Patent Description:
The invention relates to optical instruments such as endoscopes, exoscopes, and borescopes having an image sensor assembly at the distal end of the instrument shaft or, more preferably, with an image sensor assembly as part of a camera head connected to an endoscope. In some particular embodiments, the invention relates to image sensing systems that can produce a combined image from multiple image sensors located within the distal end of the instrument shaft, and to optical instruments incorporating such image sensing systems.

Instruments such as endoscopes and borescopes are used to allow a visual inspection of locations which are not readily accessible. For example, endoscopes are typically (although not exclusively) used in medical applications to provide a view of an area within a patient's body. Whether employed for medical or other applications, the instrument typically includes an elongated shaft of relatively small diameter extending from a handle to a distal end.

An imaging or viewing arrangement is included with the instrument to allow a user to obtain a view from the shaft distal end. This arrangement may include a system of lenses and a light conduit through the shaft to direct an image from the distal end to an eyepiece associated with the instrument handle. Alternatively, the imaging or viewing arrangement may include an electronic imaging device at the distal end of the instrument shaft. Such an electronic imaging device collects image data and communicates that data through the shaft and handle ultimately to a processing system that assembles the data to produce an image displayed on a suitable display device.

Depending upon the procedure for which the instrument is used, it may be necessary for the operator to view a relatively large area or view a relatively small area from different angles. In a medical procedure for example, the operator may desire to view a location which is larger than the field of view of the imaging collecting arrangement of the endoscope or view a location from different angles. It is therefore desirable to have an endoscope with a wide-angle viewing area, or with the capability to change the viewing angle. It is also desirable to provide the highest resolution possible for image display, and, particularly, for image capture, enabling thereby the ability to digitally zoom in on an region of interest (ROI), and digitally pan through the collected image, while still viewing the image at a resolution preferably at least equivalent to that of the display monitor. However, power and space limitations must be taken into consideration when utilizing high resolution image sensors.

A flexible endoscope that allows panning the image without moving the scope tip is found in <CIT> This scope uses a wide angle lens positioned at an angle to the center axis of the scope to focus light from the front and sides of the scope. The light is focused on a high resolution sensor, along which a desired area is selected to produce an image that can be digitally panned along the range of view covered by the wide angle lens. The scope shaft is flexible, and the high-resolution sensor is positioned in a distal end portion of the shaft.

<CIT> describes a wide-angle, high definition endoscope that includes at least two optical imaging channels. Two lenses are present at the scope distal tip, having different fields of view in complementary directions. Received images are transmitted along separate optical channels along the longitudinal axis of the endoscope to a single camera head that contains a wide screen image sensing device. The images directed along the independent optical channels fall onto a common sensor, each of the respective images overlapping, resulting in a wider angle image being detected by the image sensor.

<CIT> discloses an endoscopic instrument including multiple objective lens systems, and corresponding multiple optical channels, each distinct optical channel directing collected image light from its corresponding field of view onto one or more image sensors. Image processing subsequently generates a single, simulated wide angle image from the multiple images collected.

<CIT> describes a relatively large endoscope including two electronic-cameras arranged side-by-side facing along scope axis to create stereo picture pairs to permit quantitative three-dimensional (3D) imaging and analysis.

<CIT> discloses a system to provide a three-dimensional image using a single objective lens to collect light from an image space. The collected image beam is then passed through a stop containing a plurality of apertures, each aperture collecting light of the image scene from a different perspective. Each corresponding sub-beam is directed along its corresponding one of multiple optical channels, to a corresponding image sensor, and the multiple collected images, each with an individual perspective of the image scene, are used to provide a three-dimensional image of the scene.

<CIT> and <CIT>, and <CIT> describe various techniques to counter-rotate an image produced from an endoscope image sensor and thereby achieve a constant, user-defined horizon.

<CIT>, published as <CIT>, by the inventor of the present application, as well as co-pending continuation <CIT>, disclose a single optical channel system, wherein a wide angle lens is employed to capture a wide field of view, and the incoming image is split, in image space, onto two or more image sensors, the resulting image data is then stitched together by an image processing system, to create a single wide angle image of higher resolution that would be possible with only a single image sensor of the size employed by the inventive systems.

As mentioned previously image sensors with adequately high resolution can often be too large to fit into the distal tip of an endoscope, limiting thereby image resolution for distal tip sensor endoscopes. One example of a sensor of adequate quality, available at the time of filing, that is capable of fitting into the distal end of a <NUM> diameter endoscope is an HD (1080p) sensor. With current technology, it is difficult with a shaft size smaller than <NUM> to house an image sensor of HD resolution or higher. Corresponding problems are associated with the use of state-of-the-art, high resolution image sensors, such as the "<NUM> Ultra HD" image sensors currently available, having a display resolution width of approximately <NUM> pixels. Such sensors are generally too large to fit into conventional endoscopic camera heads and are the source of other practical problems associated with their high power consumption and heat generation.

There remains a need for ways to provide higher resolution capabilities for endoscopes both in circumstances when a small bore diameter is desired and also wherein high resolution images are to be proximally captured. There also remains a need in the art to provide an optical instrument such as an endoscope that allows the collection of wide-angle perspectives of the image scene as well as high resolution image capture, while remaining within the practical limitations required by endoscopy. In addition, there is a need for endoscopes which require a minimum amount of video processing to the collected images and that provide the highest quality image in the regions of interest.

An endoscope or other endoscopic instrument is provided with multiple image sensors, each capturing a portion of the image provided from an optical imaging system. One sensor receives two portions of the image light at opposing sides of the image. The output from the multiple sensors is combined and manipulated into a single high resolution image which can then be displayed to the user. A virtual horizon rotation feature is also provided which can rotate a displayed image within a combined field of view including data from the multiple image sensors. Various light directing element designs are provided to direct image light to the multiple sensors.

According to a first aspect of the invention, an optical instrument system includes an endoscopic instrument. The endoscopic instrument includes an optical channel assembly, first and second image sensors, and first and second light directing elements. The optical channel assembly includes a single channel lens system optically arranged to receive image light from an object space and condition the image light in a single optical channel to create an image space. The first image sensor is positioned to receive a first portion, but not all, of the image light, the first portion corresponding to a first central area of an optical image, and the second sensor is positioned to receive a second portion and a third portion of the image light from opposing sides of the image with respect to the first portion and at least substantially different from the first portion. The first and second light directing elements are positioned in the image space of the optical channel assembly to receive the second and third portions of the image light from the optical channel assembly and direct them toward respective first and second portions of the second image sensor.

