Spatial coding systems, decoding systems, imaging systems and methods

Abstract

A system for imaging may include an illumination system comprising a light source for generating a light beam; and a spatially encoded pattern generator including one or more optical elements for encoding the imaging beam to simultaneously illuminate an object through a plurality of different spatially encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern. The system may also include an imaging sensor for receiving the encoded imaging beam transmitted through or reflected from the object; and a processor for decoding image data from the imaging and reconstructing an image of the object.

Description

Technical Field

[0001] This invention relates to imaging. More specifically, this invention relates to spatial coding systems, decoding systems, imaging systems, and methods thereof. Background Technology

[0002] In vivo biological tissue imaging often requires careful selection among different bioimaging methods suited to specific experimental requirements and conditions. Deep-penetrating non-invasive imaging techniques such as magnetic resonance imaging (MRI), computed tomography (CT), and high-frequency and low-frequency ultrasound (US) are expensive and limited in terms of duration and spatial resolution. Other high-resolution methods, such as single / multiphoton fluorescence or confocal fluorescence microendoscopy, can be used in vivo, but are generally only useful at shallow inquiries.

[0003] Miniature endoscopes have been developed that allow for the deep insertion of optical fibers into target areas within a patient's body using minimally invasive techniques. Such devices enable long-term in vivo monitoring of biological samples. Many commercially available miniature endoscope fibers comprise bundles of cores, known as multi-core fibers (MCFs), where each core acts as a single optical fiber.

[0004] Many MCFs include multimode fiber (MMF), which allows many spatial electromagnetic modes to pass through each core, thereby increasing the intensity transmittance of the image through the endoscope. However, MMFs typically scramble the information transmitted through them both spatially and temporally. This problem can be addressed by designing the MCF with sufficient space between adjacent cores to minimize core-to-core optical coupling (crosstalk). As a result, image resolution may be compromised, and pixelation artifacts may appear in the generated image. Other solutions, such as optimization algorithms, digital phase conjugation, or transfer matrices, have been demonstrated, but they are generally sensitive to fiber bending.

[0005] Single-mode fiber bundles (SMFBs) can be used instead of MMFs, as they are generally less sensitive to fiber bending and less prone to information interference. SMFB imaging typically involves scanning heads with lenses, spectral dispersors, speckle-dependent features, and may also incorporate other techniques that can produce resolutions up to the diffraction limit. While the core-to-core length of SMFBs can be reduced, the brightness of the image transmitted through the device can also be reduced. Consequently, the signal-to-noise ratio can also be lower. Besides the necessary fiber geometry, resolution may still be limited, and the depth of observation through the scattering medium can be significantly reduced.

[0006] In MMF and SMFB bundles, various illumination methods through optical fibers are known, such as confocal microscopy with optical sectioning through sample illumination and collection of reflected light from the same bundle, speckle correlation techniques with optical sectioning without staining, etc.

[0007] Current techniques exhibit a typical penetration depth of less than 150 μm and struggle to handle real biological scattering media (e.g., blood) between the distal end of the fiber and the sample. Furthermore, typical imaging acquisition rates are quite poor (typically around 5 Hz for several minutes for a 36×36 pixel image). Summary of the Invention

[0008] Therefore, according to some embodiments of the present invention, an illumination system is provided, the illumination system including a light source for generating a light beam and a spatially encoded pattern generator, the spatially encoded pattern generator including one or more optical elements for encoding the imaging light beam to simultaneously illuminate an object through a plurality of different spatially encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern.

[0009] In some embodiments of the invention, the system further includes one or more optical elements for splitting the light beam into an imaging beam and a reference beam, and guiding the reference beam to an imaging sensor after the reference beam is combined with the imaging beam.

[0010] In some embodiments of the invention, the spatial coding pattern generator is configured to image the plurality of different spatial coding patterns onto an object across a first axis perpendicular to the propagation direction of the imaging beam, and is configured to perform a Fourier transform of the plurality of different spatial coding patterns onto the object across a second axis perpendicular to both the first axis and the propagation direction of the imaging beam.

[0011] In some embodiments of the invention, one or more optical elements for encoding the imaging beam are aligned along the optical path in the following order: a diffraction grating, a first lens, an encoding pattern element, and a second lens.

[0012] In some embodiments of the present invention, the first lens is positioned at a distance equal to the X-axis focal length of the first lens from the diffraction grating and the coded pattern element, and the second lens is positioned at a distance equal to the X-axis focal length of the second lens from the coded pattern element.

[0013] In some embodiments of the present invention, the X-axis focal length of each lens is twice the Y-axis focal length of the lens.

[0014] In some embodiments of the present invention, the optical path defined by the one or more optical elements for encoding the imaging beam includes, in the following order: a diffraction grating, a first lens, an encoding pattern element, a second lens, a second diffraction grating, and a third lens.

[0015] In some embodiments of the present invention, the first lens is distanced from the diffraction grating and the coding pattern element by a distance equal to the X-axis focal length of the first lens, the second lens is distanced from the coding pattern element by a distance equal to the X-axis focal length of the second lens, and the third lens is distanced from the second diffraction grating by a distance equal to the X-axis focal length of the third lens.

