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Патент USA US2403732

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July 9; 1946.
Filed March 11, I944
‘ . 75%24
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‘July 9, 1946. i
s. M. MacNElLLrEi
Filed March» 11', 1944
_ >FIG.4. '
s Shéets-Sheet 2
BY myéw/
July. 9, 1946.
> 2,403,732;
3 Sheets-Sheet 3
_ FiledMarch 11, 1944
FIG. 10‘.
.. M
2 w
Patented July 9, 1946
r 2,403,132
7 Stephen M. MacNeille, Oak Ridge, Tenn, assign
or to Eastman Kodak Company, Rochester,v
N. 11, a corporation of New Jersey
Application March 11, 1944, Serial No. 526,020
12 Claims.
This invention relates to range ?nders. This
(c1. 88-_-2.'7)
I posite directions. ' If, due to the presence of suit
applicationis a continuation in ‘part of one
entitled “Range ?nders,” 'case P, Serial No.
able objectives, an image is formed at or near the
combining re?ector, it. is obvious that the rota
505,016, ?led October 5, 1943, and in the series
it replaces that application and becomes case P.
The object of the present invention is to pro
effect. However, the effect is the same where
ever the images are formed and the prism unit
tion of the beams gives the required invert ?eld
vide an accurate range ?nder of the invert split
?eld type primarily for an ortho-pseudo-stereo
?nder but also usefulin those of the coincidence
used can actually be anywhere in the beams with
respect to these images; in fact, the light may be I -
colllmated as it travels through the prism unit.
One embodiment of the invention has the prism
type. .
in the converging beam optically following a pair
Most ortho-pseudo-stereo range ?nders in the
of relay lenses which ‘form images in the focal
past have had independent means for forming
planes of the eyepieces. This embodiment re;
the right and left eye ?elds, or as in-case K, Serial
quires the ?eld separating means to be located
No. 479,101, ?led March 13, 1943, Mihalyi and
at the primary images, i. e. to have the primary‘
MacNeille, have had two ?elds with a relay lens 15
images opaque over one-half of their. total area
system to image each ?eld adjacent to the other.
and requires the dividing line'to be. carefully
It is an object of thepresent invention to pro
adjusted. A second embodiment has the images
vide a system for producing both the right and
formed at or near a beam combiner, with an
left eye ?elds in a single plane. It is a primary
additional set of relay lenses for relayingv these
object to do this in a symmetrical manner, 20 images to‘the eye pieces. Since the images are
thereby eliminating many of the errors which
in the same prismunit and since the opaquing
arise in unsymmetrical range ?nder systems.
of half of each ?eld'is accordingly provided by
It is an object of the preferred embodiment
masks on this prism unit, the dividing line can be
of the invention to provide such an arrangement
carefully adjusted once and for all when the
which is as simple and as compact as possible and 25 [prism assembly is made and will remain ac
which may be made up from a number of identi
curate probably for the whole life of the instru
cal prisms. One preferred embodiment of the
invention re-employs a polarizing beam splitter
If the ?nder is to be used as a coincidence type,
such as described in copending application Serial
the pair. of images are viewed from one side of
No. 481,391, ?led by me on April 1,1943, or such 30 the combining re?ector, whereas if the instru
as a Nicol prism arranged to allow both the ordi
ment is to be used as a stereo range ?nder, means
nary and extraordinary rays to emerge. The
beam splitter described in my copending a-ppli- '
are provided for viewing both beams from one
side of the re?ector with one eye and both beams
cation is the preferred one because of the pos
the other side of the re?ector with the
sibility of selecting any desired angle ‘of in 35 from
other eye. , Preferably, a similar pair of re?ec
.cidence within a wide range.
tors is included optically to follow the beam
alternate layers of materials of high and‘ low
combining re?ector, to receive the light from,
indices of refraction with thicknesses approxi
each side thereof and to send two beams out in
mating that e?ectively equal to one quarter of
opposite directions along a second optical axis
the wave length of light so that by optical inter
parallel to the original one.
> >
ference, the composite multilayer material selec
The actual orientation of the two re?ecting sur
tively re?ects and transmits light of opposite ‘ faces
which receive the light beams from the
viewing points andsend them to the combining
According to the present invention the range
?nder is made up with two viewing points and 45 re?ector depends on the angle at which the beams
strike this re?ector. If the angle between each
some means such as pentaprisms for directing
of the light beams and the re?ector is A, then, in
the light beams, received from the target being
each beam, the pair of re?ecting surfaces should
ranged, directly toward each other along an
form a dihedral angle whose cosine is equal to
optical axis.
