U.S. patent number RE36,434 [Application Number 09/198,099] was granted by the patent office on 1999-12-07 for endoscopic device.
Invention is credited to William Habermann, David Hamlin, Arthur C. McKinley.
United States Patent |
RE36,434 |
Hamlin , et al. |
December 7, 1999 |
Endoscopic device
Abstract
An endoscopic device includes an endoscopic tube for insertion
into a cavity to be viewed; an optical system including a video
camera and illuminating means for viewing the cavity, the image on
the screen being a noninverted image; and a removable, rigid,
sterilizable or discardable sheath completely enclosing the
endoscopic tube and the illuminating means to prevent their
exposure to the cavity environment.
Inventors: |
Hamlin; David (Langhorne,
PA), McKinley; Arthur C. (Bradford, MA), Habermann;
William (Blairstown, NJ) |
Family
ID: |
26845510 |
Appl.
No.: |
09/198,099 |
Filed: |
November 23, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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148097 |
Nov 5, 1993 |
5408992 |
|
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Reissue of: |
426608 |
Apr 19, 1995 |
05690605 |
Nov 25, 1997 |
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Current U.S.
Class: |
600/109; 600/121;
600/125; 600/160; 600/170 |
Current CPC
Class: |
A61B
1/00142 (20130101); A61B 5/0088 (20130101); A61B
1/042 (20130101); A61B 1/00193 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); A61B 1/00 (20060101); A61B
1/04 (20060101); A61B 001/04 () |
Field of
Search: |
;600/109,121,125,112,111,160,166,170,171,172,173 ;433/29
;359/654,643,368,385,716,708,784 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leubecker; John P.
Attorney, Agent or Firm: Cohen; Donald S.
Parent Case Text
RELATED APPLICATIONS
This application is a continuation-in-part of Ser. No. 08/148,097,
filed Nov. 5, 1993 now U.S. Pat. No. 5,408,992.
Claims
What is claimed is:
1. An endoscopic device for viewing a field within a cavity
comprising:
a handle;
a solid state video detector within said handle;
a rigid optics tube extending distally from said handle and closed
at its distal end;
illuminating means for illuminating the field to be viewed;
optical means within said optics tube for conveying light from the
illuminated field to the video detector in a manner so as to
provide a non-reversed image at the detector; and
a .[.rigid,.]. removable, sterilizable or discardable sheath
encasing said rigid tube and said illuminating means so as to
completely isolate them from contact with the field or wall of the
cavity.
2. The device of claim 1 wherein said illuminating means is within
said rigid tube.
3. The device of claim 2 wherein said illuminating means is a fiber
optic bundle.
4. The device recited in claim 1 wherein said illuminating means is
external to said rigid tube.
5. The device recited in claim 1 wherein the said solid state
detector is part of a video camera interchangeably mounted in the
handle at the proximal end of said handle.
6. The endoscopic device recited in claim 1 wherein the optical
means creates a straight optical path coaxial with the optics
tube.
7. An endoscopic device for viewing a field within a cavity
comprising:
a handle;
means associated with said handle for mounting a video camera;
a rigid optics tube mounted to said handle, said optics tube being
closed at its distal end;
illuminating means for illuminating the field to be viewed;
optical means contained within the rigid optics tube for
transmitting and focusing a non-reversing image of light reflected
from the illuminated field to the video camera;
a .[.rigid,.]. removable, sterilizable or discardable sheath
positioned over both said rigid optics tube and illuminating means
and completely isolating said tube and illuminating means from
contact with the field or wall of the cavity; and
means for allowing light to pass from said illuminating means out
of said sheath and means for allowing light reflected from the
field to pass through said sheath and rigid tube and into said
optical means.
8. The endoscopic device recited in claim 7 wherein the handle is
of a size and shape which allows the user to comfortably hold and
manipulate the device without touching the portion of the sheath
which is inserted into the cavity to be viewed.
9. The endoscopic device recited in claim 7 wherein the sheath is
removably mounted on the handle in a manner such that the sheath
cannot rotate.
10. The endoscopic device recited in claim 9 wherein the optical
means includes a roof prism, a rod lens at least one objective lens
and a relay lens.
11. The endoscopic device recited in claim 9 wherein the
illuminating means comprises a fiber optic bundle contained within
said optic tube.
