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Патент USA US2107305

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55 H:
Feb. s, 193s.
K. N. OGL.:'l
Filed March'z, 1934
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Feb. 8, 1938.
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Feb. s, 193s.-
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Filed March 2, 1954
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Patented Feb. 8, 1938
2,107,305 '
- _
Y Kenneth
N. Ogle, Hanover,
LENSN. .11.; assignor to
Trustees o! Dartmouth Collega, Hanover, N. H.,
`_a corporation ol New
Application March z, 1934, serial No. 713,701»
'I'he presentv invention deals with the problem
of adjustably changing the size and/or shapej of
an optical image without' substantially, affecting
(Cl. 88-20)
, ’ Although such a device is of great importance
for the above discussed purpose, it is evident that
it is equally useful for diiïerent purposes involv
ing similar 'optical problems, as for example, for
exercising eyes. and it is therefore one of the
principal objects of the present invention to pro
videvq-` an optical device which permits the con
tinuousV adjustment of the magnitude or size
other characteristics of the optical system in
5 question, as especially the distance between ob
ject 'and image. This problem may arise in vari
ous branches of the optical‘art, but it is of par
tisular importance in connection with the test
ing and compensating of certain abnormal con ` and/or shape of an optical image, without sub
' v10 ditions of the human visual mechanism involv
stantial change of its position in space, that is, 10
ing the relative size and shape of the ocular i a lens system that permits gradual changes of
images of the two eyes. This subject matteris image magnitude while its optical power is not
discussed and explained at length 'in the Patent substantially affected by such changes.
Other objects are to provide such a device
No, 1,944,871 to Adelbert Ames, Jr. and Gordon
which can be conveniently operated, is compar 15
15, H. Gliddon, entitled “Clinical optical mensura
tion method and instruments”, of January 30, atively inexpensive, and permits rapid continu
1934, and the Patent No. 1,933,578 to the same ous adjustment of image size, and the exact de
inventors, entitled “Eyeglasses for correcting termination of that adjustment in a simple and
retinal image asymmetry”, of November 7, 1933, convenient manner. In another aspect, the in
0 and in a number of publications in scientific vention provides a novel composite lens system 20
periodicals, as for example in “The Journal of which changes the size of an optical image, with
the Optical Society of America”, vol. 22, pages ` out substantially aiïecting 'the distance of the
538 et seq.
image from a fixed point. A further feature of
As explained in the above-identi'ñed patent for lthe invention is such a lens system that permits
the variation of the change in magnitude with
25 “Clinical optical mensuration method,` and in
struments”, tests of patients who are examined out change fof power, by varying the separation
with the aidv of this instrument.` or of `instru
ments serving similar purposes, comprise the
measurement and compensation of the above
30 mentioned size discrepancies of the ocular
images with the aid oi’ lenses compensating this
defect. Heretofore, the magnitudes of these dif
ferences in size of the ocular images of patients
`were 'clinically determined with the aid of sets
of certain elementsof the system. Still another
object is -the continuous variation of the change
of image magnitude within a comparatively wide
range by continuously varying the lens separa 30
~tion of a composite optical system, and means
for varying the separation in a convenient, ex
act, and eiiicient manner, which means also per
mits the easy and yet reliable determination of
before one eye or both eyes, equalize the ocular
images of the eyes. Such a set of lenses consists
the prevailing change in magniñcation.
These and other aspects and objects of my in
vention will be apparent from the following ex
ci a .series of lenses of the general type described
in the above-identified Patent No. 1,933,578,
n@ made in med steps of _magniiicatiom over-all or
planation of its genus with reference to -a prac
tical application ’thereof to a device for testing
Veyes for ocular image discrepancies. The de 40
35 of lenses, by iinding those lenses which, if placed
scription refers to drawings in which:
`lFigs. 1 and 2 are diagrams showing relations
For continued practical use, such lens sets in
voire certain disadvantages, among which is the -for calculating a lens combination according to
' comparatively high cost oi a set of a necessarily
.is great number'- of lenses and the inconvenience
of nxed steps, which not only often necessitates
, a frequent change of ,test lenses primarily based
on gueœwork, with the consequent interruptions
and the prolongation of the test operations, but
5o may also impair to some extent the exactitude of
the examination. Experience has shown that it
is very desirable to have a device with which it
is possible to attain a continuous change in the
image size oi' an eye, and preferably of each
the inventiom'
l ,
Fig. 3 is a diagram indicating theoretical func
tional relationships between certain character
istics of the lens system according to the pres
ent invention; A
Fig. 4 is a diagram similar to ll'ig.l 1 showing
the arrangement of an embodiment of the ín 50
given ñnite distance, over the entire ñeld of vis
Figs. 5 to 11 are diagrams giving the typical
optical data of a set of lens. systems according
to the invention;
Figs. 12 and 13 are plan and frontelevations, 55
respectively, of the mounting for an embodiment
ion as well as on any meridian.
