Patent Description:
Dual image acquisition is a useful feature for endoscopic procedures wherein two video streams of the same scene are provided, but each video stream has different characteristics such as differing collected light spectra, different image focal planes or focal depths, or differing light intensities. In prior dual image systems, images have generally been collected, split in image space, and then focused onto two independent detectors. Such a configuration allows for some versatility, but is fairly expensive and complex, requiring an individual sensor and the associated electronics and mounting assemblies for each image acquired.

Some prior art systems do capture multiple images from a single imaging sensor chip, however these systems employ a beamsplitter placed in the image space of the camera. Such a design has significant limitations due to lack of flexibility in positioning any desired optical filters, lenses, or other elements in the optical paths downstream from the beamsplitter. Further, the cost associated with a dual imaging system may be higher than a conventional system due to duplication of certain optical components used in focusing and detecting the image light in each of the dual channels.

<CIT> discloses an optical imaging system for use with a medical scope, comprising inter alia a single beamsplitter, comprised in the first optical group, optically arranged to receive the single optical image light in an afocal state and split it into a first portion of light directed along a first optical path and a second portion of light directed along a second optical path, as well a second optical group comprising refractive elements optically arranged to receive the first and second portions of light from the beamsplitter and focus the first portion as a first image onto a first area of a common image sensor and focus the second portion as a second image onto a second area the common image sensor wherein the first and second image areas of the common sensor do not overlap.

<CIT> discloses an image pickup apparatus including an objective optical system, wherein a beamsplitter as a dividing element is placed between the optical system and an image sensor, and a first and second reflection members for reflecting back the bundle of light rays reflected by the dividing element, wherein the bundle of light rays reflected by the first and second reflection members is focused to form an image, on a first and a second area, respectively, of the image sensor.

<CIT> relates to the 3D imaging of dynamic objects, disclosing an optical prism acting as beamsplitter and comprising two external parallel and reflecting surfaces and an entrance side forming an angle β with respect to said interface and at least two exit sides forming an angle γ with respect to said interface, said external surfaces being located at different distances from said interface, the lengths and the thicknesses of the prism are chosen such that at least one beam entering through said entrance side may cross said interface at least twice and exits through said exit sides.

What is needed are devices and methods to enable an endoscopic camera to acquire dual images in a cost-effective manner. What is further needed are devices allowing the use of varied existing endoscopes for dual imaging applications, and the enablement of the detection of varied characteristics in the dual images.

The problem is solved by an optical imaging system for use with a medical scope, comprising:.

It is an object of the invention to provide for improved endoscope acquisition of dual images and allow the use of varied existing endoscopes for dual imaging applications. It is a further object of the invention to allow detection of varied characteristics in the collected dual images, based on ability to vary the optical channels of the dual images. Enhanced depth of field, high dynamic range (HDR), Indocyanine Green (ICG) and other fluorescence analysis, and polarization studies all benefit from the collection of varying versions of the same image.

According to a first aspect of the invention, an optical imaging system is provided for use with a medical scope. The system includes a first substantially afocal optical group with a first beamsplitter, a second optical group, a second beamsplitter, one or more manipulating optical elements, and first and second image sensors. The first beamsplitter optically arranged in the first optical group to receive single optical image light in a substantially afocal state and split the single optical image light into a first portion of light directed along a first optical path and a second portion of light directed along a second optical path. The second optical group includes refractive elements optically arranged to receive the first and second portions of light from the first beamsplitter and focus them. The second beamsplitter is downstream from the second optical group arranged in an image space to split the first portion of light into a third and fourth portion of light and the second portion of light into a fifth and sixth portion of light. The third and fifth portions of light are focused onto a first and second area of the first image sensor, and the fourth and sixth portions of light are focused onto a first area and a second area of the second image sensor. The first and second areas of the first and second image sensor do not overlap. The one or more manipulating optical elements are positioned upstream of the second optical group to manipulate one or more of the single optical image light, the first portion of light and the second portion of light.

According to some implementations of the first aspect, one or more of the manipulating optical elements is an element of the first substantially afocal optical group. In some implementations, the one or more of the manipulating optical elements include an anamorphic optical element in the first substantially afocal optical group, optically arranged to receive the single optical image light in an a substantially afocal state such that resulting images have an anamorphic aspect ratio. The manipulating optical elements may be prisms constructed to induce the anamorphic aspect ratio. In some implementations, the one or more of the manipulating optical elements is the first beamsplitter, and the first beamsplitter manipulates the first portion of light such that it has different optical characteristics from the second portion of light.

