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Патент USA US2410070

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Oct.
.A_ J_ HQLMAN'
'
OBJECTIVE FOR PROJECTION, ‘ PHOTOGRAPHY, TELEVISION, AND‘ FOR TELESCOPE
Filed?ct, 30, 1940
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Patented Oct. 29, 1946
2,410,069
semen rates rArsNr orrlcs
2,410,069
OBJECTIVE
FOR
PROJECTION,
PHOTOGH v
RAPHY, TELEVISION, AND FGR TELE
SCOPE
‘
'
Arthur J. Holman, ‘East Orange, N. J.
Application October 30, 1940, Serial No, 363,463 '
4 Claims.
1
2
My invention relates primarily to that type of
projecting apparatus, or camera, wherein the ?lm
pletely new and original design requires con
summate skill on the part of the designer. The
reason why this is true is quite simple: prior to
applicant’s discovery of the procedure herein
after disclosed, there has never been any prac
strip is moved continuously across the optical
axis and the effect of this movement is so com
pensated by means of moving optical rectifying
elements .as to produce a stationary image. It
has been the special object of my invention to
ticalhmethod for setting up'a multiple element
lens designby direct mathematical procedure.
provide a proper stationary element to function
with the single rotating lens Wheel having a plu
rality of identical rectifying elements disposed
symmetrically about its periphery as fully de
scribed in Letters Patent of the United States
No. 1,957,457 of May 8, 1934. My improved objec
tive is essential to the realization of the best
performance from the single revolving lens wheel
rectifying system. Due to the distinctive fea
tures of its design, the characteristics of my
objective are such that it is suited admirably for
use as a telescope objective.
It‘also may be
used to advantage, either singly or in pairs, as an
objective in photography and for television.
The distinctive features of my present design
In present design practice the designer’s math
ematical facilities have only provided means for
10
estimating the performance of a proposedlens
element assembly after the curvatures and spac
ings of the refracting surfaces have been set up.
Heretofore the initial setting up of ‘the optical
system has been based entirely on the experience
and judgment, of the chief designer.
In current practice this preliminary design is
then turned over to the computing sta? for ray
tracing trigonometrically; a process which, if
done accurately and thoroughly, may consume
several man years of effort. These computations
yield de?nite and accurate data on spherical
aberration, sine condition, achromatism, astig
are twofold: ?rst, the relative curvatures of the
matism of oblique ray bundles and other valu
refracting surfaces are determined by an optical
able ‘informationconcerning the probable per
symmetry with respect to a radius and a point 25 formance of the optical, system. Generally the
on the optical axis outside of the objective; sec
initial setup is not good enough to meet the re
ond, the relative thicknesses of the elements are
quired lens performance and the chief designer,
determined by an optical symmetry with respect
perhaps with the assistance of his staff, deter
to a point on the optical axis within the objec
mines what modi?cations should be made in the
tive. The focal length is the principal factor .30 initial lens setup to provide better performance.
in determining the locationof the ?rst point on
Again the computing staff analyzes the system
the optical axis and the curvatures of the refract
trigonometrically and again the chief designer
ing surfaces determine the position of the sec
examines the data and estimates how the lens
ond point. Given the focal length and diameter,
will probably perform if it is actually constructed.
or the f value, of a proposed objective, and the 35 This procedure may go on through several set
optical constants of the glasses to be employed,
up modi?cations until the chief designer is satis
it is a very simple matter to design my improved
?ed that the performance ‘of the lens will be
objective. The method of calculation hereinafter
sufficiently good to warrant building a sample.
disclosed for designing an objective free from
After the sample is‘ actually constructed as close
the errors and design faults usually recognized 40 to speci?cations as is humanly possible, it is
in optical computations, is the most elementary
more often than not, found to be unsatisfactory
on record, and both the method of calculation
in performance and further computing is re
and the lens design resulting therefrom are novel
quired to determine which refracting surface or
and most useful. My improved objective com
surfaces should be changed in curvature or spac
prises elements with spherical refracting sur~
ing or both to provide better performance from
faces and its manufacture presents no new or
the lens system. Current commercial practice
in lens design requires genius in the chief de
signer or inexhaustible patience in employing
photographic or projection objective, as now
“cut and try” methods plus very extensive ex
practiced quite generally by skilled technicians, 50 perience in the art of lens design.
presents a very di?icult and tedious task, par
The primary characteristic of the design meth
ticularly if the designer has no accurate per
od herein disclosed, and also of the product so
formance record from a former lens design which
designed, is this ;' the optical system, whether it
approaches closely the speci?cations to be met
be for projection, photography, television or for a
by the new design. To really fabricate a com .55 telescope, is integrated and built up from scratch
dii?cult problems to the lens maker.
