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Патент USA US2405729

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bis-arch Room
2,405,729
Patented Aug. 13, 1946
UNITED STATES PATENT OFFICE
2,405,729
FOUR-COMPONENT OBJECTIVE
Fred E. Altman. Rochester, N. Y., assignor to
Eastman Kodak Company, Rochester, N. Y., a
corporation of New Jersey
Application November 20, 1943, Serial No. 511,060
1
14 Claims. (CI. 88-57)
2
This invention relates to four component ob
jective lenses.
thereby producing sharp de?nition on the axis.
The improvement is far beyond anything pre
viously thought to be obtainable, the nearest pre
An object of my invention is to provide an
objective with critically sharp de?nition at the
axis, especially when used at ?nite conjugates,
vious approach being with another type of lens
as described in my Patent 1,880,394. Some of
these features also further reduce the Petzval
and with a reduced Petzval sum.
A particular object of my invention is to pro
sum.
vide an objective suitable for use as a relay lens
The zonal spherical aberration may be cor
rected by the most preferred shape of compo
in an optical sighting device.
nents, without making any components compound
An object of a preferred feature of my inven 10 or by making them compound and with less spe
tion is to provide a relay lens with a negative
ci?c designation of the shape, or again by mak
Petzval sum and suitable for use in sighting de
ing them compound and with the preferred fea
vices according to my copending application, Se
ture of high index elements and with still less
rial No. 511,062, ?led concurrently herewith.
speci?c designation of the shapes of the com
By ?relay lens? is meant an objective lens with 15 ponents.
real object and image at ?nite conjugates and
The series of features relating to arrangement
without any intermediate real images, the "real
and shape, some of which include some or all
object? being an image formed by another lens
of the preceding features in the series, are as
or other lenses in front of the relay lens. The
follows: One, the two negative components are
expression "real object and image" is used in a 20 between the two positive components. Two, the
strictly technical sense meaning an object in
front of the front surface and an image behind
the rear surface of the relay lens, and may in
clude an object or image which is virtual with
respect to the adjacent part of the whole optical 25
system.
Heretofore, relay lenses have usually been made
of one or more cemented achromats, the larger
the aperture ratio speci?ed, the greater the num
ber of components required so as to keep the zonal
spherical aberration within the tolerance per
mitted by the requirement for a sharp image at
the center of the ?eld of view.
The demand for sighting devices with a ?atter
image and less astigmatism in the ?eld zones
away from the axis has led to the proposal of
several expedients all of which have drawbacks
which have kept them from being generally
adopted. However, the present invention over
comes all objections and provides a lens ideally
suited to this purpose.
The present invention is an improvement in
the type of objective which is made up of two
negative components and two positive compo
nents in axial alignment forming two halves of
the objective, each half consisting of a negative
component and a positive component spaced apart
by between 0.02)? and 0.5} where f is the focal
length of the half. This arrangement reduces
the Petzval sum of the objective in known man
ner. When used at unit magni?cation, the sys
outer surface of each component is of the same
sign as that of the whole component, that is,
concave in the negative and convex in the posi
tive components. By outer surface is meant the
surface farther from the other half of the ob
jective. Three. the negative components are bi
concave and the positive components biconvex.
Four, the outer surface of each biconcave com
ponent is more strongly curved than the inner
And ?ve, the radius of curvature of the
outer surface of each biconcave component is
between 0.08 and 0.50 times that of the surface
facing toward the other half of the objective.
The necessity for these features depends on the
35 degree to which other features are present.
The series of features relating to the compound
ing of the components is similarly as follows:
One, at least one component in each half is
compound and consists of a negative element fac
40 ing toward the other half of the objective and
a positive element cemented thereto. Two, the
positive element has a higher index than the neg
ative element. Three, at least one component in
each half is compound and consists of a negative
45 element cemented to a positive element of higher
refractive index in such a way that the cemented
surface is convex toward the other half and has
positive power. It will be noted that the third
feature includes the ?rst two necessarily, that is
since the negative element has lower index it
must face toward the other half if the cemented
tem is preferably symmetrical.
surface is to be convex toward the other half and
The invention includes features relating to the
have positive power. Four, the component which
arrangement and shape of the components, oth
is compounded in this manner is speci?cally the
ers relating to the compounding of components,
negative component in each half. Five, all four
and still others relating to the indices of refrac
components are compound, at least one in each
tion of the elements, all of these features oper
half of the objective being according to the ?rst
ating to reduce the zonal spherical aberration and
30 surface.
two features of this series. And six, all four
2,405,720
3
,
components are compound, at least one in each
half being according to the third feature of this
series. As with the shape features, the necessity
Hamymm?
for these depends on whether or not certain other
Len, elements
ND
v
Imdw_____ __
1,611
574
features are present.