of the invention;
55 eye over a wide range of magnification for a
It is also de
sirable that such a device should be adapted for-
control not only by the operator, but alëQ by the
co patient.
Fig. 12u is a diagram explaining the use of an
instrument according to the invention for in
Vestigating ocular image discrepancies; and
2, 107,805
be considered, which, at a certain separation,
does not affect the position of the image of the
object' relative to the eye, but does (or in certain
instances ymay not) affect the size of the image
relative to that of the object. The virtual image ci
Figs. 14, 15 and 16 are plan, fronteievation,
and side elevation, respectively, of a' modification
of the mounting shown in Figs. 11 and 12.
'I'he embodiment of the invention now to be
ci described is suited for use in a device for testing
eyes, as for example described in copending ap
- produced by such a lens system, which may be
designated as “terrascopic”, must be upright and
plication Serial No. 706,523, filed January 13,
1934, which permits the simultaneous determina
tion of dimensional image defects whichmay be
at the same distance from N as the object, but
its size or magnitude may vary from that of the
object itself. A lens system which is terrascopic, 10
i. e., which produces a virtual image of an object
uniformly over-all, _or meridionally symmetrical,
or unsymmetrical (all these defects being shortly
referred to' as size and/or shape defects), and
_ that is situated at the same position in space as
which may be conveniently manipulated by the
clinician or the patient who is being examined.
Generally speaking, a lens system according
- to the invention and conforming to the above
described requirements has lens components
whose separation is variable and determinable,
and which components are so dimensioned and
20 arranged that, upon changing their separation,
the virtual image of an object as seen there
through does not substantially change its posi
tion relative „to the observer, but does change its
size according to the prevailing separation.
It should be observed in this connection that
the Galilean telescope, which also involves lens ~-
elements with adjustable separialtion,` isf’funda
mentally distinct'from the system according to
the present invention.
The Galilean telescope
the object is said to have zero vergence power,
that is, Q=0, since p=q. The properties of ter
rascopic systems are in most respects analogous
to those of ltelescopic ones, with the main differ
ence that, in a terrascopic system, object and
image are at a finite distance instead of at an
infinite distance as in the case of telescopic sys
For a given distance of the object field from
the eye,_ assuming two thin lens elements, and
referring to Fig. 2 where L1 and La are lenses
with focal lengths f1 and fz, respectively, S _is
the separation of the lenses, d'the distance of the
object O from the farthest lens element of the
systems-and e `the distance of that lens element
from the point N, the following relation exists
between the focal lengths of a terrascopic sys
provides substantially constant magnification
with changing power, its changes in separation
having the purpose of varying the focal distance
in order lto adjust the instrument for different
35 distances of the object which is observed, where
as the present system provides for changing mag
nification with substantially constant power, its
separation changes having the purpose of vary
ing the magnification for a given object distance.
The properties of the lens system will be con
veniently referred tovsome point N, which de
This equation isof the second degree in 'S, the
separation, and therefore if the values f1, fz and _d
are fixed, there are in general, two separations
S1 and S2 for which the lens combination is exact
ly terrascopic as above defined. At any other
separation, the system is not strictly terrascopic,
that is, it will not fulfill the previously formulated 40
requirement of unchanged relative position of
pending upon _circumstances might be taken. as 'virtual image and object, but changed magnifi
the mean nodal point or the entrance pupil of cation.