According to a second aspect of the invention, a method provides images through an endoscope. The method includes receiving image light at a distal lens of an optical channel assembly and passing the image light through a single optical channel path toward an image space. A first portion of the image light is received from the optical channel assembly with a first image sensor, the first portion of the image light forming a first image of a first part of the field of view of the distal lens. Second and third portions of the image light are received from the optical channel assembly with a second image sensor, the second and third portions of the image light from opposing sides of the image light with respect to the first portion and forming a second and third images of second and third parts of the field of view of the distal lens at least substantially different from the first part of the field of view. The method includes combining, with an image processor, the first, second, and third images to produce a displayed image.

According to a third aspect of the invention, a method provides images through an endoscope. The method includes receiving image light at a distal lens of an optical assembly and passing the image light through a single optical channel path toward an image space. A first portion of the image light is received from the optical channel assembly with a first image sensor, with a first sensor height smaller than a first sensor width, the first portion of the image light forming a first image of a first part of the field of view of the distal lens. Second and third portions of the image light are received from the optical channel assembly with a second image sensor, the second and third portions of the image light from opposing sides of the image light with respect to the first portion and forming a second and third images of second and third parts of the field of view of the distal lens at least substantially different from the first part of the field of view. An available image data area is provided as the image data collected by the first portion of the second sensor, the first sensor, and the second portion of the second sensor. A digital zoom signal indicator is received indicating a portion of the available image area as a desired image area to be displayed. If the desired image area spans only image data contained in the first image, the method produces a displayed image from the image data collected from only the first sensor. if the desired image area spans image data from the first and the second or third images, the method includes combining, with an image processor, data from the first image and one or both of the second and third images to produce a displayed image.

According to some implementations of above aspects, the optical channel assembly extends from a distal end portion of an instrument shaft coupled to a proximal camera head holding the first and second image sensors. The optical channel assembly may be housed in a distal end portion of an instrument shaft with the first and second image sensors.

According to some implementations of above aspects, the first portion of light partially overlaps with at least one of the second and third portions of light.

According to some implementations of above aspects, an optical system includes a processing unit operatively coupled to the first and second image sensors to receive first and second image data from the sensors and operable to combine image data from the first and second image data into a displayed image including image data from the first and second portions of the second image sensor positioned at opposite sides of the displayed image with the first image data displayed there between. The processing unit may be further operable to receive a zoom input control, and in response alter the displayed image to display an enlarged portion of the displayed image including only image data received from the first image sensor. The processing unit may be further operable to, when a user rotates the endoscopic instrument around an instrument shaft, rotate a displayed image to provide a view with a constant horizon. The processing unit may be further operable to detect when a zoomed image is produced entirely within the area of the image data received from the first image sensor, and further operable to disable image processing necessary to combine the first and second image data. The processing unit may be further operable to: detect, when a user rotates the endoscopic instrument around an instrument shaft, if a zoomed image is produced with a diagonal of zoomed image entirely within the area of image data received from the first image sensor, and electronically rotate a displayed image to provide a view with a constant horizon, and disable image processing necessary to combine the first and second image data.

According to some implementations of above aspects, the second and third portions of the image light are directed toward the second image sensor along an optical axis that is non-parallel to the longitudinal axis. The plane of the second image sensor may be at an angle slightly offset from parallel to the longitudinal axis.

According to some implementations of above aspects, the first light directing element includes a prism which passes the first portion of light to the first sensor and redirects the second portion of the image light to the second sensor. The second light directing element may include a mirror or a reflective prism.

According to some implementations of above aspects, a third light directing element redirects the first portion of image light toward the first sensor. The third light directing element may include reflective surfaces positioned to direct the second and third portions of light.

According to some implementations of above aspects, the second portion of image light and the third portion of image light are reflected with at least two reflective elements to provide a similar image orientation to the first portion of image light.

According to some implementations of above aspects, responsive to a user rotating the endoscopic around an instrument shaft, a displayed image is rotated to provide a view with a constant horizon, the displayed view being comprised entirely of image data collected from the first sensor if the desired image area spans only image data contained in the first image, and the displayed view including combined data from the first and one or both of the second and third images if the desired image area spans image data from the first and the second or third images.

As used herein, elements (e.g., sensors and lenses) that are "optically arranged" in relation to other elements, refers to the element's position along an optical path shared by first and other elements. For example, a relay lens group optically arranged between an image sensor and an objective, means that the relay lens group occupies a portion of the optical path that light travels (i.e., from the objective to the image sensor) for capturing images or video. "Optical image" is an image formed by the light rays from a self-luminous or an illuminated object that traverse an optical system or element.

Referring to <FIG>, depicted is a perspective view of an instrument <NUM> employing multiple proximal image sensors according to one aspect of the present invention and generally includes a scope element <NUM> including an elongated shaft <NUM>, the scope element being connected to a camera head <NUM>. The scope <NUM> can be detachably connected to the camera head <NUM> by any means known in the art, such as a bayonet connector <NUM>, the elements may be parts of a single instrument <NUM>. Shaft <NUM> extends from a proximal end shown generally at reference numeral <NUM> connected to camera head <NUM> to a distal end generally indicated at reference numeral <NUM>. A distal end portion is included at the shaft distal end <NUM>. An objective lens <NUM>, often a wide angle lens, is located at the distal end portion, although it is not shown in <FIG> due to the scale of the figure. The rigid, elongated shaft <NUM> generally comprises a relay lens system, such as a series of coupled rod lenses, to transmit an image collected by the objective lens <NUM> to the proximal <NUM> portion of the scope <NUM>. The image is then received by the camera head <NUM>. The shown shaft <NUM> is a rigid implementation, but flexible-shaft implementations are also possible, as well as implementations wherein the image sensors and associated optics are placed in the distal end of the scope <NUM>.

Camera head <NUM> receives electrical operating power through a cable <NUM> which extends from a proximal end of camera head <NUM> in this example instrument. This power may be used to operate one or more light sources or, in some embodiments, such as those with distally placed image sensors, other electronic elements mounted within distal portion <NUM>, including multiple electronic image sensors. Data signals from such an imaging device, where image sensors are distally placed, may be communicated through appropriate conduits within shaft <NUM> and handle <NUM> to cable <NUM>. These data signals may be communicated through cable <NUM> to processing equipment (not shown) which processes the image data and drives one or more video monitors to display the images collected by the instrument <NUM>. Those familiar with endoscopes and borescopes will appreciate that instrument <NUM> includes a number of additional features such as controls <NUM> for controlling the operation of the instrument. Although data transmission relating to the image sensors will be described further below, the general operation and control of instrument <NUM> will not be described further herein in order to avoid obscuring the present invention in unnecessary detail. Preferably the designs and techniques herein are employed as improvements to a endoscopic system with image sensors proximally present in the camera head <NUM>, but are also relevant to a distal mounted image sensor arrangement, such as, for example, the endoscopic system described in <CIT>.

