Date of experiment:24-2-2014
Date of submission:28-2-2014
Abstract: To disassemble an optical Microscope, identify and study it’s various
parts, identify its specific function, understand the various working mechanisms
and to re assemble the optical microscope again.
Introduction:The optical microscope, often referred to as the "light microscope",
is a type of microscope which uses visible light and a system of lenses to magnify
images of small samples. Optical microscopes are the oldest design of microscope
and were possibly invented in their present compound form in the 17th century.
Basic optical microscopes can be very simple, although there are many complex
designs which aim to improve resolution and sample contrast.The image from an
optical microscope can be captured by normal light-sensitive cameras to generate
a micrograph. Originally images were captured by photographic film but modern
developments in CMOS and charge-coupled device (CCD) cameras allow the
capture of digital images. Purely digital microscopes are now available which use
a CCD camera to examine a sample, showing the resulting image directly on a
computer screen without the need for eyepieces.Alternatives to optical
microscopy which do not use visible light include scanning electron microscopy
and transmission electron microscopy.
Tools used :Screw drivers of appropriate sizes.
Experimental Procedure:Remove the illuminator.Disassemble the parts of the
optical microscope – The stage, the eye piece, the objective lens, and the rack and
pinion mechanisms.Study the function of each part and identify the mechanism
and working.Re assemble the parts.
Product decomposition :
Ocular Lenses These eyepieces further magnify the image formed by the
objective lens. It does not improve resolution. They make up
an adjustable binocular system. The magnification of the
oculars is 10X. They are equipped with a pointer inside one
of the lenses which makes it easier to point out specific
structures or determine the real dimensions of the
specimen you are observing.
Objective Lenses There is more than one objective lens. These are the
primary lenses of a compound microscope and can have
magnification of 4x, 5x, 10x, 20x, 40x, 50x and 100x. The
magnification values are written on the side of each lens.
The objective turret, to which these lenses are attached, can
be rotated with hand to get the lens of desired
magnification to focus on the object.
Arm Connects to the base and supports the microscope head. It
is also used to carry the microscope.
Stage It is the platform below the objective lens on which the
object to be viewed is placed. There is a hole in the stage
through which light beam passes and illuminates the
specimen that is to be viewed.
Light on/off switch and intensity knob. Controls the intensity
of the light coming from the bulb.
Controls precise focusing of the object. Only the fine
adjustment knob should be used with the high magnification
lenses - high power and the oil immersion objective lenses.
Moving the fine adjustment knob also helps you to
determine the third dimension (depth) of the specimen you
This is used for rapid (or coarse) focusing on the specimen
when using the scanning objective lens and the low power
lens. This course focusing knob is rotated until the specimen
is roughly in focus and then left alone.
Stage Clips There are two stage clips one on each side of the stage.
Once the slide containing the specimen is placed on the
stage, the stage clips are used to hold the slide in place.
Base The bottom of the microscope
Diaphragm It is located on the lower surface of the stage. It is used to
control the amount of light that reaches the specimen
through the hole in the stage.
Specimen stage and objective lens
History: The Dutch spectacle-maker Zacharias Janssen is sometimes
claimed to have invented it in 1590 (a claim made by his son and fellow
countrymen, in different testimony in 1634 and 1655) Another claim is that
Janssen's competitor, Hans Lippershey, invented the compound
microscope. Another favorite for the title of 'inventor of the microscope'
was Galileo Galilei. He developed an occhiolino or compound microscope
with a convex and a concave lens in 1609. Galileo's microscope was
celebrated in the AccademiadeiLincei in 1624 and was the first such device
to be given the name "microscope" a year later by fellow Lincean Giovanni
Faber. Faber coined the name from the Greek words μικρόν (micron)
meaning "small", andσκοπεῖ ν (skopein) meaning "to look at", a name
meant to be analogous with "telescope", another word coined by the
Linceans.Christiaan Huygens, another Dutchman, developed a simple 2-
lens ocular system in the late 17th century that
was achromatically corrected, and therefore a huge step forward in
microscope development. The Huygens ocular is still being produced to
this day, but suffers from a small field size, and other minor problems.
Possible Improvements:A small camera and a screen can be attached to view
the specimen on the screen instead of viewing in the eye piece directly.A
powered mechanism to operate the rack and pinion in the stage to hold and
move the specimen according to our requirement.
Conclusion:In this experiment, we disassembled an optical microscope and
assembled it back again. In the process, through reverse engineering, we
identified the various parts and understood its functions and mechanisms.
Only the screw driver was used. The various modules were identified and
various functional and conceptual diagrams were drawn. This improved our
understanding about the process