The possibility of obtaining a system of the
the eye or as a point in the lens system itself. In
Fig. 1, as the example, N is taken as the mean desired properties arises from the fact that Equa
nodal point of an average eye which looks at tion (1) is a continuous function in S. It was
an object 0 through the lens system L. The ob
found that the vergence power of the lens system
ject distance designated by p, the image dis.
under discussion, as a function of S, the separa
tance designated by q, and the distance of the tion, is represented in a general way by the para
lens component farthest from the object desig
bolic type curve shown in Fig. 3, in which ver
nated by b will all be measured from the point gence powers Q are .plotted over lens separations
S, and where the two strictly terrascopic solu
of reference N. The quantity
tions Si and S2 are indicated. The position of
the curve relative to the system of reference and
the solutions S1 and S2 are determined by the
will be defined as the vergence power of the lens
system relative to the point N, when p and iq
are measured in meters. The visual angles sub
values of f1 and f2.
tended at the point N by corresponding points
vergence power Q for changes in S was found
to be:
60 of the object O and the image I are designated
By means of a general equation, the relation
between fi, d and S for the minimum change in the
by a and ß. The angular magnification of the
system relative to the point N will then be ex
pressed as the ratio
or in per cent magnification
m%=.(M-1) X100
It will be understood that value M determines
the size, extension or spatial quality of the image,
or elementary images, of a given object, herein
also referred to as “magnitude”.
Assuming that it is desired (as for example in
. the embodiment herein described inA detail) to 65
The characteristics of a lens system will ílrSt
have a system which is substantially terrascopic
over a certain range of separations, and exactly
terrascopic for one separation S’ within this
range, this system will at separation S’ conform
to equation (1). Combining the Equations (1)
and (2) we obtain the values of the focal lengths
of the two components of an adjustable system
which will have a minimum change of vergence
power with change in'separation for a given
range, and will have exactly zero vergence power 75
('e. g.. be terrascopic) at the separation S' within
that range, namely:
ances indicated at ,-i-t` and -t of Fig. '3, within
which changing separations effect only such
power changes that can be tolerated as. harmless
for any particular purpose of. the device. It will
now be evident that either the entire curve shown ,
in Fig. 3, with >both terrascopic points, can be
utilized, or only a portion covering the range 1'
including ~one strictly terrascopic point S2, which
latter possibility has been discussed above for .
If 4f1 and f2 are chosen according to these
formulae, the vergence power curve as a function
of S is tangent at the point S', and gives the
optimum condition for a substantially terra
scopic system. This curve for optimum terra
`scopy is indicated in dotted lines in Fig. 3.
The magnification, as defined above, produced
by such a system at any separation S is given by
optimum point S’ and is made use of in the
practical embodiment described hereinafter,
whose power-separation relation is shown in
Fig. 7. In this figure, point S" corresponds to
point Sz of Fig.- 3, and the 10 mm. separation
range of Fig. 'l corresponds to range r of Fig. 3, 15
the power tolerance in this case being +0.10 di
opter. An example of the magnitude of such
limits Will be given below when describing a
specific set of lenses for an eye testing instru
ment according to Patent No. 1,944,871, which 20
permits measurements involving ocular image~
size changes of substantially equal magnitude at
reading distances and when looking at greater
This elementary theory treats only with thin 25
lenses, as initially assumed. If the lens thick
nesses are included, the distance b will specify
the distance of the second principal plane of. the
For example, the characteristics of such a. thin
lens system to be used for an object distance
p=400 mm., with the posterior lens a distance » second or eye lens from -the mean nodal point of
30 11:30 mm. from the mean nodal point of the eye, the eye. The separation .symbol S (compare 30
a separation range of the elements from zero to Fig. 4) Will indicate the separation between the
l0_ mm., and a strictly terrascopic separation of - second principal plane of the'first lens and the
S'=5 mm. are as follows:
ñrst principal plane of the second lens. The
separation S will then be less limited by the/
Í1=182.500 mm.
F1==5A795 diopters
f2: - 182.466 mm.
F2=--5A805 diopters
first principal plane of the second lens can over
0. 00
--0. 0008
5. 63
lap, that is, pass through each other' and separate
negatively as the separation of the actual lenses
is decreased. A negative separation would then
give a diminution of the dioptric image.
0.0130 ’
This range of magniñcation is very satisfactory
45 for the requirements of testing and compensat
` ing errors'in the relative size and shape of. the
ocular images of the two eyes, and, vas evidenced
by the power values in the last column of the
above table, the system is substantially terra
scoplc overthe separations used. The change in
magnification with change in S is substantially
linear, which fact is of great convenience in the
design of thedevice. 'It will also be understood
that the same procedure can be applied to an
adjustable size lens system required to have a
substantially constant vergence power, `with
changes in magniñcation as the separation of
vthe elements is changed, whereas the relative
positions of object and image remain unchanged.