12. The endoscopic device recited in claim 9 wherein the sheath is
comprised of a metal or metal alloy.
13. The endoscopic device recited in claim 12 wherein said sheath
is stainless steel.
14. An endoscopic device for creating a three dimensional image of
an object on a video screen comprising:
a handle;
a solid state video detector within said handle;
a rigid optics tube extending distally from said handle;
illuminating means;
optical means contained within said optics tube for focussing light
reflected form the object onto a video detector means such that two
images, one displaced from the other, are focussed upon said video
detection means, at least one such image being non-reversed;
and
a .[.rigid.]. sterilizable or discardable sheath completely
encasing said optics tube which sheath includes means for
transmitting light therethrough.
Description
FIELD OF THE INVENTION
This invention relates to a device having an nonreversing imaging
system and particularly to a device having an autoclavable
endoscopic or bore-scope for viewing internal structures on a video
screen, wherein the image is not reversed with respect to the user.
More particularly, the preferred embodiment provides an
autoclavable sheath and a non-reversed imaging system which may
further include a handpiece adapter for use in such a system.
BACKGROUND OF THE INVENTION
Bore-scopes, endoscopes and similar devices for viewing internal
body structures and cavities on a video screen utilizing an imaging
device and a video camera are well known. Such devices have been
used widely in the medical field for viewing internal human tissue
and in industry for inspecting the hidden surfaces of various
structures.
A typical endoscopic system comprises an endoscopic lens device, a
video camera and a video display and/or storage media. The
endoscopic device comprises a supporting member, having a forward
end to which there is attached an endoscopic tube which enters the
internal cavity to be viewed. The endoscopic tube in some cases,
but not all (some systems rely on ambient lighting), contains a
light guide connected to a light source. e.g. a fiber optic bundle
for illuminating the surfaces within the cavity and a lens system
for conveying light reflected from these surfaces back to the video
camera. The video camera is generally mounted on the supporting
member opposite the endoscopic tube. Low level electrical signals
developed by the camera (e.g. a CCD Chip) are conveyed through
appropriate wires to a signal processing device for creating a
video display and/or recording a video image. In some smaller
endoscopic systems (e.g. intraoral devices), the endoscopic tube is
directly coupled to an SCR camera without an intervening support
member.
For infection control, one recent requirement for such devices is
that any portion of the device which enters a body cavity must be
either discarded or sterilized before reuse. Generally, in previous
apparatus, e.g. the intraoral camera system marketed by AcuCam of
Canoga Park, Calif., the entire forward end of the endoscopic
device, including the light guide and lens system, is detached from
the camera for sterilization. Since sterilization, e.g. by
autoclaving, is generally time consuming, the dentist would require
several expensive lens-fiber optic system members to be on hand for
use with subsequent patients. Further, repeated sterilization can
degrade or damage the optics and light guides. Hence, a need exists
for a device which would allow immediate reuse of a lens-fiber
optic system member without delay, damage, or inventory expense
associated with the necessity of sterilization.
Another shortcoming of the aforementioned intraoral system is that
the same member which is inserted into the oral cavity is held by
the user. While the user (dentist) generally wears protective
gloves and the portion held is generally a short distance from the
inserted portion of the device, it would still be safer for both
the user and the patient, that the user should not have to hold
that portion of the device at all while in use. Any surface not
being exposed directly, either external or internal to the
patient's body cavity is considered an environmental surface and
is/can be treated by appropriate high level disinfection rather
than by sterilization.
A further disadvantage of prior art devices is that the image
displayed on the screen is the mirror image of the actual field
being observed. In such a system, movement by the manipulator of
the device in one direction, e.g. the left, appears as movement in
the opposite direction, e.g. the right, on the screen. This often
leads to a difficulty of interpretation of orientation and
manipulation of the device. It is therefore deskable to employ an
imaging system wherein the image viewed on the screen is not
reversed with respect to the actual movement of the device by its
user.
Still another disadvantage occurring with respect to the prior art
intraoral system is that the bulkiness or size of the inserted
portion tends to block the vision of the user with respect to the
oral cavity and the patient may tend to gag.
Yet another disadvantage of some intraoral systems is that the
optical system is not sealed from the oral (or other) cavity
thereby requiring sterilization of that member containing that
system after each use. Such shortcomings are difficult or
impossible to address without potential fatal damage to precision
electronics and optics.
The novel device may substantially eliminate the above
problems.
