Broadband Sagnac snapshot type full-polarization imaging system and endoscope

Abstract

The invention belongs to the technical field of polarization imaging, and relates to a broadband Sagnac snapshot type full-polarization imaging system and endoscop.The system comprises a first non-polarized light beam splitter and a second MDCPSI system which are arranged on a first optical axis in a spaced mode, a first MDCPSI system and a first non-polarized light beam splitter which are arranged on a second optical axis perpendicular to the first optical axis in a spaced mode, and a second MDCPSI system and a second non-polarized light beam splitter which are arranged on a second optical axis perpendicular to the second optical axis in a spaced mode. The first plane mirror and the second MDCPSI system are arranged on a third optical axis at intervals, the first plane mirror, the second non-polarized light beam splitter, the polarization analyzer and the detector are sequentially arranged on a fourth optical axis parallel to the second optical axis at intervals, and the detector is electrically connected with the processor. The second plane mirror and the first MDCPSI system are sequentially arranged on a fifth optical axis parallel to the first optical axis at intervals, and the second plane mirror and the second non-polarized light beam splitter are arranged on a sixth optical axis parallel to the third optical axis at intervals. According to the invention, a high-resolution and low-noise full-polarization image can be provided, and a new scheme is provided for real-time polarization imaging in a surgical operation.

Description

Technical Field

[0001] This invention belongs to the field of polarization imaging technology, specifically relating to a wideband Sagnac snapshot-type full polarization imaging system and endoscope. Background Technology

[0002] In surgical procedures, real-time, high-precision imaging technology is crucial for surgeons to perform delicate operations. Traditional microscopic imaging methods, such as optical transmission imaging, fluorescence imaging, and confocal microscopy, are widely used in surgery, but these techniques still have some significant limitations. During surgery, reflections and glare often affect the surgeon's visual experience, especially in high-brightness areas. Reflected light interference often prevents surgeons from clearly observing the details of tissue structures, which not only affects the surgeon's judgment of lesions but may also increase surgical risks. Another common problem is blurred edges and low contrast. Traditional imaging methods often struggle to distinguish details when dealing with complex tissue structures, especially in soft tissue, small lesions, or microvessels, where the low contrast in the image fails to accurately reflect differences between tissues. Furthermore, the influence of blood flow is also a major challenge in surgical microscopy imaging. Blood flow often leads to a decrease in image quality, especially in the perivascular area. Traditional optical imaging methods cannot effectively distinguish blood from surrounding tissue, making it difficult for surgeons to clearly observe the blood flow area and its relative relationship with surrounding tissues.

[0003] To address the aforementioned issues, polarization imaging technology has been introduced into clinical applications as an advanced imaging method. This allows for the provision of more image information in areas where traditional imaging techniques cannot clearly display the image, particularly in improving image contrast, reducing reflected light interference, and differentiating tissue structures. Traditional polarization imaging techniques, such as the MDCPSI system, can effectively eliminate the effects of reflection, enhance edge resolution, and offer higher accuracy for observing dynamic tissues or blood flow areas. Among polarization imaging techniques, channel modulation polarization imaging has become a research hotspot in recent years due to its advantages such as high spatial resolution, no moving parts required, and compact structure. This technique can simultaneously acquire all Stokes parameters, making it suitable for imaging dynamic targets.

[0004] However, the introduction of broadband optical imaging has brought new challenges to channel-modulated polarization imaging technology. In broadband imaging, light interference effects can lead to severe interference fringe aliasing, making it impossible to correctly recover polarization information and thus affecting imaging accuracy. Due to this effect, traditional polarization imaging techniques can usually only use quasi-monochromatic light for imaging, thus limiting their application under broadband conditions. Furthermore, in low-light environments, the application of channel-modulated polarization imaging systems is significantly limited due to insufficient light energy and low signal-to-noise ratio, affecting their clinical applicability in surgical procedures. Summary of the Invention

[0005] In view of this, the present invention provides a wideband Sagnac snapshot-type full polarization imaging system and endoscope to solve the above-mentioned technical problems.