<FIG> shows block diagrams for two different implementations of the present invention. In order to improve clarity, elements common to both example implementations shown in <FIG> are not explicitly discussed in both implementations, where they may perform different functions. <FIG> shows a cross section diagram of a scope <NUM> separably connected with the eyecup <NUM> attaching with a bayonet connector <NUM> to a camera head <NUM>. Light from an object scene passes through a cover glass <NUM>, and objective lens <NUM> as well as any other additional lenses <NUM> necessary to shape or condition the light before passing on to a relay lens system <NUM>, generally including a series of rod lens pairs. Image light then passes into a camera head <NUM> and is received by a single channel imaging system <NUM> that focuses the light to fall onto image sensors <NUM>, <NUM>. Located within the image space <NUM> of the single optical channel are light directing elements <NUM> directing some, but not all, of the incoming image light in toward one image sensor <NUM>, while the remaining image light falls upon another image sensor <NUM>. Analog signal processor <NUM> processes the collected image information, as will be further discussed below.

<FIG>, represents a cross section block diagram of an alternate distal tip implementation of the present invention. Depicted is the distal end portion <NUM> of shaft <NUM> having a cover glass <NUM> in an inset position at its distal face <NUM>. Optically arranged at the interior side of cover glass <NUM> is an optical channel assembly positioned in the distal end portion <NUM>, including an objective lens with negative optical power <NUM> having distal and proximal sides positioned to receive image light from an object space (the area to be imaged) at the distal side of lens <NUM> and pass the image light to the proximal side. In distal sensor embodiments, the distal end portion will be connected, either through a rigid or flexible extended shaft to a handle element, somewhat analogous to the camera head element <NUM> of proximal sensor embodiments, wherein any desired operation controls may be located.

In wide-angle implementations, the field of view of the optical channel assembly may be between <NUM> and <NUM> degrees. Wide-angle implementations may include a fisheye lens as an optical element of a wide-angle lens system. The wide-angle lens system may be partially- or fullydefined by the optical channel assembly.

In the embodiment shown in <FIG>, cover glass <NUM> and lens <NUM> are fixed at a <NUM> degree angle from the scope axis, however in other versions, such as that shown in <FIG>, a non-angled face may be used, or some other angle such as <NUM> degrees may be used. The optical channel assembly typically includes lens <NUM> and a single channel imaging system <NUM> of one or more prisms, lenses, lens groups, or other optical elements optically arranged at the proximal side of lens <NUM> to receive the image light as a beam and focus, disperse, or otherwise modify the beam. By "single channel", it is meant that a beam of light forming a single image is passed through a common lens group or set of optical elements with a single perspective.

An optical channel assembly <NUM> generally directs the light toward an image space <NUM> of the optical channel assembly <NUM>. While the space is depicted as a gap in the drawings, a smaller gap or no gap may be present in some implementations, with the image, as discussed below, split within the image space of the system. At least two image sensors <NUM> and <NUM> are positioned in the distal end portion <NUM> to receive light from the image space.

In both distal and proximal detection systems, the first image sensor <NUM> is positioned to receive a first portion, but not all, of the image light corresponding to a first area, in most embodiments, a central area, of an image observed by the endoscope, and the second sensor <NUM> is positioned to receive a second and third portions of the image light redirected in the image space <NUM> by the light directing elements <NUM> and corresponding to second and third areas of the observed image. The second and third portions of the image light are from opposing sides of the image light with respect to the first portion and at least substantially different from the first portion. In this embodiment, light directing elements <NUM> are positioned to direct light from separate areas, for example, above and below the central area of image space <NUM> toward image sensor <NUM>.

The light directing elements <NUM> may be any suitable element for redirecting light, such as a prisms, mirrors, light splitters beam splitters, or fiber optic elements. Prisms are preferred because of their small size, mechanical durability and resistance to deformity.

As can be seen in these example versions, the first image sensor <NUM> is positioned with a sensor array pointing to receive light propagating along a local optical axis parallel to the longitudinal axis <NUM> of the optical channel assembly. In this figure, the sensor array is oriented substantially parallel to a longitudinal axis <NUM> of the instrument shaft. Second image sensor <NUM> is positioned with the sensor array pointing to receive light propagating perpendicularly or substantially perpendicularly to longitudinal axis <NUM>. By substantially perpendicular, it is meant that the light propagates generally radially outward from longitudinal axis <NUM> such that second image sensor <NUM> can be arranged longitudinally as shown. The angle of image light propagation and the direction of the sensor may be offset from perpendicular to mitigate reflections, for example.

The depicted arrangement, along with other embodiments herein disclosed , allows for sensors of a greater total active array area (e.g., a light sensing area) than would ordinarily be possible to be fit into the endoscope shaft. Although in <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, image sensors <NUM> and <NUM> are oriented generally parallel and perpendicular to the longitudinal axis of the endoscope <NUM>, other image sensor pointing angles may be used. For example, one or both the sensor arrays may be pointed for receiving light redirected at <NUM> degrees from the longitudinal axis of the endoscope, at <NUM> degrees, or at <NUM> degrees.

Image sensors <NUM> and <NUM> typically are part of at least one sensing module or assembly that includes a printed circuit board ("PCB") on which is mounted an imaging device including an image sensor with sensing array, typically having a transparent cover. The PCB or other electrical circuitry that reads the sensed signal off the image sensing array of the sensors may be of any suitable type, preferably the smallest and lowest profile available to fit in the limited space, particularly in distal tip implementations. For implementations where the image sensors are located in a camera head element, space, power and size may be considerations for selecting appropriate image sensors. The various portions of the sensor assembly are known and are not shown separately. It will be appreciated by those familiar with imaging sensors that these devices may be accompanied by electronic components such as transistors, capacitors, resistors, and regulators for example.

Additionally, imaging sensors <NUM> and <NUM> and their accompanying electronic components require electrical power and means for communicating image data to be processed for producing the collected images. The required operating power and data transmission may be provided through a suitable electrical cable or bus connection. These accompanying electronic components and the power/data cable are omitted from the present drawings in order to more clearly illustrate the various features of the imaging apparatus.

