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McCann et a1.‘
[45] Aug. 19, 1975
[54] CAMERA TO MICROSCOPE ADAPTOR
WITH A SPECIAL OPTICAL ELEMENT
[75] Inventors: Mary Conlin McCann, Belmont;
William T. Plummet‘; Vivian K.
Walworth, both of Concord, all of
Mass.
[73] Assignee: Polaroid Corporation, Cambridge,
Mass.
Dec. 3, 1973
1221 Filed:
[21] Appl. No.: 420,913
[51]
- [58]
Int. Cl. ......................................... .. G03b 17/48
Field of Search .................... .. 354/79, 293, 295;
350/96 R
240/1 LP, 1 EL; 350/18, 19, 36, 96 R;
355/18, 68
References Cited
UNITED STATES PATENTS
3,106,129
10/1963
Frenk et a1. ........................ .. 354/79
3,292,490
12/1966
Moore ....... ..
3,308,709
3/1967
'
"Ti
7/1967
12/1970
3,623,807
11/1971
3,721,170
3,798,665
3/1973
3/1974
Taillie ............................. .. 240/1 LP
Verge .......................... .. 350/19
Gabler et al..
350/19
Johnson .......... ..
354/79
Eloranta et a1. .................... .. 354/79
Primary Examiner—Richarcl L. Moses
Attorney, Agent, or Firm—Frederick H. Brustman;
John W. Ericson
[5 7]
US. Cl .................. .. 354/79; 240/1 LP; 350/19;
Harrick ........................... .. 350/96 R
5539008“,
0R1 m 3511/79
3,330,190
3,548,730
ABSTRACT
The invention is an optical element, one version of
which is useful for operating an automatic exposure
[52]
[56]
3,900,858
control of a self-contained camera coupled to a micro
scope without detracting from the brightness of the
magni?ed image to be recorded on the camera‘s ?lm
format. The article includes three're?ecting surfaces
arranged to extract a small part of the light emerging
from the microscope’s eyepiece and direct it into the
photodetector of the automatic exposure control. A
lens refracts the light, after the third re?ection, to im
prove the distribution of the light onto the camera’s
photodetector. The article is suitable for manufacture
as a homogeneous molding of transparent plastic.
7 Claims, 5 Drawing Figures
3,900,858
PATENTEU we 1 9 ms
SHEET 1 [IF 2
FIG. 3A
3,900,858
PATENTED AUG] 9|975 '
sum 2 UP 2
FIG. 3B
I50
FIG. 3C
3,900,858
2
CAMERA
s
TO MICROSCOPE.
- 1
ADAPT OR WITH A
tween an image-forming instrument and a camera cou
SPECIAL OPTICAL ELEMENT
pled to the instrument, at least a portion of the light
BACKGROUND OF
INVENTION
The invention described herein is" particularly useful
constituting that part of the image formed by said in
strument that would otherwise lie outside the ?lm for
mat boundary of the camera for the purpose determin
with an automatic exposure control, to an image
forming optical system such as a microscope. An im
ing the proper exposure for recording the image.
The invention described in co-pending US. patent
application Ser. No. 420, 915, ?led on Dec. 3, 1973 by
portant consideration in adapting such a camera for
Vivian K. Walworth for CAMERA TO MICROSCOPE
in an adaptor for attaching a self-contained camera,
photography through a microscope of other instrument l0 ADAPTOR WITH NIEANS FOR OPERATING AN
EXPOSURE CONTROL and assigned to the assignee
is to preserve the automatic exposure control feature
of this application recognizes and capitalizes on the
without reducing the amount of light available for the
fact that image-forming optical instruments have circu
photographic exposure of a film unit within the camera.
lar ?elds, since they are made from spherical optical
Prior art arrangements for coupling self-contained
cameras with automatically controlled exposure sys 15 elements, but that photographic ?lms are made with
rectilinear formats. For aesthetic and technical rea
tems to optical instruments propose the diversion of
some part of the useful light, light intended for the pho
sons, the circular image formed by an optical instru
tographic image, onto the photosensitive detector in
ment is enlarged to fill the corners of the ?lm’s rectilin
ear format. Thus, the chordal segments of the circular
the automatic exposure control of the camera. Typi
cally, this diversion is accomplished by a beam splitter
or similar optical element within the instrument.
