microscope depends on how much each lens bends the light. Usually, the power is written right on the microscope itself. 40x, for instance, means that the image at the eyepiece is 40 times larger than real life.

Facts:

• Most microscopes use more than one lens for the objective and the eyepiece. This helps prevent a problem called “chromatic aberration”. While it’s true that light is bent as it passes through glass, it’s also true that some colours are bent more than others. The multiple lenses in the objective and the eyepiece help to correct that problem.


• Different types of microscopes have been used to look at human cells, identify minerals, solve crimes, see how freezing affects food, study metals, and find the causes of crop diseases.


• Microscopes are an essential tool in medicine too. They have been used to identify the causes of many deadly diseases like malaria and tuberculosis.


• Microscopes can also help to find out why a person or animal died.


• Scientists can even use a microscope to figure out where illegal drugs come from. For example, looking at opium crystals through a microscope reveals different shapes depending on where the poppies they came from were grown. This information can help pinpoint the source of illegal drugs.

Sources: http://www.yesmag.ca/how_work/microscope.html, How stuff works (image), http://www.dreamstime.com/ (image)