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Патент USA US2128394

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Aug. so, ‘1938.
M. BEREK
2,128,394
MICROSCOPE
Filed Aug. 27, 1937
V
INVENTOR
BY A/ax Eerak
A ORW
Patented Aug. 30, 1938
2,128,394
UNITED STATES PATE NT OFFICE)
2128394
MICRO SCOPE
Max Berek, Wetzlar, Germany, assignor to Ernst
Leltz,
G. m. b. H., W t
'
Application August 27,
This invention rel_ ates to
croscopes for determinin
w 3 Claims.
improvements in mi- .
e zlar, Germa
1937, Serial No. 161,207
(CI. 88-40)
‘
sired identi?cati
analysis of
10
10
15
15
20
and devices for carrying on such analysis are
known.
25
An entirely differe nt
pect to the examination of
25
I'red
of extinction ninety
fierent angles. Re
depending upon
the ?eld of View
cal analysis beca me impossible.
the true line as character of
after de?ection was maintained
only in “the cent er of the
this was true 021]‘1 so long a ?eld of’ View and. even
tion of the incoming bundle5 the plane of polariza
a
55
of light re
nt, possibly 0211 31 one degree
the polarized light
1"‘ character 0
' $2,128,394
2
of the surface of the object a greater or lesser
after re?ection was no longer maintained in the
center but in some other spot within the field of
view. Hence it happened very easily that a mi
croscopist who had made certain observations one
5 day and used the same microscope for examining
the same object the following day, by inadvert
ently making only a very slight error in the ori
. entation of the polarizer, would arrive at entirely
portion of the rays which impinge uponthe sur
face passes by re?ection or diffraction back to the
observing eye' through the objective and eyepiece.
different results. Such slighterrorswere almost
They were also used with vertical illuminators
10 unavoidable because the mechanical means for
for qualitative observations invpolarized reflected
Referring now to the construction of the de
?ecting prism ii the following observations are
to be noted. As stated above, prior ordinary
total de?ecting prisms served their purpose satis
factorily so long, as ordinary light was used.
the correct orientation of the polarizer were never
su?iciently accurate and the optical criteria for
ascertaining whether the linear character of the
polarized light was correctly maintained were
15 likewise not completely certain.
be able to correctly de-,
In order therefore, to
termine and measure the anisotropic charac
10
light, it being believed that such qualitative ob
servations were sufiiciently accurate. for identi
?cation purposes. It has been shown that this
belief was erroneous. It has further been shown 15
that quantitative observations could not be made
with such prior devices and until the present dis
covery and invention weremade, nobody to my
teristics of opaque anisotropic substances under _
polarized re?ected light it became necessary to
devise some new instrumentality, researches hav
'20
ing shown that the behaviors and characteristics
of such substances heretofore attributed to the
objects themselves, were incorrect and unreliable
knowledge, knew how to construct a suitable
20
prism for this purpose.
Researches showed that if a simple right
angled isosceles prism with a .single total re
fiection at forty-?ve degrees on the hypotenuse
is compared with a trapezoid prism having three .
because of the inadequacy of the equipment used. - total re?ections, as shown in Fig. 2, the direction 25
of the incident ray being'at 90° to the entrance
' The object of this invention is the construc
25 tion of a device, namely a prism to be used in
surface of the prism, both being made of the
a microscope, for de?ecting polarized light at same glass of the refractive index of m): .516
ninetydegrees having the distinguishing char
then it will be found that (with half of the angle
acteristic that the incoming polarized light after of view being four degrees and the aperture being 30
having been re?ected remains still completely - one degree) the deviation from the required
30
linearly polarized and has the same direction of homogeneous linear polarizationI amounts to five
vibration over; the entire ?eld of view. In the point eight degrees (5.8") in the case of the sim
accompanying drawing Fig. 1 is a side view of ple rightangled isosceles total re?ecting prism if
a microscope embodying the invention with parts ' the polarization plane of the polarizer is exactly 35
in section and broken away and other parts being
35 shown diagrammatically. Fig. 2 is a sectional
view of the reflecting prism. Fig. 3 is a diagram
illustrating certain phases of the invention.
perpendicular to the entrance face of the prism
or trapezoid. It will also be found that the devia
tion of the polarized light from being truly
linear in character or in other words its elliptical
Referring to Fig. 1, the numeral l indicates a ' polarized condition amounts to within one 40
source of light suchv as a ?lament lamp for in
40 stance. ‘2 and 3 are collecting lenses for converg
ing the light rays before they enter the vertical
illuminator. 4 is a diaphragm to eliminate scat
tered light from the course of‘ the light rays.
