How To View a Specimen Under a Microscope

A microscope is an instrument that is used to magnify a specimen (a sample used for analysis).  By using a microscope, one can see the minute details of an object. The microscope is used in different fields.  Archaeologists use them to learn the composition of an artifact.  In medicine, after phlebotomy (or the extraction of blood from the vein), the laboratory technician places a thin smear of blood on a glass slide for diagnostic testing.  In schools, students may be interested to see a magnified view of a bug’s wings.  The applications are endless.

The three basic types of microscopes are light microscope, dissecting microscope and electron microscope.  A popular microscope used in a number of US schools today is the computer microscope.  Computer chip maker Intel and toy maker Mattel partnered to create this microscope, which is connected to a computer via a USB port.  Instead of an eyepiece, the image is seen on the monitor, allowing students to take snapshots or make videos out of the images.

The basic microscope parts are:

  1. Ocular lens – the eyepiece where you look into; has a lens that can magnify up to 10x
  2. Body - tube that connects the eyepiece to the objective lenses
  3. Arm – used for handling and supporting the microscope
  4. Nosepiece – rotating part that holds the different objective lenses
  5. Objective lenses – system of lenses that catches the light and magnifies the specimen
  6. Mechanical stage – platform where slides are placed
  7. Stage clips – hold the slides in place
  8. Diaphragm – controls the amount of light going to the specimen
  9. Illuminator – light source, which can either be a mirror or a light bulb depending on the type of microscope
  10. Coarse adjustment knob – moves the stage nearer or farther from the objective lens; used for focusing at a lower power
  11. Fine adjustment knob – also used for focusing the image but in more detail
  12. Base – bottom of the microscope that supports all the other parts

Here are the basic steps in viewing a specimen:

  1. Place the microscope on a flat surface with ample lighting and work space.  Depending on the type of microscope, you may need to plug it and turn on the light source.
  2. Prepare the slide.  Make sure that all your tools are clean and the slides fingerprint free.  For example, if you are taking a small sample from a urine cup to a glass slide, use a dropper.  Proper urine collection should have been observed as well to eliminate contamination of the specimen.
  3. Place the prepared slides on the mechanical stage, securing it with stage clips.
  4. Turn the coarse adjustment knob until the slide is in focus.  Adjust the slide so you can see the specimen in the center.  Focus the fine adjustment knob if you need to see more detail.
  5. Adjust the diaphragm until you have the right amount of light. The specimen should neither be too dark or too light.
  6. Focus the objective lenses by rotating the nose-piece.  Start at the lowest magnification, then work your way up. Testing the different levels is necessary so you can choose the clearest view.  Adjust the diaphragm when you move from one magnification level to another.  A higher magnification may require more light.
  7. When you’re done, return the microscope to its proper place.  Don’t forget to clean the slides and keep the extras in the right containers for future use.

Knowing how to use the microscope properly gives anyone a clearer picture of what cannot normally be seen by the naked eye.


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