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Патент USA US3089408

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May 14, 1963
Filed July 12, 1960
Patented May 14, 1963
With ~a -single supplementary -system provided in front
Karl Heinz Wilms, (lberkochen, Wurttemberg, Germany,
of the objective on the image side, the picture scale of
the camera can be increased by the ‘factor
assignor to Carl Zeiss, Oberltochen, Wurttemberg, Ger
Filed July l2, 1960, Ser. No. 42,260
Claims priority, application Germany July Z1, 1959
In this equation f is the focal length of the system and
a is the distance of the main point of the system on the
side of the object from the location of the image car
rier which the same occupies in the axially shiftable por
The invention relates to an ophthalmic camera par
tion of the retina photographing camera without a sup
4 Claims. (Cl. 95--11)
t-icularly tor photographing the retina of the human eye,
plementary system.
and in which is employed a photographic objective with
The employment of the negative system in the movable
two lenses or lens groups. The objective is designed and
portion of the camera will shift the location of the image
arranged in such a manner that the image of the pupil of
carrier a ldistance s in the direction of the light exit. The
the eye which is produced by the front system coincides 15
with the focal point of the rear system.
With such a
value of s is
photographic `objective is produced a parallel ray image
beam. This permits the solution of the problem of re
taining the relation between any :optical tangle and the cor
responding lateral distance on a light-sensitive layer inde 20
pendently of the deticiency of sight of the eye to be
These two equations Agive the ‘following results:
f n lc - l
It is often ydesirable to change the picture scale of the
photographic objective and .in particular Ato increase same.
For this purpose a supplementary lens is generally used
a: .g
which is placed in front of the objective unless, of course,
one prefers to replace the entire objective by another
Therefore, the supplementary system will maintain
one. Such a supplementary lens cannot be used in the
the relations between a and fand can be mounted into a
present case owing to the reflections yon the supplemen
readily exchangeable connecting tube which can be posi
tary lens, and also because the attachment of such a sup
tioned in the slidable portion `of the camera in iront of
plementary lens would displace the image of the pupil
produced by the ‘front »system of the objective trom the
focal point of the rear system. This wil-l nullify the in
the image carrier.
kIn a camera for photographing a retina with a picture
scale of 2.5 :and a picture angle of 30°, an area of ap
dependence of the relation between the optical angle and
proximately 22.5 millimeter diameter will be photo
the lateral ldistance from the sight deficiency of the eye to 35 graphed upon an image area of 24 X 36 millimeters. A
be photographed.
supplementary system lwith an ampliiìcation factor of
The above mentioned independence can be maintained,
vk=l.8 will increase the picture scale to 1:4.5 . When two
however, even in case the picture scale is changed when,
like supplementary systems are arranged one after an
according to the present invention, a negative lens sys
40 other, Aa picture scale «of 1:8 will be obtained. The chro
tem or a groupv of such lens system is provided on the
image side of the photographic objective and is rigidly
coupled with the axially shiftable image receiving cas
matic error of the -eye to be photographed remains cor
rected or compensated even when these supplementary
systems :are used. Any originally existing curvature of
the image area and of an astigmatism connected here
Tlie operation of such a dispersing lens or lgroup of 45 with will be practically removed by the introduction of
lenses in a telecentric system of a photographic objec
such negative systems.
tive is as follows:
A ‘camera for photographing the retina consists gen
The picture scale of the supplementary system depends
erally of a stationary camera portion containing the col
only -upon the distance of said system from the image car
lecting objective elements and a camera portion movable
rier «and upon the divergence of the light beam emerging 50 in axial direction relative to said stationary portion and
from the side of the image. The distance between the
containing the image receiver, ie. the iilm cassette. The
image carrier «and the `dispersing system will be kept con
lconnecting element which in accordance with the present
stant by the rigid coupling of the same with one another.
invention contains the supplementary negative lens mem
Since, furthermore, the angle of incidence in the tele
bers slide-s in 4a tubular extension :arranged on the sta
centric system determining the divergence of said light 55 tionary camera portion and is lixedly connected on its
beam emerging from the image side remains the same,
other end with a tubular extension -on the oassette.
the divergence `of the angle of emergence and thus the
ln case the movable camera portion contains a mirror
reflex arrangement, the tubular connection elements which
picture scale of the supplementary system will remain` con
contain the negative systems will be inserted behind the
fstant when >an axial displacement of the image carrier
together with the supplementary system becomes neces 60 mirror and are ñxedly connected to two tubular extensions
on the mirror reiiex arrangement on one hand and on the
sary, because the optical system of the eye to be photo
cassette on the other hand. They will then follow to
graphcd has .a power tof refraction which is diiierent from
gether with the cassette the movements of the entire mirror
that of the previously photographed eye, or the sight
reilex arrangement.
deficiencies and the axial `diameters of th'e eyes are dif
The present invention will now be described in detail
in the accompanying drawing which illustrates an embodi
The tangle of emergency ean be further increased by
ment of a camera for photographing the retina of a hu
an «additional supplementary dispersing system or «a plu
man eye.