To one side of this axis and co
planar therewith, there is located a semi-trans
parent, semi-re?ecting‘ mirror to act as a beam
combiner. In line with each beam are two re
?ectors such .as prisms oriented to re?ect the
beams to the combining re?ector from opposite
sides and to rotate the beams through 90° in op 55
i/% sin%
I have found in practice that the angle whose
cosine equals
may be used for this purpose including double re
+/% sin 42
lay systems. By means of prism units 25 and 26,
light from the right and left viewing point image
planes is directed respectively to opposite sides
is quite satisfactory. For convenience and to per
of a beam-combining re?ector 24 which is located
co-planar with the axis 55 and to one side thereof.
mit the eXit system to be symmetrical with the
The path of the light is perhaps bestseen in Fig.
entrance system, I preferably arranged the angle
3. As the beams strike the beam-combining re
between the incident beam and the combining re
?ector 24 they are both in a plane which is orthog
?ector to be 45°. In this case the dihedral angle 10 onal to the axis I5 and, in this plane, they strike
between each pair of re?ecting surfaces in the
the re?ector 24 at an angle A. Each beam is split
entrance system should be 62°19’, ‘78°58’, 101°D2’
by the combining re?ector 24 so that through
or 117°31'.v In the most preferred form of the in
prism 21 parts of each beam pass to the right eye
vention I arrange the prisms so that the angle of
and through prism 28 parts of each beam pass to
incidence at each of the two re?ections are equal.
the left eye. Additional prisms 3Z8, rhombs 3i
In this case the prisms which constitute the re
and eyepleces 32 have been provided to permit
?eeting surfaces can all be made identical to each
stereo viewing of these images.
other, although their shape is somewhat unusual
The actual ?elds of views 35 and 3% are shown
when they are out to be, as compact as possible for
in Fig. 2. The image 28 from the primary plane i2
any given aperture.
20 is split by the semi-re?ector 24, so that the right
The prism unit for combining these light beams
eye sees the image .20 by reflection and the left eye
is useful in any‘ system where two beams ap~
sees it (marked 29' in Fig. 2) by transmission.
proach each other and are to be combined sym
Similarly, the left eye sees the image 21 by re?ec
tion and the right eye sees it (marked M’) by
The invention will be fully understood from the‘ 25 transmission. In the prism unit 25 the light from
following description of the preferred embodi
the image I2 is re?ected twice before it strikes the
ment thereof when read in connection with the
beam-combiner 24, the two re?ecting surfaces be
accompanying drawings, in which
ing oriented to rotate the beam through 90°. From
Fig. 1 is a plan view of an optical system for an
the symmetry of the arrangement, it will be seen
ortho-pseudo-stereo range ?nder incorporating
that the beams are rotated in opposite directions
a simple embodiment of the invention, Figs. 1A
so that‘, the images are inverted one with respect
and 1B showing the ?elds in the primary image
to the other and do not overlap because of the
planes thereof.
masking of the lower half'of each of the primary
image planes.
Fig. 2 shows a binocular field of view through
the instrument shown in Fig. 1.
In addition to all of the advantages of ortho
Fig. 3 shows diagrammatically an end View of
pseudo-stereo range ?nders combined with the
the prism unit shown in Fig. 1.
advantages of invert ?eld range ?nders, the
Figs. 4 and 5 are perspective views shaded to
present system has the advantage of symmetry,
show the structure of the prism unit and vcorre
namely, constancy of image size, uniformity of
sponding respectively to the views shown in Figs. 40 illumination and balancing out of various errors
1 and 3.
and aberrations. Each eye sees an invert ?eld
Figs. 6A to 6F are various views of the indi
which may be separately used for simple coinci~
vidual prism units, eight of which are combined
dence type of ranging.
with the simple unit shown in Fig. 7 to form the
In Figs. 1 to 3, the actual angleA is not speci
total unit shown in Figs. 4 or 5.
?ed and the re?ections in the prism units may
Fig. 7 shows a prism unit in the cemented sur
be at different angles of incidence. However, if
face of which is included a semi-transparent,
for the sake of symmetry, one further speci?es
beam-combining re?ector.
that the angles of incidence at each re?ection
Figs. 8 and 9 show an alternative embodiment
be equal, and the angle A be 45°, then the simplest
using simple mirrors in place of prisms and illus
form of prism unit which can be made up from
trating the rotation of the beams.
eight identical prisms and a pair of right angle
Fig. 10 is similar to Fig. 1 and illustrates a'pre
prisms having the beam combiner cemented and
ferred embodiment of the invention.
hypotenuse surfaces is shown in Figs. 4-7. Light
Fig. 11 is similar ‘to Fig. 5 but corresponds to
the embodiment shown in Fig. 10.