According to some implementations of the first aspect, the one or more manipulating optical elements include a spectral filter whereby spectral content of the first portion of light differs substantially from spectral content of the second portion of light. In some implementations, an image processor is included, programmed to process first and second images produced from the first and second image sensors, respectively, and generate there from a single image wherein the different spectral content of the first and second images are overlaid. The first portion of light may include infrared content while the second portion of light comprises visible light. In some implementations, the second beamsplitter includes a second spectral filter such that the third, fourth, fifth, and sixth portions of light have substantially different spectral content. An image processor may be included, programmed to process the first and second images and generating there from a single image with the infrared content and visible light content.

According to some implementations of the first aspect, the one or more manipulating optical elements comprises a means for manipulating light intensity of the first portion of light such that it has a different intensity than the second portion of light. According to some implementations of the first aspect, the second beamsplitter reflects a substantially different percentage of light than it transmits. With these implementations, an image processor may be included, programmed to process the first and second images to generate a single combined image with higher dynamic range than either the first or second image taken individually.

According to some implementations of the first aspect, the one or more manipulating optical elements include an optical element in the first optical path that is not present in the second optical path such that a first image produced with light from first optical path is brought to a different focus than a second image produced with light from the second optical path. According to some implementations of the first aspect, the first and second image sensors are in different focal planes. With these implementations, an image processor may be included, programmed to process the first and second images to generate a single image with an enhanced depth of field over either the first or second image taken individually.

According to some implementations of the first aspect, the one or more manipulating optical elements include a magnifier to manipulate the first portion of light such that first and second images produced with light from the first and second optical paths, respectively, have a different magnification at the image sensor. In some implementations, the second beamsplitter reflects a substantially different percentage of light than it transmits. With these implementations, an image processor may be included, programmed to process image data produced from the third, fourth, fifth, and sixth portions of light to generate a single combined image with higher dynamic range than that contained in any of the image data produced from the third, fourth, fifth, or sixth portions of light considered individually, the single combined image including spectral content based a plurality of the third, fourth, fifth and sixth portions of light.

According to some implementations of the first aspect, one or more of the manipulating optical elements is constructed to manipulate the first portion of light in a manner selected from the group: intensity manipulation, polarization manipulation, spectral manipulation, focal manipulation, and anamorphic aspect ratio manipulation. In some implementations, one or more of the manipulating optical elements is constructed to manipulate the second portion of light in a manner different from that manipulating the first portion of light and selected from the group: intensity manipulation, polarization manipulation, spectral manipulation, focal manipulation, and anamorphic aspect ratio manipulation.

These and other features of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings.

The present invention will become more fully understood from the detailed description given herein and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:.

As used herein, first elements (e.g., sensors and lenses) that are "optically arranged" in relation to other elements, refers to the first elements' position along a common optical path that includes first and other elements. For example, a lens group optically arranged between an image sensor and an objective means that the lens group occupies a portion of the optical path that light travels (e.g., from the objective to the image sensor) for capturing images or video.

Because digital cameras, image sensors and related circuitry for signal capture and processing are well-known, the present description will be directed in particular to elements forming part of, or cooperating more directly with, a method and apparatus in accordance with the invention. Elements not specifically shown or described herein are selected from those known in the art. Certain aspects of the embodiments to be described are 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.

<FIG> is a block diagram of a medical imaging device <NUM> according to an example embodiment of the invention. Medical imaging device <NUM> ("device <NUM>") includes a camera head <NUM> which may have an endoscope <NUM> attached via connectors <NUM> and <NUM>. In some embodiments, an endoscope <NUM> and camera head <NUM> may be integrated into a single housing with no connectors needed. In some embodiments, the device <NUM> is provided as only the camera head <NUM> adapted to be connected to a suitable endoscope. Connectors <NUM> and <NUM> in this embodiment constitute what is generally called a "claw coupling" or dock-clutch coupling, comprising a clutch that couples two components, whereby at least one or both components are rotatable. Preferably, the claw <NUM> of the claw coupling is designed such that the eyepiece cup <NUM> is pushed towards the interface portion to engage the connection. When engaged the eyepiece cup and the interface portion rotate the same speed without slipping. However, the connectors <NUM> and <NUM> may be any suitable connector allowing light to pass from endoscope <NUM> to camera head <NUM>. Various structural components supporting the depicted elements are omitted in the diagrams herein, as well as other components such as illumination lights sources and controls, which are known in the art and are not shown in order to avoid obscuring the relevant details of the example embodiments of the invention.

