MICROSCOPY
1. Simple Microscope/dissecting microscope- It is used either for dissecting the material or
for less magnifications, i.e., only 6X, 12X or rarely 20X. It is mainly used for embryo separation,
taxonomic studies, etc. It has a basal foot and a limb. The ‘stage’, made up of a simple glass
plate, is attached to the limb.
For the light adjustment purposes, a mirror is attached to the limb under the stage. Mirror can be
moved vertically with the help of an adjustment screw. At the tip of the limb is present a folded
arm, on which a lens of definite magnification (6X, 12X, etc.) is fitted. Folded arm is moved to
keep the lens in the desired position on the stage.
1. A simple microscope is a convex lens of short focal length.
2. It is used to form a virtual image of an object placed just inside its principal focus.
3. It is made up of a single convex lens or a combination of lenses which functions as a convex
lens.
4. The convex lens magnifies the object and also helps to produce a magnified image of a near
object which appears to be at the distance of distinct vision.
5. Under simple microscope the enlarged image of the object is formed on the retina of the eye
of the viewer.
6. A simple lens can magnify an object only three times OX). For getting a magnification of more
than 3X, a combination of several lenses is used. Such a combination of several lenses (called
elements) functions as a single convex lens, and a magnification of about 20X can be obtained.
,2. Compound Microscope/brightfield microscope:
A compound microscope comprises either two (objectives and eyepiece) or three (condenser,
objectives and eyepiece or ocular) kinds of lenses. The condenser, located above the mirror
and below the stage, collects and focuses the light rays into the plane of the object.
Parts:
1. The instrument is so named because it consists of two or more lens systems (Fig. 145).
2. At the top is present the ocular lens. It can be turned around or may be removed. At the top of
ocular lens is written 5X or 10X signifying the 5 times or 10 times magnification, respectively.
3. Just below the ocular is a body tube, the bottom end of which contains a circular piece called
nose piece. It contains three lenses called objective lenses. Nose piece can be rotated to
change the position of objectives.
4. The flat platform present below the objectives is called stage.
5. On the arm of the microscope are present two knobs named coarse adjustment knob and fine
adjustment knob.
6. Out of the three objectives, the shortest is low power objective. It has the largest lens but its
magnifying power is least of the objective lenses. On the objective may also be written 10X as
on ocular lens. It means if a 10X ocular lens is used the magnification is 10 X 10 – 100 times.
7. The other objective is high power objective. Its magnification is equal to the number written
on it multiplied by the power of ocular i.e. 5X or 10X (objective x ocular).
8. The third objective is oil immersion. Generally, it contains a black band around the lower end.
A drop of oil is used on the slide at the time of studying with the oil immersion objective. Its
magnification can be estimated as ocular x objective.
9. Just below the stage is the condenser. Its function is to gather light from the mirror and direct
it to the objective lens. Condenser may be lowered or raised by a knob present on one side of
the microscope beneath the stage.
10. Condenser contains a shutter called iris diaphragm.
Precautions:
1. Clean the ocular and objective lenses with lens paper, and do not remove them.
2. While studying an object, learn to keep one hand on the fine focus knob and focus continually
up and down.
3. While studying any kind of preparation, do not tilt the microscope.
4. Leave the low power objective in place after finishing all the observations.
5. To examine an object, always use the low power first and then the other objectives.
6. Never allow an objective lens to strike either the stage or a slide while focusing.
7. Use always the fine adjustment with high power objective.
8. All wet-mount preparations should be pre-covered by a cover slip.
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1. Simple Microscope/dissecting microscope- It is used either for dissecting the material or
for less magnifications, i.e., only 6X, 12X or rarely 20X. It is mainly used for embryo separation,
taxonomic studies, etc. It has a basal foot and a limb. The ‘stage’, made up of a simple glass
plate, is attached to the limb.
For the light adjustment purposes, a mirror is attached to the limb under the stage. Mirror can be
moved vertically with the help of an adjustment screw. At the tip of the limb is present a folded
arm, on which a lens of definite magnification (6X, 12X, etc.) is fitted. Folded arm is moved to
keep the lens in the desired position on the stage.
1. A simple microscope is a convex lens of short focal length.
2. It is used to form a virtual image of an object placed just inside its principal focus.
3. It is made up of a single convex lens or a combination of lenses which functions as a convex
lens.
4. The convex lens magnifies the object and also helps to produce a magnified image of a near
object which appears to be at the distance of distinct vision.
5. Under simple microscope the enlarged image of the object is formed on the retina of the eye
of the viewer.
6. A simple lens can magnify an object only three times OX). For getting a magnification of more
than 3X, a combination of several lenses is used. Such a combination of several lenses (called
elements) functions as a single convex lens, and a magnification of about 20X can be obtained.
,2. Compound Microscope/brightfield microscope:
A compound microscope comprises either two (objectives and eyepiece) or three (condenser,
objectives and eyepiece or ocular) kinds of lenses. The condenser, located above the mirror
and below the stage, collects and focuses the light rays into the plane of the object.
Parts:
1. The instrument is so named because it consists of two or more lens systems (Fig. 145).
2. At the top is present the ocular lens. It can be turned around or may be removed. At the top of
ocular lens is written 5X or 10X signifying the 5 times or 10 times magnification, respectively.
3. Just below the ocular is a body tube, the bottom end of which contains a circular piece called
nose piece. It contains three lenses called objective lenses. Nose piece can be rotated to
change the position of objectives.
4. The flat platform present below the objectives is called stage.
5. On the arm of the microscope are present two knobs named coarse adjustment knob and fine
adjustment knob.
6. Out of the three objectives, the shortest is low power objective. It has the largest lens but its
magnifying power is least of the objective lenses. On the objective may also be written 10X as
on ocular lens. It means if a 10X ocular lens is used the magnification is 10 X 10 – 100 times.
7. The other objective is high power objective. Its magnification is equal to the number written
on it multiplied by the power of ocular i.e. 5X or 10X (objective x ocular).
8. The third objective is oil immersion. Generally, it contains a black band around the lower end.
A drop of oil is used on the slide at the time of studying with the oil immersion objective. Its
magnification can be estimated as ocular x objective.
9. Just below the stage is the condenser. Its function is to gather light from the mirror and direct
it to the objective lens. Condenser may be lowered or raised by a knob present on one side of
the microscope beneath the stage.
10. Condenser contains a shutter called iris diaphragm.
Precautions:
1. Clean the ocular and objective lenses with lens paper, and do not remove them.
2. While studying an object, learn to keep one hand on the fine focus knob and focus continually
up and down.
3. While studying any kind of preparation, do not tilt the microscope.
4. Leave the low power objective in place after finishing all the observations.
5. To examine an object, always use the low power first and then the other objectives.
6. Never allow an objective lens to strike either the stage or a slide while focusing.
7. Use always the fine adjustment with high power objective.
8. All wet-mount preparations should be pre-covered by a cover slip.
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