Improvements in Cameras for Producing or Superposing Multiple Images.
Year: 1892

page_text: Date of Application, 8th Mar., 1892--Accepted, 9th Apr., 1892
COMPLETE SPECIFICATION.
Improvements in Cameras for Producing or Superposing Multiple
Images.
I FREDERIC EUGENE IVES of 911 Filbert Street in the City of Philadelphia
State of Pennsylvania United States of America Photographer do hereby declare
the nature of this invention and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement :-
The object of my invention is to provide a camera whereby there can be produced
upon the same plate three or more images all from the same point of view or
showing the same perspective the device, when used in the reverse way, being also
capable of superposing the several images so that they will form but one picture at
the point of view, or can be projected as one picture upon a screen or other back-
ground.
This object accomplish in the case of the camera, by dividing the incident rays
and reflecting the divided rays so as to form the desired number of different images
or the rays from the different images are reflected, collected, and projected in the
same axial line when it is desired to superpose the images and form a single
picture.
In the accompanying drawing
Figure 1, is a perspective view of an ordinary photographic camera provided
with attachments in accordance with my invention;
Figure 2 is a diagrammatic representation of the parts to which my invention
relates;
Figures 3 and 4, are like diagrammatic representations illustrating other plans of
carrying out my invention; and,
Figure 5 is an enlarged diagram illustrating one of the features of my invention.
My invention may be stated generally as comprising a system or series of
reflecting devices, the said series comprising as many members as there are images
to be produced, all of the members, excepting the last, comprising two or more
mirrors, and the last member having one or more mirrors, all of the said
mirrors being disposed at such angles as to project the images to the desired
points, the first mirror of each member of the series being in the axial line of
the incident or undivided rays, and the secondary mirror or mirrors of those
members of the series in which such secondary mirrors are used being properly
disposed with reference to the said axial mirror and some of the said axial
mirrors being transparent or semi-transparent so as to serve
to transmit rays
as well as to reflect the same; hence when the incident rays strike the axial
mirror of the first member of the series, there will be a division of said rays,
a part of each ray being reflected, and a part being transmitted to the axial
mirror of the second member of the series, where each ray will be again divided,
part being reflected and part transmitted, and so on, if more than two transparent
axial mirrors be used.
In the camera shewn in Figure 1, and in the diagram Figure 2 the reflecting
system is intended for the production of three images, and therefore comprises
three members, the first member consisting of the transparent axial mirror a and
secondary opaque mirrors a' and a while the second member consists of the
transparent axial mirror b and the opaque secondary mirror 6', the third member
consisting simply of the opaque axial mirror d.
The axial line of the incident rays is represented by the arrow 1, in Figure 2,
hence it will be seen that these rays, striking the mirror a of the first member
of the series, are divided, a certain volume of each ray being reflected laterally
onto the mirror a¹, thence onto the mirror a³ and thence onto the plate on which

page_text: the images are to be produced, a certain volume of each ray being also trans-
mitted through the mirror so as to strike the mirror whereby the rays are
again divided, a certain volume of each ray being reflected laterally onto the
mirror, and thence again reflected onto the plate while the rays transmitted
through the mirror strike the mirror d and are thereby reflected directly outo
the plate.
The mirrors are so arranged, however, that the length of each ray in its
passage from the object which is being photographed to the plate on which the
images are to be produced, is the same, whether the ray be reflected once, twice or
thrice in its passage, as will be readily understood on reference to the lines indicating
the axial lines of the rays in the diagram Figure 2.
The mirrors, and d are all at the same distance from the plate, and it will be
seen that the length of each divided ray from the point of first division, and
reflection, say the point a, to the points of final reflection, say at y y and is the
same, hence all of the images are exactly alike as regards focus, perspective and
point of view.
It will be observed that all of the divided rays are projected finally in a direction
at right angles to the line of the incident rays striking the mirror a, hence in
applying my invention to an ordinary camera it may be advisable to mount upon
the camera a preliminary reflector to reflect at a right angle the rays coming from
the object to be pl tographed so that the camera can be used in the same position
as an ordinary camera, that is to say, facing the object.
The mirrors constituting the various members of the reflecting series may,
however, be so arranged as to project the divided rays in lines parallel with the
incident rays, for instance, each member of the series may consist of an axial mirror
and of one secondary mirror, so placed in respect to the axial mirror as to project
the divided rays rearward or in the line of said incident rays.
It is also preferable to enclose the refiecting devices so as to eliminate rays of
light other than those proceeding from the object to be photographed, hence, I
provide the front of the camera with a box or casing g having an aperture in one
of its sides, this box being hinged to the camera front so that it can be readily
moved out of the way when it is desired to gain access to the reflecting devices.
The construction shewn in Figures 1 and 2 contemplates the employment of
condensing lenses in the paths of the divided rays; such lenses, for instances, being
situated as shown by the dotted circles in Figure 2, but it will be evident that
a single condensing lens in the path of the incident rays can be used, if desired,
and in Figure 3 I have shewn an instance of such use, the mirrors comprising
the different members of the reflecting series being arranged in a manner
substantially the same as that shown in Figures 1 and 2, while in Figure 4 1
have shewn a somewhat different arrangement of the mirrors, the first and
second members of the series both having two secondary mirrors, those of the
first member being represented at a' and a, and those of the second member at b¹
and 62.
As shewn in Figure 1 the mirrors constituting the various members of the
reflecting series consist of rectangular prisms, and in order to prevent cross
reflections from the front faces of the prisms and d and also to make the rays
which pass through the said prisms traverse the same thickness of glass as in the
two prisms a' and a², said prisms and d have their front faces extended, as shewn
at w in Figure 2.
In Figures 3 and 4 I have shewn compound lenses with diaphragms in the lens
tube, but in Figure 2 I have shewn a diaphragm having three apertures i, one in
front of the mirror a', one in front of the mirror 6', and the other in front of the
mirror d, so that the amount of light transmitted to each portion of the plate can be
governed independently.
The apertures in front of the mirrors a' and are inclined slightly in respect to
the axial line of the incident rays so as to compensate for unequal reflection from
the mirrors a and b, it being apparent that a ray striking a transparent mirror, say