[0016] In some embodiments of the present invention, the X-axis focal length of each lens is twice the Y-axis focal length of the lens.

[0017] In some embodiments of the present invention, the light source is a laser generator.

[0018] In some embodiments of the present invention, the laser source is a pulsed laser source.

[0019] In some embodiments of the invention, the system is integrated into an endoscope.

[0020] In some embodiments of the invention, the system is incorporated into an imaging system, which further includes an imaging sensor for receiving the coded imaging beam transmitted through or reflected from the object; and a processor for decoding image data from the imaging and reconstructing an image of the object.

[0021] In some embodiments of the invention, in order to reconstruct an image of an object, the processor is configured to multiply the image of each of the different encoded patterns obtained from the reflected or transmitted encoded imaging beam by the corresponding decoded pattern to obtain a product, and sum all the products to obtain a reconstructed image of the object.

[0022] In some embodiments of the present invention, a decoding system is provided, comprising an imaging sensor for receiving an encoded imaging beam that simultaneously illuminates an object through a plurality of different spatially encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern, and the encoded patterns are transmitted through or reflected from the object. The decoding system further includes a processor for decoding image data from the imaging and reconstructing an image of the object.

[0023] In some embodiments of the invention, in order to reconstruct an image of an object, the processor is configured to multiply the image of each of the different encoded patterns obtained from the reflected or transmitted encoded imaging beam by the corresponding decoded pattern to obtain a product, and sum all the products to obtain a reconstructed image of the object.

[0024] In some embodiments of the present invention, a method is provided, comprising: generating a light beam; and encoding the imaging light beam using a spatially encoded pattern generator to simultaneously illuminate an object through a plurality of different spatially encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern.

[0025] In some embodiments of the invention, encoding the imaging beam includes applying time gating.

[0026] In some embodiments of the invention, time gating is applied using any of the techniques in the group consisting of short-pulse gating, coherent gating, and interference patterns generated by diffraction gratings.

[0027] In some embodiments of the invention, the spatially encoded pattern generator includes one or more optical elements for encoding an imaging beam, these optical elements being aligned along the optical path in the following order: a diffraction grating, a first lens, an encoded pattern element, and a second lens.

[0028] In some embodiments of the invention, encoding the imaging beam includes applying time gating, wherein time gating is achieved by splitting the beam into an imaging beam and a reference beam and guiding the reference beam to the imaging sensor after the reference beam is combined with the imaging beam.

[0029] In some embodiments of the present invention, a method is provided, comprising: receiving, using an imaging sensor, an encoded imaging beam that simultaneously illuminates an object through a plurality of different spatial encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern, and the encoded imaging beam is transmitted through or reflected from the object; and using a processor to decode image data from the imaging and reconstruct an image of the object. Attached Figure Description

[0030] To better understand the present invention and its practical applications, the following drawings are provided and referenced below. It should be noted that the drawings are given by way of example only and do not in any way limit the scope of the invention. Identical parts are indicated by the same reference numerals.

[0031] Figure 1A It is a graph showing the relationship between the photon count and time in the interaction between light and the scattering medium.

[0032] Figure 1B A pair of Barker-based arrays are shown, which can be used in a system for imaging through a scattering medium.

[0033] Figure 2A A system for imaging through a scattering medium using a one-dimensional illumination pattern is shown according to some embodiments of the present invention.

[0034] Figure 2BImages of light intensity at specific wavelengths on different planes are shown according to some embodiments of the present invention.

[0035] Figure 3 A system for imaging through a scattering medium using a two-dimensional illumination pattern is shown according to some embodiments of the present invention.

[0036] Figure 4 Discrete light illumination is illustrated by a system for imaging through a scattering medium, according to some embodiments of the present invention.

[0037] Figure 5 The convolution integral of a single wavelength in light illumination achieved by a system for imaging through a scattering medium, according to some embodiments of the present invention, is shown.

[0038] Figure 6 The final convolution of a single wavelength in light illumination, achieved by a system for imaging through a scattering medium, is shown according to some embodiments of the present invention.

[0039] Figure 7 The illustration shows spectral regions and pattern pixels encoded using a single-frequency grating with continuous wavelength according to some embodiments of the present invention.

[0040] Figure 8 The diagram illustrates the deflection of the grating grid frequency per second in the spatial axis plane according to some embodiments of the invention.

[0041] Figure 9 A multi-core fiber endoscope according to some embodiments of the present invention is shown, the multi-core fiber endoscope including a system for imaging an object through a scattering medium.

[0042] Figure 10 This is a diagram of a method for imaging an object through a scattering medium according to some embodiments of the present invention. Detailed Implementation

[0043] In the detailed description below, numerous specific details are set forth to provide a thorough understanding of the method and system. However, those skilled in the art will understand that the method and system can be practiced without these specific details. In other instances, well-known methods, processes, and components have not been described in detail so as not to obscure the method and system.

[0044] While the examples disclosed and discussed herein are not limited to these, the terms "multiple" and "a plurality of" as used herein may include, for example, "multiple" or "two or more". The terms "multiple" or "a plurality of" may be used throughout the specification to describe two or more components, devices, elements, units, parameters, etc. Unless explicitly stated otherwise, the method examples described herein are not limited to a particular order or sequence. Furthermore, some of the method examples described, or elements thereof, may occur or be performed at the same point in time.

