PARTS OF MICROSCOPE WITH FUNCTIONS
Eyepiece: The lens the viewer looks through to see the specimen. The eyepiece usually
contains a 10X or 15X power lens.
Diopter Adjustment: Useful as a means to change focus on one eyepiece so as to correct for
any difference in vision between your two eyes.
Condenser: Gathers and focuses light from the illuminator onto the specimen being viewed.
Illuminator: The light source for a microscope. Older microscopes used mirrors to reflect light
from an external source up through the bottom of the stage; however, most microscopes now
use a low-voltage bulb.
Arm: Supports the tube and connects it to the base. It is used along with the base to
carry the microscope
Base: of the microscope supports the microscope and houses the illuminator
Limb top: Upper part of the arm that supports the revolving nosepiece
Revolving Nosepiece or Turret: This is the part that holds two or more objective
lenses and can be rotated to easily change power.
Scanning Objective Lens (4x): A scanning objective lens provides the lowest magnification
power of all objective lenses. 4x is a common magnification for scanning objectives and, when
combined with the magnification power of a 10x eyepiece lens, a 4x scanning objective lens
gives a total magnification of 40x. The name “scanning” objective lens comes from the fact that
they provide observers with about enough magnification for a good overview of the slide,
essentially a “scan” of the slide. Some objectives with even lower power are discussed in
Specialty Objectives below.
Low Power Objective (10x): The low power objective lens has more magnification power than
the scanning objective lens, and it is one of the most helpful lenses when it comes to observing
and analyzing glass slide samples. The total magnification of a low power objective lens
combined with a 10x eyepiece lens is 100x magnification, giving you a closer view of the slide
than a scanning objective lens without getting too close for general viewing purposes.
High Power Objective Lens (40x): The high-powered objective lens (also called “high dry”
lens) is ideal for observing fine details within a specimen sample. The total magnification of a
high-power objective lens combined with a 10x eyepiece is equal to 400x magnification, giving
you a very detailed picture of the specimen in your slide.
Oil Immersion Objective Lens (100x): The oil immersion objective lens provides the most
powerful magnification, with a whopping magnification total of 1000x when combined with a 10x
eyepiece. But the refractive index of air and your glass slide are slightly different, so a special
immersion oil must be used to help bridge the gap. Without adding a drop of immersion oil, the
oil immersion objective lens will not function correctly, the specimen will appear blurry, and you
will not achieve an ideal magnification or resolution. Oil immersion lenses are also available
from some manufacturers in lower magnifications, and provide higher resolution than their "high
dry" counterparts.
Iris Diaphragm controls the amount of light reaching the specimen. It is located above the
condenser and below the stage. Most high-quality microscopes include an Abbe condenser with
an iris diaphragm. Combined, they control both the focus and quantity of light applied to the
specimen.
Coarse Adjustment Knob- The coarse adjustment knob located on the arm of the microscope
moves the stage up and down to bring the specimen into focus. The gearing mechanism of the
adjustment produces a large vertical movement of the stage with only a partial revolution of the
knob. Because of this, the coarse adjustment should only be used with low power (4X and 10X
objectives) and never with the high-power lenses (40x and 100x).
Fine Adjustment Knob - This knob is inside the coarse adjustment knob and is used to bring
the specimen into sharp focus under low power and is used for all focusing when using high
power lenses.
