Dissecting the Parts of a Microscope

Each of the parts of a microscope works to help this common lab tool accomplish one goal: make tiny objects larger. In 1590, a Dutch eyeglass maker named Zacharias Janssen invented the light microscope. He discovered that a combination of lenses and light could make extremely small objects visible to the eye.

Most school labs use light microscopes, which are also commonly referred to as compound microscopes. The reason it is called a compound microscope is because you view the specimen through a series of two lenses, the eyepiece lens and the objective lens.

While the lenses are the most important part of the magnification process, each of a microscope's parts has a specific function.

• Eyepiece: This is located at the top of the microscope and is the part that you look through. Generally an eyepiece has 10X or 15X power, adding a little more magnification.
• Tube: This is the body of the microscope that connects and supports the eyepiece and the objective lens.
• Arm:This holds the tube and attaches it to the base of the microscope.
• Base: The bottom of the microscope, used for support.
• Illuminator: These light microscope parts provide the illumination for the slide. Illuminators are usually an 110v light source, such as a bulb.
• Stage: The surface that holds the slides for viewing. It may have clips that secure slides in place.
• Revolving Nosepiece or Turret: In microscopes that work with multiple lenses, the nosepiece holds them all in place. By rotating it, you can change from one lens to another.
• Objective Lenses: Most microscopes have up to four objective lenses. By employing several different lenses, you can achieve different degrees of magnification. The most common lens powers are 4X, 10X, 40X and 100X. By combing the viewing power of the objective lens with the viewing power of the eyepiece, which is most commonly 10X, the total magnification becomes a multiple of the two lenses, such as 40X (4X times 10X), 100X , 400X and 1000X. 
• Rack Stop: This protects a microscope's lenses by preventing you from cranking the lens into the stage or a slide. ? 
• Condenser Lens: Found in some compound microscopes, this lens focuses light from the illuminator onto the specimen. 
• Diaphragm or Iris: A rotating disk located under the stage that can be adjusted to control the amount of light that shines up through a slide.