Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an image enhancing device for a
telescope, and more particularly for an auxiliary shielding
and focussing device which may be mounted on an astronomical
telescope to enhance the image viewed in such telescope as
well as to facilitate the quick focussing of the telescope to
obtain a precise sharp image.
High power telescopes such as astronomical telescopes are
constructed of a lens mounted at the light receiving front end
therein which receives the light from the object such as a
star or planet to be viewed. The light after passing through
the front lens is incident upon a concave primary mirror
located at the rear of the telescope. The reflected light from
the primary mirror is further reflected from a secondary
mirror located adjacent to and behind the front lens so as to
form the ir,lage of the object in the telescope. I'he object is
viewed by adjusting the eyepiece of the telescope until a
sharp image is formed.
In order to provide a sharp image, the primary mirror of
the telescope must have a perfect reflective surface and
curvature. ~owever, due to the size and diameter of the
primary mirror, often a bad edge such as a rolled edge or
turned down edge is present therein. Such turned down edge
will in medium and high power telescopes cause the incoming
light to scatter randomly within the telescope resulting in
the loss of overall sharpness and subtle detail of the image.
The fine detail of the image is washed out by the scattered
light. Such drawback can not be obviated by using a funct:ional
shield such that shown in U.S. Patent No. 4,729,649 to Charles
A. Thompson which provides a conical shield at the front end
of the telescope. The conical shield is provided with a
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plurality of evenly spaced oval shaped openings. The shield is
intended to shield out stray light from the ambient from
entering into the telescope. It also prevents the formation of
dew on the lens, which may interEere with the viewing oper-
ation of the telescope. However, such shield can not prevent
the formation of scattered stray light within the telescope
due to the imperfection of the reflecting mirrors.
It is a principal object of the present invention to
provide an auxiliary shielding device which may be readily
adaptable on a telescope to eliminate the formation of scat-
tered stray light within a telescope.
It is another object of the present invention to provide
an auxiliary shielding device which is operative also as a
focussing device for enhancing the precise and easy adjustment
of the telescope to obtain the sharpest image obtainable.
It is another object of the present invention to provide
an auxiliary shielding device operative for lncorporating
selected light and colour filters thereon for various viewing
purposes.
It is another object of the present invention to provide
an auxlliary shielding devlce which can operate to reduce the
luminosity of a bright image in a ~telescope as well as to
increase its resolution.
It is still another object of the present invention to
provide an auxiliary shielding device which can be readily and
easily adapted to a telescope without necessitating any
modification to be made in the telescope.
It is yet another object of the present invention to
provide an auxiliary shielding and focussing device which is
simple in construction and yet is highly efficient in opera-
tion.
The auxilary shielding and focussing device comprises a
circular disc having a substantially flat top surface and
bottom surface. The bottom surface has a round periphery
having a round slcirting flange formed therealong. The skirting
flange extends downwardly from the bottom surface and is
operative for removably mounting the disc to the light receiv-
ing end of a telescope. Two openings, preferably circular
openings~ are formed in the disc along a diameter therein. The
openings are substantially equal in size and are spaced an
equal distance from the respective immediately adjacent side
of the disc along the diameter.
In drawings which illustrate embodiments of the invent-
ion,
Figure 1 is a schematic sectional side elevation view of
an exemplary telescope showing its common general construction
and the light paths therein.
Figure 2 is a schematic sectional side elevation view of
the telescope shown in Figure I with an auxiliary shielding
~and focussing device provided over its light receiving end.
Figure 3 is a perspective bottom side elevation view of
the auxiliary shielding and focussing device according to the
present invention.
Figure 4 is a perspective top side elevation view ther-
eof.
Figure 5 is a perspective top view of the auxiliary
shielding and focussing device according to the present
invention.
Figure 6 is a sectional side elevation view along section
line VI-VI of Figure 5.
Figure 7 is a bottom perspective elevation view of the
auxiliary shielding and focussing device according to the
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present invention.
