Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVEMENTS IN MICROSCOPE
ILLUMINATION AND STEREO VIEWING
BACKGROUND OP' TFIE INVENTION
5 Field of the Invention
The present invention relates to light microscopes including
light microscopes having dual eyepiece (binocular) viewing and the
ability to produce a stereoscopic (stereo) image that can be viewed
and/or photographed in real time. The invention further relates to
1 d reflected light illumination (including epi illuminated fluorescent
images) for microscopes with reduced flare without reduced
specimen illumination.
The Prior Art
Although many microscopes are equipped with a binocular
15 ~~ng ~angement, that alone does not produce a stereoscopic
view of an object since both of the viewing eyepieces typically see
the enact same image from the same angle. Stereoscopic viewing
requires that each eye see a different image of the object. This is
accomplished by creating parallax (viewing the object from
20 d~'erent angles) in much the same way that human eye pairs create
stereoscopic vision.
At the present time there are two types of stereoscopic
microscopes widely known and used. The first of these (inclined
axes type) is. in essence, two complete microscopes with their
25 objectives close together and with their major axes inclined to each
other to permit object viewing from two different angles to create
the parallax necessary for producing a stereo pair. An example of
this type of microscope is the Nikon~ model SMZ-2B/2T.
30
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The other type of stereo microscope (parallel-axis type)
utilizes a single large objective lens followed by two smaller side-by
side lens groups whose axes are parallel to the objective lens axis
and which share the aperture of the large objective. In this
arrangement, only a small portion of the aperture of the large
objective lens is used. An example of this type of microscope is the
Nikon(J model SMZ-10.
Both of these types of stereo microscopes have the well
recognized limitation in the magnification that can be achieved.
This limitation, that prevents total magnification of more than 100
times (approximately), is imposed by the practicalities of size and
space. As magnification increases, the size of the objective (and its
focal length and working distance) decreases. In the case of the
inclined type of microscope, there is insufficient space for two
objective lenses when the objective magnification exceeds
approximately 10 times (the centers of the lenses need to be closer
together than their physical size - radii- permits). Likewise, for the
parallel-axis microscope, it is not possible to physically dispose
two side-by-side secondary lenses behind the primary objective
when the objective is diminished beyond a certain size (i.e. as the
objective magnification increases beyond 10 times - approximately).
One undesirable characteristic of reflection illumination, and
especially fluorescent illumination (either by virtue of natural
fluorescence or the use of fluorescent markers), is flare, which if
not controlled, can prevent good images from being captured. Prior
art systems using epi fluorescent illumination, for example, have
attempted to control flare by the use of an iris within the rear
aperture of the objective. Since all such irises are optically
disposed between the light source and the objective, they
necessarily reduce the light that reaches the specimen as they
reduce flare. Thus, the cost of controlling the flare is a reduction in
the amount of light that reaches the specimen (object) and a
concomitant reduction in the numerical aperture of illumination.
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While the control of flare in this way eliminates one source of image
degradation, the accompanying light loss can prevent images from being
recorded on film in some specimens and seriously reduces the quality of
images that are achieved in others.
SUMMARY OF THE INVENTION
The present invention provides improvements in microscopes
including reduced flare without reduced illumination and an improved
binocular viewing head and camera recording system in which each
eyepiece and/or camera views the object from a different angle through a
single objective, regardless of the size of the objective, and therefore,
regardless of the overall magnification of the microscope. The invention
permits the simultaneous viewing and photographing of stereo images and
convenient means for photographing images in two dimensions for the
highest possible resolution.
The objects of the invention are achieved by projecting an image of
the rear aperture of the microscope objective lens at a remote location in
space (relative to the actual rear aperture) and dividing the beam at the
proj ected image and/or placing an iris at the proj ected image to control
flare.