[0006] The technical solution of this invention is: A wideband Sagnac snapshot-type fully polarized imaging system includes a first unpolarized beam splitter, a first MDCPSI system, a second MDCPSI system, a first plane mirror, a second plane mirror, a second unpolarized beam splitter, an analyzer, a detector, and a processor. The detector and processor are electrically connected. The first unpolarized beam splitter and the second MDCPSI system are spaced apart on a first optical axis. The first MDCPSI system and the first unpolarized beam splitter are spaced apart on a second optical axis perpendicular to the first optical axis. The first plane mirror and the second MDCPSI system are spaced apart on a third optical axis, which is perpendicular to both the second and first optical axes. The first plane mirror, the second unpolarized beam splitter, the analyzer, and the detector are sequentially spaced apart on a fourth optical axis parallel to the second optical axis. The second plane mirror and the first MDCPSI system are spaced apart on a fifth optical axis parallel to the first optical axis. The second plane mirror and the second unpolarized beam splitter are spaced apart on a sixth optical axis parallel to the third optical axis.

[0007] The incident light is split into two identical beams after passing through the first unpolarized beam splitter. and light waves and After being split by the first MDCPSI system and the second MDCPSI system, the light paths are adjusted by the first plane mirror and the second plane mirror, and the propagation direction is changed. The light is then transmitted and reflected by the second unpolarized beam splitter, and finally reaches the detector for imaging through the analyzer. The processor then extracts the polarization interference information.

[0008] Furthermore, the first plane mirror is tilted and the angle between it and the third and fourth optical axes is 45°, and the second plane mirror 5 is tilted and the angle between it and the first plane mirror 4 is 90°.

[0009] Furthermore, the first MDCPSI system and the second MDCPSI system have the same structure.

[0010] Furthermore, the first MDCPSI system includes a third plane mirror and a polarizing beam splitter arranged sequentially at intervals on the seventh optical axis. A compensation plate is disposed on one side of the polarizing beam splitter, and the compensation plate is disposed close to the third plane mirror. A fourth plane mirror and the polarizing beam splitter are disposed at intervals on an eighth optical axis perpendicular to the seventh optical axis, and the fourth plane mirror is located on the side away from the compensation plate. A first blazed grating and a second blazed grating are disposed in opposite directions at intervals and are located on the optical path between the fourth plane mirror and the third plane mirror. The first blazed grating is close to the fourth plane mirror. The seventh optical axis is coaxial with the fifth optical axis, and the eighth optical axis is coaxial with the second optical axis.

[0011] Furthermore, the polarization beam splitter includes a flat beam splitter and a narrowband beam splitter arranged in sequence, with a compensation plate disposed close to the narrowband beam splitter, and the material and thickness of the compensation plate being the same as those of the flat beam splitter.

[0012] Furthermore, the distances from the polarizing beam splitter to the fourth and third plane mirrors are the same.

[0013] Furthermore, the geometric centers of the first unpolarized beam splitter, the second unpolarized beam splitter, the polarized beam splitter in the first MDCPSI system, the polarized beam splitter in the second MDCPSI system, the first plane mirror, and the second plane mirror are all located at the vertices of the same cube.

[0014] Furthermore, the polarization beam splitter, the fourth plane mirror, and the third plane mirror are tilted, and their relationships with the seventh and eighth optical axes are respectively as follows: , , Where α is the angle between the polarizing beam splitter and the seventh optical axis in °, β is the angle between the polarizing beam splitter and the eighth optical axis in °, γ is the angle between the fourth plane mirror and the eighth optical axis in °, φ is the angle between the third plane mirror and the seventh optical axis in °, and δ is the grating blaze angle of the first blazed grating 24 and the second blazed grating in °.

[0015] Furthermore, the δ is 20°~25°.

[0016] An endoscope comprising a wideband Sagnac snapshot-type fully polarized imaging system as described above.

[0017] Compared with existing technologies, this invention provides a wideband Sagnac snapshot-type fully polarized imaging system and endoscope. The system combines two MDCPSI structures to split the incident light into four sheared beams at different positions, which are then converged onto a focal plane array to form interference fringes with respect to the full Stokes parameters. This achieves wideband fully polarized detection. The entire system combines the advantages of Sagnac interferometers and grating structures, enabling real-time acquisition of complete two-dimensional Stokes parameters over a wide frequency band. This effectively compensates for the interference effects caused by wideband imaging, improves image quality, and meets the needs of real-time and precise observation in surgical procedures. Unlike traditional polarization imaging techniques, this system does not require any moving electronic control components or microarray elements to efficiently and in real-time acquire fully polarized information. In terms of structural design, the parallel Sagnac structure not only overcomes the problem of low light transmission but also improves imaging quality, enabling it to provide high-resolution, low-noise images. This effectively supports the observation and analysis of dynamic targets during surgery, expanding the application scope of polarization imaging technology and providing a brand-new solution for surgical microscope imaging technology. It can acquire complete polarization information in real time and without damage during surgery, providing doctors with more accurate image references, improving surgical precision and safety. It is highly practical and worthy of promotion. Attached Figure Description

[0018] Figure 1 This is an overall structural diagram of the present invention.