rality of systems disposed at a ñxed distance from the
The axial movement `of such a combination
The stationary portion of the camera consists of a sub
change the divergence angles of the light beam emerging
trom each single system.
movable camera portion 2 is slidably arranged. The ad
first one.
in the parallel light beam incident `from the object will not 70 stantially cylindrical housing l provided with a tubular
extension 1’ upon which a tubular extension 2’ of the
justment of the movable camera portion is effected by a
rotatable knob 2” which operates a pinion 2a meshing
with a toothed rack 2b. The stationary camera portion
1, 1' contains the photographic objective consisting of a
nonspherical _collecting front system L1 and a collecting
rear system L2. The distance between the two systems
is so selected that the image of the pupil of the eye pro
duced by the front system L1 will coincide with the focus
point of the rear system L2 on the side of the object. At
this point is arranged an inclined mirror 3 which is pro
vided with an axial aperture 3'. The incident light pass
the object side of said rear system, a movable camera
portion on said stationary portion adapted to be displaced
axially along the optical axis of said telecentric photo
graphic objective, an image receiving cassette mounted
on said movable camera portion, and a negative lens sys
tem interposed between said cassette and movable camera
portion and within the parallel ray path produced by said
telecentric photognaphic objective, said negative lens sys
tem lbeing coupled with said image receiving cassette.
2. A camera according to claim 1 in which said nega
tive lens system is carried by an exchangeable coupling
ing through the tubular portion 4 and coming from a
source of light will de deñected l‘by this mirror 3 and di
rected through the lens system L1 onto the retina of the
eye. The image rays coming from the front focal point
of the rear lens L2 will be directed by this lens L2 in par
tionary camera portion, said coupling member being de
tachably connected to said cassette and telescopically
This intermediate piece contains a negative system L3
(having a focal length j) arranged at a distance a Ifrom
lecting lens systems mounted in said tubular member
providing a telecentric photographic objective, said front
ther arrow by a distance s which corresponds to the actual
plane on the object side of said rear system, a second
member for connecting the camera cassette with said sta
mounted on said stationary camera portion.
3. A camera according to claim 1 including a mirror
allel and will form a parallel light beam on the image
reliex ñnder positioned in front of said camera cassette
side in the movable portion 2 of the camera. The latter
consisting of an inclined tiltable mirror, and an intermedi
contains a mirror reflex arrangement with a tiltable mir
ror 5 and a stationary mirror A6, an observation eye piece 20 ate coupling member arranged between said photographic
objective and said cassette in which said negative lens sys
7, and a cassette 8 receiving the image carrier. The mir
tem is mounted, said coupling member ybeing releasably
ror reiiex portion and the cassette portion are provided
connected with said mirror reñex finder and said cassette.
each with a tubular extension by which both portions are
4. In a photographic camera for photographing the
connected with each other, or they may also be con
nected with each other by an intermediate stationary piece 25 retina of the human eye, comprising a tubular member
forming a stationary camera portion, front and rear col
9 which is provided with appropriate connecting means.
and rear collecting systems being spaced a distance such
the point indicated by an arrow, which point is normally
the place of the image carrier. `By means of this system 30 that the image of the pupil of said eye produced by said
front system coincides with the stop arranged in the focus
L3 the image is displaced to a position indicated yby a fur
tubular member telescopically mounted on said first tu
length of the intermediate piece 9. The increase of the
bular member, -a camera casing with its optical axis
size of the image obtained is illustrated by the relative
aligned with the axis of said tubular members, an inter
length of the arrows. As will be noted, the mirror reñex
changeable coupling for connecting said camera casing
arrangement with the tubular extension 2', the connecting
with said second mentioned tubular member, and a nega
piece 9, and the cassette portion 8 form a rigid unitary
lens system in said coupling member in the path of
structure which can be displaced in axial direction relative
the «telecentric parallel ray path produced by said photo
to the stationary portion 1 of the camera. The dispersing
graphic objective, said negative lens system being rigidly
system L3 is hereby positioned in the parallel ray beam. 40 mounted
in said coupling member.
The divergency of the light beams emerging from this
system on the image side will not be disturbed by said
References Cited in the tile of this patent
displacement. -Due to the fixed distance between L3 and
the image receiver the size of the image will remain in
dependent of any sight deiiciency of the eye to be photo
Kuhl ________________ __ Dec. 3l, 1929
What I claim is:
1. ÁIn a camera for photographing the retina of the
human eye, comprising a stationary camera portion, col
lecting front and rear optical systems arranged in spaced
relation in said camera portion forming a telecentric pho
tographic objective, the space distance between said two
collecting systems being selected such that the image
of the pupil of said eye produced by said front system
coincides with a stop arranged in the focus plane on
Ort _________________ __ Dec. 19, 1939
Michel _______________ __ July 30, 1940
Turner _______________ __ May 8, 19511
Bechtold __________ _____ July 23, 1957
:Noyori ________________ __ Jan. 9, 1962
Great Britain _________ __ June 13, 1921
Great Britain _________ __ Mar. 19, 19311
Great Britain _________ __ Sept. 1l, 1957
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