The Microscope

The Microscope

  * A microscope is an optical instrument that uses a lens or a combination of lenses to magnify and resolve the fine details of an object.
  * The earliest methods for examining physical evidence relied solely on the microscope.

  * The magnified image seen by looking through a lens is known as a ______________, whereas an image viewed directly is known as a __________________.

  * The object to be magnified is placed under the lower lens, called the objective and viewed through the upper lens, called the eyepiece.
  * Example- compound microscope

The Compound Microscope
  * The magnification of the image can be calculated by multiplying the magnifying power of the objective lens times the magnifying power of the eyepiece lens.

  * Calculate the total Magnification:

If using a 4x objective the total magnification would be:
  4 (objective) times 10 (ocular) =

If using a 100x objective:  
100 (objective) times 10 (ocular) =

  * Know this vocabulary!   (see fig 7-3 for help)
      * Base
      * Arm
      * Stage
      * Body Tube
      * Coarse Adjustment
      * Fine Adjustment
      * Illuminator
      * Condenser
      * Objective Lens
      * Revolving nosepiece
      * Parafocal: when the microscope is focused with one objective in place, another objective can be rotated into place and the specimen remains very nearly in correct focus.
      * Eyepiece or Ocular Lens
      * Monocular: a microscope having only one eyepiece
      * Binocular:

The Comparison Microscope
  * 2 independent objective lenses joined together by an optical bridge to a common eyepiece lens
  * When a viewer looks through the eyepiece lens of the comparison microscope, the objects under investigation are observed side-by-side in a circular field that is equally divided into two parts.
  * Modern firearms examination began with the introduction of the comparison microscope, with its ability to give...