'4
Example 3, Fig. 1
5
The features relating to the indices of refrac-
EF'm?
"7'0
Rad?
tion of the elements of compound components
are: One, the positive element has an index greater than 1.64. This index can be as high as
H and m ?? " 1' m 33'8
glasses are available. At present this is about 10
2.1. Two, all the elements of the objective have
refractive indices greater than 1.6. And three,
BB1! mm!?
the positive elements in components according to
at least the first feature relating to the manner
Lem elements
of compounding have refractive indices greater 15 I dm
Pt?+'鞍�Thickness
+R,__ 15-29;,
?H-415
-g1-+R1-51.a
81-81-35
5.3:335533
?$217,238
Example 4, F193} ?M14
"-100;
"7-0
Pip-11�
m
ND
v
1,? 45 8
Rm
R__R ?40
T we?
ht do,
than 1.7. The most preferred embodiment, of
lllgnd vnIIIII 11720 2013
iRz?ii-?areii-lg�
course, has all features of all three sets just listed.
m and VI_____ 1_ 617 3?
_R?_+fe,_29 3
;,-t:-3j3
1v sndV .... -_
+R|??R0-29.3
awn-4.1
+R"_R"75?2
S"12'2
By means of the feature of positive elements
1.020 00.3
with index greater than 1.?? combined with at
least the second feature of each of the other se- 20
sie-A'g-glg
.
ries, I have succeeded in designing an objective
Example 51 Flg- 3
with Petzval sum reduced to a negative value.
Such a lens is particularly suitable for use in
H], mm
a m
sighting systems according to my copending ap-
Lens elements
EF-m.
'
ND
"m
v
Radii
plication mentioned above.
25
It is advantageous that the two halves of the
land
1.744 45.8
objective be spaced apart by between 0.04 F and F
11 and VII----- 1- 12� 29-3
where F is the focal length of the whole objecm and
1.017 30.0
tive. Observing the lower limit aidsin ?attening
IV "I"---- -- W0 60-3
the ?eld, while an upper limit is necessary if 30
vignetting is to be avoided. If a prism 01- ?lter
glass is to be included in the system, the central
space of this relay lens is a convenient place for
it because the bundles of rays are parallel or
Half system:
nearly parallel. If a prism or ?lter is included, 85 Le!? eliiments
Pt __m26
z
Thickness
+R\-?Ru-33.0
n-a-za
jglf?gfm?
51-5113;
?R4-+Ro'29.3
$333133
awe-3.1
"5:53;:
Example 6? Figs? 5 and 6
00.7 Ptz??.0007
EF-lOO;
ND
V
Rad?
Thickm?
the effective separation is taken as the path
length in the prism or ?lter divided by the refrac-
1 "1d V1 ----- --
1- 617 55-0
tlj閍jllgjg-g
tive index plus the sum of the air-spaces.
11 andV_____ __
1.007 50.1
-R.-+R.-z0'0
a-n-1I7
n1end1v~~~ 1- ?17 3&5
Qi??j?Lj�-�
?521-031
It is preferred that the objective be symmetrical and corrected for unit magni?cation, but 40
gfgf-szg
'
the invention is not limited to this form.
'
.
In the accompanying drawings:
Example 7, Fig. 5
Figs. 1 and 2 show a relay lens consisting of
Halfsystem:
four simple components.
Figs. 3 and 4 show a relay lens consisting of 45 Lemelemen"
four compound components.
Figs. 5 and 6 show a relay lens consisting of
two simple and two compound components.
Figs. 7 and 8 show a symmetrical relay lens
with a prism in the central space.
50
The data shown in Figs. 2, 4, 6, and 8 is re-
v5.0
N�
Ptz--.0Ol4
v
Rad?
?adv!----- --
L611 5?
nmdv _____ __
1,697
Tum?!