Those skilled in the art will appreciate that the electronic components and power/data cable may be connected to or included with the image sensor modules in any number of fashions. For example, some embodiments may include the electronic components mounted on the opposite side of PCB on which imaging sensor itself is mounted. The power/data cable may also be connected to the back side of PCB to provide operating power to the image sensors and allow image data to be communicated from the image sensor assembly to processing equipment remote from the shaft distal end portion <NUM>. However, the present invention is not limited to any particular mounting arrangement for electronic components which may accompany imaging sensor and a power/data connection, although some embodiments, such as those shown in <FIG> and <FIG>, may benefit from particular mounting configurations. Any accompanying electronic components and the power/data cable need only be mounted to provide the required function.

Further, although sensors <NUM> and <NUM> are shown as discreet entities, two or more of said sensors may be share, for example, a mounting substrate or housing accommodating said two or more sensors.

In <FIG>, the image sensors <NUM> and <NUM> are connected through a power and data connection to an analog signal processor <NUM>, which receives the analog sensor data and conditions it for processing by the digital portions of the system, as will be further described below. An analog signal processor <NUM> may be located in a handle for distal image sensor embodiments or the camera head <NUM> (<FIG>) of the scope device or may be located elsewhere. It is understood that metal oxide semiconductor sensors (CMOS) may have incorporated with the sensor assembly some of the digitization functions, however an analog signal processor <NUM> may provide further signal processing and control before the image data is suitable for digital processing.

<FIG> shows a light ray bundle diagram for a system such as that shown in <FIG>, including an example optical design of an optical assembly <NUM> of a camera head portion of the scope according to one embodiment. The effect of optical assembly <NUM> can be seen in the depicted light ray bundles <NUM>, <NUM>, and <NUM> which show image light directed along the optical axis of optical assembly <NUM> and directed toward first image sensor <NUM> and second image sensor <NUM>.

At the left is shown element <NUM>, an element of the single channel imaging system <NUM>, in this case a conditioning lens receiving light from the scope element into the camera head. Optically arranged or attached at the proximal side of lens <NUM> is a lens <NUM>, shown here as a meniscus lens, but many different designs are possible, to spread the incoming light to an appropriate size for the imaging process downstream in the proximal direction. Next the light passes through an optional flat plate element <NUM>, in this particular embodiment, an IR cut filter, and is received at a doublet lens <NUM>, or other suitable lens with a slight positive power. Optically arranged to receive the image light from lens <NUM> is another doublet lens <NUM> having a slight positive power to align the image light as desired in image space <NUM>. This particular optical channel assembly is only one of many suitable optical assemblies that may be used to prepare the incoming light for reception by the image sensors. Other appropriate optical assembly designs may be selected as required by the specific camera and/or endoscope system.

At the image space <NUM>, the light emerges from the single channel optical system in converging rays to focus on image sensors <NUM> and <NUM>. In this embodiment, a first portion of image light <NUM> passes straight toward first image sensor <NUM> through prism <NUM>. A second portion of the image light <NUM> is directed to second image sensor <NUM> by angle prism <NUM>, which in this embodiment is formed by a lower proximal edge of prism <NUM> providing a reflective surface from which the second portion of image light <NUM> reflects. A third portion of the image light <NUM> at the opposite side of first portion <NUM> from second portion <NUM> is also reflected toward second image sensor <NUM> by reflecting element <NUM>. Reflecting element <NUM> may be a mirror or reflecting prism. In this example the angle prism <NUM> and reflecting element <NUM> are examples of light directing elements <NUM> (<FIG>).

The depicted arrangement receives the first portion of the image light <NUM> from the optical channel assembly with the first image sensor <NUM>, forming a first image of a first part of the field of view of the (single) optical channel assembly, and receives second and third portions of the image light <NUM> and <NUM> from the optical channel assembly with the second image sensor <NUM>, forming second and third images of respective portions of the field of view.

As can be understood, the different portions of light make up different areas from the common image light fed to image space <NUM> and provide different areas of the image viewable through the scope. The image light may be maintained in the same focal conditions through light directing elements <NUM>, which may be prisms (see, for example, <FIG>) <NUM>, <NUM>, <NUM> or elements of a single prism (see, for example, <FIG>) <NUM>, or a combination of one or more prisms and/or mirrors.

As can be observed in <FIG>, second image sensor <NUM> has its image sensing surface pointed at slight angle from perpendicular to the longitudinal axis of optical assembly <NUM> along which image light passes before being redirected. This helps to mitigate deleterious reflections and diffusion off of prism <NUM>.

<FIG> is a light ray bundle diagram of a scope optical channel assembly <NUM> having a different construction of light directing elements according to another embodiment. In this version, a different arrangement of two image sensors, <NUM> and <NUM>, is shown with first image sensor <NUM> positioned facing perpendicularly to the longitudinal axis of optical assembly <NUM>, and sensor <NUM> positioned in line with the longitudinal axis, but receiving image light passed through light directing elements rather than directly.

Optical channel assembly <NUM> may include an initial wide angle objective lens (not shown) through which light rays <NUM> of the image light enter the optical channel assembly, either distally placed or located in the camera head element. A convex lens <NUM> is optically arranged to receive the image light and pass it toward lens <NUM>. Lens <NUM> is a concave-convex lens and operates to align the light rays in image space <NUM>.

A right angle irregular prism <NUM> is positioned in image space <NUM> of optical channel assembly <NUM> to receive a first portion of the image light from lens <NUM> and direct it toward first image sensor <NUM>. In this embodiment, prism <NUM> is a reflective prism having a distal surface from which the first portion of light reflects toward first image sensor <NUM> as depicted. In other embodiments, prism <NUM> may be replaced with some other light directing element, such as a mirror. Prism <NUM> includes an irregular proximal side with two reflecting surfaces formed to reflect second and third portions of the image light toward second image sensor <NUM>. Two reflecting elements <NUM> and <NUM> are optically arranged in image space <NUM> to redirect second and third portions of the image light toward the proximal reflecting surfaces of prism <NUM> as depicted. Reflecting elements <NUM> and <NUM> may be reflecting prisms, mirrors, or other suitable light directing elements. The two portions of image light reflected from reflecting elements <NUM> and <NUM> pass to the proximal reflecting surfaces of prism <NUM> and are reflected toward second image sensor <NUM>.

As can be understood from the ray diagram, first image sensor <NUM> receives a first portion image light corresponding to a first central area of an optical image, and second image sensor <NUM> receives second and third portions of the image light from opposing sides of the image light with respect to the first portion and at least substantially different from the first portion.

