Imaging spectrometer and camera with high spectral range

Abstract

An imaging spectrometer and camera including a prism that refracts incident light over a spectral range having a shortest wavelength (λ S ) and a longest wavelength (λ L ) for spectral analysis. A diffraction grating is aligned with the prism and diffracts the incident light. Both the refraction and the diffraction of a set of diffraction orders for spectral analysis increase the angle of deflection of the incident light from the original optical axis. The spectral range spans more than an octave so that λ L > 2λ S . The refraction and the diffraction are such that the second order diffraction of λ S does not overlap with the first order diffraction of wavelengths less than λ L . The second order diffraction of wavelengths between λ S and λ C and the first order diffraction of wavelengths between λ C and λ L are detected at different spatial regions for spectral analysis from λ S to λ L .

Description

Technical Field

[0001] This disclosure relates to multispectral imaging (MSI) or hyperspectral imaging (HSI) systems, and more particularly, to imaging systems and apparatuses including imaging spectrometers, especially those imaging systems and apparatuses that can operate over an extended spectral range. Background Technology

[0002] Classical video endoscopy is used to provide color video imaging of areas examined within the body. Multispectral or hyperspectral imaging can provide endoscopic users with additional information that can be used during the procedure or diagnosis. For example, in medical technology, physiological imaging using multispectral or hyperspectral methods can be used to analyze physiological parameters such as hemoglobin content and hemoglobin oxygenation in the examined area, which are displayed spatially in pseudo-color resolution. Multispectral and hyperspectral imaging also have various further applications both within and outside the medical field.

[0003] Integrating multispectral or hyperspectral imaging capabilities with medical endoscopes typically requires a miniaturized imaging spectrometer architecture that is inexpensive compared to typical imaging spectrometers used in other applications, depending on the specific application. To meet these requirements, simple spectrometers based on diffraction gratings can be constructed. However, such designs are usually limited to a single octave of the spectral range, meaning that second-order diffraction at shorter wavelengths will not be imaged onto first-order diffraction at longer wavelengths.

[0004] A common, traditional approach to this problem is to place spectral filters near the image plane to filter the shortest wavelength second-order diffraction. However, due to the physical size limitations of the filters, this method often results in gaps in the acquired spectrum. Another option is to use a sensor with a color filter array that can distinguish between the shortest wavelength second-order diffraction and the longest wavelength first-order diffraction. However, constructing filters without edge artifacts or filters that modify properties across various dimensions is generally expensive, and such filters are typically not suitable for production use. Summary of the Invention

[0005] The object of this invention is to provide an imaging spectrometer and camera that can operate over an extended spectral range. Another object of this invention is to provide a device that can efficiently sense spectral content within a desired range while being sized to fit the shape factor of a medical endoscope camera.

[0006] According to a first aspect of the invention, an imaging spectrometer includes a prism having a minimum wavelength (λ) for spectral analysis. S ) and longest wavelength (λ) LThe incident light is refracted within at least one spectral range. A diffraction grating is optically aligned with the prism and diffracts the incident light. A set of diffraction orders for spectral analysis, consisting of prism refraction and blazed diffraction grating diffraction, both increase the deflection angle of the incident light from its original optical axis. One or more sensors are positioned to detect the incident light passing through the prism and diffraction grating. The spectral range spans more than one octave, such that λ... L >2λ S The combination of prism and blazed diffraction grating results in refraction and diffraction of λ. S Second-order diffraction on one or more sensors with a wavelength shorter than λ L The first-order diffraction of any wavelength does not overlap spatially, and for the spectral range λ... S and selected wavelength (λ) C The wavelengths between λ and λ' are sufficient to diffract to the second order, such that λ' ... S and λ C Second-order diffraction between wavelengths and λ C and λ L First-order diffraction of wavelengths between λ is detected by one or more sensors in different spatial regions to determine the wavelengths from λ. S To λ L Spectral analysis is performed on the spectrum. According to some embodiments of the first aspect, a scanning system is included for manipulating the incident light such that the second spatial dimension of the image is captured as a series of frames in temporal order.