[0019] Figure 2 This is a partial structural diagram of the present invention.

[0020] Figure 3 To set the polarization state of the incident light.

[0021] Figure 4 This is an interferogram on the BSCPSI focal plane array.

[0022] Figure 5 This is the spectrum of the interferogram after Fourier transform.

[0023] Figure 6 This is the three-dimensional view after the Fourier transform of the interferogram.

[0024] Figure 7 For the reconstructed goal , , and The image. Detailed Implementation

[0025] In surgical procedures, real-time, high-precision imaging technology is crucial for surgeons to perform delicate operations. Traditional microscopic imaging methods, such as optical transmission imaging, fluorescence imaging, and confocal microscopy, are widely used in surgery, but these techniques still have some significant limitations. During surgery, reflections and glare often affect the surgeon's visual experience, especially in high-brightness areas. Reflected light interference often prevents surgeons from clearly observing the details of tissue structures, which not only affects the surgeon's judgment of lesions but may also increase surgical risks. Another common problem is blurred edges and low contrast. Traditional imaging methods often struggle to distinguish details when dealing with complex tissue structures, especially in soft tissue, small lesions, or microvessels, where the low contrast in the image fails to accurately reflect the differences between tissues. Furthermore, the influence of blood flow is also a major challenge in surgical microscopy imaging. Blood flow often leads to a decrease in image quality, especially in the perivascular area. Traditional optical imaging methods cannot effectively distinguish blood from surrounding tissue, making it difficult for surgeons to clearly observe the blood flow area and its relative relationship with surrounding tissues.

[0026] To address these issues, a novel imaging technology is urgently needed that can reduce interference from reflections and glare, improve image contrast, clearly display details, and meet the imaging needs of dynamic targets in surgical procedures. Polarization imaging, as an advanced imaging method, analyzes the polarization characteristics of light waves to provide more image information in areas where traditional imaging techniques cannot clearly display the image. It has significant advantages, particularly in improving image contrast, reducing reflected light interference, and distinguishing tissue structures. Polarization imaging effectively eliminates the effects of reflections, enhances edge resolution, and offers higher accuracy for observing dynamic tissues or blood flow areas.

[0027] Polarization imaging technology can be broadly categorized into two types: time-series polarization imaging and snapshot polarization imaging. Time-series polarization imaging includes rotating polarizer-based and liquid crystal electronically controlled techniques. These techniques are simple in principle, offer high detection accuracy, and can provide precise image data. However, these techniques rely on the movement of electronically controlled or mechanical components to achieve polarization analysis, making them unsuitable for real-time imaging of dynamic targets. In surgical procedures, surgeons often require rapid, real-time image acquisition, a requirement that traditional time-series polarization imaging techniques cannot meet due to their internal electronic or mechanical components. Therefore, the application of time-series polarization imaging in surgery is limited.

[0028] Compared to time-series techniques, snapshot polarization imaging technology has a more compact structure and can capture the polarization information of the target in real time, making it suitable for imaging dynamic targets. Snapshot polarization imaging technologies include amplitude-splitting, aperture-splitting, focal-plane-splitting, and channel modulation methods. While amplitude-splitting technology can provide high polarization information accuracy, its large structure requires multiple detectors and is costly, making it suitable for large-aperture devices but not for portable surgical microscopes. Aperture-splitting technology requires large-area detectors, providing a large detection area, but its relatively complex structure, large size, and difficult installation and debugging make it unsuitable for surgical equipment with strict size and weight requirements.

[0029] While focal plane imaging technology can achieve full focal plane imaging, current commercial chips can only detect linear polarization information and cannot effectively acquire complete full polarization information, which remains a major challenge for this technology. Nevertheless, channel modulation polarization imaging technology has become a research hotspot in recent years due to its advantages such as high spatial resolution, no moving parts, and compact structure. This technology can simultaneously acquire all Stokes parameters, making it suitable for imaging dynamic targets. However, when using broadband light imaging, channel modulation polarization imaging technology is susceptible to severe interference fringe aliasing, leading to incorrect polarization information recovery. This problem limits the technology to quasi-monochromatic light imaging and makes it unable to handle the interference effects of broadband imaging. In low-light environments, the application of channel modulation polarization imaging systems is significantly limited due to insufficient light energy and low signal-to-noise ratio.