The process of designing a modern high speed
2,410,069
4
3
as an original design about two cardinal points
of the system, namely the optical center, or
nodal point, and the point of principal focus.
The design is de?ned entirely and completelyby 5
(1) the refracting power required, (2) the par
ticular achromatism desired, (3) the optical char
acteristics of the glasses employed,v and ?nally
.
cerned primarily with design features of the ?xed
front component 4 and the combination of such
component with the revolving lens wheel to form
a complete and new optical rectifying objective.
The values of T1 and m (Fig. 2), derived math
ematically in the Letters Patent previously re
ferred to, are such that: first, the lens will have,
a speci?ed refracting power; and second, an arc
described at radius R from center I!‘ will pass
through point C at the intersection of the refract
the optical center or nodal point of the system 10
by (4) the radius R to which the system is bent.
The swinging end of radius R passes through
and the pivoting end of radius R is centered on
the optical axis of the systm at a, point closely
related to and determined primarily by the point
of principal focus. In all lens systems designed
ing surfaces and also through point F which is the
optical center of the lens. Values of T1 and r2
calculated in this manner determine a lens form
which is bent to radius R around the point (1
lying on the optical axis outside of the lens. The
in this manner, the ratios of the radii of curva 15 lens may therefore be de?ned as having an opti
ture of the retracting surfacesare determined
cal symmetry with respect to point 0 and radius
?nally by the radius R to which the system is
bent and the spacing of each refracting sur
face within/the system is determined completely
and ?nally by the radius of curvature of each
particular refracting surface in the system. The
mathematics employed is'adequate to produce a
?nal design on the ?rst trial: nothing is left to
R. 'The values determining this symmetry are,
_ 1:32- an
speculation or guess work; no ray tracing tri
gonometric check is required because the opti
cal system has been set up mathematically cor
wherein
rect. The design procedure is direct and the lens
f is the focal length of the lens
‘structure resulting from this design procedure is
0 is (index of refraction of glass) —-1
really ‘new and differs fundamentally from lens
is radius of bending of lens
structures arrived at by the “cut and try” meth 30 R
go is angle between optical axis and extreme posi
ods‘, now generally employed.
' ' My device may be best understood by reference
to the accompanying drawing in which
Fig, 1 is an elementary elevation of an opti
cal rectifying system showing rectifying elements
carried by a rotating lens wheel, the stationary
front component of the objective system and a
section of the aperture unit and the ?lm strip
tion of radius B- (Fig. 2)
for values of (p less than 8 degrees, the follow
ing approximations are very nearly correct and,
because of their simplicity, are convenient for
preliminary calculations:
__ 2Rcf .
"‘“R+¢j-
_ 2Rcf
“?nd
thereon.
v
The design of a single element lens, such as
Fig. 2 is a geometrical ?gure from which data 40
lens wheel element 3, is fully determined by the
is obtained for calculating the relative curvatures
above calculations 'forvalues of T1 and r2, except
of the refracting surfaces of the lens'wheel ele
for lens thickness which may have any value
_ments, also the curvatures of the elements of the
required by the mechanical structures without
stationary front component. ,
Fig. 3 is, a cross section of a cemented triplet 4 changing its optical symmetry with respect to
point 6 and radius R.
'
wherein the optical center of the central ele
The “design of an achromatic component or
Qment coincides with the optical center of the
complete achromatic objective involves the use of
exterior surfaces of the complete objective.
Fig, 4 is a cross section of a pair of cemented
“triplets with a. diaphragm placed centrally be
- tween them for photographic use or for use in
television cameras.
