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Патент USA US2130760

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3550-47].
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SR
OR
291300760‘
Sept. 20, 1938.
/.
2,130,760’
A. WARMISHAM
LENS
Filed May 5, 1937
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‘LENS
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2,130,760
, UNITED STATES
PATENT OFFICE
2,130,760
LENS
Arthur Warmisham, Leicester, England, assignor
to Kapella Limited, Leicester, England, a cor
poration of England
Application May 5, 1937, Serial No. 140,789.
' In Great Britain May 5, 1936
'IClaims.
This invention relates to lenses for photog
outer concave surface of the meniscus element
raphy and the like purposes, of the kind com
adjacent the diaphragm
prising a pair of collective components enclosing
(5) The relationship between the indices of
refraction ofthe meniscus and divergent ele
a' pair of compound dispersive meniscus com
I ponents placed with their concave'surfaces facing
one another and enclosing a diaphragm between
them; and its object is to provide a lens having
an aperture not less than F/2 and having a ?at
?eld of greater angular extent than has hitherto
10 been attained in such lenses.
The best type of ‘ objective known to opticians
for producing a well-corrected ?eld of total
angular extent 45-50 degrees at aperture F/2 is
that ‘described in United States Patent 1,955,591,
15
(CI. 88—57)
comprising two compound divergent meniscus
components between two simple convergent com
ponents, the divergent components turning their
concave outer faces toward the diaphragm,
placed between them, and each divergent com
ponent comprising two elements, a convergent
element of low dispersion and a divergent ele
ment of higher dispersion, cemented together.
All objectives of this type have a fault in com
mon, namely, the oblique image has a residue of
over-corrected spherical aberration‘. Speaking
broadly, the performance of all such objectives
would be improved by reducing said residue. The
recurrence of the fault in objectives of the kind
referred to, as marketed by ‘different makers,
constitutes a kind of proof that in this type of
objective the fault cannot be eliminated.
I have found that this fault, heretofore re
.
ments on the one hand and the curvature of their
common cemented surface on the other should
be such that such surface is convergent.
.
Two suitable forms of construction embodyin
all of the above mentioned features is illustrated
in the drawings, wherein:
10
Fig. 1 is a section through an objective of
known type having double divergent members,
showing an oblique ray impinging thereon;
Fig. 2 is a diagram illustrating the oblique
spherical aberration obtained with an objective
of the type shown in Fig. 1;
Fig. 3 is a section through a lens constructed
according to the present invention;
Fig. 4 is a diagram illustrating the reduced
oblique spherical aberration obtained with a lens 20
constructed as shown in Fig. 3; and '
Figs. 5 and 6 are sections through two lenses
constructed in accordance with the present in
vention.
-
>
.'
To illustrate the action of this novel construc 25,
tional feature I show, in Fig. 1, an objective of
known type having doublet divergent components 2 and 3 arranged between two collective com
ponents l and 4, and I show three rays of an
oblique pencil traced through in the meridian 30
plane. P is regarded as the axis of the oblique
pencil and it is the ray which goes through the
garded by opticians as unavoidable, can be sub- - central point of the diaphragm. ‘A is the limit
stantially reduced by constructing one or other ing ray which gets through the front aperture,
and preferably both of the divergent members of and B is the limiting ray transmitted by the back 35'
three elements, a meniscus convergent element aperture. These are shown emerging as the‘cor
adjacent the diaphragm, a divergent element responding rays P’, A’, B’. l
'y
cemented thereto on the side away from the
diaphragm and a convergent element cemented
40 to the divergent element, the index of refraction
In Fig. 2 is shown a graph of the intersectio
distances of the pencil of rays on the axis P’: the
ordinate in this graph indicates the distance of 40
of the meniscus element being higher than that
an incident ray from the axis and the abscissa “
of the divergent element.‘
represents the differences of intersection dis
-
To advantage the lens should also include some
or all of the following features in addition to
those given above:
1
(1) The index of refraction of the convergent
element should be in excess of that of the
divergent element.
(2) The power of the convergent element
should be relatively low.