[0030] This invention provides a wideband Sagnac snapshot-type full polarization imaging system and endoscope. Using an interference + diffraction compensation approach, it attempts to combine a diffraction module with a channel modulation polarization imaging system to effectively compensate for the interference effects introduced by wideband imaging, thereby solving the aforementioned technical problems in wideband imaging. To enable those skilled in the art to better understand and implement the technical solution of this invention, the technical solution will be clearly and thoroughly described below with reference to the accompanying drawings.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Furthermore, it should be further explained that in the description of the embodiments of the present invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" means two or more.

[0033] The terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first," "second," "third," or "fourth" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this invention are for illustrative purposes only and do not represent the only possible implementation.

[0037] Example 1 This invention proposes a Broadband Snapshot Complete Polarized Sagnac Interferometer (BSCPSI) system. By combining two MDCPSI structures, the incident light is split into four sheared beams at different positions and finally converged onto a focal plane array to form interference fringes with respect to the full Stokes parameters, achieving wideband full polarization detection. The entire system combines the advantages of Sagnac interferometers and grating structures, enabling real-time acquisition of complete two-dimensional Stokes parameters over a wide frequency band. This effectively compensates for the interference effects caused by wideband imaging, improves image quality, and meets the needs of real-time and accurate observation in surgical procedures.

[0038] The structural diagram of the BSCPSI system is as follows: Figure 1 As shown, it includes a first unpolarized beam splitter 1, a second unpolarized beam splitter 6, a first MDCPSI system 2, a second MDCPSI system 3, a first plane mirror 4, a second plane mirror 5, an analyzer 7, a detector 8, and a processor 9.

[0039] The detector 8 includes a lens and a focal plane array (FPA). The lens is positioned close to the analyzer 7. The detector 8 and the processor 9 are electrically connected.

[0040] In this configuration, the first unpolarized beam splitter 1 and the second MDCPSI system 3 are arranged alternately on the first optical axis. The first MDCPSI system 2 and the first unpolarized beam splitter 1 are arranged alternately on the second optical axis, which is perpendicular to the first optical axis. The first plane mirror 4 and the second MDCPSI system 3 are arranged alternately on the third optical axis, which is perpendicular to both the second and first optical axes. The first plane mirror 4, the second unpolarized beam splitter 6, the analyzer 7, and the detector 8 are arranged alternately on the fourth optical axis, which is parallel to the first optical axis. Two optical axes are perpendicular to the second and third optical axes, respectively. The second plane mirror 5 and the first MDCPSI system 2 are arranged alternately on the fifth optical axis, which is parallel to the first optical axis. The second plane mirror 5 and the second unpolarized beam splitter 6 are arranged alternately on the sixth optical axis, which is parallel to the third optical axis. The first plane mirror 4 and the second plane mirror 5 are tilted. The angle between the first plane mirror 4 and the third and fourth optical axes is 45°, and the angle between the second plane mirror 5 and the first plane mirror 4 is 90°.

[0041] Specifically, such as Figure 2As shown, the MDCPSI system is the Modified Dispersion Compensation Sagnac Interferometer (MDCPSI). The first MDCPSI system 2 and the second MDCPSI system 3 used in this invention have the same structure. The structure and working principle are explained by taking the first MDCPSI system 2 as an example.

[0042] The first MDCPSI system 2 comprises a third plane mirror 26 and a polarizing beam splitter 22 spaced apart on the seventh optical axis. A compensation plate 21 is disposed on one side of the polarizing beam splitter 22, close to the third plane mirror 26. A fourth plane mirror 23 and the polarizing beam splitter 22 are spaced apart on an eighth optical axis perpendicular to the seventh optical axis, with the fourth plane mirror 23 located away from the compensation plate 21. A first blazed grating 24 and a second blazed grating 25 are spaced apart in opposite directions and located in the optical path between the fourth plane mirror 23 and the third plane mirror 26, with the first blazed grating 24 close to the fourth plane mirror 23. The seventh optical axis is coaxial with the fifth optical axis, and the eighth optical axis is coaxial with the second optical axis.

[0043] Specifically, the fact that the first blazing grating 24 and the second blazing grating 25 are arranged in opposite directions means that the groove directions of the first blazing grating 24 and the second blazing grating 25 are opposite, that is, the blazing directions are opposite.

[0044] The first blazed grating 24 and the second blazed grating 25 have identical structures and are placed in parallel, with a distance L between them. The polarizing beam splitter 22 is equidistant from the fourth plane mirror 23 and the third plane mirror 26, respectively.