U.S. Pat. Nos. 3,130,634 and 3,292,490 exemplify
the foregoing scheme. The former shows a conven
tional arrangement with a beam splitter inside the pho~
image lying outside the rectilinear format are surplus
age. However, the illumination of the surplus chordal
segments is indicative of the central image’s illumina
tion, and the light forming them can be used for other
purposes without detracting from the recorded image ’s
totube to de?ect a large fraction of light to an exposure 25 illumination, quality or content.
control system. As with other conventional systems, the
diversion markedly reduces the available light at the
?lm plane. The latter patent shows a camera attached
The present invention includes a monolithic pris
matic optical element that extracts at least a portion of
the light forming at least one of the surplus chordal seg
to make a photograph through one eyepiece of a binoc
ments from the optical path between the instrument
ular microscope and a ?ber optic light pipe connecting
and a self-contained camera coupled to the instrument.
A monolithic element is optically more efficient and
the other eyepiece of the binocular microscope to the
simpler to manufacture than the arrangement shown in
photodetector of the camera’s automatic exposure con
co-pending application, Ser. No. 420,915. It isparticu
trol. The optical arrangement of such a microscope
larly useful when used with an adaptor such as de
uses an internal beam splitter to divert half of the avail
able light to each eyepiece. It makes light available to 35 scribed in the aforementioned co-pending application,
actuate the automatic exposure control attached to one
Ser. No. 420,915. The monolithic prismatic optical ele
eyepiece, but only at the expense of the photograph
ment, which ?ts between the camera and the instru
ment, directs the light onto a photocell so as to activate
made through the other eyepiece. This intentional re
duction in the illumination of the image, merely to ac
tuate the automatic exposure control, can have a criti
cal and deleterious effect on a photograph made
through an image-forming optical instrument because
the amount of light available is generally quite limited.
the automatic exposure control of the self-contained
40 camera. The light can be directed to an independent
exposure meter instead.
The optical element includes at least two re?ecting
surfaces molded as an integral part of it. The ?rst ex
tends into the optical path between the camera’s objec
The prior art also includes a photographic micro
45 tive lens and the instrument’s eyepiece. It extends into
scope system such as the Zeiss ULTRAPHOT II. The
photographic portion of the system is integrated with
the optical path far enough to intercept and laterally
the microscope objective optics to form a special cam
re?ect a segment of the circular beam of light coursing
along the optical path from the instrument to the cam
era. The camera is neither self-contained nor func
tional apart from its place in the system. It has a photo
detector at the focal plane and outside the boundary of
a mask de?ning its photographic format. The illumina~
tion intensity at the focal plane is the least of any loca
tion along the optical path. Thus, the focal plane is an
era but not so far between them that it casts a shadow
inside the boundaries of the camera’s ?lm format. The
second re?ecting surface is opposite the photodetector
of the self-contained camera’s automatic exposure con
trol. It is oriented to re?ect into the photodetector the
inef?cient place to locate the detector for an exposure 55 light extracted by the ?rst re?ecting surface from the
optical path. A small condensing lens located in the
control. Moreover, at the focal plane a detector is most
likely to give a spurious indication of the required ex
posure due to an anomaly in the magni?ed image.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is an integral opti
cal element to extract light from the optical path be
path of the extracted light, proximate the entrance to
the camera’s ‘photodetector, optimizes the photometric
effect of the extracted light. An intermediate re?ecting
surface can be molded into the article to accommodate
for displacement of the photodetector in two coordi
nate directions.
_
A special advantage of the present invention is the
tween an image-forming optical instrument and a self
formation of the foregoing optical arrangement so it is
contained camera coupled to the instrument for oper
ating the automatic exposure control of the camera 65 suitable for molding in a single piece as an integral opti
without affecting the recorded image.
Another object of the present invention is a prismatic
optical element to divert from the optical path, be
cal element from an optically clear plastic material.
The single piece will easily ?t in a narrow separation
between the camera and the instrument.