[0045] Unless otherwise specifically stated, it should be understood, as is apparent from the following discussion, that throughout this specification, discussions using terms such as “add,” “associate,” “select,” “evaluate,” “process,” “calculate,” “operate,” “determine,” “assign,” “allocate,” etc., refer to the actions and / or processes of a computer, computer processor, or computing system or similar electronic computing device that manipulate, execute, and / or convert data represented as physical (such as electronic) quantities in the registers and / or memory of the computing system into other data similarly represented as physical quantities in the memory, registers, or other such information storage, transmission, or display devices of the computing system.

[0046] According to some embodiments of the present invention, a novel optical device is provided, the purpose of which is to achieve deeper imaging through a scattering medium by employing spatial illumination.

[0047] Typically, four main parameters affect how light propagates within a scattering medium: the absorption coefficient μ0, measured in [m⁻¹], which determines the energy loss of the signal; the scattering coefficient μ², measured in [m⁻¹], which is a measure of the typical length light travels between scattering points; and the scattering anisotropy g, measured as an average value.<cos(θ)> , where θ is the scattering deflection angle (which allows calculation of how "forward" typical scattering is in the direction), and n is the refractive index of the medium.

[0048] From μ s The simplified scattering coefficient μs′ can be derived from g, where;

[0049] μ s ′ = μ s * (1-g) (1)

[0050] It represents the actual scattering length considering typical scattering directions. Typical scattering time can be calculated using simplified scattering coefficients and refractive indices.

[0051]

[0052] In practical imaging, a light pulse is projected onto the sample through a scattering medium. Due to scattering within the medium, the pulse spreads and can be described by ballistic, serpentine, and diffuse signal components. The ballistic component takes the shortest path through the medium and preserves image information. In contrast, diffuse light undergoes multiple scatterings, travels a long distance within the scattering medium, and contributes nothing to forming a direct image. Serpentine photons undergo some scattering in the forward direction, thus preserving some image information. The light then strikes the sample and is either scattered back or transmitted to the sensor through the scattering medium.

[0053] As mentioned earlier, the signal is stretched and can be described by ballistic, serpentine, and diffuse photons.

[0054] Figure 1 is a graph showing the relationship between the photon count and time of the interaction between light and the scattering medium. It illustrates three segments (12, 14, and 16) of photons arriving at the sensor via the interaction between the irradiating light and the sample through the scattering medium, divided according to their arrival time at the sensor. The first segment 12 includes ballistic photons arriving directly from the illumination source (B1) to the sample and ballistic photons arriving at the sensor after interacting with the sample (B2). The next segment 14, after a few picoseconds, includes two sets of photons: photons scattered by the scattering medium on their journey from the sample to the sensor (B1 and P2), and photons scattered by the medium towards the sample and ballistically from the sample to the sensor (P1 and B2). The third segment 16 includes photons scattered by the sample and by the scattering medium before reaching the sensor, making them the last to arrive.

[0055] Many methods are known to filter photons that contribute to image data from those that do not. An ideal imaging method should gate the photons in the third part, utilize the photons in the first part, and collect the maximum amount of information from the photons in the second part.

[0056] It is known that less than t has already been used s The short light pulses, and time-gated timing of less than 100 ps from the earliest arrival of the light. This requires expensive laser sources of less than a few picoseconds and dedicated time-gated sensors.

[0057] According to some embodiments of the present invention, instead of short pulses and time gating, systems for imaging through scattering media can employ narrow-angle light collection, thereby omitting scattered photons while retaining ballistic photons.

[0058] Optical systems that include long optical channels for absorbing light propagating at angles above a predetermined angle (e.g., 0.29°) are known, but may not be suitable for imaging through scattering media under real-world in-vivo conditions. Furthermore, the signals acquired in such systems are typically very weak and susceptible to stray light from photons that have undergone multiple scattering and travel uniformly in all directions.

[0059] A holographic-based approach employing an illumination source with a short coherence length allows for longer pulse times. In this method, the coherence length can be related to μ. s By comparison, only photons that undergo scattering along a path shorter than the coherence length contribute to the interference pattern, while light traveling longer distances is averaged out and contributes only to random noise. Increasing the width of the scattering medium (the length along the propagation direction of the imaging beam (ballistic path)) reduces the number of interfering photons while increasing the average noise. Therefore, the signal-to-noise ratio (SNR) can reduce the blurring and limitations in sample spatial frequency reconstruction. It is known that modulation of the phase to encode illumination has been used previously to improve the SNR. However, this assumes that the illumination system directly illuminates the sample, rather than scattering through a scattering medium as in a real in vivo scene. Furthermore, this method depends on time multiplexing, which increases the acquisition duration.

[0060] According to some embodiments of the invention, scattering limitations and high acquisition times can be addressed by using spatially structured illumination. This may require encoding the autocorrelation of the illumination pattern.

[0061] According to some embodiments of the present invention, a system for imaging an object through a scattering medium may include an illumination system and an imaging sensor, as well as a processing unit for processing image data sensed by the imaging sensor.