With reference to the drawings wherein like reference
numerals designate corresponding parts in the several views, a
telescope 10 having a light receiving lens 11 mounted at its
front end 12, and a primary reflection mirror 13 provided at
its rear end. Such telescope is commonly known as a Schmidt-
Cassegrain telescope. It is shown as an example for the
simplicity in illustrating the present invention. Light from a
star or planet enters the telescope through its front end 12,
and after passing through the receiving lens 11 is incident
upon the primary mirror 13. The reflected light from the
primary mirror 13 impinges upon the secondary mirror 14
located adjacent to and behind the receiving lens 11. The
reflected light from the secondary mirror 14 forms the image
at the focal point 15 within the telescope. The image may then
be viewed by adjusting the eyepiece 16. The secondary mirror
14, in another common construction, such as in a Newtonian
telescope, may be located close to but spaced from the receiv-
ing lens 11 so that it directs the incident light from the
primary mirror 13 to the eyepiece located at the side of the
telescope. The principle of operation and desired results
achieved according to the prPsent invention are the same for
telescopes of such different constructions.
The sharpness of the image formed within the telescope 10
is highly dependent upon the reflective quality of the mirrors
and particularly the primary mirror 13. The clarity of the
image can be corrupted by the :incident light reflected from a
turned down or rolled edge often existing in the primary
mirror 13. Such turned down edge will in medium and high power
telescopes scatter the incident light randomly within the
telescope cavity resulting in the loss of sharpness and subtle
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detail in the image. Usually, the rolled edge can have a
dimension of about 1/16th of an inch wide in a common 8-inch
or 10-inch compact portable telescope.
I have discovered that the problem of formation of
scattering stray light within the telescope can be obviated by
incorporating a lens cap like shield 20 over the light receiv-
ing end of the telescope. The shield is in the form of a
saucer 21 having a generally flat round disc body and having a
generally flat top surface 22. Two openings 23 and 24, prefer-
ably circular in shape, are formed along a diameter of thedisc and are equally spaced from the respective immediately
adjacent peripheral side oE the disc along such a diameter.
The disc is provided with mounting means such as a skirting
flange 25 along the periphery of the bottom surface of the
disc so that the disc can be quickly and removably mounted
over the light receiving end 12 of the telescope by interfer-
ence fitting. Such simple mounting means does not require any
modification to be made :in the telescope.
The shield 20 may be made of metal such as llght weight
aluminum or a suitable durable plastic material.
As best shown in Figure 2, when the shield 20 is fitted
over the light receiving end 12 of the telescope, the openings
23 and 24 will prevent the incident light from impinging upon
any rolled edge in the primary mirror, thus eliminating the
formation of stray reflected light from the primary mirror 13.
Furthermore, the separation of the two openings 23 and 24 over
the light receiving end of the telescope inherently provides a
paralla~ effect by forming double images of the object within
the telescope when the telescope is out of focus. The double
images will overlap and merge with each other into a single
sharp image when the focus of the telescope is properly
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adjusted. Thus, the shield 20 also enhances the quick and
precise adjustment of the focus of the telescope to achieve
the sharpest image the lens system can provide. This desirable
result is particulary noticeable as the power of the telescope
increases resulting in providing a larger size image. Theref-
ore, it is possible to adjust the focus of t'ne telescope in
viewing a planet or moon without having to move annoyingly and
painstakingly back and forth between a bright star and the
planets, as in common practice, in order to assure that the
sharpest image has been obtained.
Furthermore, the openings 23 and 24 inherently serve as a
shield to reduce the size of the lens opening of the teles-
cope. Such reduced lens opening is particularly advantageous
in viewing a bright planet. It will reduce the glaring bright-
ness of the image as well as will increase its resolutionsimilar to the effect of reducing the lens opening of a camera
to achieve the same image effects.
~ ilters such as solar or lunar filters may be easily and
quickly adapted at the openings 23 and 24 for viewing the sun
and the moon. Also, colour filters of selected colours can be
adapted to enhance the viewing of a planet having a predomin-
ant colour, for example, red or orange filter for viewing
Mars, yellow or blue filter for viewing Saturn, and blue or
green filter for viewing Jupiter. Moreover, a different colour
filter may be mounted in each one of the openings if desired
for selected results.
While the invention has been particularly shown and
described with reference to preferred embodiments thereof, it
will be understood by those skilled in the art that various
changes in form and details may be made therein without
departing from the spirit and scope of the present invent;on.
For example, the openings 23 and 24 may be of other shapes
than circular, and a plurality of such openings may be provi-
ded on the shield for similar purposes.