Accordingly, in one aspect, the present invention provides an
improvement in a light microscope having an obj ective lens with a rear
aperture and employing reflection illumination from an object to be viewed
by a viewing means, the improvement comprising: means projecting an
image of the rear aperture of the obj ective lens to a location in space
remote
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from the objective lens; and an variable diaphragm iris for controlling flare
optically disposed between the objective lens and the viewing means in close
proximity to the projected image of the rear aperture of the objective lens.
In a further aspect, the present invention provides an improvement in
a high power light microscope having a single objective lens with a rear
aperture through which light from an object to be viewed passes, and a dual
eyepiece viewing means for viewing an image of the object, the
improvement comprising: beam dividing means optically disposed between
the obj ective lens and the dual eyepiece viewing means in the path of the
light from the object to be viewed operative to divide the light from the
obj ect to be viewed into first and second separate light beams wherein the
first separate light beam includes light passing from one area of the obj
ective
lens rear aperture to one of the dual eyepieces of the viewing means and the
second separate light beam includes light passing from a different area of the
objective lens rear aperture to the other of the dual eyepieces of the viewing
means, wherein said beam dividing means is located remote from the rear
aperture of the objective lens; projecting lens means disposed between the
objective lens and the beam dividing means in the path of the light from the
object to be viewed operative to image the rear aperture of the objective lens
at a location remote from the objective lens and in close proximity to said
beam dividing means; and, a variable iris diaphragm optically disposed in
close proximity to the projected image of the rear aperture of the objective
lens between the obj ective lens and said beam dividing means for controlling
flare.
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For stereo viewing or recording, reflector means operate very near the
rear aperture of the objective lens to divide the light into two separate
beams
and direct those beams to the two separate viewing means (eyepieces and/or
cameras) of the binocular viewing system. A reflector means in the form of
a "V" shaped mirror reflects the light from one half of the objective (via
other reflector means ) to one of the viewing means while the other half of
the light is reflected to the other viewing means. In this way each viewing
means receives the light from one half of the objective rear aperture and
therefore views the object from a different angle, producing true
stereoscopic viewing in real-time, with real colour, using either transmitted
light, reflected light or fluoresence light.
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Because limitations of size and space for high power
microscopes make it impossible or impractical to place a mirror at
the rear aperture of the objective lens where the beam is most
advantageously divided, lenses are used to relay an image of the rear
aperture of the objective at a location in space where the mirror
can be practically located. The beam is then divided at this location
in space precisely as it would be if the mirror were physically
located adjacent the objective's rear aperture. The particular
lenses used to produce the remote imaging of the objective rear
aperture depend on whether the objective is of the "infinity focus"
type or the "finite focus" type, as well as on all the other parameters
of the particular optical system . In either case the result is the
same.
The unique combination of the projected image of the rear
aperture of the objective and the placement of an iris near that
projected image (in that proximity to the projected image of the
rear aperture of the objective lens in which the image of the iris is
not seen by the viewing means), provides for the first time the
ability to control flare in a microscope using reflected light without
having to reduce the intensity and cone angle of the illumination
reaching the specimen. Using this unique combination, it is
possible to see and record epi illuminated images (including
specimens that fluoresce) of a quality never before known. When
combined with the stereo teachings of the invention, it also
provides for the first time the ability to take high power
simultaneous stereo pair photographs of reflected light images,
including epi illuminated fluorescent images.
Thus, it is an object of the present invention to provide an
improved stereoscopic viewing system for a light microscope for
producing, viewing and/or recording stereo images of an object.
A further object of the invention is to provide an improved
head for a light microscope for stereo viewing in which the spacial
orientation of the viewed image is the same as that of the object
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being viewed.
Yet another object of the present invention is to provide a
5 high power microscope stereoscopic viewing head which can
readily produce 3D stereo pair photographs simultaneously, as well
as high resolution two dimensional photographs.
Another object of the present invention is to provide
reflection illumination (including epi fluorescent illumination) with
IO reduced flare without reducing the amount of light directed onto
the specimen (object).