Referring now more specifically to the drawing,
.in which like reference numerals indicate like
parts, il(Fig. l) is the projector or camera ap
erture unit, 2 is the ?lm strip suitably supported
thereon and arranged to be operated at uniform
velocity thereover, 3 indicates optical elements
(three shown) carried by the revolving lens wheel
and having their optical centers on a common
circle described at radius R from the center ll
of the lens wheel and 4 is the stationary compo
nent which is commonly described as the front
component of the objective system. The ele
ments 3, are carried across the optical axis by
rotation of the lens wheel, each in turn becom
ing the rear component of the objective system
and, when coacting with stationary front com
morethan one kind of glass and at least two lens
50 elements, hence the simple calculations for bend
ing ,a single element lens no longer provide a
complete solution. An excellent achromatic tri
plet, speci?cations for which are given hereinafter
in a table, designed and built to operate as front
" component ll in my revolving lens wheel projector,
is an example of a multiple element objective
having optical symmetry with respect to a point i)
and radius R and having further optical sym
metry with respect to a point F (Fig. 3) on the
60 optical axis and within the lens.
This triplet consists of a crown element
cemented between two flint elements, the latter
being both made of the same kind of glass. The
crown element is bent with respect to point i}
F and radius R ‘as if it were surroundedby air.
The interior surfaces of the flint elements con
form to the curvatures of the adjacent crown
surfaces so they may be cemented together.
The exterior surfaces (radii T1’ and r2’) vof the
ponent ll, completing the optical rectifying objec
Complete data concerning the revolving 70 ?int elements are calculated .as if the flint
. tive.
lens wheel structures are disclosed in Letters Pat
ent No. 1,957,457 hereinabove referred to, and
reference thereto is hereby made ir lieu of fur
‘ ther description of the revolving structures.
The ~
present application for Letters Patent is con
elements were one piece and no crown element
was imbedded therein. The ratio of refracting
power of the positive crown element to the total
'refracting power of the negative ?int elements
75 is proportional to the V value of the glasses
2,410,069
5
employed.
The V value for visual rays of a
glass is
7Lp~1
' ftp-7L1’!
wherein no, ns, and no represent respectively the
index of refraction for the D, F and C lines. The
proper relation between refractive powers and
V values is required, of course, to render the
objective achromatic. The algebraic sum of the
refracting powers of the elements is the refract
ing power of the triplet. The calculations thus
far have determined the curvatures of the sur
faces. There remains only the determination
of the proper thickness of elements to bring
optical center F (Fig. 3) of crown element into
exact register with optical center F of the com
bined ?int elements.
The distances a and b from optical center F
(Fig. 2) to the refracting surfaces of a double
convex lens are proportional to the radii of
curvature of the surfaces. Thus
2_’l
17
T2
6
and spacings for the refracting surfaces. A lens
system so designed will give optimum per
formance.
The mathematical conception of a single lens
element bent to radius R around a point E3 on its
optical axis may be’ stated as follows: The lens
is so formed that its optical center F and the
circle of intersection of its spherical refracting
surfaces lie on the surface of an imaginary sphere
of radius R centered on point 0. Furthermore,
all points on the surface of this imaginary sphere,
within the circle of intersection of the refracting
surfaces of the lens, are distant from these spheri
cal refracting surfaces in the ratio of 41/1) or 1‘1/1‘2.
The foregoing is merely a statement of the geo
metrical relationship existing between the curva
tures of the refracting surfaces due to the fact
that the lens is bent to radius R about the point
B as illustrated in Fig. 2 of the drawing.