3,900,858
3
DESCRIPTION or THE DRAWINGS
4
Though these and other ?gures show the inventions
used with an SX-70 Land Camera the reader will un
derstand that the inventions can be used with any cam
era having an automatic exposure control with its pho
Other objects and many of the attendant advantages
of the present inventions will be better appreciated and
the inventions will become more clearly understood by
reference to the following detailed description when
considered in conjunction with the accompanying
drawings illustrating the instant inventions, wherein:
tocell offset from the camera’s optic axis. e.g., Color
pack II and Model 300 Series Land Cameras. More
FIG. 1 illustrates a self-contained photographic cam
era attached by a holder to an optical instrument;
FIG. 2 illustrates how ?lling a rectilinear ?lm format
with a circular image results in four unused chordal
control, but with an integral light meter instead, or to
feed light to an independent light meter.
The microscope 40 shown in FIG. 1 is a conventional
binocular type with a third, vertical tube for photo
over, this invention can also be used to direct light to
a photocell on a camera not having automatic exposure
image segments; and
graphic use. Within the microscope 40 is a means (not
shown) such as a movable mirror or prism that, in one
FIGS. 3a, 3b and 3c illustrate an integral optical ele
ment to extract light from the optical path between a 15 position, directs the image to the eyepieces 52 and 54
or, in another position, allows the image to enter the
self-contained camera and an image-forming optical
vertical tube.
instrument.
THE PREFERRED EMBODIMENT OF THE
INVENTION
The following procedure explains a method for using
a SX-7O Land Camera on a microscope. An eyepiece,
not shown, is inserted in the vertical phototube of the
microscope 40. The eyepiece in combination with the
microscope 42’s objective 56 forms a magni?ed virtual
reference to FIG. 2. FIG. 2 represents a microscope
image of the subject 58 stationed on the microscope
image of a hypothetical biological specimen superim
stage 60. Microscope optics are conventionally des
posed on a square photosensitive ?lm unit. A square
25
boundary 10 represents the rectilinear format bound
inged to form the magni?ed virtual image at an appar
The concepts of this invention are best understood by
ary of a commercial photographic ?lm unit suitable for
ent distance of about 50 centimeters or so below the
use in a self-contained camera attached to an image
eyepiece. That distance is well within the close-up fo
cusing capability of the SX-7O Land Camera 44.
forming optical instrument For aesthetic as well as
other considerations, the instrument and the camera 30 The SX-7O Land Camera 44 positioned by the holder
48 over the vertical phototube receives the virtual
are matched so the instrument’s image will ?ll the cor
image of the subject 58 emerging from the eyepiece. Its
ners of the rectilinear film format. However, the typical
objective lens forms a real image of the subject 58 on
image-forming optical instrument, e.g., a microscope,
has a circular image ?eld 12. The circuitry results from
its focal plane. The most convenient means for focusing
the rotationally symmetric nature of most optical ele 35 the real image on its focal plane is the focusing knob 62
of the mimcroscope 40. Turning the knob 62 will adjust
ments. To ?ll the rectilinear ?lm format 10, the circular
the focus of the real image at the focal plane. The mi
image ?eld 12 must have a diameter at least equal to
croscopist can observe the image through the viewer 64
a diagonal of the rectilinear format 10. This results in
of the camera 44 while he turns the knob 62 to focus
four chordal segments 14, 16, 18 and 20 of the instru—
ment’s image that fall outside the boundaries of the ?lm 40 it. Good photographic results are achieved by setting
the SX-70 Land Camera for focus at a distance of
format 10. Previously, in instrument cameras, they
about 1 meter, the focal distance for which its objective
gone good unused and provisions have been made to
absorb the light destined for those chordal segments
lens performs best, and using the knob 62 to focus the
image on the camera’s focusing screen.
l4, 16, 18 and 20.