[0007] According to a second aspect of the invention, an imaging spectrometer camera is adapted to receive incident light from a medical endoscope. The imaging spectrometer camera includes an optical channel for receiving and focusing the incident light, and an imaging spectrometer located downstream of the optical channel. The imaging spectrometer includes a scanning system for adjusting the relative position of the imaging spectrometer with respect to the optical channel. Prism refraction is used for spectral analysis with the shortest wavelength (λ). S ) and longest wavelength (λ) L The incident light is within at least one spectral range of the prism. A blazed diffraction grating is optically aligned with the prism and diffracts the incident light. The prism refraction and blazed diffraction grating diffraction, both part of a set of diffraction orders used for spectral analysis, increase the deflection angle of the incident light from the original optical axis. A focal plane array sensor, located downstream of the prism and blazed diffraction grating, simultaneously detects λ along a spatial axis within the spectral range. S and selected wavelength (λ) C Second-order diffraction between wavelengths and λ C and λ L First-order diffraction between wavelengths. The spectral range is greater than one octave, making λ... L >2λ S The combination of prism and blazed diffraction grating results in refraction and diffraction of λ. S The second-order diffraction at the focal plane array sensor will not be shorter than λ. LFirst-order diffractions of any wavelength overlap in space.

[0008] According to some embodiments of the first and second aspects, the diffraction grating is a blazed diffraction grating, and at a wavelength (λ) P The grating blaze angle at which the first-order maximum diffraction efficiency is obtained is such that 0.65 < λ. P / λ L <0.8.

[0009] According to some embodiments of the first and second aspects, the spectrometer has a spectral range of approximately 430-1000 nm. In this embodiment, λ C The value is likely to be approximately 525 nm.

[0010] According to some embodiments of the first and second aspects, the spectrometer has a spectral range of approximately 500-1100 nm.

[0011] According to some embodiments of the first and second aspects, one or more sensors include a single focal plane array sensor that simultaneously detects λ along a spatial axis. S and λ C Second-order diffraction between wavelengths and λ C and λ L First-order diffraction between wavelengths. One spatial dimension of the image can be captured along the sensor axis perpendicular to the axis capturing the spectral range.

[0012] According to some embodiments of the first and second aspects, λ is used when calculating the resultant spectrum. C First-order and second-order diffraction at nearby wavelengths.

[0013] According to some embodiments of the first and second aspects, a spectral filter is included that blocks wavelengths outside the spectral range of the spectrometer from entering the spectrometer.

[0014] These and other features of the invention will become apparent from the following description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0015] The present invention is further explained through exemplary descriptions of the following specific embodiments.

[0016] Figure 1 This is a block diagram of an imaging spectroscopy device according to an exemplary embodiment of the present invention; Figure 2 This is a partial cross-sectional view showing a camera constructed with optical components according to an example embodiment; Figure 3 It shows Figure 2 A magnified view of a portion of the imaging spectrometer.

[0017] Figure 4 An enlarged view of a portion of an imaging spectrometer according to another embodiment is shown; Figure 5 A graph illustrating the characteristics of a diffraction grating according to some embodiments is shown; Figure 6 A schematic diagram of the spatial distribution of first-order and second-order diffraction in a sensor plane according to some embodiments is shown; Figure 7 A schematic diagram showing the diffraction position along an image sensor according to some embodiments is shown; and Figure 8 This is a hardware block diagram of a system including an example image capture device according to an example embodiment of the present invention. Detailed Implementation

[0018] Figure 1 This is a block diagram of an imaging spectrometer device 100 according to an exemplary embodiment of the present invention. The imaging spectrometer device 100 (“device 100”) includes a camera 101, which may have an endoscope 102 attached via connectors 108 and 109. In some embodiments, the endoscope 102 and the camera 101 may be integrated into a single housing, eliminating the need for connectors. In some embodiments, the device 100 is provided solely as a camera 101 adapted for connection to a suitable endoscope or other medical endoscope. In other embodiments, the imaging spectrometer described herein may be used with other imaging arrangements that do not use an endoscope. Connectors 108 and 109 in this embodiment constitute what is generally referred to as a “claw coupling” or mating clutch coupling, including a clutch connecting two components, wherein at least one or both components are rotatable. Preferably, the claw (109) of the claw coupling is designed such that the eyepiece cup (108) is pushed toward the interface portion to engage the connection. Connectors 108 and 109 may be any suitable connector that allows light to be transmitted from the endoscope 102 to the camera 101. Various structural components supporting the illustrated elements, as well as other components known in the art, such as lighting sources and control devices, are omitted from the figures herein in order to avoid obscuring the relevant details of the exemplary embodiments of the present invention.

[0019] Camera 101 includes an optical subsystem 110 that transmits light for hyperspectral or multispectral imaging in a desired spectrum, which may include wavelengths of invisible light. The optical subsystem 110 is located at or behind the central window of connector 109 to receive and modulate image light from endoscope 102. The optical subsystem 110 typically includes multiple lenses for focusing, as described further below. Many suitable lenses and lens combinations are available for the optical subsystem 110.