[0062] According to some embodiments of the present invention, the illumination system may include a light source for generating a light beam. In some embodiments, the light source may be, for example, a white light source, a light-emitting diode (LED), a continuous laser source, or a pulsed laser source (e.g., femtosecond, picosecond, nanosecond, millisecond pulsed laser source, etc.) for generating an imaging light beam.

[0063] A spatially encoded pattern generator can be used to encode an imaging beam so that an object can be simultaneously illuminated by multiple different spatially encoded patterns, each of which is characterized by a different wavelength of the imaging pattern.

[0064] Some different coding patterns may overlap completely or partially but are unrelated, or have a correlation function with a sharp maximum at a specific point (between these different coding patterns).

[0065] An imaging sensor can be used to receive an image beam transmitted through or reflected from an object, and a processing unit can be used to reconstruct an image from the image data sensed by the sensor.

[0066] In object image reconstruction, the processing unit can be designed to execute an image reconstruction algorithm that decodes the coded spatial pattern illuminating the object and ignores photons scattered by the scattering medium by ignoring any image data representing deviations from the coded spatial pattern. For example, if a green photon arrives at an area that should be illuminated by other colors (or multiple colors), it will be ignored in the object image reconstruction, assuming it is not a ballistic photon (e.g., it does not travel directly from the light source to the location where it is detected and is most likely scattered along its path).

[0067] In some embodiments of the invention, time gating is used to separate ballistic photons from scattered photons. Time gating can be achieved, for example, by applying very short laser pulses, or by applying short coherence gating (e.g., via interference). For example, coherence gating can be achieved by employing the earliest arrival light (FAL) method to perform coherent shaping of the illumination to obtain the desired time gating.

[0068] For example, in order to apply the FAL method, a reference beam can be separated from the beam generated by the light source and guided into the sensor along another optical path, thereby allowing interferometric measurements.

[0069] Spatial coding patterns can be obtained, for example, by employing a Barker-based array. A set of laterally shifted Barker-coded patterns can be projected onto the sample. Figure 1B (As shown above). Such a shift can cause a pattern scan of the sample.

[0070] One-dimensional (1D) scanning can enhance two-dimensional (2D) images in all directions, regardless of the original scan orientation. Another feature associated with the illumination produced by the system according to some embodiments of the invention is its ability to simultaneously project multiple patterns of different wavelengths. Sample images of the shifted pattern illumination can then be separated and analyzed (e.g., using wavelength multiplexing) to increase acquisition time.

[0071] Figure 1B A pair of Barker-based arrays are shown, which can be used in systems for imaging through scattering media. In this example, a 13×13 Barker-based array (a) is shown, where each row is a 5-pixel shift of the basic Barker-coded vector. Array (b) is the autocorrelation of the Barker array of (a). Other arrangements (other pixel numbers, other coded vectors) may also be used in some embodiments of the invention.

[0072] Can be with Figure 1AThe coherence length is calculated accordingly. A direct approach could involve determining the coherence length such that photons from only the first part will interfere. Increasing the coherence length allows for the collection of more photons from the middle part, thus increasing both signal and noise. Spatial coding then eliminates noise from B1+P2 photons that do not contribute to the data, while preserving the snake photons that do contribute to the data.

[0073] Figure 2A A system for imaging through a scattering medium using a one-dimensional illumination pattern is illustrated according to some embodiments of the invention. The system can be designed to perform different spatial encodings on different wavelengths of the illumination beam to achieve resolution enhancement and see beyond the scattering tissue.

[0074] System 100 includes an illumination source 102, such as a laser beam generator, including continuous-wave lasers and pulsed lasers (e.g., femtosecond or picosecond pulsed lasers in some embodiments, and nanosecond or millisecond pulsed lasers in others—faster pulses can better contribute to high-resolution imaging results). The beam generated by the light source 102 can be split into two beams by a beam splitter 104. One beam serves as a reference beam and is guided by mirrors (106 and 118) through a second beam splitter 126 into an optical imaging sensor 130. The other beam (hereinafter referred to as the imaging beam) is guided through a spatially encoded pattern generator 105, such as a series of optical elements. According to some embodiments of the invention, the spatially encoded pattern generator is configured to image a plurality of different spatially encoded patterns onto the object to be imaged across a first axis perpendicular to the propagation direction of the imaging beam, and is configured to perform a Fourier transform of the plurality of different spatially encoded patterns onto the object across a second axis perpendicular to both the first axis and the propagation direction of the imaging beam.