SUMMARY OF THE INVENTION
An endoscopic device for viewing, on a screen, a field within a
cavity comprising illuminating means for illuminating the field to
be viewed; optical means for transmitting and focussing light
reflected from the illuminated field onto the plane of a video
camera or other image detector in a manner wherein the image
potrayed on the screen is not reversed with respect to the actual
field being viewed. The preferred embodiment further comprising a
handle; means associated with said handle for mounting an image
detector e.g. a video camera; a rigid optics tube mounted to said
handle, said optics tube having a closed distal end; illuminating
means for illuminating the field to be viewed; optical means
contained within the rigid optics tube for transmitting and
focusing light reflected from the illuminated field back to the
image detector in a manner such that the image to be portrayed on a
screen coupled to the detector is not reversed; a rigid, removable,
sterilzable or discardable sheath over both said rigid optics tube
and illuminating means and completely isolating said tube and
illuminating means from contact with the field or walls of the
cavity; and means for allowing light to pass from said illuminating
means out of said sheath and means for allowing light reflected
from the field to pass through said sheath and rigid tube and into
said optical means. Still another embodiment of the invention
comprises means for creating a three dimensional image.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side, partially cut-away, elevational view of a
preferred embodiment of the assembled device.
FIG. 2 is a bottom elevational view of the device of FIG. 1 without
the sheath.
FIG. 3 is a side cross-sectional view of the device of FIG. 1
without the sheath.
FIG. 4 is a side cross-sectional view of the sheath.
FIG. 5 is a from cross-sectional view of the optics tube of the
device of FIG. 1 along section 5--5.
FIG. 6 is a front cross-sectional view of the optics tube of the
device of FIG. 1 along section 6--6.
FIG. 7 is a side, partially cross-sectional view, of another
embodiment of the device.
FIG. 8 is a side, partially cross sectional view of yet another
embodiment of the invention useful for ENT purposes wherein the
optical path is straight.
FIG. 9 is a side cut-away view of an embodiment of the invention
suitable for creating a three dimensional image.
DETAILED DESCRIPTION OF THE INVENTION
In general, the preferred novel endoscopic device comprises a
handle; means associated with the handle for mounting a video
camera thereto or therein; a rigid optic tube mounted to the handle
and containing therein optical means for transmitting a focussing
light reflected from a surface to be viewed onto the video camera
for display on a video screen and/or video recording wherein the
displayed image is non-reversed; illuminating means for
illuminating the surface to be viewed; video camera means,
preferably detachably mounted to the handle; and a rigid,
removable, sterilizable or discardable sheath over the rigid tube
and illuminating means such that the tube, the optical system
therein and the illuminating means are completely isolated from
direct exposure to the surfaces to be viewed or surrounding
surfaces.
The handle is preferably of a size and shape so as to allow the
user to easily and comfortably hold and manipulate the device
without touching the portion of the sheath which is inserted into
the cavity to be viewed. Typically, the handle is formed from a
plastic but may be made of other materials as well, e.g. wood,
ceramic or metal.
The means for mounting a solid state video camera to the handle can
be any means known in the art. For example, the handle can be
provided with a hollow bore having internal screw threads into
which a camera can be screwed, or a simple tapered bore can be
provided which mates with a tapered camera housing or a key and
groove interconnection or a quick release snap-on interconnection
can be provided.
The rigid optics tube is generally affixed to the handle opposite
the camera. It may be permanently affixed to the handle or
removably affixed thereto. If permanently affixed, the dimensions
of the endoscopic portion of the device as well as the optical
system contained within the tube are likewise fixed. Where the
optics tube is removably affixed so that an alternate tube can be
placed on the handle, the length of the tube as well as the focal
plane and magnification, if any, of the optical system can be
changed.