60 Itshould be noted that for a given visual dis
tance p, if the separation is to be uniquely .and
substantially terrascopic within certain separa
tions, themagniflcation change is automatically
The values of the curves of the lenses as actu
ally used can be determined uniquely, provided
the optical thicknesses of the lenses are specified
This is easily done, for the optical thickness (e)
of the lenses will be approximately:
„For large visual‘dis'tances, as for example an
inlìniteV distance (as represented by approxi
mately 6 m.), `the range of magniñcation of a
substantially true-terrascopic system -according
to the above theory would be too small. For
such distances, an >approximately terrascopic
system having certainoptical powers within pre
determined permissible limits, and being strictly
terrascopic for one point within these limits can
be used.`
" '
¿ These limits may be defined‘ïby certain toler
where t1 and ’tz are the thicknesses of the objec-~
tive and ocular lenses respectively.
If it is known that the powers of the system
will remain within'desired limits, for a given
range of magniiications, `the constants of the
individual lenses can be found directly.- The
conditions for the determination of the-device
when the magniflcations are to be specified for
a given >object distance p from the eye, and the
near lens at a given distance b from the eye
(compare Fig. 4)-, are:
It may, for
example, be made negative when the actual
lenses are in contact, if the first and second
lenses (or lens systems), are so designed that the
second principal plane of the first lens and the
Ata sepe-I Magniñca Vergence
ration of
» physical properties of the system.
(1) At a separation So of the interior principal
planes (lenses in contact), the device is to have
a magnification Mo; and
(2) At a separation S of the interior principal
planes, where S=So-|-a, where a ls the change in
separation as compared with Su, the device is to 70
have a_ magnification of M, and zero vergence
power (condition of terrascopy).
Thus, three conditions, namely for Mn. M, a,
are specified for finding the three' optical con
stants of the system, viz: 1p1.. «p'z and S (orîSn), 75
The lens curvatures so obtained would prob-`
where qu and «p2 are the true powers of the two
elements, respectively. For paraxial rays the
value of S can be found from:
ably require tools not now in commercial use. In
order to utilize tools already on hand, the ap
proximate powers «p1 and :pz (or F1 and Fz) may
be obtained from the elementary theory, and the
Mrp-(p-b) (_Q-»bimen
final curves for the lenses found by simple par
axial ray tracing using trial and error.
saLÍbQAMm-(pîbM) (p-b-e+.1)+
Lenses of the vtype of the embodiment herein '
more specifically described, namely test lenses for
imp-rafle] -l-AZM
use with instruments for determining ocular im
age disparities, were designed to_conform to the
following conditions, whereby 'it is understood
_._ M- 1
that other uses of the new lens system will requir
other conditions:
. k0-
9- p_,l
ration lens systems are employed, one for over
- all and one for meridional, image size changes,
(l) Due to the facts that two-` variable sepa
`_ Mo-i
and that other corrective elements must be placed
in front of the eyes, the available space is limited.
TheV separation of the inner surfaces of the ele 20
ments of 'each lens system is therefore given, and
in the present embodiment assumed to be ap
which is usually about 1.3 to 2.0 mm.
Solving this equation for S, for example by proximately 10 mm.
(2) In accordance with the image size differ
Horner’s method, one can then find ci, and «pz by
ences which actually occur in binocular vision, 25
the image magnification should for convenience
' be4 continuously variable through differences of
and e is the total optical thickness of the lenses,
about 5%, as for example, approximately be
tween -1v% and -|-4% of any linear dimension
as seen without the lens system.
l(3) The vergence power for all separations,
If the lens surfaces are denoted by-their focal v and for all visualization distances (that is in
powers F1, F2, F3 and F4 as indicated in Fig. 2,
two of them must be known, that is, specified in
actual practice for 40 cm. and 6 m.) should be
a minimum, preferably below the threshold dif
ference of power sensitivity, that is, less th
35 order to solve for any of the actual surfaces.
Thisis usually the desirable thing to do.
0.12 diopter.