5 These parts are shown, diagrammatically; In
the illuminator‘ there is mounted a_ polarizing
twenty-eighth (1&3) measured by the proportions
of the main axes of the polarization ellipses.
These errors,_however small they may appear
to be, make it impossible underv certain circum
stances to use the observation forpurposes of 45
diagnosis."
prism 5, an iris diaphragm 6 and a lens ‘I. The
The trapezoid prism is more unfavorable un
der the same. conditions than that of the simple
latter not only renders the incoming light rays
parallel but also, in conjunction with the objec
right angled prism, at least with respect to the
deviation from the true lineation of polarization, 50
microscope forms an image of the . because although the error in the azimuth is
tive 8 of the
iris diaphragm 6 in the planeofthe bbject 9 ' only one point seven degrees (13°), the error
with respect to the lineation, i. e. the ellipticity
"wwupon the microscope stage in.
The numeral ii designates the trapezoid mul
of the polarization is greate , namely one twen
tiple re?ecting prism according to this inven
tion which, having a refractive index as herein
after set forth, will re?ect an incoming linear
polarized light beam so that its linear character
is retained throughout the ?eld and its direc
tions of vibrations remain parallel to each other
so within the field of view. The prism is suitably
mounted upon a support 12. Within the micro
scope ‘tube l3 is-mounted on analyzer prism it
between two anastigmatic correction lenses l5,
tieth (1750).. With errors ‘of such magnitude, the 55
polarization condition of the bundle of rays is
insufficiently homogeneous and insufficiently lin
ear for quantitative measurements and investiga
tions,and a dependable analysis of the optical con
stants of the polished surfaces becomes impossible. 60
The proportions become even materially more un
polarizer deviates from the re
‘ favorable if the
quired orientation with respect to the main plane
of incidence of the prism, even if it is only a
fractional degree, because even though the polar 65
65 porting the several parts and i1 is the usual izer is oriented most carefully such small errors
are unavoidable. From this it will be seen that
vmicroscope eyepiece.
.
' '
The object, for instance an opaque anisotropic an ordinary trapezoid prism having an uneven
the stage. The polar-_ number of total‘ re?ections cannot be used for
substance, is placed upon
70
‘ ‘ized light, after having passed through the il
the purposes of this invention.
Figure 2 illustrates a trapezoid glass prism for '
70 luniinator, strikes the prism ii and is re?ected
downward through the objective 8 and upon the de?ecting polarized light at an angle of ninety
l5.
l6 designates the microscope stand for sup
7 object which is then illuminated by a bundle of
light rays circuiarin cross section, the size of
the circle being‘governed by the size of the open
75 ing of the diaphragm 6; According to the nature
degrees. This prism is di?erentjrom the ordi
nary trapezoid prism in- that it is constructed
in accordance with this invention and is char- 75
2,128,394
3.
is truein the case 01' solutions in which'the
number of re?ecting surfaces z=6q+3, where q
represents a number from the uneven row of
‘ numbers 0, 1, 2, 3,
etc. gill these cases lead to a
refractive index of n=\/3 and for these the phase
difference is greatest for an angle ‘ofincidence
10
10
.15
15
re?ections. Experience has demonstrated that
the critical limits of plus or minus five percent '
must be maintained or'the desired results can
not be obtained.
20
25
.3c E.
to .5' degrees.v
found
that the errors in polarization after a 90 ' degree
30
' de?ection of the bundle of rays,‘ if the polarizer
has its plane
multiple of 1r.
The relative refractive indices .11 between the '
medium of incidence and.
(a) Ina simple total re?ecting prism of glass
having a refractive index of 12:1.5161
40
For the rays
Azimuth
errors
35
Ellipticity
blow?
moms
H
50
ground on ‘the one glass body, then the value
12. obtained from the above equation. will be
found to be
:55
'_
I
| l
|
(b) In a prism of trapezoid ‘cross section with
ree total re?ecting surfaces in a glass body
having a refractive index of n=1.74:-—
~
.n=
For the rays
Accordingly,
6mm
Ellipticity
_
re?ecting surfaces‘
(z=5), a useable value for the refractive index '
is obtained only if p='0, namely n=1.495. with
seven re?ecting surfaces a useable value is ob~
tained only if 11:0, namely n=l.453. These
values result, in the case oi.’ a parallel bundle of
rayswith an angle of incidence of 45° on each
surface, in a condition of polarization which is
55 v.
'
.
Di’é‘ét
A _______________________________________ __
B.
C_
~
0. 001
—0. 00
—0. 04
+0. 000
+0. 000
D-
+0.00
—0. 002
E_
+0. 04
—0. 000
-0. 00
+0. 001
~ F_
G;
H..
.T _________ __
e
-
.
+0.
g;
.