One important distinction between the operation of the embodiment of <FIG> and that of <FIG>, relates to the method of recombination of the collected images and the type of image sensors used. As is known in the art, CCD image sensor generally operate in a "global shutter" mode, that is, the entire image is captured at a single instant as a single frame. By contrast, CMOS sensors frequently utilize a "rolling shutter" mode to capture the image. That is, each pixel along a row of pixels is captured sequentially, followed by the next row. Therefore, conventional rolling shutter CMOS sensors, which at the time of filing are the industry standard for small CMOS sensors, can present particular problems associated with dividing an image, in image space, and directing the resulting partial images onto different image sensors, as in the present invention. For example, in the embodiment of <FIG> there can be a disconnect in the acquisition time of a given line of pixels collected by the second image sensor <NUM> in relation to the image collected by the first sensor <NUM>. In order to simplify the description, the "top" of the second image sensor <NUM> will be considered to be to the right in the Figure, and the "bottom" of the image sensor is to the left in the Figure, (corresponding to the top and bottom of the image in image space). The "top" and "bottom" of the first image sensor <NUM> can be considered conventionally (e.g. the arrow points to the top of the sensor). In this case, the top of the image in image space is collected in the middle of the second image sensor, and proceeds to the top of the sensor. The central part of the image is collected on image sensor <NUM>, with the top of the central image at the top of the first sensor <NUM> and proceeding to the bottom of the first sensor. The bottommost portion of the image is collected, starting from the middle of the second detector <NUM> and proceeding to the bottommost portion of the second image sensor. This creates problems, when an embodiment like that of <FIG> is used with a rolling shutter image sensor, as the synchronization of the image regions will be imperfect as the collection sweeps across, in particular, the second image sensor. Other embodiments, such as that presented in <FIG> do not suffer from the same problems, as the double-reflection between prisms <NUM> and <NUM> result in the image captured at the second image sensor <NUM> being sequentially captured top to bottom, rather than from the center out.

<FIG>, <FIG>, and <FIG> represent alternative configurations that, like the embodiment of <FIG>, minimize the rolling shutter effect as discussed above.

<FIG> is a light ray bundle diagram of a scope optical channel assembly <NUM> having a different construction of light directing elements according to another embodiment. The effect of optical assembly <NUM> can be seen in the depicted light ray bundles <NUM>, <NUM>, and <NUM> which show image light directed along the optical axis of optical assembly <NUM> and directed toward first image sensor <NUM> and second image sensor <NUM>.

At the left is shown element <NUM>, an element of optical channel assembly <NUM>, in this case a conditioning lens receiving light from the scope element into the camera head. Optically arranged or attached at the proximal side of lens <NUM> is a lens <NUM>, preferably a concave-concave lens with a negative power to spread the incoming light to an appropriate size for the imaging process downstream in the proximal direction. A convex-convex lens <NUM> is bonded to lens <NUM> in the downstream direction with a positive power. Next the light passes through an achromatic doublet <NUM> including a convex-convex lens and a meniscus lens. A similar achromatic doublet lens <NUM> is arranged with the meniscus lens facing lens <NUM> to receive the light from lens <NUM> and complete the optical manipulation to align the light for image space <NUM>.

At the image space <NUM>, the light emerges from the single channel optical system to focus on image sensors <NUM> and <NUM>. In this embodiment, a first portion of image light <NUM> passes straight toward first image sensor <NUM>. A second portion of the image light <NUM> is directed to second image sensor <NUM> by a reflective element <NUM> directing light <NUM> upward, and another reflective element <NUM> reflecting light <NUM> toward image sensor <NUM>. A third portion of the image light <NUM> at the opposite side of first portion <NUM> from second portion <NUM> is also reflected toward second image sensor <NUM> by reflecting elements <NUM> and <NUM>. Reflecting elements <NUM>, <NUM>, <NUM>, and <NUM> may be mirrors or reflecting prisms.

As can be understood, the different portions of light make up different areas from the common image light fed to image space <NUM> and provide different areas of the image viewable through the scope. The image light may be maintained in the same focal conditions along the depicted paths from reflecting elements <NUM> to <NUM>, and reflecting elements <NUM> to <NUM> so that the two partial images can be easily reconstructed. The use of two reflecting elements in the light path for light <NUM> and light <NUM> allows simultaneous line-by-line scanning along both image sensors with reduced line artifacts in the combined image.

<FIG> shows a light ray bundle diagram of a scope optical channel assembly <NUM> having a different construction of light directing elements according to another embodiment. In this particular embodiment both sensors are positioned on the same plane, which is particularly beneficial as it enables the two sensors to potentially share a single circuit board, or, potentially, be elements of a single, larger sensor. The effect of optical assembly <NUM> can be seen in the depicted light ray bundles comprising portions of image light <NUM>, <NUM>, and <NUM> which show image light directed along the optical axis of optical assembly <NUM> and directed toward first image sensor <NUM> and second image sensor <NUM>.

Elements <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are similar to elements <NUM>-<NUM> as described with respect to <FIG>. At the image space <NUM>, the light emerges from the single channel optical system to focus on image sensors <NUM> and <NUM>. In this embodiment, a first portion of image light <NUM> passes straight toward first image sensor <NUM>. A second portion of the image light <NUM> is directed to second image sensor <NUM> by a reflective interior surface <NUM> of irregular prism element <NUM>, directing light <NUM> upward, and another reflective interior surface <NUM> reflecting image light <NUM> toward second image sensor <NUM>. Second portion of image light <NUM> passes through optical block <NUM>, and then optical block <NUM> to second image sensor <NUM> to maintain identical focal conditions to third portion of image light <NUM>.

A third portion of the image light <NUM> at the opposite side of first portion of image light <NUM> from second portion of image light <NUM> passes straight through irregular prism element <NUM> and is then reflected toward second image sensor <NUM> by reflecting elements <NUM> and <NUM>. Reflecting elements <NUM>, and <NUM> may be mirrors or reflecting prisms. Third portion of image light <NUM> passes through optical block <NUM> before hitting second image sensor <NUM> to maintain identical focal conditions to second portion of image light <NUM>.

As can be understood, the different portions of light make up different areas from the common image light fed to image space <NUM> and provide different areas of the image viewable through the scope. The image light may be maintained in the same focal conditions along the depicted paths, each including two reflections, so that the two partial images can be easily reconstructed. The use of two reflecting elements in the light path for light <NUM> and light <NUM> allows simultaneous line-by-line scanning along both image sensors with reduced line artifacts in the combined image.