If Fa and F3 are specified (in the design given
below as an example, F2=-F3) the procedure is
as follows:
(4) It is in many cases desirable to grind the
lens surfaces with tools used by the optical
manufacturers for making conventional lenses,
and the present example is designed with this
condition in view, although it may in other cases
be desirable to provide specially made tools. In
that latter case, since no regard has to,be given
to tools, more leniency is given the designer.
(5) 'I'he distortion should be a minimum, so',_
(1) Find C: by: _
far as compatible with condition (2).
(6) The device should permit the reading of
magniñcations on the same scale for all visuali
. zation distance.
(7) Means for continuously changing the over~
all magnification as» well as for changing the
magnification in any single meridian must be
provided, both complying with the preceding con- '
It was found that in order to accomplish these 55
(2) Find C1 by:
objectives it is advantageous to use'for each _eye
four variable separation lens pairs, two giving
over-all magnification for near and distant
vision, respectively, and two giving meridional
magnification also for near and distant vision,
respectively, in a set up schematically shown for
one eye and one distance in Fig. 4.
(4) Find F4 from:
I and 2, and C,the spherical system with lenses
3 and 4'. The lens arrangement Vis quite similar
for near and distant vision. The approximate
lens distances from the eye, suitable for purposes
of the instrument, are given in millimeters, in
relation to the mean nodal point N of the 'eye
E. It is ofcourse understood that a'similar 70'
(5) Find t1 and t2 from:
arrangement is used with each eye, so that a
complete variable size lens equipment for a clini- ^
The characteristics of the system can. -be found
cal instrument of the type-,referred to comprises
two lens sets (one set for the-right and one for
by simple ray tracing through the system for
75 several separations.
In this
ñgure, A is the cylindrical system with lenses
Vthe left eye), each set- having two lens groups 75
(a spherical vlens group anda cylindrical lens
group), each group having two'lens pairs (one
The unusual mounting of the lenses as though
bent convex to the eye produces for increasing
adjustable separation.
separation slightly increasing pincushion distor
stantial change in power. In Figs. 5, 6 and 8 to
11 the curvatures are given in diopters and the
lens thickness in mm, the refractory index being
tion. This distortion is unimportant for the use
in the eye testing instrument above referred to,
since the device is used for a finite peripheral
angle. The device is calibrated for that angle so
that the magnification of the image for that angle
is known for any given separation.
It should further be observed that the lens sys
n=l.523. In Fig. 5, IOI and |02 are the spheri- . tems according to the invention are not neces
cal lens elements of the system for distant vision, sarily without power, that is true power as defined 15
and in Fig. 6, I 03 and |04 are the spherical ele » by parallel incident lightrit is only necessary
that the vergence power does not appreciably
ments for near vision. Fig. 7 indicates the rela
vary with the changing magnification when the
tion between the separation S. in mm, the mag
niiication in per cent, andthe vergence power in separation is varied. Such constant power can
diopters, for the lens systems according to Figs.> be eliminated, if required, by means _of lenses 20
5 and 6. It will be observed from Fig. 7,'that the of opposite power combined with the instrument
range of magni?cation is practically the same according to the invention. It will be evident
that in this case there is no truly terrascopic
for near and distant vision, that there is practi
point within the whole range of lens element
cally no change in vergence power over the en
tire magnification range `for near vision, that separation, but a point which strictly gives a 25
the magniilcations vary linearly within the range certain speciiied pf‘wer or separation of virtual
of -l to +4%, and that the power at distant image and object, whereas the other separations
vision is within the range of :0.1 diopter, which produce varying magniflcations with a `negligible
was found practically to be near the threshold power variation within a certain tolerance.
Figs. 12, ‘12ß and 13 show the mechanical ar
of power sensitivity for the eye.
rangement of the device as it may be incorpo
' Figs. 8, 9, 10, and 11 indicate in a similar man
ner the data of practical lens. pairs for image rated in a clinical instrument similar to that of
the above-mentioned copending application Serial
size changes in‘one meridian, and Vzero per cent
magnification in the meridian at right angles. No. 706,523, one such device being provided for
Figs. 8 and 9 relate to the system for distant each eye. In Figs. 2 and 12B, these mechanical
vision andy give the dimensions in two meridians, details are schematically shownin order to indi
e. g., at 90° and 180°, respectively. Figs. 10 and cate their function in correlation with the opti
.11 similarly supply the data of the lens pairs for
near vision. The relation between Ilens element
40 separation, power, and magniñcation are in the
90° meridian, >which is the one effective for image
magnification, quite similar to those depicted in
Fig. 7.