[0045] Specifically, in actual operation, after the light rays are incident on the polarization beam splitter 22, they are split into two beams orthogonal to the vibration direction: transmitted p-polarized light and reflected s-polarized light. The p-polarized light, after being reflected by the fourth plane mirror 23, is diffracted to the first order by the first blazed grating 24. Then, after passing through the identical second blazed grating 25 placed in opposite directions, the diffraction angle is eliminated. At this point, the light ray is parallel to its transmission direction before incident on the first blazed grating 24. After being reflected by the third plane mirror 26, it exits through the polarization beam splitter 22, with the exit point slightly offset from the center. The magnitude of this offset is... ,in This is a constant related to the system structure parameters. Similarly, after the s-polarized light passes sequentially through the third plane mirror 26, the second blazed grating 25, the first blazed grating 24, and the fourth plane mirror 23, it is finally reflected by the polarizing beam splitter 22, and the distance of the outgoing light from the center is... The distance between the two emitted beams is called the shearing amount, which is proportional to the wavelength.

[0046] This invention achieves precise diffraction control and optical path difference compensation, ensuring that the offset shearing of two polarized beams is proportional to the wavelength. Furthermore, it compensates for the optical path difference caused by the difference in film thickness using a compensation plate, thereby ensuring the accuracy of the system in high-precision optical measurements.

[0047] It is important to note that the MDCPSI system requires the p-polarized light transmitted by the polarization beamsplitter 22 and the reflected s-polarized light to have the same optical path difference. This means the distances from the polarization beamsplitter 22 to the fourth plane mirror 23 and the third plane mirror 26 are equal. The polarization beamsplitter 22 comprises a planar beamsplitter and a narrowband beamsplitter film arranged sequentially. However, because the narrowband beamsplitter film is deposited on one side of the planar beamsplitter in the manufacturing process of the polarization beamsplitter 22, the transmitted light travels a longer distance than the reflected light. This distance has a non-linear relationship with the wavelength and cannot be compensated for by adjusting the length of the two arms. In the design of the device, a compensation plate 21, with the same material and thickness as the planar beamsplitter, can be placed on the other side of the polarization beamsplitter 22 for compensation. This forms a stacked structure consisting of the planar beamsplitter, the narrowband beamsplitter film, and the compensation plate 21, ensuring that the optical path difference between the two beams remains the same. Specifically, the compensation plate 21 is a glass substrate.

[0048] The polarization beam splitter 22, the fourth plane mirror 23, and the third plane mirror 26 are all tilted, and their relationships with the seventh and eighth optical axes are as follows: (1) (2) Where α is the angle between polarizing beam splitter 22 and the seventh optical axis, in °; β is the angle between polarizing beam splitter 22 and the eighth optical axis, in °; γ is the angle between the fourth plane mirror 23 and the eighth optical axis, in °; φ is the angle between the third plane mirror 26 and the seventh optical axis, in °; and δ is the grating blaze angle of the first blazed grating 24 and the second blazed grating 25, in °.

[0049] More specifically, δ is 20°~25°, preferably 22.5°, to ensure that the light is incident perpendicularly on the first blazed grating 24 and the second blazed grating 25.

[0050] Specifically, in order to ensure the optical path difference of the BSCPSI system on the focal plane array, the geometric centers of the first unpolarized beam splitter 1, the second unpolarized beam splitter 6, the polarized beam splitter 22 in the first MDCPSI system 2, the polarized beam splitter 22 in the second MDCPSI system 3, the first plane mirror 4, and the second plane mirror 5 are all located at the vertices of the same cube.

[0051] Since MDCPSI systems can only achieve linear polarization imaging, artificial targets have strong circular polarization information, and the transmission distance of fully polarized information is much longer. Therefore, fully polarized imaging has a wider range of applications in target detection and identification. Two light beams can only modulate a maximum of three Stokes vectors. To obtain all Stokes vectors, more beams are needed to participate in the interference to modulate all Stokes vectors. Therefore, the BSCPSI system provided by this invention combines two MDCPSI structures to split the incident light into four sheared beams at different positions. After passing through the analyzer 7 and the lens, these beams converge onto the focal plane array to form interference fringes with respect to all Stokes parameters, achieving wide-band fully polarized detection.