38(1)
-—0. 000
.65 non-elliptical and azimuthally correct. These
Experience has demonstrated that the quan
titative measurements are a?ected if the azimuth 65.
noticeably exceeds the proportion of 1: 1000.
70
A comparison of the two tables given shows to
is the onein which the ‘value of n,
proximate angle-oi’ incidence of 415°, shows the
The prism has been shown as an
element in a speci?c form of microscope. _ It will
75 least possible variation in the phase di?erence
be understood of course that the construction of
the prism and its use in examining opaque aniso
when the angle of incidence is changed:
70
tropic substances in polarized re?ected light is 75
A;
i
2,128,894
the main object of this invention and does not
depend upon its use in a speci?c type of micro
scope.
1. A microscope for determining the optical
constants of opaque anisotropic substances in po
larized re?ected light comprising an objective, an
analyzing prism and an eye piece in optically op
having a light entrance surface and a light emit
ting surface at ninety degrees to each other, the
light entrance surface being at ninety degrees to
the incoming rays, said trapezoid ‘de?ecting prism
having three total de?ecting surfaces for de?ect
ing the incoming linear polarized light rays from
the polarizing prism at ninety degrees to the ob
jective, the refractive index of the said trapezoid
de?ecting prism being n=\/3=1.'732 to within
erative relation with a common optical axis; a
?ve per cent thereof, the polarized light emerging
polarizing prism, means for supporting the same
from the said trapezoid de?ecting prism without
10 in the path of the incoming light rays with the
optical axis of said prism at a right angle to the
optical axis aforesaid, a de?ecting prism inter
posed between said polarizing' prism and the ob
jective for de?ecting at ninety degrees the light
15 rays from the said polarizing prism to the said
objective; said de?ecting prism having a light
entrance surface and a light emitting surface at
ninety degrees to each other, the light entrance
surface being at ninety degrees to the incoming
20 rays, said de?ecting prism having an uneven num
ber of total re?ecting surfaces, the relative re
fractive indices between the medium of incidence
and the medium externally surrounding said total
re?ecting surfaces having a value of n7_—\/3=1.732
25 to within ?ve per cent thereof for the purpose of
affecting a linear and azimuthal homogeneous
correction of the polarization condition of the
de?ected light from the polarizing prism to the
so
objective.
'1
v
2. A microscope for determining the optical
constants of opaque anisotropic substances in po
larized re?ected light comprising an objective, an
analyzing prism and an eye piece in optically
operative relation with a common optical axis; a
35 polarizing prism, means for supporting the same
in the pathof the incoming light rays, a trapezoid
prism interposed between said polarizing prism
and the objective for de?ecting at ninety degrees
the light rays from said polarizing prism to the
40
changes in the linear polarization thereof.
3. A microscope for determining the optical
constants of opaque anisotropic substances in po 15
larized re?ected light comprising a microscope
tube, an eye piece at the upper end thereof and
an analyzing prism in ‘the lower end thereof in
optically operative relation with a common opti
cal axis, a housing secured to the microscope tube
below the analyzing prism therein and extending 20
to one side of the microscope tube, an objective
in said housing in optical alinement with the
analyzing prism and the eye piece, a lens system
in said housing having its optical axis perpendic
ular to the optical axis of the objective and con;
sisting of a polarizing prism in the path of the
incominglight rays and a trapezoid prism having
three total re?ecting surfacesfor de?ecting said
incoming linear polarized light rays from the po 30
larizing prism to the microscope objective, the
said trapezoid de?ecting prism having a light en
ninety degrees to the incoming
' trance surface at
rays from the polarizing prism and a light emit
ting surface at ninety degrees to the optical axis
of the objective, the refractive index of the said
trapezoid prism being n=\/3=l.'732 to within ?ve
per cent thereof, the polarized light emerging
from the said trapezoid de?ecting prism without
changes in the linear polarization thereof.
’
Patent No. 2,128,394.
'
40
MAX BEREK.
said objective; said trapezoid de?ecting prism
-
10
Certi?cate of Correction
7
August 30, 1938.
MAX BEREK.
-
‘
'
It is hereby certi?ed that errors appear in the printed speci?cation ef the
15,above
after
Page
3,
?rst
column,
hne
numbered patent requmng correction as follows:
the word and period “directions.” insert the sentence In accordance with, this invention '
hereinafter set forth; andlines 31, 32, and 33,
the_prism must
comply with the data
_
“,
for
all the rays of the bundle amount'to an un
strike out the comma and words
Patent should be-read with these
even multlple of er”; and that the said Letters
corrections therein that thelsame may conform to the record of the case in the Patent
Signed and sealed this 15th day of November, A. D. 1938.
Actznngltlgmiiasgkwrielrsga??ents.
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