A. KÖNIG.
ANGLE MEASURING APPLIAÑGE.
APPLICATION FILED 00T. 4, 1907.
PATENT orricn.
' Arnnn'r'xöme, or JENA, GERMANY, AssIGNon To FIRM or CARL zeiss, or JENA,
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GERMANY.
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A'NeLn-MEAsu'nING,APPLIANCE.
942,393.
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l Specification 'of Letters Patent. u
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i Patented Deo. 7, 1999'. ,
Y Application filed October 4, 190'?.v Serial No. 395,908. ~
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To all lwhom it may cbncem: ` i
Be it known that I, ALBERT
KÖNIG, ‘a ' citi- -
vzen of the German Empire, and residing at
,points .A' and-_ B, when viewed direct, lieV
apart from each other by the angle of sepa
rationA w ofthe Rochon/prism. " If the
prism had an angle of separation
Carl-Zeiss strasse, Jena, in the'Grand Duchy Rochon
arbitrarily alterable from zero-to a maxi
vof Saxe-Weimar, Germany, have -invented a. mum value, with such a prism evidently the .
new and useful Angle-Measuring Appliance,
of which the following is` a specification.
angle subtended Lby the well-known dimen
The' invention relates to double ‘image sion of any object whatever u _ to the maxi
’ angle-measuring >appliances in which the
mum angle of separation coul be measured
’ according -to the coincidence method just set 65
10 combination of prisms known as the Rochon forth, that is tosay, it would besuitable -to
prism is employed., This combination con,
fdr' determining the distance
sisting of two.or more prisms, of which lone _serve by itself
~A
double image angle-measur- ' '
of
objects.
at least is a double refracting crystal, for
in
which Rochon prisms are
ing
appliance,
example, calcite, -is as is well known ar
in
whichgsuch alterable an 70
made
use
of
and
ranged, so> that to one incident ray two.
1,5 emergin ‘rays correspond, the directions of -'gle of. -separation is produced, forms the sub
which differ by a certain angle, say fw, and ject matter of the .present invention. To
this appliance it may -in the- ñrst _
of the two deíiections'of which: from the ’ explain
place be'brought tomind, that two glassl
direction of incidence'even the larger ldeflec-- wedges inserted one behind the_other,„when _
t1on'1s 1n general smaller than the anglelof`
rotated -~about the _incident vray through separation w and in no case much larger.
equal angles in npposite directions, are .
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Double image angle- measuring> appli equivalent to a statlonary wedge having a
ances are ordinarily employed to determine refracting
variable withthe amount
the distance of objects of» which atleast one of rotation angle
and
producinga
deilec
dimension perpendicular -to the direction lof tion-corresponding to this variable
angle. It the
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vision is known to the observer.- In these
appliances the distance between the double
images of such an object can" be micro
metrically made equal tothe said dimension
and then the angle subtended bythe dimen
sion read oli". Angle andv dimension to
« gether allow’of the distance of. ther object be'
ing calculated. When a Rochon prism is
made use of for producing the -double
35 images, the appliance consists of a telescope
between the objective and the image _ñeld
of which the prism is slidably fitted, the dis
tance between the double images being the
larger the less the prism is distant from the
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glass wedges' bel substituted _by Rochon
prisms, then in rotation the deñectíon kof'
-eitherof the two` emerging rays fromthe
direction óf. incidence `is'varied and hence,
in general, the angle of separation is changed.
There arise', however, in general, still two
secondaryemerging rays ofother directions,
because the planes of- polarization of' the
rays proceeding from the first Rochon', prism
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planes of the second so that each ray _is once
again decomposed into4 two rays. ’ To do
away> With'these disturbing secondary rays
a circularly polarizing double refracting
The object of thewpresent invention is crystal plate, for example, a diskv of mica,
to make >use of the properties of the is firmly connected with each Rochon prism
on the side turned to the other prism. The
Rochon prism for constructing a doublev two
>rays are -circularly'l olarized after'
objective.