+Ё-?R""3皛7
"""m
50.1
? "Ha-72.3
?R|-+R|-2l.7
s,-s,-11.7
a-il-eo
mmd 1v~---- ?17 3?
+?R?R?_?_?*;�'1;&�
"El-?g
i
Example 8? F 98' 7 ?I 8
peated here along with additional examples In
each case the unit of length may be taken to be a
EF-lOO;
Half system:
EF-IOO;
fl7.8
Ptz?+.0009
millimeter, and each example is given on the scale
of 100 units focal length to facilitate comparisons. 55 Lem element!
Example 1? F 198' 1 am?
mm?
Lensolemeuts
-
H ?鞍'
No
m
V
Ptz=+00008
'
Radii
Thickness
60
N�
V
Rid"
Thick?!
rendrv ..... --
1.611 57.2
+R1-?Rn-+28.15
a-a-aos
lIandIII
P...
1.040 ass
:g::I�:-:&g
Here-+12?
822731?;
Sea-s:
_______ n
.
'
\
,
The following table shows details of the ex
Imdw----- -- 1- 611 57-?
11 and
1. 040 33.8
iggggggg
53-3333;
amples embodying features of the invention.
?R;-+Re-24.4
17-11-10
Other features are obvious from the drawings and
+R?"R"m-5
8"?? 65 the above tables.
Example 2, Fig. 1
Half system:
lenselements
EF-lOO;
Np?
.
117.0
V
.
Example N0.
Ptz-+0.00191
RBI!!!
R -?R -27.1
1v
Thidmw
7-1-4 7
70 F ___________ __ 131
genpgn .... -- 0.43
2
no
0.25
3
4
6
6
7
355
0.20
109
0.11
105
0.13
m
0.20
108
0.15
8
m
0.44
.
Imdw
1 611 57 2
ig;-+R;-g�.3
sf-gLgg
on?? ----- -- 0.20 0.30 0.10 2.: 8.; 0;: (to: 0.20
nmd
L617 36.6
1821-2127911
t15:11:11
Evian-1:131? ifiii' i.'6ii'1.t17 1.017 1:017 1:011 'ifBii
vvulvll nuw?
2,405,729
In this table ?F? is the focal length of the whole
relay lens, ?Separ." designates the e?'ective sep
aration of the two halves as previously de?ned,
6
ponents in axial alignment forming two halves
which are effectively spaced apart by between
"Inner R and Outer R" mean the absolute values
0.04 F and F where F is the focal length of the
objective, each half consisting of a biconcave
of the radii of curvature of inner and outer glass
air surfaces respectively of the biconcave com
ponents, ?Np? and "NN? are the respective refrac
tive and a biconvex component spaced therefrom
tive indices of a positive element and a negative
element which are cemented together, the largest
component facing the other half of the objec
by between 0.02 f and 0.5 f where j is the focal
length of the half, characterized by the radius
of curvature of that surface of each biconcave
such difference in index being indicated, and the 10 component which faces the biconvex component
lowest N is shown to indicate the preferred fea
being less than that of the surface which faces
ture of all the refractive indices being greater
the other half of the objective and by one com
than 1.60.
ponent in each half being compound and consist
The half system focal length is given in the
ing of a negative element facing toward the other
drawings for more accurate comparison with the 15 half of the objective and a positive element with
prior art and between examples. It will be noted
higher refractive index cemented thereto.
that except for Example 2, the whole lens has
5. A lens according to claim 4 in which the
larger focal length, i. e., less power than either
refractive index of said positive element is greater
half alone. The fact that these examples are
than 1.64.
,
symmetrical and work at unit magni?cation 20
6. A lens according to claim 4 in which all
means that the light between the halves is col
four components are compound.
limated and hence that the center space is not
7. A symmetrical objective lens consisting of
very critical and in turn that the whole lens focal
four components in axial alignment forming two
length may be varied (by changing the central
equal halves which are effectively spaced apart
space) without materially affecting the correc 25 by between 0.04 F and F where F is the focal
tions. Hence, the half system focal length is the
length of the objective, each of the equal halves
critical one relative to correction of aberrations.
consisting of a biconcave component and a bi
convex component, the biconcave component be
of the invention, I wish to point out that correc
ing nearer the other half, characterized by at
tion, and ultimately over-correction, of Petzval 30 least one component in each half being compound
sum in a lens of this type is best obtained by
and consisting of a negative element cemented to
- separating the elements or components as much
a positive element of higher refractive index and
as possible in each half consistent, of course, with
by the cemented surface being convex toward the
tolerable vignetting of the oblique pencils of light.
other half and having positive power.