Fig. 12 is a perspective view corresponding to
Figs. 4 and 5 (or to Fig.’ 11).
In Fig. 1 light from a target being ranged is
received at spaced viewing points, by optical
squares l0 and directed through objectives ll
into focus in right and. left ?elds l2 and 13 re
spectively, adjacent to which are located ?eld
lenses. The deviation of one beam relative to the
other is provided in the usual way by a light de
viator I4. It will be noted that the two beams are
directed exactly toward each other along optical
axis l5 and are not offset in any way.
Figs. 1A
from the left viewing point is re?ected by prisms
4t and 4! through prism M to the beam-combin
ing re?ector 24 and similarly light from the right
viewing point is re?ected by prisms 42 and 43
through prism 45 to the other side of the beam
combiner 24. An identical exit system is made
up of prisms Alt, 4?, 48 and 49. The details are
shown in Figs. 6 and 7. Each prism unit is essen
tially a simple one with entrance and exit faces
50 and 52 and a single internal re?ecting surface
5!. To permit assembly of the prisms in the
minimum space, corners of each prism not used
for transmitting light are cut away. Further
more, to permit the eight re?ecting prisms to be
identical, certain additional facets are cut un
necessarily on the outer prisms, 4i} and 132, say, but
which correspond to necessary facets on prisms
4i and 43 to permit assembly; Similarly, certain
and 1B show the two ?elds l2 and 13 with images
20 and 2! of the target respectively in each ?eld.
The lower half of each ?eld is masked off so that
when the two ?elds are brought together in in:
verted relation, there will be nooverlapping of
the images. Relay lenses 22 and 23 are employed
facets which are necessary .on the outer prisms
to re-image the light beams in the focal plane of
appear on the inner .prisms'but are unnecessary
the eyepieces, but various other optical systems 75 here.
bly in the form of a biconcave or plane-concave.
~-lnfFigs.i 8- and Qasimpli?ed form of ‘them
airspace if this is desired. vIn any case the lenses
vention is shown in whichrthe light beams from
image's-'80 and T0 traveling towardv eachother'
82,- 83 and '85 should be’ of su?icient diameter to
‘utilize substantially 'all'of the entrant and exit
faces- of the prism assembly,
along axis 15 strike mirrors '81 and »'H,-respe'c
'tively, the orientation of the beams at this sur
In' Fig. 10 the whole lens system between‘ the.
face being shown by arrows 62 and ‘I2. 1 The re
flected beams then strike mirrors~83 and ‘I3 re-v
spectively, the orientation being shown by ar
rows 64 and ‘I4 and travel thence to the beam
combining re?ectorv 24 to strike opposite sides
viewing points‘ [0 and the ‘prism unit, can be
considered as one for forming ‘the vimage near
the beamcombining re?ector. That- is, the pri
mary images themselves’ may be formed in- the
.prism~84\by~ a single lens in place of the lenses
thereof-with the beams 65 and 15 inverted rela
tive to‘ one another. If the lower half of ‘each ' 'll,80'and82.1
' When the beam combining re?e'ctoris oflthe
of the images 60 and ‘I0 is masked off as in Fig.
polarizing’ type, the adjacent'image plane may
1, the resulting beams at the beam-combiner-24,
15 be in the position shown with masks 81 and 88
or wherever the actual images are formed, are of
for cutting off complementary halves or alter
the split-?eld invert-type.