[0020] An optional beam splitter 114 is located downstream of the first optical subsystem. The beam splitter splits the light into two beams, one of which is directed to the first image sensor 214, which produces a visible light image to complement the image produced by the other beam using a spectrometer.

[0021] Imaging spectrometer 220 receives imaging light from beam splitter 114. Imaging spectrometer 220 includes spectrometer optics 115, scanning mechanism 116, and image sensor 216. In some embodiments, more than one image sensor may be used, but a single image sensor is preferred. Spectrometer optics 115 is optically positioned downstream of the beam splitter and includes various elements for collimating, refracting, and diffracting the image light, as well as elements of the scanning system. In embodiments without a beam splitter, spectrometer optics 115 is located directly downstream of optical subsystem 110, and image sensor 214 may not be present. In this embodiment, scanning mechanism 116 is mechanically coupled to at least a portion of the spectrometer optics to enable the mechanical movement required to perform the scanning operation. Scanning mechanism 116 may be a push-broom scanning mechanism that works in conjunction with a slit in the spectrometer optics, or another suitable scanning mechanism that can move or rotate one or more optical elements to perform line-by-line scanning of the spectrometer, as further described below.

[0022] In some embodiments, device 100 includes an endoscope 102 as shown on the left side of the block diagram. The depicted endoscope is merely an example, and many endoscope designs are suitable, including rigid and flexible endoscopes. Endoscope 102 includes a cover glass 105 located at its distal tip, in which version the cover glass 105 is oriented directly along the longitudinal axis of the endoscope, but it can also be angularly positioned relative to the longitudinal axis as is known in the art. A preferred location for objective lens 106 is shown behind or near the cover glass 105, positioned close to or very close to the cover glass 105, and preferably constructed to be assembled with the cover glass. Objective lens 106 may be part of objective lens group 104, which may include one or more additional lenses 103. The specific number and arrangement of lenses in endoscope 102 will vary widely depending on the application. A flexible fiber optic bundle or a series of one or more rod lenses 107 is arranged or attached to the proximal optical arrangement of the objective lens 106 or objective lens group 104 to allow light to pass through the endoscope 102 in a proximal direction. For embodiments with a flexible axis, a flexible fiber bundle is used. For a rigid or semi-rigid axis, one or more rod lenses 107 are employed, which may be spaced apart by spacers or other lenses in any suitable manner known in the art.

[0023] Figure 2This is a partial cross-sectional view illustrating a camera 101 constructed according to an example embodiment of the optical components. The cross-section includes a ray diagram showing image light 302 passing through the component and then being guided by beam splitter 114 towards image sensor 214 for white light imaging and image sensor 216 in spectrometer 220 for image spectroscopy. The depicted optical components are presented graphically only and are not drawn to scale. The depicted optical components can be used with devices and systems having an integrated camera or an externally detachable camera.

[0024] As shown in the figure, in this embodiment, image light 302 enters the optical assembly at the cover glass 201. The image light 302 is then passed downstream to the optical subsystem 110, which in this embodiment includes a dual-lens system 202 and a dual-lens system 203. Dual-lens 202 includes a biconvex lens and a concave-convex lens, which together have slightly positive power. Dual-lens 203 includes a convex-concave lens and a biconvex lens; this lens pair together has positive power for focusing image light 302. These two lens pairs are designed to focus and align image light 302 along the central optical axis toward beam splitter 114, while optionally mitigating chromatic aberration. In various embodiments, various other lens combinations can be used to achieve the same result.

[0025] In this embodiment, the beam splitter 114 consists of two prisms with a suitable beam-splitting layer formed by a partially reflective coating along their adjacent surfaces. This beam-splitting layer splits the image light into a first part and a second part. The first part passes through the first optical path shown by the image light 303, and the second part reflects upward along the second optical path shown by the imaging light 304. In this embodiment, the partially reflective coating reflects the image light of the visible spectrum, preferably reflecting as little white light as possible required for imaging, to maintain most of the image light intensity in the visible range and all light in the invisible spectrum for spectral analysis. The first image sensor 214 is located downstream of the cover glass or protective layer 213, and the image sensor is oriented perpendicular to the longitudinal axis of the camera 101.

[0026] Imaging spectrometer 220 is located downstream of beam splitter 114 to receive incident light 303 from beam splitter 114. Imaging spectrometer 220 typically includes spectrometer optics 115 and a second image sensor 216, as well as a scanning mechanism (…). Figure 1 (116 in the example). In this embodiment, the spectrometer optical assembly 115 includes an optional filter 222 for filtering the incident light to remove wavelengths outside the spectral range required for spectral analysis. Typically, the spectral range has a minimum wavelength (λ). S ) and longest wavelength (λ) L This varies depending on the application in different embodiments.

