Polarization Imaging Research Articles

Multispectral polarization image demosaicing using redundant Stokes representation

This paper proposes a deep-learning-based demosaicing algorithm, multispectral polarization demosaicing with redundant Stokes (MPD-RS), designed for multispectral polarization filter arrays. The proposed MPD-RS effectively learns the correlation across spatial, spectral, and polarization domains, utilizing a newly constructed dataset of multispectral polarization images (MSPIs). Initially, MPD-RS performs interpolation using a position-variant convolutional kernel to generate a preliminary MSPI. This is followed by conversion to a new Stokes representation, to our knowledge, where the data is decomposed into four components, including a term to capture polarization redundancy. The intensity component is processed with a multi-stage three-dimensional convolutional network, while the remaining components are handled by a lightweight, attention-based network. Experimental results validate the effectiveness of MPD-RS, demonstrating superior peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) for MSPI reconstruction, with an average PSNR improvement of 3.873 dB over the Global Cross-Attention Network, as well as reduced mean squared error in Stokes parameters. The method maintains high accuracy across images with a diverse range of polarization levels, highlighting its adaptability.

End-to-end physics-informed multi-branch GAN for enhanced DoFP polarization image reconstruction

End-to-end physics-informed multi-branch GAN for enhanced DoFP polarization image reconstruction

Quantitative Large-Area Polarized-Light Microscopy

Abstract This article describes the elevation of polarized-light microscopy (PLM) to a technique for quantitative large-area material characterization in the Microscopy Today Innovation Award-winning CrystalViewTM laser PLM. CrystalView is enabled by narrow-band laser illumination, bistatic design, and strict qualification of polarization optics, resulting in accurate polarization imaging over an instant field-of-view (FOV) that exceeds 2 cm2. This FOV is effectively demonstrated by the critical concept of seamless stitching, which confirms low error and is then applied to obtain even larger effective FOVs with industrial utility. Linear combinations of image irradiances, known as polarization features, are related to physical material properties, for instance, crystal orientation, through the combination of Mueller matrix polarimeter design and classical electrodynamics. While CrystalView is applicable to any reflective or transmissive material that exhibits PLM contrast, in this article it is demonstrated for orientation imaging of hexagonal and cubic metal polycrystals, titanium and stainless-steel alloys respectively, the latter printed by laser powder-bed fusion (LPBF) and reliant, for texture imaging, on chemical etching that can also reveal phase structure.

Polarimetric Photodetectors with Multi‐Control States for Multi‐Valued Encoding Communication and Polarization Image Applications

AbstractPolarimetric photodetectors hold significant promise in optical communication and polarization imaging applications due to their additional ability to detect polarization states of light. The strategy of multiple states modulation plays a crucial role in performance optimization and multi‐valued logic output, enabling higher information transmission density and clearer polarization recognition. Following this context, a Ta2PdSe6/MoTe2 semimetal/semiconductor heterojunction‐based polarimetric photodetector with multi‐control states that can enable the multi‐valued encoding communication and high‐contrast polarization imaging applications is developed. As dual‐electrically controlled states, the gate and bias voltages can significantly modulate the performance metrics. As a result, the device can be configured with tunable detectivity from 3.6 × 1010 to 2.19 × 1012 Jones and polarization ratios from 3.8 to 8.14 under 808 nm illumination. By further combining additional dual‐optically control states (light intensity and polarization angle), the device achieves four logic states output, thus realizing multi‐valued encoding optical communication with higher transmission efficiency and information density. Leveraging these four control states, a polarization imaging system capable of operating at different angles is also realized, with an enhanced degree of linear polarization from 0.51 to 0.8, allowing better differentiation of object features under different polarization states. This work demonstrates a polarimetric photodetector with multi‐control states, showing promising potential in high‐density communication and high‐resolution imaging applications.

A multi-scale infrared polarization image fusion method based on polarization-forming

A multi-scale infrared polarization image fusion method based on polarization-forming

Electrically tunable polarization imaging through configurating a single layer of infrared twisted nematic liquid-crystal (IR-TNLC) module before a common camera

Electrically tunable polarization imaging through configurating a single layer of infrared twisted nematic liquid-crystal (IR-TNLC) module before a common camera

Self-Adaptive Polarized Photoresponse in Organic Single-Crystal Phototransistors for Bionic Night-Time Polarization Perception.

