Note: Descriptions are shown in the official language in which they were submitted.
2735~-3
The preseilt invcntion relates to a system for displaying addi-
tional informatioll in the optical path of a telescope.
A telescope having a compass bui]t into its top surface is
familiar from German utility patent 7 907 058, sa.id compass incorporating a
scale card in the form of a rhumb card in place of the conventional needle,
said compass card consi.sting, at least in i.ts outermost areas, of a transparent
or translucent materi.al. The image of this scale card is incorporated in the
optical path of the telescope by the use of special optics. Thus the person
using the telescope obtains simultaneous information on the direction in which
he is viewing. Ilowcver, over and above this it is often desired to have a
specifically associated map section incorporated in the correct position in
each instance.
~or this reason it is the aim of the present inventioi~ to create
a device for incorporating correctly oriented map sections.
I~ccording to a broad aspect of the present invention, there is
provided a system for incorporating i.nformation regarding direction in the
optical path of a telescope, comprising means for holding a slide or film strip
outside the optical path of the telescope, the slide or film strip containing
a map sector with angle information, means for illuminating the slide or film
strip from behind, an arm containing optical means, the arm being movable be-
tween a front position in which an image of the slide or film strip is super-
imposed on the optical path of the telescope and a second position in which said
image is removed -~rom said optical path, and means for rotating said image
manllally .
I`he slide or film strip itself may be rotated using a thumb-
wheel to achieve the :;mage rotation or a prism forming part of the optical
means may be adapted for rotation using another thumb-wheel to achieve the
:i.mage rotcltion.
- 1 - .
The present invention will now be described in greater detail on
the basis of an exemplary version shown in the accompanying drawings, in which:
Figure l is a perspective view of an auxiliary device having a
pivotable arm that can be swung into the optical path of a telescope;
Figure 2 is a diagram showing details of the optical system o-E
the inventive device.
In certain situations, for example, when sailing or flying, it
is extremely difficult, if not impossible, to use a map in th~ usual manner.
It is in such cases that a map sector, continued on a slide or film strip 10
that can be illuminated from behind by an illuminating system 11, is extremely
useful. In addition, the slide 10 contains angle information from which the
particular associated points of the compass can be read off. As described in
greater detail below, a prism assembly 17 can be rotated by means of a thumb-
wheel 32 and thus the map sector can be oriented to the particular sigh-ting
direction for the viewer, if necessary also by a reflected compass. Alter-
natively, slide 10 with the map sector can be rotated by means of a thumb-
wheel 12 and thus matched to the direction of viewing registered by the compass.
Thumb-wheel 12 is shown in Figure 2 although it should be realised that both
thumb-wheel 12 and thumb-wheel 32 would not usually be present on the same
embodiment.
Since, in many cases, it would be undesirable were such map
sectors always incorporated in the field of view, the incorporation of the map
sector contained on the slide 10 takes place by means of an arm 13 that can be
swung into the optical path of the telescope; said arm can also be swung clear
of the field of view if it is not desired to view the map slide 10. In such a
case, the telescope can be used as a normal instrument. The arm 13 can be
held by form-locking or force-fit detent means ~not shown) in different
positions.
The deflection of the image -rays f-rom the map slide or film strip
10, respectively, takes place through a deflector prism 15 incorporated in the
pivoting arm 13, said deflector prism 15 being of trapezoidal shape. A lens
system 16 is provided at the reflection (exit) side of the pivoting arm 13Z
i.e., adjacent to the deflection prism 15, from where the slide 10 is re-
presented to infinity and incorporated into the optical path 14 of the tele-
scope.
Furthermore, in order to arrive at the smallest possible leng-th
and at the same time permit rotation of the map sector, a Pechan prism assembl~
17 consisting of two prisms 18, 19, is installed ahead of the deflection
prism 15. Of course, it is possible to use other prisms that are similar to
the Pechan prism. In addition, the slide 10 can boe rotated mechanically and
the Pechan or similar prisms dispensed with.
The image rays from the slide or film strip 10, respectively,
pass through the incidence plane 20 that is substantially perpendicular to the
optical axis, are deflected on a line of separa-tion 22 between the -two prisms
18 and 19 that is inclined substantially at an angle of 45 to the optical
axis, and after several deflections the image rays pass through the line of
separation 22 between the two prisrms 18 and 19. After repeated deflections
within the second prism 19 the image rays leave the prism assembly 17 through
the reflecting plane 21 that is perpendicular to the optical axis, from where
they enter the deflection prism 15, on the exit side of which the lens system
16 is arranged.
By rotating the prism assembly 17 about the optical axis the
image of the map sector, which is incorporated in the optical path, is rotated
for the viewer.
If i-t is desired to include the map sector, the pivoting arm 13
is first swung into the optical path 1~ of the -telescope where it enters into
detent means (not shown) and is loc~ed in this position. The viewer can if
necessary establish the sighting direction by using the already familiar
reflected scale disc of a built-in compass or by using other familiar means.
The map sector is now rotated Eor the viewer with the help of the thumb-wheel
32 so that it appears correctly oriented iTI the user's field of view; this can
be verified on the basis of the angle information of the map sector. Tf this
is done, the sighting direction and the alignment of the map sector will co-
lU incide. The user of the telescope thus has a direct connection be-tween map
section and direction of sight, which considerably simplifies orientation.
Alternatively, as indicated above, the map sector can be rotated
using thumb-wheel 12 instead of th~mlb-wheel 32.
There is no need for the laborious folding of maps that is so
frequently a problem, particularly in windy conditions.
The film strip may be contained in a cassette and advanced as
desired longitudinally in the cassette.