[0027] Optically downstream of the optional filter 222 is a slit 224, located at the focal point produced by the optical subsystem 110 and oriented perpendicular to the optical axis of the incident light 303, such that, relative to the figures, the slit extends into the page to provide a horizontal slit on the incident light. Optically downstream of the slit 224 is a collimating lens group comprising binoculars 226 and 228, each comprising a convex-convex lens and a concave-convex lens, which are selected to collimate diverging incident light while optionally minimizing chromatic aberration across the entire spectral range. In various embodiments, various other collimating lens arrangements can be used to achieve the same functionality.

[0028] Figure 3 It shows Figure 2 A magnified view of a portion of the imaging spectrometer 220. (See reference...) Figure 2 and Figure 3 Optically located downstream of the collimating lens group is a prism 230, which refracts collimated incident light within at least one spectral range for spectral analysis. A baffle 229 can be used to block light from outside a designated area from entering the prism 230. The prism 230 refracts the incident light at an angle from its optical axis, as shown downwards in the figure. A blazed diffraction grating 240 is optically aligned with the prism 230 to receive the refracted incident light. As shown, the diffraction grating 240 is oriented at an angle to the original optical axis of the optical assembly 115. The diffraction grating 240 diffracts the incident light and is oriented such that both the refraction from the prism 230 and the diffraction from the diffraction grating 240 increase the deflection angle of the incident light relative to the original optical axis of a set of diffraction orders used for spectral analysis. In this embodiment, the set of diffraction orders used are the first and second order diffractions, as further described below.

[0029] Diffracted incident light from the diffraction grating 240 is focused toward the image sensor 216 by a pair of dual lenses 250 and 252. Various lenses and lens combinations can be used to perform the focusing function in different embodiments. In this embodiment, the lens dual 250 includes a biconvex lens and a concave-convex lens. The lens dual 252 also includes a convex-concave lens and a biconvex lens. In some embodiments, such as... Figure 2 and Figure 3 As shown, the double lenses 250 and 252 are related to lenses 226 and 228 ( Figure 2 They have the same convex-convex structure and crescent structure.

[0030] Image sensor 216 is located downstream of dual lenses 250 and 252 to detect incident light passing through the prism and diffraction grating. In this embodiment, image sensor 216 is a single-focal-plane array sensor that simultaneously detects λ along a spatial axis. S and λ C Second-order diffraction between wavelengths and λ C and λL First-order diffraction between wavelengths. Due to refraction and diffraction, various spectral portions of the incident light are distributed along one axis of the image sensor 216, which is positioned to detect these portions, including selected first and second-order diffraction from the diffraction grating 240. The spectral range of the imaging spectrum spans more than one octave, such that λ L >2λ S The combined refraction and diffraction of prism 230 and diffraction grating 240 makes λ S The second-order diffraction at one or more sensors is not shorter than λ. L First-order diffraction at any wavelength overlaps in space. As follows regarding... Figure 5 and Figure 6 Further described, for λ in the spectral range S and selected wavelength (λ) C The wavelengths between λ and λ' have sufficient second-order diffraction to allow one or more sensors in different spatial regions to detect λ. S and λ C Second-order diffraction between wavelengths, and λ C and λ L First-order diffraction between wavelengths, thus affecting the wavelength from λ S To λ L Spectral analysis was performed on the spectrum.

[0031] In this embodiment, the imaging spectrometer 220 is held in a modular assembly consisting of a scanning mechanism 116 ( Figure 1 The slit 224 moves to perform a scanning function. This movement, in a push-broom manner relative to the attached diagram in the vertical direction, moves the slit 224 to different positions within the incident light 303 to acquire new imaging spectrometer data lines. Multiple lines are acquired in this way to produce an imaging spectrometer image.

[0032] Figure 4 An enlarged view of a portion of an imaging spectrometer 420 according to another embodiment is shown. The depicted embodiment is applicable to... Figure 2 The imaging spectrometer 220 is applicable to implementing imaging spectrometers according to other embodiments. As shown, in this embodiment, the prism 230 is optically arranged after the diffraction grating 240, rather than the diffraction grating being after the prism. The prism 230 is optically aligned with the blazed diffraction grating 240 to receive refracted incident light. As shown, the prism 230 is oriented at an angle to the original optical axis of the optical assembly 115. The prism 230 refracts the incident light and is oriented such that both diffraction from the diffraction grating 240 and refraction from the prism 230 increase the deflection angle of the incident light relative to the original optical axis of a set of diffraction orders used for spectral analysis. Regarding... Figure 2 and Figure 3The described characteristic also exists in this embodiment, namely, the spectral range of the imaging spectrum performed has a span greater than one octave, such that λ L >2λ S The combined refraction and diffraction of prism 230 and diffraction grating 240 make λ S The second-order diffraction at one or more sensors is not shorter than λ. L First-order diffractions of any wavelength overlap in space.