The optics tube is preferably completely enclosed so that the
optical system is protected thereby. Also, it is generally
preferable, but not necessary, that the optics tube also contain
therein the illumination means. The illumination means generally
comprises a bundle of light transmitting fibers which transmits
light from a light source, through the fiber bundle and out of the
device so as to illuminate the area to be viewed. Typically, the
optics tube is made of a rigid durable material such as stainless
steel, but can be made of virtually any rigid material. When the
tube is opaque, at least one transmitting window must be provided
therein to allow light reflected from the surface to be viewed to
be collected by the optical system for transmission onto the camera
and when the optics tube also contains the illuminating means
therein, a light transmitting window for the illuminating light
must also be provided. This can be two separate windows or a single
enlarged window. Any light transmitting material, e.g. glass or
quartz, is suitable as a window material. Where the optical tube is
itself transparent, a separate window is not required but the tube
should be flat and polished in the area through which the light is
transmitted so as not to distort the image. A feature of the novel
invention is the use of a rigid, removable sheath which as
indicated completely surrounds and isolates the optical tube,
optical system and illuminating means. The sheath should itself be
devoid of any optical components other than possibly one or more
light transmitting windows aligned with the illuminating mean/and
optical system to allow light to pass out of and into the device,
respectively. The sheath should either be made of a material which
is sterilizable, i.e. autoclavable, e.g. stainless steel or other
non-corrodible metal or alloy, a high temperature plastic or a
ceramic, or may be made from an inexpensive rigid plastic which may
be discarded after use. Preferably, the sheath fits coaxially over
the optics tube, has a closed distal end and is secured to the
handle in a manner to substantially prevent its rotation or
movement during use.
This invention also contemplates an embodiment wherein a solid
state video detector, e.g. a CCD chip is positioned so as to be
directly illuminated with light reflected from the field to be
viewed without the need for intermediate lens, prisms or the
like.
Also contemplated are embodiments employing a straight optical path
(or one at an acute angle for use use in the ear, nose and throat
(ENT) as well as an embodiment wherein the lens system creates two
displaced images for the creation of a 3-D image.
All of the embodiments have in common the use of a handle for
continously holding and manipulating the device; a removable,
sterilizable sheath protecting the optics; the creation of
non-inverted images for viewing on a screen; and preferably, the
absence of any occular piece for direct viewing.
A preferred embodiment of the novel device particularly useful as
an intraoral endoscopic device is described with reference to FIGS.
1-7.
Referring to FIGS. 1-6 there is shown a novel device 1 comprising a
hollow central support member 10 which acts as the handle for
holding the assembled device 1 when in use; a narrow elongated lens
tube 12 having an appropriate lens system 14 contained therein said
tube 12 being mounted within and extending from the distal end 16
of the support member 10. A removable sheath 18, adapted to fit
over and completely protect and isolate the lens tube 12 from
exposure to the oral cavity or other cavity to be viewed so as not
to become contaminated therefrom, is positioned over the lens tube
12. Means are provided with respect to the support member 10 and
the sheath 18 such that the sheath 18 will not be disengaged or
move while the device 1 is in use. A solid state video camera 22 is
removably mounted within the proximal end 24 of the support member
10. In addition, a fiber optic bundle 26 is provided. The fiber
optic bundle 26 is coupled to a light source (not shown) at one end
thereof and extends into and terminates within the narrow lens tube
12.
The support member or handle 10 is made in a shape and size which
facilitates holding the device in operation without having to touch
any portion of the device which may be inserted in the cavity to be
viewed. e.g. the mouth. It may be made of any convenient rigid
material including plastics and metals.
The distal end portion 16 of the handle 10 is cylindrical and is
provided with a shallow groove 28 circumferentially the area around
into which is placed an O-ring 30. A narrow lens tube hole 32 is
centrally bored axially through the distal end portion 16 of the
handle 10. This narrow lens tube hole 32 communicates with a
centrally bored wide camera hole 34 which extends through a main
body portion 36 of the handle 10. The distal part of the main body
portion 36 of the handle 10 is provided with a flat surface 38. In
addition, a fiber optic entrance hole 40 which communicates with
the camera hole 34 is provided through the proximate end of the
handle 10 below the camera hole 34.
The proximate end of the camera hole 34 is provided with means,
such as a threaded portion 42, so as to removably accept the solid
state video camera 22 therein.