[0075] First, the imaging beam passes through a diffraction grating G1 108, for example, 300 rows per millimeter, with other gratings ranging from 200 to 2 / λ (center illumination wavelength) rows per millimeter, and is diffracted into multiple parallel beams. Then, when passing through a cylindrical lens L1, a Fourier transform is performed in the X-axis direction. L1 is characterized as having two different focal length values ​​for each of the two orthogonal axes (e.g., f in the Y-axis and 2f in the X-axis, for example, 25.4 mm and 50.8 mm respectively), with the diffraction grating G1 108 positioned 2f (the X-axis focal length of L1) away from L1, such that the Fourier conjugate plane in the X-axis lies at the X-axis focal point of L1, and the imaging plane of the beam lies at the Y-axis focal point. This causes the imaging beam to separate into multiple beams of different wavelengths at different deflection positions, corresponding to their wavelengths in the X-plane, while the original height of the beam in the Y-plane remains unchanged. Encoded pattern elements 112 (e.g., two barker-based arrays 114, such as...) Figure 1BThe array depicted is further positioned downwards along the propagation direction of the imaging beam at a distance of 2f (the X-axis focal length of L1) from L1 to encode each of the multiple beams of different wavelengths accordingly. Next, the imaging beam passes through lens L2 116, whose X-axis focal length is again twice the Y-axis focal length of the lens (e.g., 25.4 mm and 50.8 mm, respectively). The coded pattern element 112 is positioned 2f (the X-axis focal length of L1) from L1110 (L1), forming an image of the coded pattern on the Y-axis at this point, and lens L2 116 is located at a distance of 2f (the X-axis focal length of L1) and serves to widen the imaging beam back to its original width on the X-axis.

[0076] The light emitted from L2 116 is directed onto a sample (e.g., tissue within a patient's body), which may be located at a distance of L2 2f (the X-axis focal length of L2). The light is transmitted through the sample and collected by the optical imaging sensor 130. A beam splitter 126 may be positioned in this path to combine the reference beam with the imaging beam before impacting the optical imaging sensor 130.

[0077] The corresponding X-axis focal length and Y-axis focal length of L1 and L2 can be the same or different.

[0078] Figure 2B Images of light intensity at specific wavelengths on different planes according to some embodiments of the present invention are shown. Image (a) shows the intensity image of the imaging beam when it reaches L1, at the X-axis focal plane, just before the coded pattern. Image (b) shows the intensity image of the imaging beam after traversing the coded pattern. Only one line passes clearly, coded on the Y-axis. Image (c) is the projected intensity of the imaging beam on the object.

[0079] Finally, in the example of Figure 2, the result for each wavelength (from L1) is a light spot that follows a coded pattern on the Y-axis and the original beam profile on the X-axis. Depending on the coded pattern, each wavelength will produce a different pattern on the object.

[0080] By using coded patterns to introduce a set of laterally shifted patterns (e.g., a 2D image, coded as a single row of patterns as shown in Figure 2, with each wavelength shifted and coded row), we can support image enhancement and coherent gating signals, as explained in the introduction.

[0081] Figure 3 A system for imaging through a scattering medium using a two-dimensional illumination pattern is shown according to some embodiments of the present invention.

[0082] The design of System 200 is similar to Figure 2AThe system 100 has additional optical elements in the spatial coding pattern generator, which are, in sequence along the optical path of the spatial coding pattern generator: a second diffraction grating 120 and a third lens L3 122. The X-axis focal length of the third lens L3 122 is twice the focal length of the lens on the Y-axis (e.g., 25.4 mm and 50.8 mm, respectively).

[0083] The diffraction grating 120 (e.g., 300 rows per millimeter, other gratings may be in the range of 200 to 2 / λ (center illumination wavelength) grating rows per millimeter) is located at the X-axis focal point of lens 116 and the X-axis focal point of lens L3 122.

[0084] The focal lengths (X, Y) of the lenses do not need to be the same (in Figure 2B and Figure 3 (in any of the systems shown).

[0085] Because of the addition of optical elements, the spatially encoded pattern projection generated in this setup is two-dimensional.

[0086] Some embodiments of the present invention may utilize discrete wavelength coding patterns. Some embodiments of the present invention may utilize continuous wavelength (bandwidth) coding patterns.

[0087] The second diffraction grating G2 120 can be designed to meet the required functions.

[0088] For example, for discrete wavelengths, G2 is designed to have a frequency Where v0 is the frequency of G1, f L1X and f L2X These are the X-axis focal lengths of L1 and L2.

[0089] For a continuous wavelength band, a grid with a single frequency G2 can have a frequency ΔΩ such that: Where, N num It represents the number of different patterns projected onto the target, where λ0 is the minimum projection wavelength and Δλ.

[0090] Use coded patterns to introduce a set of laterally shifted patterns (e.g., Figure 1B The 2D image of the pattern shown (by cyclically shifting the code by one pixel in the horizontal direction for each wavelength) can enhance image reconstruction and obtain a coherent gated signal as described above.

[0091] The mathematical description of the optical setup of the spatially encoded pattern generator is provided below:

[0092] For a plane U(X0, Y0), assume the wavefront is constant and tilted θ towards the grid:

[0093]

[0094] The plane U(X1, Y1) behind the grid G1 with frequency v0.

[0095]

[0096] The Fourier transform of plane U(X2, Y2) scaled by f1*lambda. We assume we only take the first diffraction order and obtain:

[0097]

[0098] u2(x2,y2)=δ(x2-[f1·sinθ+f1v0λ])

[0099] For discrete wavelengths:

[0100] The lens has different focal points, such that the length between U(x1, y1) and plane U(x2, y2) is fx = 2*fy, thus it can produce an image in the y-plane and a Fourier transform in the x-plane.

[0101] In the X-plane, the lens has a finite aperture D, such that there is enough space in the plane U(x2, y2) to place the pattern with minimal variation in illumination intensity.