[0033] Figure 5 Figure 500 shows the characteristics of a diffraction grating according to some embodiments. The vertical axis represents the diffraction efficiency, and the horizontal axis represents the wavelength of light in nanometers (nm). Figure 502 shows a diffraction grating (such as...) Figure 2 The first-order diffraction efficiency of the diffraction grating (240) is shown in Figure 504, while the second-order diffraction efficiency is shown in Figure 504. In this version, the spectrometer's spectral range is approximately 430–1000 nm, as shown by λ in Figure 500. S and λ L As shown. As used herein, "approximately" means that a particular value may differ slightly from the required value, for example, by at most 5%. The diffraction grating has a grating blaze angle and a first-order maximum diffraction efficiency at 750 nm, denoted as λ. P The wavelength is shown.

[0034] The selected cutoff wavelength λ is shown. C Below this wavelength, the imaging spectrometer described herein uses second-order diffraction instead of first-order diffraction to detect spectral content. In this embodiment, λ C Approximately 525 nm. In other embodiments, different values ​​of λ may be used. C It mainly depends on the total spectrum to be analyzed, i.e., λ S and λ L The value of λ. For example, in another embodiment, the spectrometer has a spectral range of approximately 500-1100 nm and uses a higher λ value. C Value. For example... Figure 5 As shown in the graph, at wavelength λ C At and near the sensor, due to diffraction efficiency, the intensity or power of first-order and second-order diffraction is relatively low. Therefore, in some embodiments, λ C First-order and second-order diffraction at nearby wavelengths can both be used to calculate spectral content, as described further below. "Near" means that this technique can be used to calculate adjacent spectral bands with such low intensities on either side.

[0035] In this embodiment, the blazed diffraction grating is at wavelength λ P The grating blaze angle with the highest first-order diffraction efficiency at 750 nm is λ.P It is λ L 0.75 times the longer wavelength. Typically, the inventors have discovered that when the diffraction grating is selected such that 0.65 < λ... P / λ L When <0.8, the combination of spatial dispersion of diffraction and refraction spectra can achieve, for example... Figure 5 The required efficiency characteristics are shown below, and the following is about Figure 6 The spatial distribution is discussed. Embodiments utilizing this characteristic of diffraction gratings offer the following advantages: allowing detection of a large spectral range without spatial overlap between first-order and second-order diffraction, while still providing sufficient power in each spectral band for fast and efficient detection using a single sensor. This combination also allows for the reduction of components such as filters typically optically positioned in front of the sensor to block overlapping second-order diffraction. Therefore, the overall size of the spectrometer optics can be reduced while still allowing imaging spectroscopy over a relatively large frequency range greater than an octave. Furthermore, the cost of such a spectroscopic system may be reduced compared to conventional systems.

[0036] Figure 6 A graph 600 is shown illustrating the spatial distribution of first-order and second-order diffraction in a sensor plane according to some embodiments. The horizontal axis represents the position on the sensor plane along the diffraction direction. The shaped points represent the diffraction patterns formed by... Figure 5 The points on Figures 502 and 504 indicate the spatial locations of the various wavelengths. The area marked on the figure is region 601, which the sensor aims to capture, from λ... C First-order diffraction extended to λ C The second-order diffraction. Region 601 is used to detect and calculate the diffraction from λ. S To λ L A continuous spectrum. It is preferable not to use wavelengths shorter than λ. C First-order diffraction and wavelengths longer than λ C The second-order diffraction. Typically, light from these unused areas will fall outside the effective region of the sensor and will not be collected. Preferably, the prism and diffraction grating are designed to diffract λ. S The spatial position of the second-order diffraction and λ L The first-order diffractions are slightly separated.