Secondly, the collective components should have
8. An objective lens consisting of four com
as high an index of refraction as possible, and the
ponents in axial alignment forming two halves
negative components should have as low an index
which are effectively spaced apart by between
as is permissible consistent with the correction
0.04 F and F where F is the focal length of the
of spherical aberration. To assist in the correc
objective, each half consisting of a negative com
tion of spherical aberration and to permit a cer 40 ponent facing the other half of the objective and
tain amount of the color correction to be pro
a positive component spaced therefrom by be
vided in each component separately. the prefer
tween 0.02 I and 0.5 f where f is the focal length
able form of the invention has each component
of the half, that surface of each component which
compound. That is, the correction of color be
faces away from the other half being of the same
came increasingly dimcult with increased spac
sign as the whole component, characterized by
ing and the lowering of the index in the nega
each negative component being compound and
tive component, but this was best solved by mak
consisting of a negative element facing the other
ing the negative components compound and hy
half and a positive element with higher refrac
perchromatic.
tive index cemented thereto.
The characteristic features of my invention are
9. A lens according to claim 8 in which the
By way of review of the fundamental theory
best described by the accompanying claims.
said positive element of each negative component '
What I claim and desire to secure by Letters
Patent of the United States is:
1. An objective lens consisting of four com
has a refractive index greater than 1.64.
10. An objective lens comprising four com
ponents in axial alignment forming two halves
which are optically spaced apart by between 0.04
F and F where F is the focal length of the objec
ponents in axial alignment forming two halves
which are effectively spaced apart by between 0.04
F and F where F is the focal length of the objec
tive, each half consisting of a negative com
tive, each half consisting of a biconcave com
ponent facing the other half and a positive com
ponent and a biconvex component spaced apart
ponent spaced therefrom by between 0.02 f and
by between 0.02 f and 0.5 f where f is the focal
0.5 f where f is the focal length of the half, that
length of the half, the biconcave component fac
surface of each component which faces away from
ing the other half of the lens, characterized by
the other half being of the same sign as the
the radius of curvature of that surface of each
whole component, characterized by having all
biconcave component which faces the biconvex
the four components compound each including a
component being between 0.08 and 0.50 times
positive and a negative element and by two com
that of the surface which faces the other half
ponents of like sign being cemented doublets,
of the objective.
each consisting of a negative element facing the
2. A lens according to claim 1 which is sym
other half of the objective and a positive element
metrical with respect to the central space.
of higher index cemented thereto.
3. A lens according to claim 1 in which at least 70
11. An objective according to claim 10 in which
one component in each half is compound and
the positive element of each of the said two
consists of a negative element facing toward the
cemented doublets has a refractive index greater
other half of the objective and a positive element
than 1.7 and a dispersive index greater than 35.
with higher refractive index cemented thereto.
12. An objective lens comprising two dispersive
4. An objective lens consisting of four com
doublets spaced between two collective doublets,
8,405,729
7
the central space being less than F and the outer
two spaces being less than 0.5 F, where F is the
focal length of the objective, each doublet con
sisting of a negative element cemented to a posi
tive element, in which the positive elements of
the outer components are biconvex, face outward,
and have a higher refractive index than that of
8
tween 0.02 I and 0.5 f where f is the focal length
of the half, that surface of each component which
faces away from the other half being of the same
sign as the whole component, characterized by at
least one component in each half being a cement
ed doublet consisting of a positive element with
refractive index greater than 1.7 facing away
from the other half of the ?objective and a nega
13. An objective lens consisting of four com
tive element with refractive index less than that
ponents in axial alignment forming two halves 10 of the positive element.
which are effectively spaced apart by between
14. A lens according to claim 13 for use as a
0.04 F and F where F is the focal length of the
relay lens in a sighting device and having a nega
objective, each half consisting of a negative com
tive Petzval sum.
ponent facing the other half of the objective and
a positive component spaced therefrom by be 15
the negative components cemented thereto.
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