<FIG> depicts an embodiment of the present invention which may be particularly advantageous in distal tip implementations of the invention. A light ray bundle diagram of a scope optical channel assembly <NUM> having a different construction of light directing elements is shown. The effect of optical assembly <NUM> can be seen in the depicted light ray bundles comprising portions of image light <NUM>, <NUM>, and <NUM> which show image light directed along the optical axis of optical assembly <NUM> and directed toward first image sensor <NUM> and second image sensor <NUM>. For distal tip implementations, for which this embodiment is particularly well suited, some optical elements for conditioning incoming light from a scope (<NUM>) may be omitted, or replaced by objective optical elements as are known in the art.

Elements <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are similar to elements <NUM>-<NUM> as described with respect to <FIG>. At the image space <NUM>, the light emerges from the single channel optical system to be directed at image sensors <NUM> and <NUM>. In this embodiment, a first portion of image light <NUM> passes straight through irregular prism element <NUM> and into reflective prism <NUM>. First portion of image light <NUM> is then reflected upward off an interior reflective surface of reflective prism <NUM> toward first image sensor <NUM>.

A second portion of the image light <NUM> is directed to second image sensor <NUM> by a reflective interior surface <NUM> of irregular prism element <NUM>, directing light <NUM> upward, and another reflective interior surface <NUM> reflecting light <NUM> toward second image sensor <NUM>. Second portion of image light <NUM> passes through optical block <NUM>, and then into reflective prism <NUM>, where it is reflected downward to second image sensor <NUM>.

A third portion of the image light <NUM> at the opposite side of first portion <NUM> from second portion <NUM> passes straight through irregular prism element <NUM> and is then reflected toward second image sensor <NUM> by reflecting elements <NUM> and <NUM>. Reflecting elements <NUM>, and <NUM> may be mirrors or reflecting prisms. Third portion of image light <NUM> passes into reflecting prism <NUM> and is reflected downward to hit second image sensor <NUM>.

As can be understood, the different portions of light make up different areas from the common image light fed to image space <NUM> and provide different areas of the image viewable through the scope. The image light may be maintained in the same focal conditions along the depicted paths, each including two reflections, so that the two partial images can be easily reconstructed. In this embodiment the first portion of image light <NUM> is reflected one time, while the second and third portions of light <NUM> and <NUM> are reflected three times, providing the same mirror orientation as first portion of image light <NUM>. This arrangement allows simultaneous line-by-line scanning along both image sensors with reduced line artifacts in the combined image. As mentioned above, this embodiment is particularly beneficial in distal tip implementations of the invention, as both sensors are positioned in the same, or nearly the same, plane perpendicular to the shaft distal end <NUM>, and in this way the circuit board (or boards) containing the sensors can be positioned along the shaft at its maximum inner diameter, maximizing, thereby, the possible size of the sensors and/or minimizing the diameter of the shaft for a given sensor size.

<FIG> is a block diagram of an optical instrument system according to an example embodiment of the present invention. While this example circuit is shown for an endoscope, the present invention is applicable to more than one type of medical scope instrument, but typically is applicable for scope applications that employ image capture at the instrument distal tip, such as endoscopes, borescopes, or exoscopes, for example.

A light source <NUM> illuminates subject scene <NUM> and light <NUM> reflected from (or, alternatively, as in the case of certain fluorescent or digital microscope arrangements, transmitted or emitted by) the subject scene forms an optical image via an optical channel assembly <NUM>, where the light is focused, typically aligned with the scope axis or a desired optical axis, and passed to a proximal side of optical channel assembly <NUM> where light directing elements <NUM> direct different portions of the light to form different portions of the image on two solid-state image sensors <NUM> and <NUM>.

In the present invention, optical channel assembly <NUM> includes a single-channel imaging system and may be constructed according to a large variety of known methods suitable for placement in a scope distal tip or camera head, including the preferred optical channel assembly of <FIG>. Image sensors <NUM> and <NUM> convert the incident light to an electrical signal by, for example, integrating charge for each picture element (pixel). The image sensors <NUM> and <NUM> may be active-pixel type complementary metal oxide semiconductor sensors (CMOS APS) or a charge-coupled devices (CCD), to give just two possible examples. The output analog signal from the image sensors is processed by analog signal processor <NUM> and applied to analog-to-digital (A/D) converter <NUM> for digitizing the analog sensor signals. In some versions (typically CMOS designs), the analog signal processing and A/D converters may be integrated into individual sensor models attached to each sensor <NUM> and <NUM>.

The system's camera <NUM> generally includes timing generator <NUM>, which produces various clocking signals to select rows and pixels and synchronizes the operation of image sensors <NUM> and <NUM>, analog signal processor <NUM>, and A/D converter <NUM>. One or more motion sensors <NUM> such as, for example, an accelerometer, gyro, or magnetometer, may be mounted in the endoscope shaft, tip, or handle to aid in detecting movement, including rotation, of the endoscope. A scope distal tip electronic assembly typically houses image sensors <NUM> and <NUM>, while the locations of each of analog signal processor <NUM>, the A/D converter <NUM>, and the timing generator <NUM> may vary, for example in the scope handle <NUM> or partially integrated into the distal tip electronic assembly. The functional elements of the camera <NUM> may be fabricated as a single integrated circuit as is commonly done with CMOS image sensors or they may be separately fabricated integrated circuits.

The system controller <NUM> controls the overall operation of the image capture device based on a software program stored in program memory <NUM>. This memory can also be used to store user setting selections and other data to be preserved when the camera <NUM> is turned off. Data connections <NUM> and <NUM> carry the digital image data of image sensors <NUM> and <NUM>, respectively, to image processing circuitry <NUM>, which may be integrated with system controller <NUM> in some versions or may be a separate programmable logic device or data processor. A data bus <NUM> provides a pathway for address, data, and control signals. In some variations, data bus <NUM> may also carry data connections <NUM> and <NUM>.

Image processing circuitry <NUM> performs image processing operations including the operations to combine the three partial images from image sensors <NUM> and <NUM>, as necessary, and to perform rotation functions as further described below. Image processing circuitry <NUM> is operable to combine image data from the first and second image data into a displayed image including image data from the first and second portions of the second image sensor <NUM> positioned at opposite sides of the displayed image with the first image data from first image sensor <NUM> displayed there between. Processed image data are continuously sent to video encoder <NUM> to produce a video signal. This signal is processed by display controller <NUM> and presented on image display <NUM>. This display is typically an HD, UHD, or <NUM> format liquid crystal display backlit with light-emitting diodes (LED LCD), although other types of displays are used as well. The processed image data can also be stored in system memory <NUM> or other internal or external memory device.