[0037] In some embodiments, during the computation of synthetic spectral analysis, λ is detected and combined. C First-order and second-order diffraction at nearby wavelengths. "Nearby" refers to the wavelength at λ. C At that location, possibly in λ C There are one or two quantization spectral bands around it, and two diffraction orders can be used. For example... Figure 6As shown, the exact size of the frequency range using two diffraction orders may vary depending on the frequency quantization method and the spatial positioning of the sensor relative to the diffracted light. For example, as Figure 5 As shown in the graphs, the points per 25 nm on graphs 502 and 504 represent the quantization level of the calculated spectral content. Due to the characteristics of the prism and diffraction grating, the spatial spacing between quantization levels increases towards the longer end of each diffraction order. This is just one example; higher spectral resolution is preferred if possible. For example, if a sensor with 1080 lines along the correlation axis is used, then... Figure 6 As shown, with the increase of spatial diffraction, the portion of the spectrum measured for each line decreases. Therefore, in order to pass through the wavelength span λ S To λ L The spectrum is quantized, and each quantization level uses an increasing number of sensor lines. For example... Figure 6 As shown, with second-order diffraction and λ L Compared to first-order diffraction, fewer sensor lines (e.g., one or two) will be used to detect the quantization level λ. C The first-order diffraction at [location]. This example aims to illustrate how to detect portions of two diffraction orders, and that the specific methods used to calculate, quantify, and display the spectrum may vary in different embodiments.

[0038] Figure 7 A schematic diagram of the diffraction position along the image sensor 700 according to some embodiments is shown. Figure 6 The dimensions shown from left to right are oriented from top to bottom on the image sensor 700. In this embodiment, the sensor 700 is a single focal plane array sensor, whose detection region 702 is along the vertical spatial axis λ. C and λ L First-order diffraction of wavelengths between, simultaneously detecting along the vertical spatial axis λ in sensor region 704. S and λ C The second-order diffraction of wavelengths between [wavelengths]. The horizontal dimension of the image sensor 700 captures a horizontal line or band of incident light in a single frame. This band is updated to be scanned "line by line" with reference to the incident light field, using a scanning system such as slit 224 and scanning mechanism 116, which incrementally moves the slit or other selective blocking structure along the incident light field. The scanning system operates on the incident light such that the second spatial dimension of the image spectral image is captured as a series of frames in temporal order. Various other scanning systems can be used in various embodiments to achieve the same result.

[0039] Figure 8This is a block diagram of an optical instrument system according to an exemplary embodiment of the present invention. The depicted design is applicable to implementing the various embodiments described above, as well as other embodiments. Although this example circuit is shown for use in an endoscope, the invention is applicable to other instruments, such as duct endoscopes or exoscopes, and other mirrors and imaging systems useful for imaging spectroscopy techniques, particularly in a compact form.

[0040] Light source 8 illuminates the object scene 9, and light 10 reflected from the object scene (or, optionally, transmitted or emitted by the object scene in some fluorescence imaging applications) forms an optical image through optical channel assembly 11, where the light is typically relayed to a camera using a relay system including rod lenses. At the camera, the light is focused, aligned with the mirror axis or desired optical axis, and relayed to the proximal side of optical channel assembly 11, where light guiding elements 12, such as the aforementioned beam splitter 114, guide different portions of the light to form an image on the first solid-state image sensor 214 and guide the light through spectrometer optics and scanning system 13 to a second solid-state image sensor 216. Although two image sensors are shown in this embodiment, a single-sensor design can be achieved by removing the first image sensor 214. In the single-sensor embodiment, white light images are not captured.

[0041] In this embodiment, the optical channel assembly 11 includes an imaging system and can be constructed according to various known methods. Image sensors 214 and 216 convert incident light into electrical signals, for example, by integrating the charge of each image element (pixel). Image sensors 214 and 216 can be active pixel-type complementary metal-oxide-semiconductor sensors (CMOS APS) or charge-coupled devices (CCDs), to name just two possible examples. The output analog signals from the image sensors are processed by analog signal processor 22 and applied to analog-to-digital (A / D) converter 24 for digitizing the analog sensor signals. In some versions (typically CMOS designs), the analog signal processing and A / D converter can be integrated into the respective sensor modules attached to each sensor 214 and 216.

[0042] The system's camera 28 typically includes a timing generator 26 that generates various clock signals to select lines and pixels and synchronize the operation of image sensors 214 and 216, analog signal processor 22, and A / D converter 24. The scanning mechanism of the scanning system can be controlled by the system controller 50 or by a local timing mechanism within the camera 28. The camera electronics typically house the image sensors 214 and 216, while the location of each of the analog signal processor 22, A / D converter 24, and timing generator 26 can vary (e.g., within the lens handle 102). The non-optical functional elements of the camera 28 can be fabricated as a single integrated circuit, like the CMOS image sensor, or they can be separately fabricated integrated circuits.