The present invention recognizes that the brightness 45 Experiments indicate that many microscope eye
pieces magnify the microscope objective 56’s image
of the image in the chordal segments 14, 16, 18 and 20
enough to ?ll the corners of the ?lm format with the
is indicative, in most cases, of the image’s brightness
within the rectilinear ?lm format l0’s area. Therefore,
camera’s objective focused at about 1 meter. In some
light from the image-forming optical instrument des
instances the eyepiece regularly supplied with the mi
tined to form one or more of the chordal segments l4, 50 croscope will not magnify the image enough to com
16, 18 and 20 can be usefully diverted to the light sen
sor of the automatic exposure control of a camera con
taining the ?lm unit 10 without stealing light from the
useful (recorded) image area within the ?lm format
pletely ?ll the corners of a camera’s ?lm format, this
situation can be corrected to some extent by adjusting
the camera’s objective to focus closer than 1 meter. It
is preferable though to use a wide angle eyepiece in the
boundary 10 and without superimposing a light sensing 55 vertical phototube. Wide angle eyepieces are available.
Ideally, the ?eld of view subtended by the optics of the
probe on the useful image.
.
FIG. 1 illustrates a microscope 40 ?tted with a novel
fully automatic and self-containedd SX-7O Land Cam
era 44 sold by the Polaroid Corporation. The ?gure il
lustrates a holder 48 for attaching such a camera to the
photocube of a microscope. The SX-7O Land Camera
44 has an automatic exposure control utilizing a photo
detector that looks in the same direction as the objec
camera and the microscope will slightly over?ll the ?lm
format area so their alignment is not important to ?lling
the comers of the film format. Those skilled in the art
will now understand that the foregoing procedure and
the holders will also work quite well with a plain mon
ocular microscope and the following explanation is ap
plicable to such an arrangement too.
tive lens but is laterally displaced in the shutter housing 65 In the foregoing arrangement for coupling the SX-7O
Land Camera 44 to the microscope 40, a place to ex
from it. An accessory article for diverting light in
tract some light from the optical path is the small space
tended for the chordal sectors of the image formed by
separating the camera’s objective lens from the micro
the microscope 40 is described below.
3,900,858 ‘
'
5
scope’s eyepiece. An integral molded optical element
light between'the element 131) and the automatic expo
for doing so is‘ described below.
sure control. his not essential to the successful func
‘
-
-
The holder 48 has two knobs?? and 68.-The lowe
knob 66 controls a clamp (not shown) that. locks the
holder onto the vertical phototube of the microscope
40. The upper knob 68 adjusts the’ position of the
molded optical element (not shown in FTG. 1) that di
verts the light from a chordal segment to the automatic
exposure control of the camera 44. This position ad
justment is a feature to maximize the transfer of
chordal segment light into the automatic exposure con
trol, but it is not necessary for the proper operation of
tioning of the invention.
1
'
The path of light through the element 130 is better
understood by reference to FIG. 3c in which the ray
158 (with directional arrowheads) represents the gen
eral path of light through the element 130. The bundle
of light rays intercepted by the element 130 at the end
proximate the re?ecting surface 150 is converging to
ward the exit pupil of the microscope eyepiece 134.
The bundle of rays continues to converge inside the el
ement 130 as it proceeds toward the lens 156 and
control’s function by varying the amount of chordal
achieves its minimum size in the vicinity of the edge
152. It then diverges. The lens 156 has a focal length.
segment light reaching the photodetector through the
approximating the optical path distance, in the element
molded optical element. In this way it can supplement
130, to the light ray bundle’s minimum cross-section.
The minimum cross-section corresponds to the exit
pupil of the eyepiece 134. Its location in the element
130 will depend on the design of the eyepiece and of
the invention. it can also adjust the automatic exposure
the function of the camera 44’s trim control.
Reference to FllGS. 3a, 3b and 3c is useful in under
standing this invention. It shows an integral optical ele~
ment 130 that directs light for an otherwise unused por 20 the element 130 as well as other factors those skilled in
the art can recognize. The focal length of the lens 156
tion of a microscope image into the automatic exposure
is selectedso it will reimage the eyepiece 134’s exit
' control of a camera. The integral optical element 130
pupil at in?nity, i.e., so it will collimate the light emerg
(shown enlarged in the isometric view of HG. 3c) fits
ing from it. This arrangement optimizes the transfer of
in the separation between the shutter housing 132 of an
SX~7O Land Re?ex Camera and the eyepiece 134 of a 25 light onto the sensor of the camera 44, but it isn’t man
datory.