[0102]

[0103] u2(x2,y2)=δ(x2-[f1·sinθ+f1v0λ])sinc(D·x2)

[0104] Spatial coding pattern elements (coding masks) can be placed in front of the focal plane of L1 to obtain a sine function of the same diameter again.

[0105] Under these conditions, different color patches at discrete locations, centered at [f1·sinθ+f1v0λ], can be obtained before encoding the mask. For each location, an encoding pattern can be matched, such as... Figure 4 As shown. In system 400, laser source 402 generates an imaging beam that passes through grating grid 404 and lens 406 and illuminates discrete, separate color points (blue 410, green 412 and red 414) onto spatially encoded pattern elements 408.

[0106] Plane x3 multiplied by the coded pattern:

[0107]

[0108] Planar X4 Fourier transform scaled by f2*lambda:

[0109]

[0110] Introducing grid2:

[0111] To combine the spots together, grid2 should be combined with... same:

[0112]

[0113] Planar X6 Fourier Transform:

[0114]

[0115] This means that the grid deflects each wavelength to the optical axis position, regardless of the wavelength.

[0116] Another solution involves generating a continuous wavelength band, a frequency grating.

[0117] The lens has different focal points, such that the length between U(x1, y1) and plane U(x2, y2) is fx = 2*fy, thus it is possible to obtain the image in the y-plane and the Fourier transform in the x-plane.

[0118] In the X-plane, the aperture D can be opened such that, in the plane U(x2, y2), there exists a δ function for each wavelength:

[0119] Plane x3 multiplied by the coded pattern:

[0120] u3(x3,y3)=δ(x3-[f1·sinθ+f1v0λ])B(x3-f1v0λ min (11)

[0121] Note that in the example discussed, the encoded pattern is from a size ΔX pt N p It is constructed from discrete pixels, which means that each pattern may require a length of L. pt =N p ΔX pt If the expected value is N num If there are several different patterns, then a size of L may be required. num =N num L pt =N num N p ΔX pt The light spot. This means the laser spectral band should be:

[0122] f1ν0Δλ=N num N p ΔX pt (12)

[0123]

[0124] Planar X4 Fourier transform scaled by f2*lambda:

[0125]

[0126] Introduce a power grid G2 with only one frequency:

[0127] Assume t f1 = f2 and θ = 0:

[0128]

[0129] Where ΔΩ will currently be the undetermined plane X5 multiplied by grid 2:

[0130]

[0131] Planar X6 Fourier Transform:

[0132]

[0133]

[0134] For a single wavelength, Figure 5 The equation's 10-volume integral for a single wavelength is shown. The top is the left component of the equation, the bottom is the right component, and... Figure 6 The final convolution for each wavelength is depicted in the diagram.

[0135] Figure 6 Equation 10 shows the final convolution involving a single wavelength.

[0136] Therefore, for an unlimited number of orders, the entire space can be covered with coded patterns, but scaled-up Buck codes may be required.

[0137] The position of minimum wavelength is:

[0138] x0=λ0f3ν0 (11)

[0139] The next wavelength that overlaps with the first wavelength is:

[0140] λ0f3v0=λ1f3(v0-ΔΩ)

[0141] Typically, the nth overlap is:

[0142]

[0143] To utilize the entire bandwidth, a grid frequency is employed, enabling precise acquisition of N. num One copy:

[0144]

[0145] at last:

[0146]

[0147] if f1≠f2 And it's everywhere. θ=0 :v0, then replace it with

[0148]

[0149] Typically, the nth overlap is:

[0150]

[0151] Note that from equation (14), each pattern region λ n -λ n-1 Since they have different spectral dimensions, the patterns should be scaled in each pattern area.

[0152] Figure 7 A diagram of the spectral axes is shown, with different spectral regions marked. The wavelengths starting in each region are marked with black dashed lines. Each region will eventually be shifted to the base spectral region.

[0153] The pattern pixels in each region are scaled to fit N equally spaced pixels in the basic spectral region. At the bottom of the figure, each pattern pixel is shown by a blue line, and different patterns are shown by filling the space within a specified pattern pixel. The coded pattern placed at the X-axis focus of the L1 lens should consist of the entire coded pattern at the corresponding positions of these wavelengths, as shown in the overall pattern at the bottom.

[0154] Figure 8 The spectral regions and pattern pixels of solution 2 are shown. The nth spectral region has λ. n -λ n-1 The regions are divided into areas, each with a different spectral size. Pixels within the regions are marked by blue lines, and each pattern is filled with different spectral pixels. Ultimately, the encoded mask includes the same pattern as shown in this paper at the corresponding position in the spatial axis of the plane in the X-axis focal plane of lens L1.

[0155] To find the scale at which Np pixels are equally spaced in the first region, the first pattern overlap via grid multiplication is obtained from equations (14) and (15):

[0156]

[0157] Furthermore, in the first state, λ1-λ0 is divided into Np equally spaced pixels, and the length of each pixel is:

[0158]

[0159] And the initial spectral wavelength of each pixel is:

[0160]

[0161] Therefore, in each nth copy, the initial spectral wavelength of the mth pixel is:

[0162]

[0163] Solution 3: We recommend continuous wavelength, multi-frequency gratings.