The lens tube 12 is of a diameter such that it securely fits within
the lens tube hole 32 of the handle 10. As can be seen from FIG. 3,
the optical system 14 contained within the lens tube 12 comprises
the fiber optic bundle 26 through which light from a light source
(not shown) is transmitted through the lens tube 12 and emanates
from the lens tube 12 via a lens tube transmissive window 44. Light
reflected from the surface to be viewed is transmitted back into
the lens tube 12 via an optical window 46 adjacent and proximate to
the transmissive window 44. The reflected light entering optical
window 46 adjacent and proximate to the transmissive window 44. The
reflected light entering optical window 46 then passes through a
series of optical imaging devices including a right angle roof
prism 48, a set of objective lenses 50, a rod lens 15 and a video
relay lens 52. Inherent in the function of the roof prism 48 is the
reinversion of the reversed image to be viewed such that the image
to be viewed on the screen is not inverted with respect to the
actual visual appearance of the field being viewed by the user of
the device. In this way, movement of the image of the device on the
screen with respect to the field, e.g. to the left, mimics the
direction of actual movement of the device in the cavity being
viewed. Absent the roof prism, the lens system as shown, inverts
the image resulting in a mirror image of the field on the viewig
screen. It should be understood that while use of the lens system
with the roof prism as set forth above is preferred, any lens
sysyem which provides a nonreversed non-inverted) image on the
viewing screen is contemplated as part of this invention. For
example, other suitable lens system include the use of a pair of
lenses, the first reversing the image while the second returning
the image to a nonreversed state. The final image is made to focus
upon the solid state camera 22 which is mounted on the opposite end
of the handle 10. The end 53 of the lens tube 12 is closed so as to
prevent contamination of the optics. As can be seen with reference
to FIGS. 5 and 6, the optical fibers 26 extend axially through lens
tube 12 adjacent rod lens 15 until they approach the area of window
44 where the fibers are bent 90 degrees downwardly so as to
terminate with their ends adjacent the window 44 in a direction
essentially perpendicular to the axis of the lens tube 12. It will
be understood that the invention is not limited to any specific
lens system and any lens system which conveys the light to the
video detector of the camera so as to give a non-reversed sharp
image is suitable. In fact, a lensless system wherein the video
detector is directly illuminated also falls within the scope of the
invention. Further, for non-oral cavity applications, it may be
preferred to use a straight path or acute angle path lens and
illuminating system wherein the illuminating light eminates in a
direction essentially parallel to or at an acute angle to the axis
of the lens tube 12 and the light reflected from the field is
picked up by the lens system at essentially the same angle.
The sheath 18 is closed at its distal end 54 and when in operating
position, concentrically surrounds lens tube 12. The proximal end
56 of the sheath 18 snugly fits over the distal end portion 16 of
the handle 10. The O-ring 30 forms a seal so as to prevent
contamination from entering the cavity formed by the space 57 (see
FIG. 1) between the outside of the lens tube 12 and the inside of
the sheath 18, thus preventing contamination of the lens tube 12
and obviating the need for sterilization of the lens tube 12. The
proximal end portion 56 of the sheath 18 is provided with an
extension 58 having a flat upper surface 60 which snugly mates with
the flat surface 38 provided on the handle 10. This prevents
rotation of the sheath 18 during use. The sheath is also provided
with light transmitting glass or quartz windows 62 and 64 which are
in registration with windows 44 and 46 of the lens tube so that
light emanating from the lens tube 12 can pass out of the sheath
18, and the light reflected from the surface to be studied can pass
through the sheath 18 into the optical lenses of the lens tube
12.
The embodiment shown in FIG. 7 is essentially the same as the
previously described embodiment except that the lens system is
replaced by a solid state video detector 66 positioned adjacent
window 46 in tube 12 and means 68 are provided for transmitting the
signal produced in the detector to the signal process or of the
video camera. Also, the fiber optic illuminating means 26 is
outside of, but adjacent the tube 12.
Referring to FIG. 8, there is shown a device similar to that shown
in FIG. 3 except that the distal end is configured so that the
light path is along the axis of the lens tube 12. More
particularly, the fiber optic bundles 26a which supply illumination
are not curved at there ends as in the embodiment of FIG. 3, but
instead continue parallel to the axial direction of the lens tube
12 until there termination. Similarly, the lens system eliminates
the right angle roof prism and any associated mean for providing a
90 degree angle with respect to the axis of the lens tube 12 and
replaces this with a lens 67, the axis of which is in line with the
axis of the lens tube 12 and which, preferably terminates in the
same plane at the distal end of the lens tube 12 as does the fiber
optic bundles 26a. Of course, in this embodiment, a transmission
window 46a is located at the distal end face of the lens tube 12
and a corresponding transmission window 64a is located at the
distal end face 54 of the sheath 18. While only one large window is
shown for each of the lens tube and the sheath, one could employ
separate windows for the fiber optic bundle and the lens system, if
desired. This straight light path configuration is particularly
suitable for ENT endoscopes.