Camera head <NUM> includes a collimating lens <NUM> positioned at or behind a central window of connector <NUM> to receive and condition optical image light from the endoscope <NUM>. Optically positioned in the optical channel after collimating lens <NUM> is a first substantially afocal optical group <NUM> including one or more manipulating optical elements <NUM> optically arranged to receive the optical image light and perform some type of optical manipulation, as further described below. By the term "substantially afocal," it is meant that the optical group as a whole does not have a significant focusing effect on the imaging light passing through and is not positioned in the image space of the optical system, and so does not receive focused image light. A beamsplitter <NUM> is optically arranged to receive the optical image light in a substantially afocal state from the endoscope <NUM> and split the optical image light into a first portion of light directed to a first optical path and a second portion of light directed to a second optical path as depicted by the two arrows showing the light path to second optical group <NUM>. The first and second optical paths are further described with respect to the example embodiments below.

Second optical group <NUM> includes refractive elements optically arranged to receive the first and second portions of light from the beamsplitter <NUM> and focus them toward second beamplitter <NUM>, placed within the image space of the optical system. The second optical group <NUM> may also include further optical manipulating elements. The second beamsplitter <NUM> further splits the incoming two portions of light into four portions of light directed toward distinct areas of first and second image sensors <NUM> and <NUM>. Second optical group <NUM> typically includes at least one focusing lens, with the group having a total positive power. Many suitable lenses and combinations of lenses may be used for second optical group <NUM>. The sensor signal, containing two images, is processed as further described with respect to FIG. <NUM> and FIG. <NUM> to provide a combined image.

In some embodiments, system <NUM> includes an endoscope <NUM> as depicted at the left of the block diagram. The depicted endoscope is an example only, and many endoscope designs are suitable, including rigid and flexible endoscopes. Endoscope <NUM> includes a cover glass <NUM> at its distal tip, which in this version faces directly along the longitudinal axis of the endoscope <NUM>, but may also be positioned at an angle relative to the longitudinal axis as is known in the art. Behind, or on the proximal side of, the cover glass <NUM> is shown a preferred position for the objective lens <NUM>, set against or very near cover glass <NUM> and preferably assembled together with the cover glass in construction. While a wide-angle lens is preferred for objective lens <NUM>, this is not limiting, and any suitable lens may be used in various embodiments. Objective lens <NUM> may be part of an objective lens group <NUM> which may include one or more additional lenses <NUM>. The particular number and arrangement of lenses in the endoscope <NUM> will vary widely depending on the application. Optically arranged or attached at the proximal side of objective lens <NUM> or objective lens group <NUM> is a series of one or more rod lenses <NUM>, which serve to pass the light down endoscope <NUM> in the proximal direction. Typically, several rod lenses <NUM> are employed, which may be separated by spacers or other lenses in any suitable manner known in the art. While the endoscope <NUM> may be of rigid design, shaft design variations are also known to allow rod lenses to be used in a semi-flexible shaft in which flexible joints are present in one or more places along the shaft between the rod lenses, while the shaft is rigid along the portions containing a rod lens. Such a shaft design may be used in various embodiments of the invention.

<FIG> is a partial cross section diagram of a camera head <NUM> showing the optical assembly construction according to an example embodiment. The cross section includes a light ray diagram showing the passage of image light through the assembly to image sensors <NUM> and <NUM>. The depicted optical elements are in diagram form only and are not drawn to scale. The depicted optical assembly may be employed with endoscope devices and systems having an integrated camera or an external detachable camera head. As shown, the optical assembly starts at collimating lenses <NUM> where the image light enters the camera head. Collimating lenses <NUM> may have a slightly positive or negative power in order to adjust the image light to the desired condition to be received by first substantially afocal optical group <NUM>, preferably with light rays close to parallel. First substantially afocal optical group <NUM> in this version a includes a first beamsplitter <NUM> optically arranged to receive single optical image light in a substantially afocal state and split the single optical image light into a first portion of light <NUM> directed along a first optical path and a second portion of light <NUM> directed along a second optical path. In this embodiment, beamsplitter <NUM> is constructed of prisms, including the lower right angle prisms <NUM>-<NUM> and <NUM>-<NUM> with a suitable partially reflective coating along their adjacent surface, by which the image light is split with a first portion passing through along first optical path <NUM> and a second portion reflected upward along second optical path <NUM> as depicted. Adjacent to the beamsplitter <NUM> is an upper prism <NUM> that reflects light along the second optical path <NUM> as depicted. As discussed above, the first and second portions of light may include different spectral content.