[0043] System controller 50 controls the overall operation of the image capture device based on a software program stored in program memory 54. This memory can also be used to store user setting selections and other data to be retained when camera 28 is off. Data connections 27 and 29 transmit digital image data from image sensors 214 and 216 to image processing circuitry 30, which in some versions may be integrated with system controller 50, or may be a separate programmable logic device or data processor. Data bus 52 provides a path for address, data, and control signals from spectral analysis circuitry 32, as well as spectral analysis data. Control signals are sent to spectrometer optics / scanning system 13 and timing generator 26. In some variations, data bus 52 may also carry data connections 27 and 29.

[0044] Image processing circuit 30 performs image processing operations, including forming an image from image sensor 214 and a partial spectrometer image from image sensor 216, i.e., combining the individual frames for spectral analysis. Spectral analysis circuit 32 receives the partial spectrometer image and performs spectral analysis, including normalizing the data based on the spectral transfer function of the spectrometer optics, calculating spectral content, and creating a combined image spectral dataset comprising spectral data for each image pixel acquired based on a complete line-by-line scan of the scanning system. Spectral analysis circuit 32 can also perform spectral analysis to identify, classify, or highlight features found in the image spectral dataset and prepare representative images for display, visualization, or other presentation of the spectral data in the dataset. Therefore, spectral analysis circuit 32 can perform any suitable processing and visualization techniques used with multispectral imaging (MSI) and hyperspectral imaging (HSI) analysis.

[0045] The processed image data is continuously sent to the video encoder 80 to generate a video signal. This signal is processed by the display controller 82 and displayed on the image display 88. This display is typically an HD, UHD, or 4K liquid crystal display (LED LCD) with LED backlighting, but other types of displays may also be used. The processed image data may also be stored in the system memory 56 or other internal or external storage devices.

[0046] User interface 60, including all or any combination of an image display 88, user input 64, and status display 62, is controlled by a combination of software programs executed on system controller 50. User input typically includes some combination of a keyboard, computer pointing device, buttons, joysticks, joysticks, rotary dials, or touchscreen. System controller 50 can manage a graphical user interface (GUI) presented on one or more displays (e.g., on image display 88). The GUI typically includes menus for selecting various options.

[0047] Image processing circuitry 30, spectral analysis circuitry 32, system controller 50, system and program memories 56 and 54, video encoder 80, and display controller 82 can be housed within camera control unit (CCU) 70. CCU 70 can be responsible for powering and controlling the light source 8 and / or camera 28. As used herein, "CCU" refers to a unit or module that powers, receives, manipulates, transmits, and / or forwards data from the optical instrument camera. CCU functionality may be distributed across multiple units, which may be referred to as, for example, "connection modules," "link modules," or "header modules."

[0048] As used herein, the terms “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” etc., should be understood as open-ended, meaning including but not limited to. The use of ordinal terms such as “first,” “second,” and “third” to modify claim elements in claims does not, in itself, imply any priority, precedence, or order of one claim element relative to another, nor does it imply a chronological order of the execution of the method. Rather, unless otherwise specified, these ordinal numbers are used only as labels to distinguish one claim element with a particular name from another element with the same name (but only using ordinal numbers for distinction).

[0049] The foregoing has broadly outlined the features and technical advantages of the invention to provide a better understanding of the following detailed description. Those skilled in the art will understand that the disclosed concepts and specific embodiments can be readily used as the basis for modifications or the design of other structures to achieve the same objectives as the invention. Those skilled in the art will also recognize that such equivalent constructions do not depart from the scope of the invention as set forth in the appended claims.

[0050] Although the invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and modifications may be made herein without departing from the scope of the invention as defined by the appended claims. The combinations of features described herein should not be construed as limiting, and the features herein can be used in any working combination or sub-combination of the invention. Therefore, this specification should be construed as providing written support for any working combination or certain sub-combinations of the features herein under U.S. patent law and any applicable foreign patent law.

[0051] Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, material compositions, means, methods, and steps described in the specification. Those skilled in the art will readily understand from the disclosure of this invention that, according to the invention, processes, machines, manufactures, material compositions, means, methods, or steps that are currently existing or developed later can perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, means, methods, or steps within their scope.