natively may be anywhere in the‘ unit includ
‘In a preferred embodiment of the invention, the
ing- planes optically following the beam com
beam-combiner 24 is made of- an optical inter
bining re?ector. For example if the; images
ference multilayer ?lm to re?ect and transmit
light of opposite polarization.’ The focal planes 20_
I2 and I3 may then be optically after the prism
unit and separation of they ?eld is then provided
by two polarizing ?lters, respectively, over each
are formed on the exit faces of the prisms 84 in
stead of on the entrant faces, the masks 8'lland
88 should ' be omitted. The complementary
masking is then done‘by polarizing ?ltersvover
the exit faces as'shown'by broken lines. I These
half of each ?eld with their vibration axes mutu 25 broken-lines are drawn partly with long sections
, ally at right angles. It will be noted that no
and partly with short sections= to ‘represent
polarizing ?lter or other selecting‘ ?lter is neces
schematically the orientation of the vibration:
sary in‘ embodiments of the invention wherein the »
axis of the ?lters. The sections labelled 108
focal planes I2 and 13 are ahead of ‘the prism - will serve to illustrate the function of the polariz
unit and are masked over half of their ?eld. '
In Fig. 10 ‘the primary images are formed on
?eld lenses 8!] and’ 8| which differ from Fig. 1
by the fact that there is no opaque mask cover
ing half ‘of the images at these points. These
ing ?lter in this embodiment; Primarily-the
polarizing ?lters must have exaetly'the vsame
action as the opaque masks 81 and 88.» That
is the ray 94 must be transmitted by the “filter
I00, both the part re?ected and the part trans
images are relayed by lenses 82 and 83, which 35 mitted at the beamwcombirling re?ector 86. -_The
are of shorter focal length thanthe correspond
part re?ected at the surface 86 due to the polar
ing lenses of Fig. 1, so that in the presentcase
izing action of this surface has its vibration'axis
perpendicular to the plane of the paper and is
the images are formed on the optical front sur
hence transmitted by the ?lter I00. Similarly
faces of prisms 84 (corresponding to 44 and 45
of Fig. 5). These images are then relayed by 40 the part of the ray 94 which is transmitted by
_ the surface 86 has its vibration axis parallel to
additional relay lenses 85 to form images in the
the plane of the paper and accordingly is transj
focal planes of the‘ eyepiece 32. To permit the
mitted by the ?lter I00 as shown. Onjthe other
lenses 85 to be located; in the positions shown
hand the ray 9| which in this embodiment is not
longer rhombs 19 are used to replace. the rhombs
3| in Fig. 1. At these secondary images on the 45 v‘masked by any mask 88 is divided or split by
the-"surface 86 but is-polarized therebyso that
surfaces of the prisms 84, masks ‘81 and 88 are
both the transmittedportionand the re?ected
located opaqing one-half of each image (see
portion are stopped by the polarizing ?lters 100.
Fig. 11). This is indicated by the stoppage of
The other two parts of the polarizing ?lters are
the light represented by arrows 9| and 92, where
as, the light represented by arrows 93 and 94 50 similarly arranged as shown to transmit both
parts of the ray 93 but to stop both- parts of the
passes through in each case to be split at the
ray 92. Obviously such an arrangement of
semi-transparent mirror surface. The position
polarizing ?lters can be used at the image planes
of the mask 81 is unique, but except for the slight
wherever they are located, providing of course
out of focus edge,.the mask 88 could be replaced
by one located by positions shown by broken 55 that the operation of the polarizing beam split
ter is not adversely affected. 1
line 96. A mask in the position 88 is preferable
Fig. 12 is added merely for clarity in demon
however. The edges 89 and 90 of the masks must
strating the path of the two beams through. the‘
correspond optically to one another since they.
prism. As shown the two beams are combined
represent and produce the dividing line in the
and emerge only toward one eyepiece, the other
ultimate ?eld. This is one of the chief advan 60 emerging beam being omitted from the drawing
tages of this embodiment of, the invention since
since it would tend to confuse the picture. This
the edges 89 andi9ll will stay in adjustment, once
they are ?xed whereas in Fig. l, the masks pro
ducing the dividing line are located on elements.
I2. and I3 separated from each other so that they
are liable to get out of adjustment. The advan
tages of having a clean, accurate dividing line
without any overlapping and without any sepa
ration, is well known to any one who has ‘used 70
a split ?eld range ?nder.
The double relay system in this embodiment
shown in Fig. 10 has the additional advantage of
optical e?iciency. If desireda ?eld lens could
be included near the center of the prism assem
Fig. 12 corresponds either to Figs. 4 and 5or to
Fig. 11.
Having thus described the preferred embodi
mentsof my invention, I wish to point out that
it is not limited to these structures but is of the
scope of‘the appended claims.
I claim:
1. A range ?nder comprising means at spaced
viewing points for receiving light beams from
the target being ranged'and for directing them
toward each other along an optical axis, a beam
combining re?ector lying coplanar with the axis
78 and to one side thereof, a plurality of re?ecting
surfaces in each beam oriented to direct the
beams to opposite sides .of said re?ector :andto
rotate .them through 90° in opposite directions,
lens means for focusing each beam to form
images which, due to the rotation of the beams,
are inverted relative to one another andmeans
ing light of opposite polarizations lying coplanar
with the axis and to one‘ side- thereof, a pair of
re?ecting surfaces in each target beam oriented
to direct the beams to opposite sides of said re
1 ?ector and to rotate them through 90° in oppo
site directions, lens means for. forming right and
for viewing the images from Eat least one side of
left viewing point images superimposed in invert
the combining re?ector. ,
ed relation in right and left eye image planes op
2. A range ?nder comprising meansat spaced
viewing points for receiving light beams from the
target; being ranged andrfor directing them to—.
ward each other along an optical axis, a beam
combininggre?ectorylying coplanar with the axis
and to one side thereof, a pair of re?ecting sur
faces‘in each beam oriented to direct the beams
to opposite sides of said re?ector and to rotate
thenrthrough 90° "in opposite directions, lens
means for focusing each beamto form images
which, due to the rotation of the beams,’ are in
tically after the said beam-combining re?ector,
a pair of polarizing ?lters with their vibration
axis mutually at right anglesat and dividing each
of the said image planes and means for stereo
viewing the images.