.microscope‘(see FIG. 3b). The eyepiece 134 ?ts in the
In the preferred embodiment of the monolithic opti
vertical phototube 136 of a microscope. The holder 48
cal element 130 the top and bottom surfaces 131 and
positions the SX-7O Camera so its objective lens (not
133 are parallel. The re?ecting surface 150 makes an
shown in FIG. 3b) is coaxial with the eyepiece 134
included angle with the bottom surface 133 of 525°.
along the optic axis 138. Only a portion of the holder
The intermediate re?ecting surface 152 is normal to
48 is shown in FIG. 3b.
the top and bottom surfaces 131 and 133 and makes an
The prismatic integral optical element 130 is posi
angle of l57.5° with a surface 135 that is normal to the
tioned by a support 142 that slides axially with shaft
plane of the reflecting surface 150. The re?ecting sur
143 but ‘will not rotate. Rotating the knob 68 attached
to the threaded shaft 143 causes the support 142 vto 35 face 154 and the top surface 133 subtend an included
move axially on the screw thread 145. The shaft will ro
tate but is restricted from axial movement. Other
means of positioning the prismatic integral optical ele
ment 130 will occur to users of‘ the concepts disclosed
herein.
The opticalv element 1311 comprises two smooth par
allel surfaces 131 and 133 with a ?rst mirror 150 that
re?ects light entering through one of the smooth sur
faces lengthwise between them. Total internal re?ec
tion causes the optical element 130 to act as a “light
pipe”'conveying the trapped light to an intermediate
re?ecting surface 152 which re?ects it to another re
?ecting surface 154 that re?ects the light through a
lens 156 on the second smooth surface.
The entrance window 144 to the'photodetector of
the self-contained camera’s automatic exposure con
angle of 45° and its intersection with the top surface
131 forms a 675° included angle with the intersection
of the top surface 131 and the intermediate re?ecting
surface 152.
Surface 150 is metal coated and painted black on its
rear to eliminate spurious re?ections of light into the
camera. The re?ecting surfaces 152 and 154 can be left
unmetalized and internal re?ection can be relied on at
these surfaces. However, because of the variety of an
gles of incidence between the surfaces 152 and 154 and
the light rays in the bundle, in some applications they
may require an aluminum or other metal ?lm to pro
mote re?ection of the light incident on them.
The size of the element 130 is selected so its re?ect
ing surface 150 will extract the light of a chordal seg
ment of the microscope’s image without casting its
shadow on the photosensitive area of a ?lm unit in the
trol is displaced in two coordinates from the optic axis
camera, and the reflecting surface 154 and the lens 156
138 of the objective lens 146. FIG. 3a shows the rela
tionship best. it also shows the monolithic optical ele 55 at the other end can direct the extracted light into the
window 144 of the camera’s automatic exposure con
ment 130 in place where its ?rst reflecting surface 150
trol. FIG. 3c includes the sizes of the angles best suited
re?ects light entering the optical element through its
to the‘ preferred embodiment for use with the SX-7O
bottom surface toward the longitudinal edge 152. The
Land Re?ex Camera.
optical element 134) is preferably positioned so any
The holder 48, as illustrated in FIG. 1, using an
.shadow cast by the edge of its re?ecting surface 150 at
SX-7O Land Re?ex Camera makes it easy to adjust the
.the ?lm plane is parallel to an edge of the camera’s ?lm
‘format.
Total internal re?ection of light incident on edge 152
‘conducts it toward the re?ecting surface 154. The re
element 130 so it doesn’t cast its shadow within the ?lm
format’s boundary. The user has merely to watch
through the viewer 64 as he positions the integral opti
‘?ecting surface 154 re?ects the light upward into the 65 cal element 130 by rotating knob 68. He can see then
if its leading edge is parallel to the ?lm format’s edge
window 144 of the automatic exposure control. The
lens 156, formed as an integral part of the prismatic op
tical element 131), promotes the effective transfer of
and, if it casts an unwanted shadow, make appropriate
adjustments. 1n the case of a non-re?ex camera, a series
3,900,858
8
7
2. The optical element of claim 1, further comprising
of trial exposures aid in empirically positioning the in
a total internal re?ective surface on said homogeneous
tegral optical element 130. Alternatively, its location
can be ?xed by appropriate engineering design with
transparent medium to re?ect said light from said ?rst
re?ecting means to said second re?ecting means.