Whereas the lens combinations for over-all
above-mentioned Patent No. 1,944,871. The pow
er of each of the lenses is left unchanged by the
lens pair for distant vision and one lens pair for
near vision) and each pair comprising a negative
and a positive lens element with continuously
Figs. 5 and 6 show diagrammatically the opti
Vcaldata of the spherical lens pairs for near and
distant vision, respectively, of a s_et of practical
lenses for over-all magniñcation Without sub
size changes require only spherical surfaces, the
meridional magnification systems were found to
cal system for varying the image magnification
without substantially varying the vergence power.
In Figs. 12 and 13, I I is a lens support plate which 40
has a flange I2 for a semi-transparent reflector
and extends into a rod I3 forming a track forl
certain eye testing devices. The plate II extends
into a lens block It supporting two ñxed lens»
holders I5 and I6 and having two grooves I7 45
and I8 guiding adjustable lens supports Il' and
demand double toric lens elements, as shown in - i8’.
Figs. 8 toll. Single piece double toric lenses
Fixed to one side of the lens block I4 are two
would be preferable,Y but since such lenses can at
pinion sleeves 2l and 22 with indicator discs 23
and 20, respectively.` In these sleeves are jour 50
naled shafts 25 and 26 with pinions 21 and 23,
respectively, located within grooves I1 ‘and i8, re
spectively, the shafts being fastened at their
.the present time not be ground with ordinary
means, the lenses are preferably spl/itinto two
`~single toric elements, with "identical inner sur:
fä'ê‘sïwlîi'cliwäïëmtlfiëñwdëiïìented together with
these surfaces in properly aligned position. Some
other ends to manipulating elements 3l . and 32
with knurled knobs 33 and 34 and scale .discs 35 55
diiiiculty was encountered in laying out a sys
tem for near vision with zero per cent magniii if and 30. Knobs and scale discs are preferably
cation in one meridian in order to adhere to tools ‘fastened to the shafts with separate means, for
ordinarily available. The 'near lens combination example, the set screws shown in Fig. 12, for the
purpose of preventing disadjustment of the scales
shown in Figs. 10 and l1 is, however, quite satis
in case the knob should be turned forcibly after
60 factory, having in the 180° meridian zero per
cent magnification with a power oi' approximate
ly 0.05 diopter, which' is negligibly small.
In the actual design of these lenses the initial
magnification, that is, the magniñcation of the
65 device when the .lenses are in contact was speci
fied to be --1%, that is M=0.99. In order to
accomplish this, the lenses making up the indi
, vidual components were schematically bent con
vex to the eye, sutilciently so that the interior
70 principal planes of the two `elements crossed,
that is, the optical separation became negative,
. until,-when the lenses were in contactthe mag
the lens supports are-,stopped in ultimate posi
tion. Racks di and 42 are fastened to lens sup
ports il’ and I8', respectively, and mesh with
pinions 2li and 26. The distances between hold
ers I 5 and I6 and supports I‘l’ and I8', respec
tively, can therefore be gradually and continu
ously changed by turning knobs 33 and 34, re
spectively. The scale discs 35 and 36 rotate-in
contact with indicator discs 23 and 24, respec
tively, the discs being suitably graduated to per 70
mit direct reading of percentual magniiications
corresponding to certain separations betweenthe
lens elements in holders I5 and I6 and supports
lenses` to accomplish a combined ,power and size . Il’ and I 8', respectively. ìIt will be evident that
change effect is. for example. described in the one revolution of the pinions and of the scale 75
niñcation was 0.99., This bending or cupping of
discs corresponds approximately to the maximum
lens separation of about 10 mm.
The lens holders are semi-circular and grooved
to receive the mountings of lens elements 50,
5 which, in the case of cylindrical lenses, may be
provided witl_1_I_iiairrigllesdopnojllîher ins'tîuh'ientalities
are obtainable by suitably operating arrange
ments similar to that shown in Figs. 14 to 16, in
a manner which will now be yevident without
further explanation.
While the herein described apparatus _and its 5
operation conform to a most frequently applied
clinical test, it will be evident that the new ad-v
‘ the visualu?ieridian with respectmto which they> > vice can be advantageously employed with dif
`_spp_întended t'ó‘effèîtïñïage size changes. In
10 “the present embodiment, holders |5 and'“|6""are
shown with double grooves, one groove being pro
vided for other trial lenses.