4
‘
(3) The power of the divergent element should
be relatively high.
I
tance.
The curves indicate the general run of
the oblique spherical aberration in these lenses:
- over a reasonable area there is a good approxi
45
mation to correction shown by the approximation
of the central part of the curve to a vertical
straight line: but there is always a pretty rapid
degeneration over the outer half of the effective
area, and in the sense shown, 1. e. the marginal 50
rays focus too long.
'
In Fig. 3 two triplet divergent components 20
(4) The surface of - contact between the
and 3a are arrangedbetween two collective com
meniscus and divergent elements should be , ponents l and 4, and a similar oblique pencil is
strongly curved and of shorter radius than the traced through the new lens and the corrective 55
2
2,130,760
Example II
action exerted by the strongly curved cemented
convergent surfaces is seen thus: consider the
angles of incidence of rays P and B on the
strongly curved convergent cemented surface of
Relative aperture F/2
the front divergent component. Evidently, as
one progresses from P outward to B, said angles
increase: from P to A they remain small. The
larger the angle of incidence the larger the
deviation, and by refraction at this surface ray
10 B, therefore, suffers relative convergence toward
ray P, whereas the relative action on P and A
is slight. Next, consider the several angles of
incidence‘ on the strongly curved convergent
cemented surface of the second divergent mem
15 ber.
Evidently as one progresses from P toward
A said angles increase, and from P to B they re
main small;v by refraction at this surface ray A,
therefore, su?‘ers relative convergence toward
ray P while the relative action on P and B is
20 slight. The net result is that in a more or less
symmetrical manner a convergent e?ect has been
introduced into both halves of the oblique pencil,
and, since the convergent e?ect increases rapidly
for the marginal rays, the maximum of the con
25 vergent effect is obtained where it is needed and
this explains the improved approximation of the
graph in Fig. 4 to a vertical straight line which
means an improved approximation to condensa
tion to a point focus.
30
In addition to the main value of this new con
structional feature in improving~the spherical
aberration in oblique pencils, it is a useful help
in expanding the aperture by its effect on the
Thickness Separation
on
V
R|=+ .6925
D1=. 082
l. 613
R,=+2. cs2
59. 3
,.
10V
S1=. 001
Ra=+ .3697
Dz=. 062
1. 621
60. 4
R4=+l.429
,
Da=. 040
1. 605
38. 2
D4=. 054
l. 652
33. 5
1. 652
33. 5
R5=+ .2012
Re=+ .2439
S2=. 160
R1=— .2882
D5=. 054
15
Rg=— . 2132
Da=. 030
1. 605
38. 2
D1=. 055
1. 621
60. 4
Ro=+2. 00
R1n=—- .387
20
Sa=. 001
R11=+2. 083
'
Da=. 060
Rn=—1.0012
1. 621
60. 4
What is claimed is:
1. Lenses comprising a pair of convergent com
ponents enclosing a pair of compound divergent
meniscus components separated by air spaces,
and'placed with their outer concave surfaces fac
ing one another and ,enclo
a dia hra m e
tween them, in which each of the divergent com
ponents is compounded of three elements com
prising two outer elements and a divergent ele
30
greater than that of the inner member to which
ment positioned therebetween of which the outer
elements adjacent to the diaphragm are con 35
vergent menisci, each of which has a refractive
index higher than that of the inner element ad
it is cemented.
jacent to it.
axial spherical aberration, most especially when
35 the dispersion of the convergent element is
'
I now give data for the construction of two
40
Radil
Equivalent focal length 1.004
examples, illustrated in Figs. 5 and 6 respectively
of the drawings. The notation is that the suc
cessive radii of curvature, counting from the
'
2. Lenses comprising a pair of convergent com
ponents enclosing a pair of compound divergent 40
meniscus components separated by air spaces and
placed with their outer concave surfaces facing
front, are called R1, R2, etc., the sign + denoting
one another and enclosing a diaphragm between
that the curve is convex toward the incident
them‘, in which each of the divergent components
light, and - that it is concave toward the same. . is compounded of three elements comprising two ' 45
outer elements and a divergent element posi-_
tioned therebetween'of which the outer elements
adjacent to the diaphragm are convergent
?ned in terms of the mean refractive index up, menisci, each of which has both refractive index
‘and dispersion greater than that of the inner
50 as conventionally employed. The Abbe V num
50
member to which it is cemented.
