Scientific research occurs across many different length-scales, from the study of individual atoms to vast distances across the universe. The micron, or micrometer, is a unit of length that is equal to one millionth of a meter (approximately one 25 thousandth of 1 inch). There are many different methods that can be used to measure a micron. The simplest of these requires the use of an optical microscope and a stage (slide) micrometer.
Switch on the microscope light source and place the stage micrometer in the sample stage.
Turn the revolving turret to the lowest microscope power. This is usually 4-5x on most microscopes.
Look down the microscope and use the focus knob to bring the gradations upon the stage micrometer into focus. Adjust the light intensity until an image can be clearly seen.
Change the microscope objective lens to the next highest power and repeat step 3. Once at the highest objective lens, you should see graduations that are equal to approximately 10 microns. Under a sufficiently high power (500 times magnification), you should be able to measure objects that are approximately 1 micron and greater.