Optically arranged downstream of first substantially afocal optical group <NUM> is a second optical group <NUM> including refractive elements optically arranged to receive the first and second portions of light from the first beamsplitter and focus them. In this embodiment, second optical group <NUM> includes a lens pair <NUM> having a total positive power to focus and align the first and second portions of light along first and second optical paths <NUM> and <NUM>. A second lens pair <NUM> is optically arranged downstream of lens pair <NUM>, including a biconvex lens with a positive power followed by a bi-concave lens with a negative power to align first and second optical paths <NUM> and <NUM> with a second beamsplitter <NUM>. As can be understood from the ray diagram, lens pair <NUM> and the rest of second optical group <NUM> are preferably symmetrically arranged with respect to the first and second optical paths <NUM> and <NUM>, and large enough to span both paths. That is, second optical group <NUM> is positioned with the axis pointing between the first and second paths such that each path has similar incidence on lens <NUM>, symmetrical about the central axis of group <NUM>.

A second beamsplitter <NUM> is positioned downstream from the second optical group <NUM> and arranged to split the first portion of light <NUM> into a third and fourth portion of light and the second portion of light <NUM> into a fifth and sixth portion of light, as can be seen in the light ray diagram with the respective portions of light directed to first and second image sensors <NUM> and <NUM>.

The third and fifth portions of light are focused onto a first and second area of first image sensor <NUM>, and the fourth and sixth portions of light are focused onto a first area and a second area of second image sensor <NUM>. As can be seen, the first and second areas of the first and second image sensors <NUM>, <NUM> do not overlap. First image sensor <NUM> is positioned downstream of a cover glass or protective layer <NUM>, with the image sensor lying parallel the longitudinal axis of camera head <NUM>, while second image sensor <NUM> is positioned downstream of a cover glass or protective layer <NUM>, with the image sensor standing perpendicularly the longitudinal axis.

In some embodiments, one or more manipulating optical elements are positioned upstream of second optical group <NUM> to manipulate one or more of the single optical image light, first portion of light <NUM>, or second portion of light <NUM>. The one or more of the manipulating optical elements may be an element of the first substantially afocal optical group, such as an anamorphic optical element optically arranged to receive the single optical image light in a substantially afocal state such that resulting images have an anamorphic aspect ratio. The anamorphic optical element may include one or more lenses constructed to induce the anamorphic aspect ratio. The manipulating optical element may be first beamsplitter <NUM>. For example, first beamsplitter <NUM> may manipulate the incoming light such that the first portion of light <NUM> has different optical characteristics from second portion of light <NUM>.

In some embodiments, the one or more manipulating optical elements include a spectral filter whereby spectral content of first portion of light <NUM> differs substantially from spectral content of the second portion of light <NUM>. For example, first portion of light <NUM> may include infrared content with second portion of light <NUM> including visible light. Second beamsplitter <NUM> may include a second spectral filter such that the third, fourth, fifth, and sixth portions of light have substantially different spectral content.

In some embodiments, the one or more manipulating optical elements include an intensity filter for manipulating light intensity of first portion of light <NUM> such that it has a different intensity than second portion of light <NUM>. Second beamsplitter <NUM> may be constructed to reflect a substantially different percentage of light to first image sensor <NUM> than it transmits to second image sensor <NUM>.

In some embodiments, the one or more manipulating optical elements include an optical element in the first optical path that is not present in the second optical path such that a first image produced with light from first optical path is brought to a different focus than a second image produced with light from the second optical path. The first and second image sensors may be in slightly different focal planes to accommodate for different focal lengths in the optical paths.

In some embodiments, the one or more manipulating optical elements comprises a magnifier to manipulate the first portion of light such that first and second images produced with light from the first and second optical paths, respectively, have a different magnification at the image sensor.

The second optical group <NUM> includes refractive elements optically arranged in both the first and second optical paths to receive the first and second portions of light from the beamsplitter <NUM> and focus the first portion as a first image onto a first area of a common image sensor <NUM> and the focus second portion as a second image onto a second area the common image sensor <NUM>, different from the first area.

