Compound microscope
Microscope is a powerful and crucial basic tool in the field of
microbiology. Microbiology is the science dealing with the organisms
too small to be seen with unaided eye. The microscope produce high
magnification of very small objects, which are too small to be
distinctly seen by the naked eye.
Principle:
The light is made to pass through the thin transparent object. A
magnified image called the real image of the object is obtained by the
objective lens. The eyepiece or the ocular lens then magnifies the real
image more and is viewed as the virtual image. The final image is
flipped relative to the original object.
The compound microscope consists of:
1, Eye piece:
The lens in which the viewer looks through to see the specimen. Eye
piece usually contains a 10X 0r 15X power lens.
2, Body tube:
The body tube connects the eye piece to the objective lenses.
3, Arm:
The arm connects the body tube to the base of the microscope.
4, Coarse adjustment knob:
The coarse adjustment brings the specimen on the slide into general
focus.
5, Fine adjustment knob:
The fine adjustment knob tunes the focus and increase the details of
the specimen present on the slide.
6, Objective lenses:
One of the most important parts of microscope because they are the
lenses closest to the specimen.
A standard microscope has three, four or five objective lenses that
range in power from 4x to 100x. When focusing the microscope, be
careful that the objective lens doesn’t touch the slide, as it could break
the slide and destroy the specimen.
7, Nosepiece:
The viewer spins the nosepiece to select different objective lenses.
8, Stage:
The stage is the platform where the slide is placed.
9, Stage clips:
Stage clips are the metal clips that hold the slide in place.
10, Condenser:
Condenser helps to gather and focus the light from the illuminator
onto the specimen being viewed.
11, Base:
The base supports the microscope and it’s where the illuminator is
located.
12, Light Source:
It is either mirror or electric illuminator present at the base. Some
microscopes have reversible mirror with one side flat and other
concave. Concave side of the mirror is used for sunlight and its flat
side is used for artificial light.
Uses of compound microscope:
. The identification of diseases or illness becomes easy in pathology
lab.
. The presence or absence of metals & minerals can be detected with
the help of a compound microscope.
. The study of bacteria and viruses becomes easy.
. Human cells are drawn and examined under a microscope in forensic
laboratories to detect and solve various crime cases,
. It helps in the visualization and comprehension of the
microbiological
world of bacteria and viruses, which is otherwise undetectable to the
naked eye.
Advantages of compound microscope:
. It is versatile and convenient to handle.
. The specimen is placed on a stage and doesn’t require to be
held close to the eye.
. It provides a wide field view.
. It has a wide range of magnifications.
. Its light gathering powers are far superior to a simple
microscope, thus the image remains very clear and bright
even at highest magnification.
. Living cells or protozoans and stained sections are clearly
visible.
Care for the microscope:
Following points should be kept in mind while handling the
microscope:
1. Instrument should be kept in special cabinets while not in use.
2. Microscope should be held firmly by holding the arm with right
hand and base with left arm.
3. All the lens systems should be cleaned with lens tissue to remove
dust,oil, etc., which may decrease the efficiency of the microscope.
Blotting paper, cloth or towel should not be used for cleaning.
Precautions:
. Tilting or shaking the microscope while it is in the use
should be avoided.
. The specimen must first be focused with a low resolution
lens before being targeted with a high resolution lens.
. Both arms and base of the microscope should be used to lift
the microscope.
. Use a clean slide or clean the slide with suitable water and
wipe it clean so that any stains do not show up under the
microscope.
. The lower power objective lens must be focused on the stage
once you have finished using the compound microscope.
. Don’t touch the glass part of the lenses with your fingers.
Use only special lens paper to clean the lenses.
. Always keep the microscope covered when not in use.