There are other objects of the invention which in part are
obvious and in part will become apparent from the description of
the invention set forth herein below.
15 BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration of a binocular optical
system for stereoscopic viewing incorporating one embodiment of
the present invention;
Figure 2 is an isometric view of the beam-dividing mirror of
2 0 Figure 1;
Figure 3 is a schematic drawing of a binocular optical system
for stereoscopic viewing incorporating another embodiment of the
present invention in which the rear aperture of the objective lens is
imaged in space;
25 Figure 4 is a perspective view of an embodiment of the
invention including image spacial orientation optics.
Figure 5 is an overhead view of the embodiment of Figure 4
showing the head of the present invention with cameras positioned
to receive part of the image beams;
30 Figure 6 is the same as Figure 5, with the eyepiece reflecting
mirrors positioned out of the beams' path.;
Figure 7 is the same as Figure 6, with the polyhedron reflector
rotated to a new position wherein all of the beam is reflected into one
camera;
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Figure 8 is an alternative embodiment to that shown in
Figure 4 with the addition of means for two dimensional photo
recording through a minimum of glass; and
Figure 9 is a perspective view of an embodiment of the
invention including epi illumination and flare control.
DETAILED DESCRIPTION OF' THE INVENTION
Referring to Figure 1, a microscope objective 11 (typically
composed of a plurality of lens elements) receives a light beam 10
from an illuminated object 12 located at a specimen plane 13. A
V-shaped mirror beam dividing means 17 divides the beam 10 into
two separate beams, l0a and lOb. The separate beam l0a follows a
path to a left eyepiece mirror 18 and left eyepiece 14 of binocular
~e~ng system 15. The other separate beam lOb follows a path to a
right eyepiece minor 19 and a right eyepiece 16 of binocular
viewing system 15. An image 12' of the object 12 is created at the
focal plane 20 of eyepiece 14 and focal plane 25 of eyepiece 16.
The V-shaped mirror 17 is formed by a left panel 21 having a
reflective surface 22 and a right panel 23 having a reflective surface
24 joined together at a right angle along a mirror edge line 26.
The mirror 17 can take anyone of several forms including that
resulting from silvering the two faces of a prism (see Figure 4).
The essential elements of the mirror 17 for the purposes of the
present invention are two reflecting surfaces at approximately right
angles positioned at approximately 45 degrees to the optical axis
OA of objective lens 11. By placing the mirror 17 in close proximity
to. and with its edge line 26 generally bisecting the rear aperture
27 of objective 11 (edge 26 falling along a diameter of the rear
aperture), half of the light passing through the rear aperture 27 of
objective lens 11 will be reflected to the left eyepiece 14 by way of
left eyepiece mirror 18 and the other to right eyepiece 16 by way of
right eyepiece mirror 19.
By virtue of this arrangement of components, the left
eyepiece views the object 12 from the angle of the left half of the
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objective lens 11 while the right eyepiece views the object from
the angle of the right half of the objective lens, thereby giving rise
to a stereoscopic view of the object through the binocular viewing
system 15.
In order for the mirror 17 to capture a full field of view and
provide well separated left and right images, the minor 17 needs
to be disposed in very close proximity to the rear aperture of
objective lens 11, as shown in Figure 1. If the lens 11 and the V-
shaped mirror 17 are too close, however, some of the reflected
light from mirror 17 will be blocked from the eyepiece mirrors 18
and 19 by the lens 11. Thus the lens 11 and mirror 17 should be
as close as possible to the rear aperture of the objective without
causing loss of field by the lens itself.
While it is practical in the case of low-power microscopes to
locate the mirror 17 in close proximity to the rear aperture of the
objective lens, it is impractical, if not impossible, in the case of
high-power microscopes where the objective lenses are very small
and typically mounted so as to make their rear apertures physically
inaccessible. High-power microscopes typically include a turret
mount having a plurality of lens receiving stations where lenses of
various magnifications can be attached so that during examination
of an object several different levels of magnification are readily
selectable. To accommodate this arrangement, objective lenses for
high-power microscopes are typically imbedded within a lens
holder designed to be compatible with the turret mount for easy
attachment to and detachment therefrom. In these circumstances,
the rear aperture of the objective lenses are even less accessible
and it is, thus, impossible to dispose a minor (such as V-shaped
mirror 17) at sufficiently close proximity to the rear aperture to
realize the full advantages of the present invention.