Further, while lenses <NUM> and <NUM> in this embodiment focus and direct both portions of light, other versions may include one or more lenses that perform focusing or diverging operations on only a single one of the optical paths. For example, lens <NUM> and/or <NUM> might be replaced with a separate focusing lens for each path.

<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 other instruments such as 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 passed to the camera head, typically using a relay system comprising rod lenses. At the camera head the light is focused, aligned with the scope axis or a desired optical axis, and passed to a distal 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 first and second solid-state image sensors <NUM> and <NUM>.

In this embodiment, optical channel assembly <NUM> includes an imaging system and may be constructed according to a variety of known methods. 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>. A camera head 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>. The non-optical, 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 two images from image sensors <NUM> and <NUM> as necessary, including processing the sub-images based on the third, fourth, fifth, and sixth portions of light. Image processing circuitry <NUM> is programmed to process image data produced from a plurality of the third, fourth, fifth, and sixth portions of light, and, in some embodiments, to generate a single combined image including image data produced from the third, fourth, fifth, or sixth portions of light. In some embodiments, the combined image has higher dynamic range than that contained in any of the image data produced from the third, fourth, fifth, or sixth portions of light considered individually. In some embodiments, the combined image has an enhanced depth of field over that of image data from the first and second image sensors individually.

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 may be 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 diagram representing image light focused on an image sensor <NUM> according to the prior art to capture image data for a single image labeled Image <NUM>. Sensor <NUM> illustrates the sensing area of the image sensor with light-sensitive pixels shown as a grid. <FIG> depicts various portions of image light focused on first and second image sensors according to some embodiments. As depicted, the third and fifth portions of light are focused on first image sensor <NUM>, forming Images labeled Image <NUM> and Image <NUM>, and the fourth and sixth portions of light are focused on second image sensor <NUM> forming images labeled Image <NUM> and Image <NUM>. In this diagram images <NUM>, <NUM>, <NUM>, and <NUM> exhibit an anamorphic aspect ratio, representing embodiments where the incoming light, in most cases, is manipulated to achieve this aspect ratio, in order to maximize the number of pixels of the sensors receiving useable image information. Image processing is then used to conform the displayed image back to the proper aspect ratio.

<FIG> is a flowchart of a method for producing endoscopy images according to an example embodiment. The method may be performed employing any of the various example embodiments of endoscope and camera head devices as described herein, with a suitable camera control unit such as that described above to process the image data. The method begins at process block <NUM> where it includes receiving the image light from an endoscope. The endoscope device used may be a separate device attached to a camera head or an endoscope integrated with a camera head. At process block <NUM>, the process directs the received image light along a single optical channel. At block <NUM>, the process alters the image light, still in a single optical channel, to have an anamorphic aspect ratio. The final anamorphic ratio is designed to allow improved use of image sensor area when the image light is directed at the sensor. Some embodiments may not include block <NUM> as indicated by the dotted lines. Next at process block <NUM>, with the image light in a substantially afocal state, the process includes splitting the image light from the single optical channel into a first portion of light and a second portion of light. Then at block <NUM>, the process directs the first portion of light along a first optical path and the second portion of light along a second optical path. Directing the light is preferably done with a first beamsplitter such as the example splitters described herein.

Next at process block <NUM> the process includes optically manipulating the first or second portions of light relative to each other. As described above, the optical manipulation at this block may include one of manipulating the spectrum of the light, manipulating the intensity of the light, manipulating the focus of the light, manipulating the depth of field of the optical path, manipulating the polarization of one beam relative to the other, magnifying or applying an optical filter of some type.

Then at process block <NUM>, the process includes splitting the first portion of light into a third and fourth portion of light and then directing the third portion of light to a first image sensor and directing the fourth portion of light to the second image sensor. As described above, the splitting is typically accomplished with a second beamsplitter. While in the diagram the splitting is shown separately from the optical manipulation at block <NUM>, these functions may be accomplished separately or simultaneously (such as with a beamsplitter that manipulates one emerging beam relative to the other while splitting). At block <NUM>, the process splits the second portion of light into fifth and sixth portions of light and directs the fifth portion of light to the first image sensor and the sixth portion of light to the second image sensor. In some embodiments, this splitting is performed by the second beamsplitter employed at block <NUM>, while in other embodiments a separate beamsplitter is used for the second portion of light.