[0164] In the previous section, a grid G2 with a frequency was shown that folds the projected illumination at the minimum wavelength deflection position of G1.

[0165] Conversely, this can be accomplished using different G2 gratings with multiple frequencies, each deflecting a different wavelength toward the desired location. The advantage of this method is that it allows the imaging beam to be deflected closer to the optical axis compared to the single-frequency grating method.

[0166] To calculate the required frequency and wavelength to begin each new pattern, the iteration can be considered as follows: λ1, v1

[0167]

[0168]

[0169] In this case, the copy in the optical axis can Figure 8 The figure shows the deflection of each new G2 grid frequency on the spatial axis plane. Three example grid frequencies are shown. The thicker line (on the lambda(λ) axis) marks the separating wavelengths between each different coded pattern frequency.

[0170] Applying the above iterative relationship forces each new frequency in the grid to deflect the wavelength to a known position, such that a portion of the laser source bandwidth remains between specific calculated wavelengths in a particular portion. Note that while the set of spatially encoded patterns is complete in the first spatial portion between (G1-v0)λ0 and (G1-v0)λ1, the spatial region can be magnified by employing additional wavelengths, shifting, or projecting another time to the wavelength reaching the spatial position.

[0171] In the reconstruction of an object image, the image of each of the different encoded patterns retrieved from the encoded imaging beam reflected from or transmitted through the object can be multiplied by the corresponding decoded pattern to obtain a product, and all products can be summed to obtain a reconstructed image of the object.

[0172] According to some embodiments of the present invention, decoding in the manner described above is suitable for imaging through scattering media and for improving imaging resolution to super-resolution.

[0173] Figure 9 A multi-core fiber endoscope 800 according to some embodiments of the present invention is shown, comprising a system for imaging an object through a scattering medium. The endoscope 800 may include an elongated multi-core fiber body 802 having one or more illumination fibers 804 and one or more imaging fibers 812. A spatially encoded pattern generator 806 may be provided, optically linked to one or more illumination fibers 804, the illumination fibers 804 being designed to guide multiple different spatially encoded patterns generated by the spatially encoded pattern generator 806 through the endoscope body 802 to its distal end, in order to illuminate an object 814 (e.g., tissue within a patient's body). The one or more imaging fibers 812 of the endoscope receive reflected illumination light from the object 814 and transmit it (e.g., via a beam splitter 808) to an imaging device 810, the imaging device 810 including an imaging sensor 816 and a processing unit 818.

[0174] Figure 10 This is a diagram of a method for imaging an object through a scattering medium according to some embodiments of the present invention. Method 900 may include generating a light beam 902. Method 900 may also include encoding the imaging light beam 904 using a spatially encoded pattern generator to simultaneously illuminate the object through a plurality of different spatially encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern.

[0175] Method 900 may further include using an imaging sensor to receive 906 an encoded imaging beam transmitted through or reflected from an object, and using a processor to decode 908 image data from the received encoded imaging beam and reconstruct an image of the object.

[0176] Some embodiments of the present invention may be implemented as a system, method, or computer program product. Similarly, some embodiments may be embodied as hardware, software, or a combination of both. Some embodiments may be embodied as a computer program product stored on one or more non-transitory computer-readable media (or media thereof) in the form of computer-readable program code embodied thereon. Such non-transitory computer-readable media may include instructions that, when executed, cause a processor to perform method steps according to the examples. In some examples, the instructions stored on the computer-readable medium may be in the form of an installed application and an installation package.

[0177] Such instructions can be loaded and executed, for example, by one or more processors.

[0178] For example, a computer-readable medium can be a non-transitory computer-readable storage medium. A non-transitory computer-readable storage medium can be, for example, an electronic, optical, magnetic, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof.

[0179] Computer program code can be written in any suitable programming language. The program code can be executed on a single computer system or on multiple computer systems.

[0180] The foregoing references flowcharts and / or block diagrams illustrating methods, systems, and computer program products according to various embodiments describe some of the embodiments.

[0181] The features of the various embodiments discussed herein can be used in conjunction with other embodiments discussed herein. The foregoing description of the embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the precise forms disclosed. Those skilled in the art will understand that many modifications, variations, substitutions, alterations, and equivalents are possible in light of the foregoing teachings. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations falling within the true spirit of the invention.

Claims

1. A lighting system for illuminating in a scattering medium, comprising: A light source used to generate light beams; as well as A spatially encoded pattern generator includes multiple optical elements for encoding a beam that forms an imaging beam, so that an object is simultaneously illuminated by multiple different spatially encoded patterns through a scattering medium. Each of the different encoded patterns is characterized by a different wavelength of the imaging pattern. The plurality of optical elements used to encode the imaging beam are aligned along the optical path in the following order: diffraction grating, first lens, coding pattern element, and second lens; Wherein, the first lens is at a distance from the diffraction grating and the coding pattern element equal to the focal length of the first lens perpendicular to the first axis of the optical path, and wherein the second lens is at a distance from the coding pattern element equal to the focal length of the second lens perpendicular to the first axis of the optical path.

2. The lighting system according to claim 1, wherein, The first axial focal length of each lens is twice the second axial focal length of the lens, which is perpendicular to both the optical path and the first axis.