'I‘he new lens combination is also very well
suited for bringing about or correcting asymmet
15 rical image distortions in the following manner.
It is evident from the foregoing theoretical dis
cussion that, since a change of the lens element
ferent mounting and adjusting arrangements,
and for different purposes involving continuous
changes of image size.
It should be understood that the present dis
closure is for the purpose of illustration only,
and that this invention includes all modifications
and equivalents which fall within the scope of the 15
appended claims.
I claim:
separation influences the magnification but not
1. An optical system of the type described
l the power, an inclination of the lens planes (that
comprising towards the object _a positive lens -
having a focal length of approximately one-half 20
the principal planes of the lens elements) causes its interval from said object, and a negative back
a magnißßäiign
realises .._asimmßßrîß2L,1,,1Y,l lens having a focal length of approximately the
e image plane,_ whose
position, however.; distance between said object and said back lens
multiplied by the difference of said interval and
25 l;
not Substantial?.
clîäîîaëtëîlstms of the lens system. Mu- ` the separation of said two lenses, and divided by 25
said interval.
„Milaeline-Hogg.ilieimlenselenie?te pfiîalees twice
2‘. An optical system according to claim 1 fur
pair can 'lîëlîrmight about by various means'fbut'
the one shown in Figs. 1 to 16 is especially suited ther characterized by a separation giving a pre
for this purpose, since it permits mutual lens ele-` determined optical power of said system for said
30 ment inclination without change of the mean dis-_ distance between front lens and eye.
3. An optical system according to claim 1 fur
tance between inclined lens and eye.
Figs. 14, 15, and 16 show a lens holder 5| which ther characterized by a separation imparting to
may be permanently fixed to lens block I4 or said system, for said distance between front lens
20 is, different distances betweenvcoaxial points of
detachably fastened thereto by means of pins 52,
35 53 extending from pad 54 and fitting into holes
55, 56 of block I4 (Fig. 13). A pivot support 6|
sliding with a dovetail arc 62 in holder 5|, has a
journal boss 63 with a journal bore 64. A lens
support 1| is provided with a circular disc 12
40 and a pivot pin 13, disc 12 resting against boss
63 and being retained in position by pin 13 which
may be secured in hole 64 with a nut 14 or by
other suitable means. Disc 12 has a scale 16
permitting the operator to read the angular move
45 ment of journaled support 1|, with the aid of
index mark 11 on journal boss 63. Lenses can
be inserted in support 1| which has a groove
similar to that of holder Iiiv (Fig. 13). It will
now be evident that this arrangement permits the
rotation of lens element 50 about pivot 13, as in
and eye, the optical vergence power zero.
4. An optical system according to claim 1 fur 35
ther characterized in that for separations vary
ing within a certain range, the optical vergence
power of said system varies within predetermined
'limits of tolerance.
5i. An optical system of the type described com 40
prising towards the object a. positive front lens
having a focal length of approximately one-half
its distance from said object, and a negative back
lens having a focal length of approximately one
half its distance from. the object multiplied by
the quantity one minus the separation of saidtwo lenses divided by said distance of the front
lens from the object.
61. A device of the type described comprising
an optical system including two lens elements 50
dicated in Fig. 14 with dotted lines. The axis of
substantially equivalent toa thin positive lens
pivot 13 again may be brought into different an
gular positions by rotating dovetail arc 62 in
holder 5|. This movement can be evaluated by
55 means of a scale 18 and index 19 on parts 6|
and 5|, respectively. It is further evident that
having a focal length of approximately one-half
its interval from the object to be observed com
bined with a thin negative lens having a focal
length of approximately the distance between
said object and said negative lens multiplied with
the difference of said interval and the separation
of said two lenses and divided by twice said inter
val, the optical vergence power of said optical
suitable means, as for example set screws, can>
be arranged for arresting members 6| and 1| in
~any given position relatively to holder- 5|.
