When invented by Janssens, the compound microscope let scientists dramatically advance the field of microbiology. The simple light microscopes could magnify an object 266 times its size. In contrast, today's compound microscope can magnify objects by 2,000.
The eyepiece connects to the body tube. Stage clips hold the slide in place. The slide rests on the stage, which has a hole in it covered with glass, which allows light to travel through the slide. This hole is the aperture. Students point the objectives at the slide and adjust them to change the focus of the microscope. They point the objective they want to use at the slide. Compound microscopes come with an on and off switch. The base at the bottom of the compound microscope keeps the microscopes stable. The compound microscope's arm attaches the top part of the microscope to the bottom part and holds the top part suspended over the bottom part.
When students move the compound microscope, they should hold it by the arm, the most stable part of the microscope. When using the microscope, the arm should face toward the student. Student turns the course adjustment knob to raise the body tube. The student moves the nose piece until the low-power objective lens secures a place. When the student adjusts the diaphragm and the mirror, the student will know when the microscope is ready by looking through the eyepiece and adjusting the microscope until he sees a bright white circle of light.
The student places the specimen under the microscope inside the slide. He puts the slide on the stage and then slowly lowers the body, using the course adjustment knob, until the power objective almost touches the slide. The student slowly adjust the coarse adjustment knob until he sees the specimen.
Teachers commonly use the compound microscope because it's one of the most affordable, costing as little as $150. In contrast, the electron microscope can cost more than $50,000. While the compound microscope does not create the level of detail found in the other, more expensive microscopes, they are financially in the reach of most schools.
When students clean the optical lens, they should only use lens paper. Other types of paper will scratch the optical lens and ruin it. Students should always carefully focus on the slide and should not push the objective lens into the slide, or else they could damage the objective lens. To protect the compound microscopes, the students should cover the microscopes after use.