[0052] The specific working principle of the BSCPSI system is as follows: The incident light from the target is split into two identical beams after passing through the first unpolarized beam splitter 1. and light waves and After being split by the first MDCPSI system 2 and the second MDCPSI system 3, the light propagates. After the light path is adjusted by the first plane mirror 4 and the second plane mirror 5 and the propagation direction is changed, the light is transmitted and reflected by the second unpolarized beam splitter 6 respectively. Finally, after passing through the analyzer 7, the light reaches the detector 8 and is focused onto the focal plane array by the lens of the detector 8 to form an image.

[0053] To ensure precise focusing and uniform distribution of light, a front telescope system 10 is installed on the incident light side of the first unpolarized beam splitter 1. The front telescope system 10 includes an objective lens, a field stop, and a collimating lens arranged sequentially on the same optical axis. The objective lens, field stop, and collimating lens recollect, define, and collimate the light beam from the auxiliary mirror, ensuring that the light enters the main optical system in a uniform and aberration-free state. The front telescope system 10 must be installed close to the front end of the microscope and strictly coaxial with the optical axis to ensure clear and stable imaging. Specifically, the objective lens ensures that the image acquired from the surgical area maintains high resolution and low distortion, accurately capturing tissue details. The field stop controls the size of the field of view and adjusts the amount of light entering the front telescope system 10, avoiding excessively bright or dark lighting that could affect image quality. The collimating lens straightens the light into a parallel beam, ensuring that subsequent optical elements can accurately receive the light from the surgical area and preventing light divergence, thereby ensuring image clarity.

[0054] In use, light is focused by the objective lens and enters the front telescope system 10. The field of view is controlled by the field stop, which adjusts the amount of light entering the front telescope system 10. Finally, after being collimated into a parallel beam by the collimating lens, the light enters the first unpolarized beam splitter 1 and is split into two identical light waves I.A with I B Among them, I A The beam enters the main structure of the second MDCPSI system 3 and is separated into two beams in the x-direction; I B The light beam enters the main structure of the first MDCPSI system 2 and is also split into two beams in the y-direction. Subsequently, the two beams from the second MDCPSI system 3 have their optical paths adjusted by the first plane mirror 4, and the two beams from the first MDCPSI system 2 have their optical paths adjusted by the second plane mirror 5. The four beams obtained after the above separation and adjustment are re-converged at the second unpolarized beam splitter 6. The converged beam is then polarized and modulated by the analyzer 7, which is at a 45° angle to the –y axis, and focused onto the focal plane array FPA by the lens to achieve imaging, realizing the simultaneous acquisition of multi-channel polarization interference information. Finally, the processor 9 completes the extraction and analysis of the multi-channel polarization interference information.

[0055] The shearing amount generated by the Sagnac broadband linear polarization imaging structure is: (3) in, It is the shearing amount generated by the Sagnac broadband linear polarization imaging structure. It is the wavelength of the incident light. It is a constant. The value of is related to the design parameters of the Sagnac broadband linear polarization imaging structure.

[0056] By introducing the first blazed grating 24 and the second blazed grating 25, the dispersion of the carrier frequency in the PSI structure can be compensated. Figure 2 As shown in the MDCPSI unfolded diagram, p-polarized light propagates from left to right, and s-polarized light propagates from right to left. After passing through the first blazed grating 24, the light is diffracted to the first order, and then through the second blazed grating 25 with the same structure, the diffraction angle is eliminated, at which point the light is parallel to the original propagation direction.

[0057] After processing by the BSCPSI system described above, the incident light is split into four modulated coherent beams. The four coherent beams emitted by the BSCPSI system... xoy The beams are arranged in a cross shape on the plane, similar to the sheared beam distribution produced by the Sava plate polarization interferometry imaging system. The BSCPSI system... x shaft and y The shear amount in the axial direction is: (4) in, and These are the BSCPSI system in x shaft and y Shear amount in the axial direction, It is the lateral shear amount of the MDCPSI subsystem. m It is a diffraction order. It is the wavelength of the incident light. d L is the grating period, and L is the distance between the first blazed grating 24 and the second blazed grating 25 in each MDCPSI subsystem.

[0058] The interference intensity on the focal plane array can be expressed as: (5) in, The interference light intensity on the focal plane array of the BSCPSI system. Let x be the electric field vector in the x-direction. Let be the electric field vector in the y-direction. , , and These are the cumulative phases of the four beams of light arriving at the focal plane array.