Referring to Figure 3, an illuminated object 32 (at a specimen
plane 33) transmits light 30 to the front element 40 of an objective
lens 31. This light is ultimately directed to a left eyepiece 34 and a
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right eyepiece 36 of a binocular viewing system 35 as described .
above in connection with the embodiment of Figure 1. Because the
rear aperture 37 of objective lens 31 is physically inaccessible, a V-
shaped mirror 38 having reflective surfaces 38a and 38b with the
same characteristics as described in connection with mirror 17
reflective surfaces 22 and 24 (Figures 1 and 2), for splitting the
light from the objective into left and right components is of
necessity disposed at a location remote from the rear aperture 37.
In order for mirror 38 to effectively divide the light into left
and right components, an image 37' of the rear aperture 37 is
projected to a location at or very near mirror 38 by a set of relay
lenses (indicated generally at) 39. By imaging the rear aperture 37
to a remote location and locating mirror 38 in close proximity
thereto, the division of the light from the rear aperture 37 of the
objective lens 31 is accomplished with the same effect as if the
mirror 38 were in fact located immediately adjacent the rear
aperture 37 itself (as described above in connection with the
embodiment of Figures 1 and 2). Thus, the minor 38 directs half
of the light from the rear aperture 37 of the objective lens 31 to
the left eyepiece 34 by way of left eyepiece mirror 41, and the
other half to the right eyepiece 36 by way of right eyepiece mirror
42. When the V-shaped mirror is placed at the projected image of
the objective rear aperture (rather than at the rear aperture itself
as in the embodiment of Figure 1), there is no lens element in such
close proximity as to occlude any of the reflected light and thus the
V-shaped mirror can be placed virtually at the rear aperture.
The best results are achieved by placing the V-shaped mirror ,
38 as near to the image 37' as possible. As the distance between
the mirror 17 and the rear aperture 27 (Figure 1) or mirror 38 and
the image 37' of the rear aperture 37 (Fig. 3) increases, the parallax
decreases until at some distance the two minors of the V-shaped
mirror 38 see the same image (from the same angle) and the
stereoscopic effect is lost (and a portion of the field of view is lost).
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Thus, in the present invention, the dividing V-shaped mirror ( 17 in
Figure 1 and 38 in Figure 3) must be within that range of the
objective rear aperture or its projected image that produces
different images at the two reflective surfaces (22 and 24 of Figure
l and 38a and 38b of Figure 3) of the dividing mirror and thereby
produces a stereoscopic effect.
While the beam dividing and directing means described above
has been shown as a V-shaped mirror, one or more prisms could
also be used for that purpose.
The embodiment of the present invention wherein an image
of the rear aperture is projected to a remote location (Fig. 3),
permits an iris 45 to be located near the image 37' of the rear
aperture 37 of the objective in order to control flare and scattering
of light and to improve contrast and depth of field as well. The
advantages accruing to locating the iris out of the specimen
illumination path (where it is found in the prior art) are described
in detail below in connection with Figure 9.
The various arrangements and specifications of lenses 39
used to create an image 37' of the rear aperture 37 of the objective
lens 31 at a remote location in space (where the mirror 38 and iris
45 can be physically disposed in close proximity thereto), are well
known to those skilled in the art of microscope optics and as such
2 5 do not themselves form a part of the invention. For a given
objective lens the arrangements are numerous and the optical
design can vary considerably.