3. An adaptor for functionally joining a self
reference to speci?cations of a speci?c camera and mi
croscope and holder.
A most important feature of the element 130 is its
contained photographic camera to an image-forming
optical instrument, said adaptor comprising:
suitability for being molded inexpensively as a single
piece of transparent material such as polymethyl meth
attaching means for joining said camera to said opti
cal instrument so that the image formed by said op
tical instrument may be photographed by said cam
acrylate, polycarbonate or polystyrene.
Certain specimens, samples, or subjects 58 yield an
era, said attaching means including clamping
means for releasably locking said attaching means
asymmetrically illuminated image with marked differ
ences of illumination between the unused portions of
tosaid optical instrument, retaining means for re
leasably receiving said camera, and means for pro
viding a separation between said camera and the
the image. With the foregoing invention, such a subject
58 can be rotated on the microscope stage 60 to pres
ent a particular chordal segment to the light pickup
(the means for diverting the segment’s light out of the
opening in said optical instrument through which
optical path) to obtain optimum photographic results
from the camera’s automatic exposure control. Selec
tion of a chordal segment for diversion can be done
through the microscope or through the cameras’s 20
viewer or it can be done empirically in accord with the
said image emerges; and
prismatic optical element means, located in said sep
aration, for diverting, from the optical path be
tween said instrument and said camera, at least a
portion of the light forming a segment of said image
results of exposure tests.
otherwise destined to lie outside the ?lm format
It will be understood that variations and modi?ca
tions of the invention are possible in light of this disclo
sure, and it will be apparent to those skilled in the art 25
that various changes in form and arrangements may be
boundary of said camera, and for conducting said
light to a light sensor, said prismatic optical ele
ment means including optically transparent mate
made to suit speci?c requirements without departing
bounded by a pair of smooth parallel surfaces, a
?rst re?ecting surface for re?ecting said light as it
enters said optically transparent material through
a ?rst of said smooth parallel surfaces along the
from the spirit and scope of the invention. Therefore,
it is to be understood that within the scope of the ap
pended claims, the invention may be practiced in a
manner than otherwise speci?cally described herein.
rial with a refractive index greater than 1.0
channel de?ned by said smooth parallel surfaces,
and
What is claimed is:
second re?ecting surface for re?ecting said light
1. An optical element intended for coupling the auto
matic exposure control of a photographic camera hav
coursing through said channel through the second
ing a rectangular photographic format to an image 35
forming optical instrument by diverting light from at
least one portion of said image that will not ?t within
said format to said automatic exposure control, said op
of said smooth surfaces.
4. The adaptor described in claim 3 wherein said pris
matic optical element means further includes:
an intermediate re?ecting surface for re?ecting said
light so as to change its direction within said chan
nel toward said second re?ecting surface.
a first re?ecting surface parallel to an edge of said 40
5. The adaptor described in claim 4 wherein said pris
format and oriented to re?ect light from said opti
matic optical element means further includes:
cal instrument laterally with respect to said cam
a positive refracting surface on the portion of said
era’s optic axis;
second smooth surface through which said light
second re?ecting surface oriented to re?ect said
emerges from said optically transparent material,
light into said camera’s automatic exposure con 45
'
whereby
said refracting surface changes the solid
trol;
tical element comprising:
angle otherwise subtended by said light emerging
dioptric surface, between said second re?ecting
from said second smooth surface.
6. The adaptor described in claim 5 wherein said pos
surface and said automatic exposure control, for
changing the solid angle subtended by said light so
as to increase the amount of said light reaching the 50 itive refracting surface substantially collimates the light
emerging from it.
photosensitive detector of said automatic exposure
7. The adaptor described in claim 6 wherein the focal
control; and
length of said positive refracting surface approximates
the optical path distance through said prismatic optical
homogeneous transparent medium through which
said light travels from said ?rst re?ecting means to
said dioptric surface via said second re?ecting 55 element to the exit pupil of said optical instrument.
*
means.
65
*
*
*
*