[0059] The four emitted rays travel the same optical path before reaching the lens, therefore the cumulative phase can be expressed as: (6) in, , , and These are the cumulative phases of the four beams arriving at the focal plane array. Indicates the imaging focal length. m It is a diffraction order. d It is the grating period, and L is the distance between the first blazed grating 24 and the second blazed grating 25 in each MDCPSI subsystem. x i , y i These are the coordinates of the image plane.

[0060] Considering only the diffraction of the blazed grating to the first order, let m =1, and based on the phase factor, the formula for calculating the light intensity on the focal plane array is: (7) in, For focal plane array x i ，y i Interference light intensity at that location, , , , For Stokes vectors, x iand y i It refers to the spatial location of the image coordinates. The carrier frequency representing the interference fringes: (8) use get (9) in, For focal plane array x i ，y i Interference light intensity at that point , , , For Stokes vectors, x i and y i It refers to the spatial location of the image coordinates. The carrier frequency represents the interference fringes. Representing complex numbers The argument (phase angle).

[0061] The formula for the focal plane array light intensity of MDCPSI can be expressed as: (10) in, It is the intensity of the MDCPSI focal plane array light. , and For Stokes parameters, Indicates the imaging focal length. d It is the grating period. Indicates the distance between two flashing gratings. The coordinates are the image plane coordinates. The carrier frequency is independent of the wavelength, indicating that BSCPSI, like MDCPSI, is an achromatic system capable of wideband imaging.

[0062] Comparing formulas (10) and (7), it can be seen that the MDCPSI system can only modulate three Stokes parameters, while the BSCPSI system can modulate all four Stokes parameters with different carrier frequencies, thereby achieving full polarization information detection.

[0063] Taking a Fourier transform of equation (9) yields: (11) in, This is the Fourier transform of the interference light intensity on the focal plane array of the BSCPSI system. This is the Fourier transform form of the Stokes vector. Indicates spatial frequency, This indicates the carrier frequency of the interference fringes.

[0064] As can be seen from formula (11), the frequency domain corresponding to the intensity interferogram of BSCPSI contains 7 parts, which are respectively concentrated in , , , , By selecting the appropriate filter to choose the required channel and then performing an inverse Fourier transform on it, all the polarization information of the target can be demodulated.

[0065] (12) in, , , , For Stokes vectors, This is the Fourier transform form of the Stokes vector. The carrier frequency represents the interference fringes. This is the inverse Fourier transform. Let be the real part of the complex number. It represents the imaginary part of a complex number.

[0066] The following uses MATLAB numerical simulation to demonstrate the ability of the BSCPSI system to acquire fully polarized information, setting the Stokes parameters of the incident light. like Figure 3 As shown.

[0067] According to formula (7), the interference pattern on the BSCPSI focal plane array can be calculated as follows: Figure 4 As shown, shaft and There are alternating bright and dark interference fringes along the axial direction.

[0068] Performing a Fourier transform on the interferogram yields the following spectrum: Figure 5 As shown, the three-dimensional perspective is as follows Figure 6 As shown in the figure, seven spectral peaks can be clearly seen. The center position is... S Channel 0, -45 degrees is S Channel 1, with four peak values: top, bottom, left, and right. S 23 aisle.

[0069] Based on the theoretically calculated carrier frequency, a rectangular filter is selected to extract information from each channel, and the frequency is shifted to the center position for inverse Fourier transform to reconstruct the target. , , , Image as Figure 7 .

[0070] Furthermore, it should be noted that the wideband Sagnac snapshot-type fully polarized imaging system provided in this invention can be applied to endoscopes to significantly improve image clarity.

[0071] This invention provides a wideband Sagnac snapshot-type fully polarized imaging system and endoscope. By combining two MDCPSI structures, the incident light is split into four sheared beams at different positions, which are then converged onto a focal plane array to form interference fringes with respect to the full Stokes parameters. This enables wideband fully polarized detection, effectively improving image contrast and reducing reflected light interference. Especially in areas where blood flow has a significant impact, it greatly enhances image observation capabilities, ensures image clarity, and is highly practical and worthy of promotion.