When using the new lens combinations in the
embodiment described, the patient’s head 'is fixed
in relation to the instrument, and lens elements
for near vision are inserted in the holders. The
clinician then adjusts the lenses by turning knobs
65 33 and “and the corresponding knobs _f_or the
other eye, and by turning the lens mounts of the
meridional or cylindrical lenses in their holders,
until the test means appear as required, for ex
l ampie, as described in one of the aforementioned
70 patents. The image magnitude changescan be
directly read on scale discs 35, 36 and the pa
tient’s defects determined accordingly. The
lenses for near vision- are then exchanged for
those for distant vision, and the test repeated at
76 distant vision. Asymmetric image size changes
system varying Within predetermined limits of
tolerance for separations of said -lens elements
varying within a certain range, and means for
changing said separation.
7. A device of the character described for test
ing or exercising ocular defects involving the 65
magnification of an ocular imageof a test object
observed at a given distance from the eyes. com
prising a lens support, means for holding sepa
rate test lens elements arranged .on said support
for adjustment relatively to each other in align 70
ment for observation of said test object through
such lens elements, a lens system having two
lens elements. each mounted on respective ones
of said holding means and each formed of lens
medium of a given index of refraction and hav- 75 `
ing surface powers computed according to said
indices and according to the spaced relation of
said elements. with the surfaces of'each- of said
elements being dependent, upon the other, said
object distance and the distance of said system
from the eye, to produce at certain values of
separation, within the range of said adjustment
ranged on said support before one eye for ad- «
justment relative to eachother in alignment for
`observation of said test object means through
such lens elements, and a lens system having two
lens elements each mounted on respective ones
of said holding means and each formed of lens
medium of a given index of refraction and hav
of said holding means on said support, varying ing surface powers computed according to said
magniñcations of said Ocular imageI while main
indices and according to the spaced relation of
taining the vergence power of said system within said elements, with the surfaces of each of said
physiologically4 substantially ineiIective limits, elements being dependent upon the other, said 10
and means operatively associated with said hold
object distance and the distance of said system
ing means for indicating the amount of said ocu
from the eye, to produce at certain values of
lar image magnification corresponding to said separation, within the range of said adjustment
15 separation values.
of said holding means on said support, varying
8. A device of the character described for test
sizes of said ocular image while maintaining the
ing or exercising ocular defects` involving the. vergence power of said system within physiolog
magniiication of an ocular image, comprising test ically substantially ineffective limits, and means
object means, a lens support, means for holding operatively associated _with said holding means
20 >separate test lens elements arranged on said sup
for indicating said ocular image size relation cor 20
port before one eye for adjustment relative to responding to said separation values. ,
each other in alignment for observation of said
10. A device of the character described for test
test object means through such lens elements, ing defects of binocular vision involving the
means substantially determining the distance of measurement of the size of one ocular image of
‘ said support from said test object, a lens system
having two lens elements each mounted on re
spective ones oi’ said holding means and each
formed of lens medium of a given index of re
fraction and having surface powers computed
30 according to said >indices and according to a given
separation of said elements, with the surfaces of
each of said elements being- dependent upon the
other, said object distance, said given separation,
and the distance of said» system from the "eye, to
produce at certain valuesof separation within the
range of adjustment of said holding means on
said support and including said given separation,
varying magniñcations of said ocular image while
maintaining the vergence power of said system
within physiologically substantially ineffective
limits, and means opera‘tively associated with said
given test object means at a given distance from 25
the eyes, in relation to the other ocular image
of said test object means, comprising a lens sup
port, means for holding separate test lens ele
ments arranged on said support before one eye
for adjustment relative to each other in align
ment for observation of said test object means
through such lens elements, and a lens system
having a negative and a positive lens element
each mounted on respective ones of said holding
means and each formed of lens medium of a given
index of refraction and having surface power's
computed according to said indices and accord
lng to the spaced relation of said elements, with
the surfaces of each of said elements being de
pendent upon the other, said object distance and 40
the distance of said system from the eye, to pro
holding means for indicating the amount of said f duce at certain values of separation, within the
ocular image magnification corresponding to said _range of said adjustment of said holding means ,_
separation values.
on said support, varying sizes of said ocular im- '
9. A device'of the character described for test
age while maintaining the vergence power of said
ing defects of binocular vision involving the meas
urement of the size of one ocular image of given
test object means ata given distance from the
eyes, in relation to the other ocular image of said
test object means, comprising a lens support,
means for holding separate test lens elements ar
1" c
system within physiologically substantially inef
fective limits, and means operatively associated
with said holding means for indicating Vthe
amount of said ocular image size relation corr spending to said separation values.
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