9. A range ?nder comprising means at spaced
viewing points for receiving light beams from the
target being ranged and for directing them to
ward each other along an optical axis, an objec
tive in each beam for forming images in primary
image planes, right and left eye eyepieces and a
verted relative to one another and means for 20 relay system for relaying both images to. each
viewing the images from at least one side of the.
eyepiece," said relay system including a beam
combining re?ector.
combining re?ector lying coplanar with said op
,3. A range ?nder according to claim 1 in
tical axis and to one side thereof, a pair of re
which the viewing means is binocular with right
?ecting surfaces in each beam oriented to direct
and left eye eyepieces for receiving respectively 25 the beams to opposite sides of said re?ector and
light from opposite sides of the combining re
to rotate them through 90° in opposite directions,
?ector whereby ortho-pseudo-stereo ?elds are.
a relay lens in each beam for relaying the pri
mary image to form a secondary image near the
4. A range ?nder according to claim 2 in
re?ector, masking means at each of the‘second
cluding a similar pair of re?ecting surfaces in 30 ary image planes for masking o? complementary
each of the beams from opposite sides of the
combining re?ector.
5. A. prism unit for combining light beams
halves of the images and secondary relay lens
means for relaying the transmitted parts of both
secondary images to each eyepiece.
which are approaching each other along an axis
10. A range ?nder according 'to claim 9 in
comprising a beam-combining re?ector coplanar 35 which the secondary images are optically ahead
with the axis and to one side thereof, two en
of the beam-combining re?ector vand the mask
trance faces on the unit orthogonal to the axis
ing means are opaque over one-half of each
and in line therewith to receive the beams, and
re?ecting surfaces on the unit for totally in
v11. A range ?nder according to claim 9 in
ternallyre?ecting each beam twice, oriented to. 40 which the beam combining re?ector is'a polariz
direct the beams to opposite sides of the combin
111g beam splitter for transmitting and re?ecting
ing reflector and to rotate the beams through
light of opposite polarizations, the secondary
90‘? in opposite directions.
images are formed optically after the re?ector
6. A prism unit including the combining unit
and the masking means at each image plane
according» to claim 5 and an identical unit fol-'
of a polarizing ?lter with adjacent halves
lowing, the re?ector for sending parts of both
oriented with their vibration axis at right angles
beams. in each direction out along .a second axis
to selectively mask the two images.
parallel. vto the ‘original axis.
7. A, range ?nder comprising means at’ spaced
12. A range ?nder comprising means at spaced
viewing points for receiving light beams from the 50' viewing points for receiving light beams-from the
target being ranged and for directing'them to
target being ranged and for directing them to»
ward each other ‘along an optical axis, right and
ward each other along an optical axis, an objec
left eye eyepieces and means for directing both
tive in each beam for forminggimages in primary
beams to each eyepiece including a beam com
image planes, .right and left "eye eyepieces and a
relay system for relaying both images to each . bining re?ector lying coplanar with said optical
axis and to one‘ side thereof, a pair of re?ecting
eyepiece, said relay, system including a beam
surfaces in each beam oriented to direct the
combining. re?ector lyingcoplanar with said op~
beams to opposite sides of said re?ector and to
tical-axis and to one side thereof, a pair of re
rotate them through 90° in opposite directions,
?eeting surfaces in each beam oriented to direct
lens means in each beam optically between the
the beams to opposite sides of said re?ector and
viewing point and the re?ecting surfaces for
to ‘rotate them through 90° in opposite-directions
and ‘relaylens means in each beam, correspond
forming near the beam combining re?ector an
ing halves of each of the primary image planes
image of the target, the two ‘images being opti
being masked off.
cally inverted relative to one another, masking
.8. .A range .?nder comprising means at spaced 65 means at each of the image planes for masking
off complementary halvesof the image and relay
viewing points-for receiving light beams from the
target being ranged and for directing them to
lens means for relaying the unmasked parts of
ward each other along an optical axis, a beam
both images to each eyepiece.
combining re?ector for transmitting and re?ect
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