page_text: as indicated at m.in Figure 5, will be reflected with greater intensity than a ray
striking the mirror as indicated at n in the same figure, hence when the aperture in
the diaphragm is inclined in respect to the axial line of the incident rays, as shewn
in said diagram Figure 5, the effective size of the aperture in the direction of a
ray proceeding from the point m is less than the effective size of the aperture in the
direction of a ray proceeding from the point n so that the bundle of stronger rays is
smaller than the bundle of weaker rays, and the illumination is thereby equalised.
When an adjustable diaphragm is employed it is also mounted so as to move in a
plane at an angle to the axial line of the incident rays, as shewn for instance in
Figure 2, where represent pivoted diaphragms so mounted, the diaphragm
being conical, so that it will not interfere with the transmission of rays from the
mirror a to the mirror b.
Where the angle of view is small, inclined apertures will not be necessary, and
in such cases, the constructions shewn in Figures 3 and 4 may be adopted.
When the camera is used as a transmitting camera the rays of light, passing
through the separate images upon the plate in the reverse direction from that
indicated by the arrows in Figure 2, are reflected by the various members of the
reflecting series onto the axial mirrors whereby they are all projected in the same
axial line to one point, such as an eye piece or screen, the various images being
superposed at that point so as to produce a single picture which will be perfect as
regards focus and perspective, owing to the fact that the series of images was
originally produced from the same point of view and by rays of precisely the same
length.
It will be evident that by simply increasing the number of members in the
reflecting series the number of images produced may be increased accordingly
without departing from the nature of my invention.
In some cases the desired situation of the different images upon the plate may, as
before stated, render it advisable to employ a secondary reflector in combination
with the reflector d constituting the third member of the series, but, as shewn by
the drawing, this is not essential, when the images are projected in a direction at
right angles to the incident or undivided rays.
The reflector d might also be transparent, but as the volume of light reaching
the same is limited, an opaque reflector at that point is, of course, always to be
preferred.
The axial reflectors in advance of the reflector d are, however, necessarily
transparent.
The transparent reflectors may be of glass, either platinized or thinly or incom-
pletely silvered, coloured or uncoloured. When uncoloured glass is used for
transparent reflectors in advance of the lenses, as in Figure 2, it should be thin and
have perfectly parallel surfaces in order that the two reflections, one from each
surface of the glass, shall be practically coincident for objects at a considerable
distance from the camera, and the image free from doubling of outline.
When objects are very near to the camera, or when the plain glass reflectors are
used between the condensing lens and the sensitive plate, one plane surface should
be very slightly inclined in respect to the other in such direction and to such degree
as will make the two reflections practically coincident at the focus of the condensing
lens or lenses.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is :-
First. A camera for producing or superposing a number of images shewing the
same perspective, said camera having reflecting devices comprising a series of
inclined reflectors situated in the axial line of the incident or undivided rays, the
said reflectors facing in different directions, and some of them being transparent, and
secondary inclined reflectors combined with the necessarily transparent axial
reflectors, substantially as and for the purpose herein before set forth.

page_text: Second. In a camera such as is claimed by the preceding claiming clause the use
of an apertured diaphragm for the reflecting devices for each image, substantially
as herein before specified.
Third. In a camera such as is claimed by the preceding first claiming clause the
use of an apertured diaphragm for the reflecting devices for each image, some of the
said apertures being in planes inclined in respect to the axial line of the incident or
undivided rays, substantially as hereinbefore specified.
Fourth. In a camera such as is hereinbefore claimed by the first claiming clause,
the use of an apertured diaphragm for the reflecting devices for each image, some
of the said diaphragms being moveable in planes inclined in respect to the axial
line of the incident or undivided rays, substantially as hereinbefore specified.
Fifth. In a camera such as is herein before claimed by the first claiming clause
the use of a supplementary or preliminary reflector whereby the incident or
undivided rays are deflected at a right angle, substantially as hereinbefore
specified.
Sixth. In ી camera such as is hereinbefore claimed by the first claiming
clause the use of an apertured box or casing for enclosing the reflecting devices,
substantially as.hereinbefore specified.
Seventh. In a camera such as is hereinbefore claimed by the first claiming clause
the use of a rectangular prism having its front side extended, substantially as herein-
before specified.
Dated this 8th day of March 1892
J. H. JOHNSON & Co.,
Agents.