The mathematical conception of the achromat
ic triplet, which is the basic disclosure of the
present application, may be stated as follows:
The triplet comprises a crown element so formed
that its optical center F and the circle of inter- -
section of its spherical refracting surfaces lie on
Employing this relationship and using T1 and 12
the
surface of an imaginary sphere having radius
(Fig. 3), the distance a is determined for the
R centered on point 0, and two ?int elements so
crown element. To this value a is added the
formed and of such thicknesses that their joint
center thickness of the thinner ?int element and
optical center and the circles of intersection of
the resulting value (1' together with T1’ and m’
(Fig. 3), is used to calculate b’. The value b 30 their internal and external spherical refracting
surfaces lie on the surface of the imaginary sphere
for the crown element subtracted from the value
having radius R centered on point 0. Furtherb’ for the complete triplet gives the center
more,
all points on the surface of this imaginary
thickness of the thicker ?int element. Thus the
sphere within the circle of intersection of the
thickness of each element has been determined
and the exact position of the common optical 35 refracting surfaces of the crown element are dis
tant from these refracting surfaces in the ratio
center has been ?xed. A triplet built to these
of (1/2) or ri/rz, and all points on the surface of
dimensions is optically symmetrical both inter
this imaginary sphere within the circle of inter
nally and externally with respect to point t] and
section of the exterior refracting surfaces of the
radius R and moreover, the crown element and
the combined ?int elements have a common opti
cal center F.
When the curvatures and thickness dimensions
of the elements of such a triplet are drawn to '
scaie, we have the conditions shown in Fig. 3
wherein an arc of radius R described around cen
ter 0 on the optical axis passes through F, the
common optical ‘center of the central crown
?int elements are distant from these refracting
surfaces in the ratio of a’/b’ or r1'/r2'. The fore
going is a statement of the peculiar geometrical
relationships existing between all refracting sur
faces because of the bending of the lens and spac
ing of the surfaces as illustrated in Fig. 3 of~the
drawing. The ratio of refracting power of the
crown element to the total refracting power of
the ?int elements is proportional to the V values
of the crown and ?int glasses.
It is to be noted that the triplet design, wherein
a crown element of lower refracting power is
cemented between ?int elements of higher re
fracting power, possesses one highly important
advantage over other forms of lenses wherein
?int elements in this triplet are related in a
a crown element of low refracting power forms
very unusual and unique way: a way wherein
an exterior surface. When the glasses of higher
they would never have become related by accident
refracting power form the glass-air surfaces, as
or by any method of computation other than
in Fig. 3, the radii T1’ and T2’ are longer, for a
the method hereinbefore disclosed. There never
given lens power, than they would be if a crown
has been heretofore, any design of lenses or any
method of computation which would make one 60 element formed a glass-air surface. Flatter ex
terior surfaces contribute to a reduction in
?int element (front) so thin and the other ?int
spherical aberration and therein lies one im
element (rear) so thick as is illustrated in Fig. 3
element and of the combined ?int elements, and
also through the point of intersection C’ of the
crown refracting surfaces (extended) and
through the point of intersection C” of the ex
terior ?int refracting surfaces (extended).
Obviously, the spherical surfaces of the crown and
which is drawn to scale. The design procedure,
as hereinbefore described, is straightforward and
simple, consisting of two principal steps; ?rst,
portant advantage of the present triplet design.
Tests on several triplets designed in the fore
going manner for widely varying applications
calculation of the curvatures of the refracting
have shown image quality heretofore unattain~
surfaces and, second, calculation of the spacing of
able. -It is believed that the relatively simple
each refracting surface from the nodal point of
conceptions herein disclosed comprise all the
the optical system. Any lens system calculated
fundamental factors requiring consideration in
in this manner possesses the geometrical relation 70 the design of a highly corrected objective. The
ship of refracting surfaces, with respect to curva
simple expedient of bending a triplet symmetri
tures and spacings, which is peculiar to and
cally with respect to a point on the optical axis
characteristic of this design. The lens system
exterior to the lens and proportioning the thick
thus designed is mathematically correct: for its
nesses of the elements to provide a common op
type, there is no better combination of curvatures 75 tical center, i. e., providing optical symmetry
2,410,069
~
8
high speed distortion free photographic objec
with respect to a point on the optical axis and
within the lens, has eliminated entirely the la
borious and tedious ray tracing method ofdesign
tive or an objective of excellent quality for the
television camera. Innumerable other applica
tions of these design features will occur to those
skilled in the art of lens design. The appended
which often requires several man years of com
puting to arrive at an approximate speci?cation
.claims are drawn to cover any and all lens sys
for a high speed photographic objective.