Claims

1. An imaging spectrometer, comprising: Prisms, which have the shortest wavelength (λ) used for spectral analysis S ) and longest wavelength (λ) L The incident light is refracted within at least one spectral range; A diffraction grating, optically aligned with the prism, diffracts the incident light, wherein, for a set of diffraction orders used for the spectral analysis, both the refraction from the prism and the diffraction from the grating increase the deflection angle of the incident light relative to the original optical axis; and One or more sensors are positioned to detect incident light passing through the prism and diffraction grating. Wherein, the spectral range spans more than one octave, such that λ L >2λ S Furthermore, the combined refraction and diffraction of the prism and the diffraction grating cause λ to... S The second-order diffraction at one or more sensors is not shorter than λ L The first-order diffractions of any wavelength overlap spatially, and for the spectral range λ... S and selected wavelength (λ) C The wavelengths between λ and λ' are sufficiently diffracted to the second order, such that λ' ... S and λ C Second-order diffraction between wavelengths and λ C and λ L First-order diffraction of wavelengths between λ is detected by one or more sensors in different spatial regions to determine the wavelengths from λ. S To λ L Spectral analysis was performed on the spectrum.

2. The imaging spectrometer according to claim 1, wherein the diffraction grating is a blazed diffraction grating, and at a wavelength (λ) P The grating blaze angle at which the first-order maximum diffraction efficiency is obtained is such that 0.65 < λ. P / λ L <0.

8.

3. The imaging spectrometer according to claim 1, wherein the spectral range of the spectrometer is approximately 430-1000 nm.

4. The imaging spectrometer according to claim 3, wherein λ C It is approximately 525nm.

5. The imaging spectrometer according to claim 1, wherein the spectral range of the spectrometer is approximately 500-1100 nm.

6. The imaging spectrometer of claim 1, wherein the one or more sensors comprise a single focal plane array sensor that simultaneously detects λ along a spatial axis. S and λ C Second-order diffraction between wavelengths and λ C and λ L First-order diffraction between wavelengths.

7. The imaging spectrometer of claim 6, wherein one spatial dimension of the image is captured along a sensor axis perpendicular to the axis that captures the spectral range.

8. The imaging spectrometer of claim 7 further includes a scanning system that operates on the incident light such that the second spatial dimension of the image is captured as a series of frames in chronological order.

9. The imaging spectrometer of claim 1, wherein λ is used when calculating the composite spectrum. C The first-order diffraction and the second-order diffraction at nearby wavelengths.

10. The imaging spectrometer according to claim 1, further comprising a spectral filter, the spectral filter blocking wavelengths outside the spectral range of the spectrometer from entering the spectrometer.

11. An imaging spectrometer camera adapted to receive incident light from a medical endoscope, comprising: The optical channel receives and focuses incident light; and An imaging spectrometer, located downstream of the optical channel, includes: A scanning system for adjusting the relative position of the imaging spectrometer with respect to the optical channel; Prisms, which have the shortest wavelength (λ) used for spectral analysis S ) and longest wavelength (λ) L The incident light is refracted within at least one spectral range; A diffraction grating, optically aligned with the prism, diffracts the incident light, wherein, for a set of diffraction orders used for the spectral analysis, both refraction from the prism and diffraction from the grating increase the deflection angle of the incident light relative to the original optical axis; and The focal plane array sensor, located downstream of the prism and the diffraction grating, simultaneously detects λ within the spectral range along a spatial axis. S and selected wavelength (λ) C Second-order diffraction between wavelengths and λ C and λ L First-order diffraction between wavelengths, The spectral range spans more than one octave, such that λ L >2λ S Furthermore, the combined refraction and diffraction of the prism and the diffraction grating cause λ to... S The second-order diffraction at the focal plane array sensor is not shorter than λ. L First-order diffractions of any wavelength overlap in space.

12. The imaging spectrometer camera according to claim 11, wherein the diffraction grating is a blazed diffraction grating, which has a wavelength (λ) P The grating blaze angle at which the first-order maximum diffraction efficiency is obtained is such that 0.65 < λ. P / λ L <0.

8.

13. The imaging spectrometer camera according to claim 11, wherein the spectral range of the spectrometer is approximately 430-1000 nm.

14. The imaging spectrometer camera according to claim 13, wherein λ C It is approximately 525nm.

15. The imaging spectrometer according to claim 11, wherein the spectral range of the spectrometer is approximately 500-1100 nm.

16. The imaging spectrometer camera according to claim 11, wherein, One spatial dimension of the image is captured along the sensor axis perpendicular to the axis that captures the spectral range.

17. The imaging spectrometer camera of claim 16, wherein the scanning system operates such that the second spatial dimension of the image is captured as a series of frames in chronological order.

18. The imaging spectrometer of claim 11, wherein λ is used when calculating the composite spectrum. C The first-order diffraction and the second-order diffraction at nearby wavelengths.

19. The imaging spectrometer of claim 11, further comprising a spectral filter that blocks wavelengths outside the spectral range of the spectrometer from entering the spectrometer.

20. The imaging spectrometer of claim 11, wherein the diffraction grating is located downstream of the prism.

Images