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do not always coincide with-the lprincipal p
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image angle-measuringv appliance without
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the aid of a telescopic system. But it will emergence from the ñrst prlsm by its- suit
ably , 'orientated crystaly plate. After this _'
>_be understood that such an appliance may ~the
two rays are always rectilinearly p'olar- "
serve as an adjunct to telescopes. In this
by the other crystal plate orientated tocase it is -Íixed either before the objective or ized
the second Rochon prism', however may be
the an lar position, of this plate relatively 105
the rst plate, so that the planes of polar-J
following reíiections. If in looking through to
ization coincide with the principal planesl
a Rochon prism a certain point, say A', of of
second prism, further decomposition `
one of the double images coincides with an 'of the
the two rays through the second lprism_
other certain point, say B', of the vother
'behind theocular.
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The inventive idea has arisenfrom the
double image, the corresponding `object
thus being prevented.
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i 942,393
In the annexed drawing: Figure 1 is a I split up into two partial rays.
. One of _these 40
front View of an'appliance according to the l partial rays is supposed to retain
the direc
invention, its'handhng in both hands as a tion of the incident ray on account of the__
self-contained instrument being indicated refractive index chosen for the component _
by dotted lines. Fig. 2 is an axial section 2.
The Rochon prism b having ~the same
through the same appliance.l Fig. 3 is ~a I
as a, this ñrst partial ray passes
diagram repeating the optical parts " from construction
unbroken through the whole appliance. 45
Fig. 2 and showing the path of the rays._ _The
other partial ray is ,deflected away from
Fig. 4 is a sectional ’plan View of the appli
10 ance of Fig. 2 on a smaller scale and in an the edge of the» component _1, but its passage
- inverted position, the appliance being slipped from the component 2 to the mica plate f is
over the objective casing of a prism tele unaccompanied by a noticeable deviation. 50
On emerging from the plate f the second
scope shown in dotted lines.
partial ray is further deflected and the angle
' The two Rochon prisms a and b are rota» between
the two partial »rays thereby en-15 table by means of their mounts a" and ö",
hanced,
but
this additional deflection is an
the former in the casing part c, the second
nulled when the ray enters the mica plate g.
in the casing part (l. The mounts are pro The
Rochon prism b has a like iniiuence on
vided with bevel Wheels a1 and b1. A bevel
the
second
partial ray as a, the- ray being
wheel c, which can be vrotated by the milled
20 -head ef’ygears into the bevel wheels a1 and further deflected on passing from the calcite
1 to the glass component 2 and
Ö1, which are equal in size, and ,produces component
once
more
on
emerging from the latter com
equally large, but opposite, _rotation of the
prisms. The prism a is equipped with a ponent. The final angle between the two
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partial rays is varied, as above explained, by
mica `or other> double refracting plate f, the compensatory
rotations> of the two optical
prism b with a similar one g. On the inner
conical surface of the casing part d the scale members a f and g b of the appliance, the
of angles Íz and on the cover ring of the position of. the members as shown in Figs. 2
' mount b" the index z' (Fi g.
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1) is arranged.
For rotating the prisms 1n opposite direc
tions, 'but with equal angular velocity, any f
other mechanical coupling may be made use
of. The measuringappliance proper may
be executed in any other less simple form.
and 3 corresponding to the maximum angle.
Iclaim:
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A double image angle-measuring appli- i
ance, consisting of two Rochon prisms, two
circular polarizing double refracting crystal
plates', the plates being secured on the inner
sides
of the prisms, aund means for rotating
The Rbchon prisms a and b consist each
the prisms through. equal angles, butin op~
of a calcite prism 1 (Fig. 3) and a glass posite directions.
prism' 2. A' ray incident normally on the
-outer surface of the component l of the
Witnesses:
Rochon prism a, on passing through the in
PAUL KRÜGER,
terface between the components l and 2,- is
FRrrz SANDER.
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ALBERT KONIG.
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