Point 9, of course, always lies onthe optical
axis of the lens, but radius R may vary somewhat
tems wherein groups of elements and/ or the en
tire system may possess-the optical symmetry
herein speci?ed.
depending upon the function to be performed
Having thus fully described my invention, what
by the particular lens. For example, in the re- 10
I claim is,
volving lens wheel projector (Fig. 1) radius R.
1. A triplet comprising a central crown element
for lens wheel elements 3, is the radius of the
and a pair of ?int elements, said crown element
circle whereon the optical centers of the recti
having the radii of curvature of itsv two refract
> fying lens elements are located in the lens wheel
ing surfaces so related that said crown element
assembly as more particularly described in Let- 15 meets the specification of being bent to radius
ters Patent No. 1,957,457. In the case of a tele~
R. about a point ii on the optical axis of said
scope objective, which is used normally for view
triplet, said pair of ?int elements having the
ing distant objects and is therefore focussed
radii of curvature of its internal and external
at or near in?nity, it is advisable to make R
refracting surfaces so related that said pair of
equal to or slightly greater than the focal length. 20 flint elements meets the‘ speci?cation of being
In the case of objectives operating at ?xed focus
bent also to said radius R about said point 0.
B may be equal to the distance from the optical
2. A triplet comprising a central crown ele
center of the lens to the plane of ?xed focus.
ment and a pair of ?int elements, said crown ele
The designer selects the radius of bending to
ment having the radii of curvature of its two
best suit the conditions whereunder the objec- 25 refracting surfaces so related that said crown
tive is to function.
element meets the speci?cation of being bent
A typical triplet for use as front component
ii, in my revolving lens Wheel optical rectifying
objective, was built to the following speci?ca~
tions calculated as hereinbefore described:
to radius R about a point ii on the optical axis
of said triplet, said pair of ?int elements having
the radii of curvature of its internal and external
30 refracting surfaces so related that said pair of
?int elements meets the speci?cation of being
bent also to said radius R about said point 0, the
external refracting surfaces of said ?int ele
Diameter ___________________________ __
2.375
Center thickness ___________________ __'_
.7Ll8 35 ments intersecting the optical axis of said triplet
at points displacedfrom the nodal point of said
R, equals ___________________________ __ 11.25
crown element inproportion to the radius of
curvature of each of said external refracting sur
Glass
m;
V
faces of said ?int elements.
Inches
Focal length _________________________ __
o
____________________________________________ __
____________________________________________ -_
Dimension
r2
Grown
1. 5230
1.6228
Flint
.
Thickness ______________________________ ..
9.92
58
36.1 40
Flint
.
. 410
. 070
. 268
3. A triplet comprising a central crown ele
ment and a pair of ?int elements, said crown
element being so formed that its optical center
F and the circle of intersection of its spherical
refracting surfaces (extended) lie on the sur
face of an imaginary sphere having radius R
centered on point e, and said ?int elements
being so formed and of such thicknesses that
their joint optical center and the circles of inter
section of their internal and external spherical
refracting surfaces (extended) lie on the surface
All linear dimensions are in inches.
of said imaginary sphere,
4. An optical rectifying objective comprising
While I have described in detail a cemented
a plurality of identical lenses mounted on the
triplet, it is obvious that many combinations of
periphery of a lens wheel, said identical lenses
elements and varieties of glass may be used in
each having its principal focus at a common cen
designing and constructing a lens’ system which
ter on the axis of said lens wheel, the ratio of the
may possess, either in its entirety or in groups
radii of curvature of the refracting surfaces of
of its elements, the optical symmetry with re
each of said identical lenses determining a lens
spect to a radius R and a point ii on the optical
bent around said common center, and a multiple
axis exterior to the system, and the optical sym
metry with respect to a point F on the optical 50 element stationary front component wherein the
ratios of the radii of curvature of the refracting
axis within the system, which is the basic dis
surfaces determine a. front component bent to
closure of this application. A triplet, such as I
radius B, said radius B being equal to the focal
have described, used alone makes a most satis
length of each of said identical lenses mounted
factory telescope objective or a long focus photo
graphic objective. A pair of these triplets sult- 65 on the periphery of said lens Wheel.
ably spaced and provided with a centrally lo
cated diaphragm (Fig. 4) makes an excellent
ARTHUR J. HOLMAN.
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