[0072] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A broadband Sagnac snapshot-type fully polarized imaging system, characterized in that, The system includes a first unpolarized beam splitter (1), a first MDCPSI system (2), a second MDCPSI system (3), a first plane mirror (4), a second plane mirror (5), a second unpolarized beam splitter (6), an analyzer (7), a detector (8), and a processor (9). The detector (8) and the processor (9) are electrically connected. The first unpolarized beam splitter (1) and the second MDCPSI system (3) are arranged alternately on the first optical axis, and the first MDCPSI system (2) and the first unpolarized beam splitter (1) are arranged alternately on the second optical axis perpendicular to the first optical axis. The first plane mirror (4) and the second MDCPSI system (3) are arranged alternately on the third optical axis, which is perpendicular to the second optical axis and the first optical axis respectively. The first plane mirror (4), the second unpolarized beam splitter (6), the analyzer (7) and the detector (8) are arranged alternately on the fourth optical axis, which is parallel to the second optical axis. The second plane mirror (5) and the first MDCPSI system (2) are arranged alternately on the fifth optical axis, which is parallel to the first optical axis. The second plane mirror (5) and the second unpolarized beam splitter (6) are arranged alternately on the sixth optical axis, which is parallel to the third optical axis. After the incident light passes through the first unpolarized beam splitter (1), it is split into two identical light waves. and light waves and After being split by the first MDCPSI system (2) and the second MDCPSI system (3), the light paths are adjusted by the first plane mirror (4) and the second plane mirror (5). After changing the propagation direction, the light is transmitted and reflected by the second unpolarized beam splitter (6) respectively. Finally, the light passes through the analyzer (7) and reaches the detector (8) for imaging. The polarization interference information is extracted by the processor (9).

2. The wideband Sagnac snapshot-type full polarization imaging system according to claim 1, characterized in that, The first plane mirror (4) is tilted and the angle between it and the third optical axis and the fourth optical axis is 45°. The second plane mirror (5) is tilted and the angle between it and the first plane mirror (4) is 90°.

3. The wideband Sagnac snapshot-type full polarization imaging system according to claim 1, characterized in that, The first MDCPSI system (2) and the second MDCPSI system (3) have the same structure.

4. The wideband Sagnac snapshot-type full polarization imaging system according to claim 3, characterized in that, The first MDCPSI system (2) includes a third plane mirror (26) and a polarizing beam splitter (22) arranged at intervals on the seventh optical axis. A compensation plate (21) is provided on one side of the polarizing beam splitter (22). The compensation plate (21) is located close to the third plane mirror (26). A fourth plane mirror (23) and the polarizing beam splitter (22) are arranged at intervals on an eighth optical axis perpendicular to the seventh optical axis. The fourth plane mirror (23) is located on the side away from the compensation plate (21). A first blazed grating (24) and a second blazed grating (25) are arranged at intervals in opposite directions and are located on the optical path between the fourth plane mirror (23) and the third plane mirror (26). The first blazed grating (24) is close to the fourth plane mirror (23). The seventh optical axis is coaxial with the fifth optical axis, and the eighth optical axis is coaxial with the second optical axis.

5. The wideband Sagnac snapshot-type full polarization imaging system according to claim 4, characterized in that, The polarization beam splitter (22) includes a flat beam splitter and a narrowband beam splitter arranged in sequence. The compensation plate (21) is arranged close to the narrowband beam splitter, and the material and thickness of the compensation plate (21) are the same as those of the flat beam splitter.

6. The wideband Sagnac snapshot-type full polarization imaging system according to claim 5, characterized in that, The polarization beam splitter (22) is at the same distance from the fourth plane mirror (23) and the third plane mirror (26).

7. The wideband Sagnac snapshot-type full polarization imaging system according to claim 6, characterized in that, The geometric centers of the first unpolarized beam splitter (1), the second unpolarized beam splitter (6), the polarized beam splitter (22) in the first MDCPSI system (2), the polarized beam splitter (22) in the second MDCPSI system (3), the first plane mirror (4), and the second plane mirror (5) are all located at the vertices of the same cube.

8. The wideband Sagnac snapshot-type full polarization imaging system according to claim 7, characterized in that, The polarization beam splitter (22), the fourth plane mirror (23), and the third plane mirror (26) are tilted, and their relationships with the seventh and eighth optical axes are respectively as follows: ， ， Where α is the angle between the polarization beam splitter (22) and the seventh optical axis, in °; β is the angle between the polarization beam splitter (22) and the eighth optical axis, in °; γ is the angle between the fourth plane mirror (23) and the eighth optical axis, in °; φ is the angle between the third plane mirror (26) and the seventh optical axis, in °; and δ is the grating blaze angle of the first blazed grating (24) and the second blazed grating (25), in °.

9. The wideband Sagnac snapshot-type full polarization imaging system according to claim 8, characterized in that, The value of δ is 20°~25°.

10. An endoscope, characterized in that, Includes a wideband Sagnac snapshot-type full polarization imaging system as described in any one of claims 1 to 9.

Images