Referring to FIG. 9, there is shown an optics tube having a lens
system which allows for the provision of a three dimensional image
when the output of the video camera associated therewith is coupled
to a video processor as is known in the art for producing three
dimensional video images from a pair of displaced two dimensional
images of an object. Here, however, the two images are produced
along a single lens path. In accordance with this embodiment, a
lens tube 12b contains therein a fiber bundle 26b for transmitting
illuminating light to an object 68 to be viewed. A window 44b is
provided in the lens tube 12b for allowing the light to be
transmitted outside the lens tube 12b. An objective lens 70 for
focussing the image on the detector(s) is essentially centrally
located in the lens tube 12b proximately of the video detector (not
shown)). Distally from the objective lens 70 in order of location
is an optical system comprising a collimating lens 71, a first pair
of rod lenses 72 and 74, a triangular prism 76, a second pair of
rod lenses 78 and 80 and a pentaprism 82. The various members of
the lens system all have their optical axes alligned with the axis
of the lens tube 12b except for the triangular prism which
preferably, is somewhat tilted. Windows 84 and 86 are provided in
the lens tube 12b so as to be registered with and allow light
reflected from the object to enter the triangular prism 76 and the
pentaprism 82, respectively. The objective lens may either be a
thin lens for focussing the displaced images created by the system
on a single plane on the face of a solid state video detector, or
may be a thick lens creating a pair of longitudinally displaced
images which can be focussed on a pair of longitudinally displaced
video detectors.
In operation, light eminating from window 44b of lens tube 12b,
strikes the object 68 and is reflected therefrom. The reflected
light enters the lens system through windows 84 and 86 and into
prisms 76 and 82 respectively. The light is then transmitted along
the optical path to the objective lens and focussed on the video
detector. Light entering through the pentaprism 82 creates a non
reversed image, while light entering the triangular prism 76
through window 84 creates a reversed image which may be processed
to a nonreversed image by means of known electronic video
processing techniques. By tilting the triangular prism jus a few
degrees, one can obtain a better separation of the reversed and
nonreversed images. The video processor converts the images to a
three dimensional video display.
The novel device and system have several advantages over prior art
devices. One primary advantage is an easily removable sheath which
can be made of a rigid plastic material or of a metal such as
stainless steel and which can be discarded (when made of and
inexpensive plastic) or autoclaved or otherwise sterilized,
separate and apart from the optical system, and which completely
protects and isolates the tube containing the optical system from
exposure to contamination.
A second advantage is the provision of a universal handle which
negates the necessity of touching any part of the device which is
inserted into the cavity to be viewed and also provides for quick
and easy changing of video cameras according to the application. In
addition, the lens tube could also be made interchangeable so that
one can readily alter the lens system to fit ones need depending
upon the application. Such interchangeability of camera and/or
lenses greatly broadens the practical use of the device without
substantial cost.
Another important advantage is the provision of a noninverted
screen image whereby the movement depicted on the screen mimics the
actual direction of movement of the device in the field being
viewed.
Still another advantage is that due to the preferred lens system,
the width of the endoscopic portion of the device can be made
relatively narrow e.g. 1/4", so that it does not block the users
field of view.
It should be understood that the embodiment shown and described
herein is but one embodiment of the invention and it is not meant
to be limiting but only exemplary. For example, while it is
preferred that the handle be of a size large enough and shaped so
that the user can easily hold and manipulate the device, the size
and shape are not critical. Also, while engagement of the video
camera to the handle is shown to be by means of a screw thread,
virtually any means known for making readily disengageable
connections, e.g. quick-disconnects, key and slot, snap-on, set
screw, or other connections known in the art are suitable.
Similarly the means for removably mounting the sheath over the lens
tube and to the handle is not critical and may be altered in any
manner which would accomplish sealing of the lens tube from the
environment without rotation of the sheath. Also, where the sheath
is a light transmitting plastic, the separate windows provided in
the sheath can be eliminated. Further, while for use as an
intraoral device the typical length of the lens tube and sheath is
from 4 to 6 inches, these members can be made of virtually any
length provided the optics can be made to accommodate the length
either by different lens systems or transmission of a focused image
to the camera such as by means of optical fibers.
* * * * *