A Brief introduction on telescopes

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A Brief introduction on telescopes

• The presentation is divided into three parts
• The origin of telescopes, first telescope made
• The principle of telescopes, how does it work
• The new insight brought to us
• Topics related
• Optics
• Lenses

Done by Tianyi Song, Yuzheng Wang
Wenhe Mao
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Origin of telescope
The first telescope was invented in 1608 by three
Dutch. Two of them were originally spectacle
makers whose names are Hans Lippershey and
Zacharias Janssen. The third person named Jacob
Metius. One year later, Galileo Galilei further
enhanced and modified the telescope. His
principle on telescope was used until today.
Hans Lippershey
Zacharias Janssen
Jacob Metius
Galileo Galilei
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Origin of telescope
The first telescope made by Galileo Galilei
consist of one convex lens and one concave lens
placed at each end of the metal tube which has a
length of 4.2cm. That is the first telescope
known to the world.
First telescope made by Galileo Galilei
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Principle of telescope
The basic principle of telescope is placing two
convex lenses in a tube so that when we look
through the eyepiece, we can see things which are
really far away. The trick for a telescope is
the distance between the two convex lenses. This
is very important because only when you find the
right distance between the two lenses, then you
will be able to see the effect of a telescope.
The distance between the two lenses depends on
the focal length of each lens. The main idea here
is that the two lenses must be put in a distance
so that when we add up the focal length of the
two lenses, it is just equal to the distance
between them.
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Principle of telescope
Objects from far
Eyepiece
Objective lens
Eye position
A simple diagram of the principle of telescope
and how does it work
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Principle of telescope
From the diagram we can see clearly that the
distance between the objective lens and the
eyepiece is just the sum of the focal length of
each lens. When parallel ray of lights from an
object came far away and passes through the
objective lens they will form an image on the
focal plane of the first lens. At the same time,
the image formed by the objective lens act as an
object to the eyepiece and it is being placed on
the focal point of the eyepiece. As a result
parallel ray of lights will be coming out of the
eyepiece. When an observer look through the
eyepiece, it will have the feel that he is
looking at something at an infinite distance and
the image of the object from infinity is
magnified.
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New insights brought to us
By finding out more about telescope we knew that
actually there are many interesting phenomena
around us. We might not realize them because they
are hidden in small things. Just like the
invention of the telescope, the invention was
actually by chance. It just happened that Hans
Lippershey placed two spectacle lenses in a row
and discovered this big invention. So if we make
some effort to take notice of small things around
us, maybe we can even came up with something new
and interesting. Finally it give us the idea
that it is possible to make a simple telescope
when we need to look at something far and without
a real telescope around us