High power light microscopes popularly in use at the present
time employ one of two types of objective lens. One type of lens,
produces a beam that is focused at infinity (basically parallel) to
permit the distance between the eyepieces and the objective to be
varied when necessary to accommodate other equipment. The
other type of lens produces a beam which is focused at a finite
distance, thereby fixing the distance between the objective lens and
the eyepieces of the binocular viewing system. It might appear, in
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the case of the infinity focus lens, that it would be possible to place -
a mirror, such as mirror 38, at a remote location from the rear
aperture of the objective lens and still obtain a full field of view. In '
practice, however, although the beam from the objective is focused
at infinity, the beam envelope diverges. Thus, at a distance from
the objective lens where a mirror such as minor 38 could be
located, the divergence of the beam would cause a significant part
1 O of the field of view to be lost and the parallax between right and left
images would be greatly reduced. Thus, whether a microscope is
one employing a finite focus objective lens or an infinity focus
objective lens, it is necessary to create a remote image of the rear
aperture of the objective lens adjacent to the dividing mirror 38. It
I5 may be necessary to interpose between the rear aperture 37 and
the lenses 39 optics, such as a roof prism, for reversing the image
so that the image that is viewed at the binocular eyepieces has the
same orientation in space as the object being examined.
Referring to Figure 4, light beam 60 passing through an
20 objective lens 61 is folded by mirrors 62a and 62b (to reduce the
size of the head) and directed through a field lens 63 to a roof
prism 64 which established the correct background-foreground
orientation to the viewer by directing the left eye view to the left
eyepiece 74 and the right eye view to the right eyepiece 71. A
2 5 deviation prism 70
( which can be separate from or integral with roof prism 64 - in
this embodiment it is shown integral with the roof prism 64)
orients the axis of the light beam 60 at an angle comfortable to a
viewer. The light beam 60 then passes through a series of lenses 66
30 that act as a relay system to image the rear aperture of the objective
.lens 61 in close proximity to the edge of V-shaped planes 65 (only
one of which is shown) of a polyhedron dividing minor 67. An iris
68 is disposed in the light path between the lenses 66 and the
mirror 67 in order to reduce flare.
A first separate beam 60a of the divided beam is
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reflected into an eyepiece 71 by beam deflection means mirrors 72
and 73 (72 may be partially silvered to permit transmission as well
S as reflection), while the other part 60b of the beam is reflected into
eyepiece 74 by mirrors beam deflection means 76 and 77 (76 may
be partially silvered to permit transmission as well as reflection).
The use of a two mirror reflection means to reflect the beam into
an eyepiece as opposed to a single mirror (as in the embodiments
of Figures 1 and 3) adds an additional reflection which reverses the
image giving it correct left-right orientation to the viewer.
The roof prism 64 operates on the beam not only to bend it
to a more user friendly angle but also to orient the image so that
the background-foreground orientation is the same to the observer
as the actual specimen being observed. However, in doing so,
prism 64 also reverses the left-right orientation of the specimen
thus requiring minors 72 and 76.
Other arrangements of mirrors and prisms, some well known
in the art, can be employed in the system of the present invention
2 0 to orient the image to the observer to correspond to the orientation
of the specimen relative to the observer .
In addition to an observer viewing the stereoscopic image
through eyepieces, the present invention affords the ability to
create high power simultaneous stereo pair photographs.
2 5 Referring to Figures 5, 6, and 7, a first photographic camera
port 46 is located in the path of the light beam that passes through
the partially silvered mirror 76, while a second photographic
camera port 51 is located in the path of the light beam that passes
through the partially silvered mirror 72. Photographic cameras 46a
30 ~d 51a are attached to the camera ports 46 and 51, respectively.
When it is not necessary to provide an image of the object to
the eye-pieces, the mirrors 72, 73, 76, and 77 can be selectively
positioned out of the paths of the beam 60a and 60b (see Fig. 6) to
permit the reflecting surfaces 65 of the polyhedron dividing means
minor 67 to reflect beams directly into the cameras ports 46 and
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51 so as to increase the light available to the cameras 46a and 51a. .