ber also is given:—
3. A lens system, comprising two collective
Example I
'members, two compound meniscus dispersive
members between said collective members, a dia
phragm between the latter, saidjdispersive mem
Relative aperture F/2
Equivalent focal length .9897
55
The axial thicknesses of the elements are de
noted by D1, D2, etc., and the separations of the
components by S1, S2, etc. The material is de
bers being arranged with their concave exterior ‘
Radii
Thickness Separation
surfaces facing one another and one of such dis
m:
V
1. 613
59. 3
R1=+ .6921
D1=. 082
60
R1=+2. 632
.
on the side away from the diaphragm and a con-,
60; 4
vergent element cemented to the divergent ele
ment, the index of refraction“ of the meniscus
Sl=.001
Ra=+ .3850
'
Dz=. 062
l. 621
Ds=. 040
1. 576
41. 4
D4=. 054
1. 621
60. 4
R4=+ .6985
65
'
R5=+ .2010
Re=+ .2500
R1=— .2890
'
.
-
-
1. 621
60. 4
De=. 040
1. ‘576
41. 4
D1=. 045
1. 623
56. 4
members, two compound meniscus dispersive ,
members between said collective members, a dia
phragm between the latter, said dispersive mem 70
56. 4
surfaces facing one another and each comprising
three elements, a meniscusv convergent element
D5=. 054
R10=— .4071
Ss=.00l
Rn=+2. 632
Da=. 060
75
'
4. A lens system, comprising two collective
Ro= -5.'0
Riz=- .8862
60
element being higher than that of the divergent
element to reduce the oblique spherical aberra
tion.
I
=. 160
Rg=— 2132
persive members comprising three elements, a
meniscus convergent element adjacent the dia
phragm, a divergent element cemented thereto
1. 623
bers being arranged with their concave exterior
adjacent the diaphragm, a divergent element
cemented thereto on the side away from the dia-l
75,
56- UV! Hi5
b'earch Roon
I.
2,180,760
phragm and a convergent element cemented to
the divergent element, the index of refraction of
the meniscus element being higher than that of
the, divergent element to reduce the oblique
'
'
3
persive members comprising three elements, a
meniscus convergent element adjacent the dia
phragm, a divergent element cemented thereto
on the side away from the diaphragm and ‘a con
members between said collective members, a dia
vergent element cemented to the divergent ele 5
ment, the index of refraction of the two outer
elements being both higher than that of the
intermediate element to reduce the oblique
phragm between the latter, said dispersive mem
spherical aberration.
Ul spherical aberration.
'
5. A lens system, comprising two collective
members, two compound meniscus dispersive
it) bers being arranged with their concave exterior
surfaces facing one another and one of such dis
7. A lens system, comprising two collective 10
members, two compound meniscus dispersive
persive members comprising three elements, a
meniscus convergent element adjacent the dia
phragm, a divergent element cemented thereto
phragm between the latter, said dispersive mem
bers being arranged with their concave exterior
15 on the side away from the diaphragm and a
convergent element cemented to the divergent
element, the index of refraction of the convergent
element being higher than that of the divergent
element to reduce the oblique spherical aberra
20 tion.
6. A lens system, comprising two collective
members, two compound meniscus dispersive
members between said collective members, a dia
phragm between the latter, said dispersive mem
25 bers being arranged with their concave exterior ,
surfaces facing one another and one of such dis
members between said collective members, a dia
surfaces facing one another and each comprising 15
three elements, a. meniscus convergent element
adjacent the diaphragm, a relatively high power,
divergent element cemented thereto on the side
away from the diaphragm and a relatively low
power convergent element cemented to the di 20v
vergent element, the index of refraction of both
the meniscus element and the convergent element
being higher than that of the divergent element
to reduce the oblique spherical aberration.
ARTHUR WARMISHAM.
25
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