The user interface <NUM>, including all or any combination of image display <NUM>, user inputs <NUM>, and status display <NUM>, is controlled by a combination of software programs executed on system controller <NUM>. User inputs typically include some combination of typing keyboards, computer pointing devices, buttons, rocker switches, joysticks, rotary dials, or touch screens. The system controller <NUM> may manage the graphical user interface (GUI) presented on one or more of the displays (e.g. on image display <NUM>). The GUI typically includes menus for making various option selections.

Image processing circuitry <NUM>, system controller <NUM>, system and program memories <NUM> and <NUM>, video encoder <NUM>, and display controller <NUM> may be housed within camera control unit (CCU) <NUM>. CCU <NUM> may be responsible for powering and controlling light source <NUM> and/or camera <NUM>. As used herein "CCU" refers to units or modules that power, receive data from, manipulate data from, transmit data to, and/or forwards data from optical instrument cameras. CCU functionalities may be spread over multiple units known as, for example, a "connect module", "link module", or "head module".

<FIG> is a flowchart of an example process for combining and rotating the partial images received from the multiple sensors according to some embodiments, which may be employed with the example hardware and camera designs herein, or may be employed with other hardware designated with a similar purpose, such as software program code executed by a GPU or other image processor. The depicted process starts at block <NUM> with receiving image light at a distal lens of an optical assembly and passing the image light through a single optical channel.

Next at block <NUM>, the process directs a first portion of the image light toward the first sensor. Second and third portions of the image light is also be directed at a non-zero angle to the longitudinal axis of the endoscope at block <NUM>. As can be understood blocks <NUM> and <NUM> may be performed by two different light directing elements or a single light directing element such as a compound prism.

At block <NUM> the process receives the first portion of the image light from the optical channel assembly with the first image sensor, the first portion of the image light forming a first image of a first part of the field of view of the distal lens. This image stream is digitized and transferred to an image processor at block <NUM>. Simultaneously at block <NUM> the process receives the second and third portions of the image light from the optical assembly with the second image sensor to produce second and third image streams at block <NUM>, both provided through the second image sensor in this embodiment. The second and third portions of the image light are from opposing sides of the image light with respect to the first portion and at least substantially different from the first portion. By substantially different it is meant that the majority of image is different, while relatively small portions may overlap with the first portion of image light. That is, the first image preferably has a partially overlapping field of view with the second and third images, assisting in registration of the collected images.

At block <NUM>, the process determines if the region of interest (ROI), that is the image area to be displayed, as selected by a digital zoom indication received from a user, a digital pan indication received by a user, and a rotation indication received by the instrument, spans more than the image area received by the first image detector. Typically block <NUM> will be skipped the first iteration through the process, until zoom and rotation inputs are received. (In some embodiments there will be no digital zoom implementation, and therefore, this step will not be relevant. ) If so, the process goes to blocks <NUM> and <NUM>, where image processing steps are conducted on both image streams. At block <NUM>, the process includes combining the first, second and third images to produce an image of the combined field of view of the sensors, when the ROI spans more than the image area of the first image sensor. If the ROI does not span more than the first image sensor at block <NUM>, the process goes to block <NUM> where it selects only the first image stream for processing thus saving processing cycles and increasing power efficiency of the overall process. The combined image typically has a higher resolution than would otherwise be possible with a single sensor. Block <NUM> may include steps to adjust for relative misalignment of the sensors, such as applying a rotation to image data from one or both sensors (preferably provided in calibration of the instrument), and may include recognizing edges at the edges of the first, second, and third images so that those edges can by aligned in the combined image.

The depicted process blocks that are in parallel are typically performed with parallel processing, as are many of the other processing functions in preferred designs. At blocks <NUM> and <NUM>, the process may perform one or more image processing steps, with these shown in dotted lines to indicate it is optional in some embodiments.

If overlapping pixels are available as described above, the process may include cross-correlating these overlapping pixels to find the highest point of alignment, or applying a shift to one or both of the images to account for an offset detected in calibration. Such edge detection and correlation are known in the art and will not be further described. The combined image is then subjected (at block <NUM>) to image processing such as dynamic range adjustment, filtering, color range adjustment, feature recognition, and any other suitable image processing techniques for endoscopic imaging.

The combined image or a selected sub-image from the total combined image are transmitted to an electronic display for display to the operator at block <NUM> and may also be recorded and saved with any suitable video or image recording format. The entire image is then available for viewing, image processing, and manipulation according to any suitable medical imagery techniques. In some scenarios, the entire combined image may be displayed, while in others a desired aspect ratio (for example that of a standard HD display) image smaller than the total image may be selected out of the entire combined image for display, allowing panning of the displayed image within the overall collected image area. A diagram of such an image may be seen in <FIG>, in which the combined field of view of a first sensor <NUM> and a second sensor <NUM> are shown each with a different fill pattern. The circle <NUM> represents the area of the image light coming from the round lens that is captured by the combination of the two sensors <NUM> and <NUM>. As can be understood from the diagram of <FIG>, the second sensor <NUM> receives image light from opposing sides of the central image light hitting the first sensor <NUM>. These portions of image light are received by the depicted first and second portions of second sensor <NUM>, forming a second and third images of second and third parts of the field of view of the distal lens at least substantially different from the first part of the field of view received at first sensor <NUM>. As is made clear from <FIG>, seams <NUM>, <NUM> between the collected images are present in the overall presented image if the zoom, pan, and rotation settings require a combined image stream. At these seams, the images collected by the two image sensors <NUM>, <NUM> are reassembled by image processing circuitry. While high quality image processing seeks to minimize any apparent visual artifacts created by combining these disparate regions of the two sensors, some artifacts are likely to be present at and around these seams. However, it is a primary benefit offered by the present invention that the central region of the image, which generally contains the primary region of interest (ROI), that is the area of the overall viewed object space of most interest to the operator, contains no seam and therefore is not subject to any image processing artifacts associated with reassembly of the image. Further, as is shown clearly in <FIG>, when the displayed image <NUM> falls completely within the area captured by the first image sensor <NUM>, there is no need to apply any image processing to reassemble the image, saving valuable computer processing power. Of course, if the entire image is to be recorded, such processing may still be performed, or alternatively, the images received by each detector may be recorded individually and reassembly processing may be performed as necessary at a later time. The displayed image area <NUM> may be digitally panned, as indicated in the example scenario shown in <FIG> by the arrow <NUM>, and once the displayed image area encompasses data collected by the second image sensor, appropriate image processing may be engaged to provide a combined image as necessary to fill the displayed image area.