Because the present invention permits stereo photos to be
taken of the right image and the left image simultaneously, the
present invention provides, for the first time, a stereoscopic
microscope viewing system capable of taking high power stereo
pair photographs of objects (such as living organisms) whose
images are in constant flux.
For two-dimensional, high resolution photography using a
single camera, the present invention provides the polyhedron
dividing mirror 67 with an integral 45 degree reflective surface 70
which when rotated into the path of the light beam 60 (see
Figure 7) directs the light beam 60 directly into camera 46a. The
mirrors 76 and 72 remain out of the beam path.
Referring to Figure 8, an alternative embodiment of the
invention provides a mirror 62b' which is partially silvered (e.g.
80/20) to permit most of the light (80% for example) to pass
directly through to a camera port 80 with the rest of the light
(20%) reflecting from mirror 62b' and then passing through to the
viewing eyepieces 71 and 74 as previously described with reference
to Figure 4. The advantage of this embodiment is that the light
beam 60 enters the camera port 80 directly and before it passed
through the multiple lens and prism system necessary to produce
2 5 correctly spatially oriented stereo images to a viewer. The port 80
thus sees an image whose quality is undiminished. Where viewing
of the image is no longer necessary, the mirror 62b' can be
selectively positioned out of the path of light beam 60 to permit
the entire beam 60 to enter the camera port 80.
Thus, the present invention teaches a system whereby an
object can be viewed under high power magnification in 3D with
high resolution and simultaneous 3D stereo pair photos can be
taken either while still viewing the object or after the viewing
means has been disabled to enable all of the available light to be
directed to the photography recording apparatus. Two
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dimensional high power high resolution photographs can also be taken while
viewing the object in 3D.
Referring to Figure 9, a reflection light source 82 (shown by way of
example only as an epi illumination light source 82 including a fiber optic
bundle 83 with a lens 84 for focusing purposes - other known forms of
reflected light, including side lighting, can be used as well). The light from
source 82 is directed onto, and reflected by, a beam sputter ( such as a half
silvered mirror) 86 and a mirror 87 and then through the objective 61 to a
specimen 88. The light reflected by the specimen passes through the
objective 61 onto the mirror 87 and through the half silvered mirror 86 to
mirror 62b and into the optical system described with reference to the other
Figures. The benefits to a reflection illumination microscope of the
combination of the projected image of the rear aperture of the objective lens
and an iris in close proximity to that projected image are enjoyed by two
dimensional viewing systems as well as by the 3D system of the present
invention. Since the light from the source 82 is not constricted by an iris as
it passes to and from the specimen (not shown), essentially all of the
available illumination from the light source 82 reaches and illuminates the
specimen (not shown), and the full numerical aperture of illumination is
operative.
The iris 68, previously described, is optically disposed near the
projected image 37' (see Figures 3 and 8) of the rear aperture of the
objective
in a portion of the reflection path of the beam 60 which is not coincident
with any part of the illumination path of the beam 60 from the light source
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to the specimen. In order to avoid a reduction in the field of view and
maintain uniform lighting over the entire field of view, the iris is
preferably
within that near proximity of the projected image of the rear aperture where
the iris is not seen by the viewing means (human observer, camera, etc.).
The iris, so located, has the same effect as an iris within the rear aperture
of
the objective; it limits the flare before the image carrying beam 60 reaches
either the eyepieces 71 and 74 or the camera ports 46 and 51. Because the
iris of the present invention is not in the illumination path, however, it
does
not restrict the light from the light source 82 to the specimen (not shown).
In this way flare is effectively controlled without reducing the light
available
to light a specimen, including the illusive specimens that the advent of
fluorescent illumination has made possible to record and see.
Obviously, many modifications and variations of the present invention
are possible in light of the above teachings. It is, therefore, to be
understood
that within the scope of the appended claims, the invention may be practiced
otherwise than as specifically described.