3. The lighting system according to claim 1 or 2, wherein, The optical path defined by the plurality of optical elements used to encode the imaging beam includes, in the following order, the diffraction grating, the first lens, the coded pattern element, the second lens, the second diffraction grating, and the third lens.

4. The lighting system according to claim 3, wherein the third lens is spaced from the second diffraction grating by a distance equal to the first axial focal length of the third lens.

5. The lighting system according to claim 4, wherein, The first axial focal length of each lens is twice the second axial focal length of the lens.

6. The lighting system according to any one of claims 1 to 4, wherein, The light source is a laser generator.

7. The lighting system according to claim 6, wherein, The laser source is a pulsed laser source.

8. The lighting system according to any one of claims 1 to 7, wherein the system is integrated into an endoscope.

9. The illumination system according to any one of claims 1 to 8, wherein the system is incorporated into an imaging system, the imaging system further comprising: An imaging sensor for receiving an coded imaging beam transmitted through or reflected from an object; as well as A processor for decoding image data from the received coded imaging beam and reconstructing an image of the object.

10. The lighting system according to claim 9, wherein, In order to reconstruct an image of the object, the processor is configured to multiply the image of each of the different encoded patterns obtained from the reflected or transmitted encoded imaging beam by the corresponding decoded pattern to obtain a product, and sum all the products to obtain a reconstructed image of the object.

11. A decoding system, comprising: An imaging sensor is used to receive an imaging beam encoded by an illumination system according to claim 1, the encoded imaging beam being simultaneously illuminated by a plurality of different spatial encoded patterns through a scattering medium, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern, and the encoded imaging beam is transmitted through or reflected from the object. as well as A processor for decoding image data from the received encoded imaging beam and reconstructing an image of the object. In order to reconstruct an image of the object, the processor is configured to multiply the image of each of the different encoded patterns obtained from the encoded imaging beam by the corresponding decoded pattern to obtain a product, and sum all the products to obtain a reconstructed image of the object.

12. An encoding method, comprising: Generates a beam of light; as well as A spatially encoded pattern generator is used to encode the imaging beam so that the object is simultaneously illuminated by multiple different spatially encoded patterns through a scattering medium. Each of the different encoded patterns is characterized by a different wavelength of the imaging pattern. The spatial coding pattern generator includes multiple optical elements for coding the imaging beam, which are aligned along the optical path in the following order: a diffraction grating, a first lens, a coding pattern element, and a second lens. Wherein, the first axis focal length of each lens, which is perpendicular to the optical path, is twice the second axis focal length of the lens, which is perpendicular to both the optical path and the first axis.

13. The encoding method according to claim 12, wherein, Encoding the imaging beam includes applying time gating.

14. The encoding method according to claim 13, wherein, The time gating is applied using any of the techniques in the group consisting of short-pulse gating, coherent gating, and interference patterns generated by diffraction grating grids.

15. The encoding method according to claim 13, wherein, Encoding the imaging beam includes applying time gating, wherein the time gating is achieved by splitting the beam into an imaging beam and a reference beam, and guiding the reference beam to the imaging sensor after the reference beam is combined with the imaging beam.

16. The encoding method according to claim 12, wherein, The plurality of optical elements used to encode the imaging beam define an optical path, the optical path comprising, in the following order: the diffraction grating, the first lens, the coded pattern element, the second lens, the second diffraction grating, and the third lens.

17. The encoding method according to claim 16, wherein, The first lens is positioned at a distance equal to the first axial focal length of the first lens from the diffraction grating and the coded pattern element, wherein the second lens is positioned at a distance equal to the first axial focal length of the second lens from the coded pattern element, and wherein the third lens is positioned at a distance equal to the first axial focal length of the third lens from the second diffraction grating.

18. The encoding method according to any one of claims 12 to 17, wherein, The beam is generated by a laser source.

19. The encoding method according to claim 18, wherein, The laser source is a pulsed laser source.

20. The encoding method according to any one of claims 12 to 19, further comprising: An imaging sensor is used to receive an encoded imaging beam transmitted through or reflected from the object, and Using a processor, image data is decoded from the received encoded imaging beam and an image of the object is reconstructed.

21. The encoding method according to claim 20, further comprising: To reconstruct an image of the object, the image of each of the different encoded patterns obtained from the reflected or transmitted encoded imaging beam is multiplied by the corresponding decoded pattern to obtain a product, and all products are summed to obtain a reconstructed image of the object.

22. A method for reconstructing an image using an coded imaging beam, comprising: The imaging sensor receives an encoded imaging beam, which, according to claim 12, simultaneously illuminates an object through a scattering medium by a plurality of different spatial encoded patterns, wherein each of the different encoded patterns is characterized by a different wavelength of the imaging pattern, and the encoded imaging beam is transmitted through or reflected from the object; and The processor decodes image data from the received coded imaging beam and reconstructs an image of the object, wherein reconstructing the image of the object includes: multiplying the image of each of the different coded patterns obtained from the reflected or transmitted coded imaging beam by the corresponding decoded pattern to obtain a product, and summing all products to obtain a reconstructed image of the object.

Images