Referring again to <FIG>, while displaying the combined image stream, at block <NUM> the process detects the physical rotation of the scope distal end, which may be through sensors such as motion sensors <NUM> and recognized by the system controller <NUM>. In some embodiments, detecting rotation may also be done by detecting such rotation in the received stream of images through image processing. An operator may set the current orientation as the desired viewing orientation through the user interface <NUM> or through a button on the scope handle, for example, after which the process will digitally rotate the display to make counter-rotations to the displayed images in the opposite direction of the scope physical location to maintain 'virtual horizon' constant viewing orientation as shown at block <NUM>.

The orientation of the displayed image is kept constant, as shown in the diagram of <FIG>, by the process of selecting the view over different portions of the partial images received from the image sensors, in which the combined field of view of a first sensor <NUM> and a second sensor <NUM> are shown each with a different fill pattern. As depicted in this example diagram, an operator rotating the endoscope in the clock-wise direction causes the process to counter-rotate the image in the counter-clockwise direction within the available field of view, maintaining the view orientation to avoid the common problem of operator visual disorientation during examination procedures. The opposite physical rotation of course causes an opposite digital rotation. While this version provides a displayed image area that is able to maintain the depicted aspect ratio (<NUM>:<NUM>) while displaying a full image <NUM> using data from both sensors, other operating modes may be provided to display a larger portion of the total imaged area, or all of the image area. In this case, as long as the diagonal of the displayed image area <NUM> is equal to or smaller than the collected lens field of view <NUM>, the image can be rotated, without displaying any non-image information (generally data containing only dark pixels, as no light is detected in these regions outside of the field of view). As the image is rotated, and the displayed region <NUM> contains data collected from both image sensors <NUM>, <NUM>, image processing may be engaged to recombine the images as necessary, as well as performing virtual-horizon maintaining processing.

<FIG> shows in diagram form an example of rotating a digitally zoomed image within the field of view shown in <FIG>. The illustrated process receives a digital zoom signal indicator indicating a portion of the available image area as a desired image area to be displayed as image <NUM>. Digital zooming, as is known in the art, generally comprises the step of selecting a portion of the available image data and displaying only this portion and conforming the zoomed region <NUM> to fill the display as completely as possible. In this example scenario, the portion identified is wholly contained within the image area of the first sensor <NUM>. In the process, if the desired image area <NUM> spans only image data contained in the first image from first image sensor <NUM>, the process produces a displayed image from the image data collected from only the first sensor, therefore image processing is not required to combine image data from the second image sensor <NUM>. Further, if a diagonal of the displayed image <NUM>, generally the ROI, is smaller than the height of the central region produced by first image sensor <NUM>, and the ROI <NUM> is appropriately located, as is the case in <FIG>, the endoscope may be rotated and a virtual horizon maintained, without the need to perform additional image processing required to combine the image data received from the second image sensor <NUM> with that of the first image sensor <NUM>. As discussed above, however, the image data from both sensors can be collected and stored for later combination as necessary. If the desired image area spans image data from the first and the second or third images, via digital panning (further discussed below), digital zooming, endoscope rotation, or a combination thereof, the image processor combines data from the first and one or both of the second and third images to produce a displayed image. For example, if the depicted desired image <NUM> were panned to the right, it would overlap with the <NUM>st portion of second sensor <NUM>, causing image data from that portion to be combined with image data from first image sensor <NUM> to produce a displayed image.

<FIG> shows an example diagram of another ROI display area <NUM> showing digital panning over the available combined image area. As can be seen from the overlay of the lens field of view <NUM> on the diagram, this version does not make full use of the lens field of view. The image processing system can determine if the ROI <NUM> is contained wholly within the boundaries of the central sensor and adjust processing procedures accordingly. It can also permit digital panning, that is the movement of the displayed, digitally zoomed ROI within the available area of the first sensor without additional processing necessary to combine data from the image sensors. Digital panning along the combined image may also be provided in any of the embodiments, in which the up/down and right/left arrows shown in <FIG> shows how a display area may be panned along the available combined image data. The vertical direction of the diagram represents the vertical direction of the wide angle lens field of view in the diagram of <FIG>. In some versions or modes, rotation of the view may cause "vignetting" or rounded off dark corners or edges where the desired display area exceeds the available image data from the combined image from the sensors. In some implementations a processing unit may correct or modify the distortion characteristics of the image.

Because digital cameras employing endoscopic instruments and related circuitry for signal capture, processing, and correction and for exposure control are well-known, the above description is directed in particular to elements forming part of, or cooperating more directly with, a method and apparatus in accordance with the present invention. Elements not specifically shown or described herein are selected from those known in the art. Certain aspects of the embodiments may be provided in software. Given the system as shown and described according to the invention in the following materials, software not specifically shown, described or suggested herein that is useful for implementation of the invention is conventional and within the ordinary skill in such arts.

The invention being thus described, it will be obvious that the same may be varied in many ways. Implementations include optical scopes such as exoscopes and borescopes. Further, although sensors <NUM> and <NUM> are shown as discreet entities, two or more of said sensors may share, for example, a mounting substrate or housing accommodating said two or more sensors.

Claim 1:
An optical instrument system comprising an endoscopic instrument, the endoscopic instrument including:
an optical channel assembly (<NUM>) including a single channel lens system optically arranged to receive image light (<NUM>) from an object space and condition the image light (<NUM>) in a single optical channel to create an image space (<NUM>);
first and second image sensors (<NUM>, <NUM>), the first image sensor (<NUM>) positioned to receive a first portion, but not all, of the image light (<NUM>), the first portion (<NUM>) of the image light (<NUM>) corresponding to a first central area of an optical image, and the second image sensor (<NUM>) positioned to receive a second portion (<NUM>) of the image light (<NUM>) and a third portion (<NUM>) of the image light (<NUM>) from opposing sides of the image with respect to the first portion (<NUM>) and at least substantially different from the first portion (<NUM>); and
first and second light directing elements positioned in the image space (<NUM>) of the optical channel assembly (<NUM>) to receive the second and third portions (<NUM>, <NUM>) of the image light (<NUM>) from the optical channel assembly (<NUM>) and direct them toward respective first and second portions of the second image sensor (<NUM>).