 We
are all acquainted with the common telescope in which a series of lenses
is mounted in a long barrel, which can be shortened by sliding the segments
together. This is technically known as a refractory type. In building
a giant telescope it is impractical to make a barrel long enough to accommodate
the giant lenses. So a system of mirrors is combined with the lenses, and
we have what is known as a reflecting telescope. The 200 inch lens of the
new telescope described on
page 18 is actually
a mirror.
Fig. 1 - Drawing of Hale 200" Telescope at Mt. Palomar
At right is reproduced an artist's conception of how it will look set
up in the observatory, above is a diagram explaining how it works.
The starlight having entered the open tube is reflected from the 200
inch mirror AA back to a focal point at B. An observer can reach this point
of first focus by bridge J (Fig. 2). To send the rays to a second focal
observation point D (Figs. 1 and 2) a convex mirror C intercepts the rays
from A and B and reflects them down to observation point D, where Fig. 2
shows a platform suspended underneath the 200 inch mirror. The rays arriving
at D come through a tube fixed in the center of the mirror. The rays may
also be extended from mirror C to E, from E to F, from F to G and from G
to H (Fig. 1). I is another point of focus, and down inside the
huge arm (an open section of which is shown) is a chamber for spectographic
work. These arms on each side of the tube are parallel to the polar axis.
The control board is located at K (Fig. 2). The great housing running at
nearly right angles to the telescope is the counter weight to the telescope.
It permits the giant apparatus to be moved and aimed With delicate control.
Figure 2 - Artist's Concept of Hale 200" Telescope at Mt. Palomar
Here is an ad on my RF Cafe website from the May 1948 Saturday Evening Post pitching the
200"
Mt. Palomar Telescope Pyrex Mirror Blank by Corning
Posted May 5, 2012
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