Year: 1886

page_text: Date of Application, 29th Mar., .1886.
Complete Left, 29th Dec., 1886.
Complete Accepted, 1st Feb 1887
RESERV
I, CARL ERNST MARTIN ROHRBACH, of 11 Galberg, Gotha, in the Empire of
Germany, Doctor of Philosophy, do hereby declare the nature of this invention to be
as follows:-
This invention relates to telescopes producing erect images, photographic cameras
and similar optical apparatus.
In these as ordinarily constructed much inconvenience is experienced from light
reflected directly from bright surfaces or dust and misty particles which is always
more or less polarized in such instruments.
Now the present invention has for object to obviate this evil by the use of a
polarizing device such as a Nicol's or other polarizing prism suitably arranged in the
instrument.
In applying the invention in a terrestrial telescope or in a Galilean telescope the
polarizing device is arranged in the eye piece of the telescope close behind or in front
of the narrowest diaphragm; in the case of a photographic camera, in the lens chamber.
In a camera the arrangement may be such that the polarising prism can be removed
as required when the object to be photographed is toned down by means of shades,
blinds or otherwise to such an extent that there are no dazzling rays. In such a case
the polarizer would be superfluous and it is removed to gain intensity of light.
In operating with instruments of the kind referred to furnished with polarising
prisms according to this invention it is necessary to insert the prism in such a manner,
or to bring the instrument into such a position that the plane of the main section of
the prism passes through the source of light so as to entirely destroy all polarized
light. In simple telescopes this may be easily effected by rotating the whole
instrument, in double telescopes and cameras by rotating the prisms themselves.

page_text: In place of a Nicol's polarizing prism evidently some other polarizer might be used,
as for example, a combination of glass plates the arrangement depending upon the
particular application.
The loss of light that must unavoidably result from the use of a polarizer can be
compensated in other ways; in telescopes for example by providing light intensifying
lens arrangements; in photographic apparatus by longer exposure of the object..
It is advisable in the case of telescopes to apply the polarizing prism in the interior
of the tube in the place or point where the cone formed by the rays is of least diameter
so as not to reduce the field of view.
The polarizer may be fixed or moveable in the instrument.
I am aware astronomical telescopes have been used with polarizers for purely
scientific purposes, but such application and use form no part of my present invention.
W: LLOYD WISE,

page_text: I, CARL ERNEST MARTIN ROHRBACH, of 11 Galberg, Gotha, in the Empire of
Germany, Doctor of Philosophy, do hereby declare the nature of this invention, and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This invention relates to telescopes producing erect images, photographic cameras
and similar optical apparatus.
In these as ordinarily constructed much inconvenience is experienced from light
reflected directly from bright surfaces or dust and misty particles which is always
more or less polarized in such instruments.
Now the present invention has for object to obviate this evil by the use of a
polarizing device such as a Nicol's or other polarizing prism suitably arranged in the
instrument.
In applying the invention in a terrestrial telescope or in a Galilean telescope the
polarizing device is arranged in the eye piece of the telescope close behind or in front
of the narrowest diaphragm; in the case of a photographic camera, in the lens
chamber. In a camera the arrangement may be such that the polarizing prism can
be removed as required when the object to be photographed is toned down by means
of shades, blinds or otherwise to such an extent that there are no dazzling rays. In
such a case the polarizer would be superfluous and it is removed to gain intensity of
light. In operating with instruments of the kind referred to furnished with polarizing
prisms according to this invention it is necessary to insert the prism in such a manner
or to bring the instrument into such a position that the plane of the main section of
the prism passes through the source of light so as to entirely destroy all polarized
light. In simple telescopes this may be easily effected by rotating the whole
instrument; in double telescopes and cameras by rotating the prisms themselves.
In place of a Nicol's polarizing prism evidently some other polarizer might be used,
as for example, a combination of glass plates the arrangement depending upon the
particular application.
The loss of light that must unavoidably result from the use of a polarizer can be
compensated in other ways; in telescopes for example by providing light-intensifying
lens arrangements; in photographic apparatus by longer exposure of the object.
It is advisable in the case of telescopes to apply the polarizing prism in the interior
of the tube in the place or point where the cone formed by the rays is of least
diameter so as not to reduce the field of view.
The polarizer may be fixed or moveable in the instrument.
I am aware astronomical telescopes have been used with polarizers for purely
scientific purposes, but such application and use form no part of my present
invention.

page_text: Referring to the accompanying sheet of drawings Figs. 1 and 2 shew in longitudinal
section the eye piece of a terrestrial telescope and of a Galilean telescope respectively.
Fig. 3 is a similar section of part of a photographic camera and attached lens chamber.
In each of the arrangements shown a is the polarizing device such as a Nicol's
polarizing prism. In the arrangement shown in Fig. 1 the polarizer is shown
placed behind the narrow diaphragm b; in fig. 2 it is shown in front of the diaphragm,
and in Fig. 3 it is shown in the lens chamber of the camera, in which it should be so
placed that it may be readily removed when not required. As hereinabove mentioned
the plane of the inain section of the prism should be arranged to pass through the
source of light for the purpose of destroying all polarized light passing through the
eye piece or lens chamber.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed I declare that what 1 claim is :-
In optical apparatus such as telescopes producing erect images, and cameras, the
application and use of a polarizing prism or other polarizer substantially in the manner
described above for the purpose set forth.