At block <NUM>, the process includes optically manipulating the two portions of light directed to one of the image sensors, either the third and fifth portions of light and/or the fourth and sixth portions of light. The optical manipulation may include the various options listed with respect to block <NUM> and is typically selected to compliment the manipulation performed at block <NUM>. For example, block <NUM> may perform a spectral filter to separate fluoresced light, while block <NUM> may adjust the intensity of light to provide low intensity image data based on the third and fifth portions of light and high intensity image data based on the fourth and sixth portions of light. This combination enables the use of fluoresced imaging along with HDR imaging. As another example, block <NUM> may adjust the focal depth of one of the first and second portions of light, while block <NUM> adjusts the light intensity. Preferably, such a focal depth adjustment is accomplished by offsetting the focal plane of one sensor. This combination enables imaging with a high depth-of-field along with HDR imaging.

At block <NUM>, the process focuses the third and fifth portions of light on separate areas of the first image sensor and focuses the fourth and sixth portions of light on separate areas of the second image sensor. Next at block <NUM>, image processing is performed on the image data from the first and second image sensors. In some embodiments, the image processing is applied to image data based on the third, fourth, fifth, and sixth portions of light to generate a single combined image including first characteristics resulting only from the third and fifth portions of light (from the first image sensor) and second characteristics resulting only from the fourth and sixth portions of light (from the second image sensor). In other embodiments, the process creates two images based on the image data from two or more of the portions of light. The processing is performed by a CCU such as the CCU <NUM> of <FIG>, or other suitable image processing circuitry.

The image characteristics from the different portions of light may be designed to be any of a number of characteristics desired to be measured through the endoscope. For example, in some versions the spectral content of the first portion of light differs substantially from the spectral content of the second portion of light. The first portion of light may include infrared content with the second portion of light including visible light, for example. A combined image based on such a scheme may use designated colors to show the infrared content superimposed on the visible light content in a manner known in the art. In another embodiment, the first portion of light has a different intensity range than the second portion. This may be accomplished by reflective characteristics of the beamsplitter, or by a filter or filters or other suitable optical element or elements placed in one or both of first and second optical paths. Processing the image data with different intensity ranges provide a high dynamic range (HDR) single combined image with higher dynamic range than either the first or second image taken individually. The HDR imagery may further enhanced by also performing optical manipulation to the intensity at the second manipulation step, resulting in four images of the same scene of varying intensity. In another example embodiment, the process includes focusing the first image on the common image sensor differently than focusing the second image. The image processing of block <NUM> may extract features that are in sharper focus in one of the two images, or, as with the varying intensity value, four such focal positions may be captured and combined. Such an embodiment results in a single image with a larger depth of field than either the first or second image taken individually. Still other of the many possible embodiments may place a polarized filter within the beamsplitter or in the first and second optical paths, allowing the dual images to each acquire light with a different polarization. Known image processing techniques for polarization studies may be applied in processing the dual images from such an embodiment. And of course, any of the first manipulations discussed above may be combined with a second manipulation of a different type; for example, a first manipulation by intensity, and a second manipulation by spectrum is only one of the many possible combinations all represented by the present invention.

Claim 1:
An optical imaging system (<NUM>, <NUM>) for use with a medical scope (<NUM>), comprising:
a first substantially afocal optical group (<NUM>) comprising a first beamsplitter (<NUM>) optically arranged to receive single optical image light in a substantially afocal state and split the single optical image light into a first portion of light (<NUM>) directed along a first optical path and a second portion of light (<NUM>) directed along a second optical path;
a second optical group (<NUM>) comprising refractive elements optically arranged to receive the first and second portions (<NUM>, <NUM>) of light from the first beamsplitter (<NUM>) and focus them;
a second beamsplitter (<NUM>) downstream from the second optical group (<NUM>) arranged in an image space to split the first portion of light (<NUM>) into a third and fourth portion of light and the second portion of light (<NUM>) into a fifth and sixth portion of light;
wherein the third and fifth portions of light are focused onto a first and second area of a first image sensor (<NUM>), and the fourth and sixth portions of light are focused onto a first area and a second area of a second image sensor (<NUM>), wherein the first and second areas of the first and second image sensor (<NUM>, <NUM>) do not overlap; and
one or more manipulating optical elements (<NUM>) positioned upstream of the second optical group (<NUM>) to manipulate one or more of the single optical image light, the first portion of light (<NUM>) and the second portion of light (<NUM>).