The emerging semiconductor micro/nanocrystals with intrinsic anisotropy have provided new perspectives for low-cost and simplified polarimetry. However, the low polarization sensitivity of state-of-the-art polarimeters based on anisotropic semiconductors under weak and partially polarized light severely hinders their practical application in complex dim environments. Here, a photo-adaptive polarization-sensitive organic phototransistor (POL-OPT) is demonstrated for bionic weak-light polarization perception. The combination of highly anisotropic organic crystals with charge-storage accumulative effect enables a self-adaptive polarized photoresponse of the phototransistor to imitate the bionic scotopic adaptation process. Consequently, an ultrahigh dichroic ratio (DR) of over 105 is achieved through time accumulation under an ultraweak light intensity of 200 nW cm-2, which is among the highest in polarization-sensitive photodetectors. Furthermore, POL-OPT array is constructed for effective polarization perception in an artificial moonlit environment with a low degree of linear polarization (DoLP) down to 0.26, reaching the detection threshold of night-active dung beetles. This study offers a new opportunity for the development of new-generation high-performance polarimeters for polarization imaging, bionic navigation, and artificial visual systems.

Polarimetric imaging of peripheral nerves: an intraoperative aid

In this work, we present a real-time method to aid intraoperative peripheral nerve identification. Using LEDs as the light sources, the device contains a driving motor that rotates a pair of orthogonally oriented linear polarizers. By performing lock-in processing to frames taken under the rotating crossed polarization imaging (RXPI) system, the AC components of the periodic intensity signal of chicken tissues are acquired and compared. With an area under the curve (AUC) of 93%, the chicken sciatic nerve is distinct for automatic identification. In both chicken thigh and cadaver arm models, the contrasts of nerve tissues are successfully enhanced in the lock-in processed output image. Real-time automatic nerve masking is successfully demonstrated in the chicken model using a portable prototype weighing 525 g. In conclusion, the RXPI system with lock-in processing methods can potentially serve as an intraoperative nerve identification aid.

An Underwater Polarization Imaging Technique Based on the Construction and Decomposition of the Low-Rank and Sparse Matrix in Stokes Space for Polarization State Imaging

Traditional underwater polarization imaging methods can only provide clear degree of polarization (DOP) and intensity images of the object but cannot provide images of the polarization state of the object. This paper proposes a method to extract clear object information from turbid water in all four Stokes parameter (I, Q, U, and V) channels by using the full Stokes camera, enabling clear polarization state image reconstruction. The method utilizes multiple images from different angles to construct a low-rank and sparse matrix. Then, by decomposing this matrix into sparse and low-rank components, clear Q, U, and V images (i.e., the full polarization state) can be obtained. Unlike traditional methods that assume the circularly polarized component (V component) to be zero, this method retains V channel information, allowing for circular polarization component measurement. The study successfully reconstructed clear underwater images of samples with inhomogeneous DOP distribution and obtained the clear polarization states of polarizers and fish in the turbid water. The results show that the proposed method can visualize and analyze the object’s polarization state quantitatively with high accuracy in turbid water for the first time, potentially extending the applicability of polarization underwater imaging in ocean exploration.

2D Perovskite Heterojunction-Based Self-Powered Polarized Photodetectors with Controllable Polarization Ratio Enabled by Ferro-Pyro-Phototronic Effect.

Metal halide perovskites (MHPs) are commonly used in polarization-sensitive photodetectors (PDs) for applications such as polarization imaging, remote sensing, and optical communication. Although various methods exist to adjust the polarization-sensitive photocurrent, a universal and effective approach for continuous control of MHPs' optoelectronic and polarized properties is lacking. A universal strategy to electrically modulate the polarization ratio (PR) of self-powered polarized PDs using the ferro-pyro-phototronic effect (FPPE) in 2D perovskites is presented. By varying the amplitude and direction of ferroelectric polarization voltage, the built-in electric field in the heterojunction can be modulated, allowing for controllable PR regulation and adjustable polarization characteristics. Moreover, the polarized pyroelectric photoresponses are realized, significantly enhancing the responsivity, response speed of the polarized PDs. Both the pyroelectric currents and photocurrents exhibit obvious polarization characteristics. This method's versatility is demonstrated by creating three additional quasi-2D MHP ferroelectric-based polarized-sensitive PDs. A proof-of-concept for encrypted optical communication is achieved using the UV-sensitive PDs as light-sensing units. These findings highlight FPPE's potential to enhance ferroelectric device polarization control, enabling high-performance and self-powered polarization photodetection.

Imaging polarimetry of a few-pixel object with a division-of-focal-plane polarization imager

Imaging polarimetry of a few-pixel object with a division-of-focal-plane polarization imager

Deep learning-based polarization 3D imaging method for underwater targets.

The significant absorption and scattering of light during its propagation in water severely degrade the quality of underwater imaging, presenting challenges for developing high-precision 3D imaging techniques based on optical methods. Polarization imaging has demonstrated effectiveness in mitigating the effects of scattering, making it a valuable approach for underwater imaging. Additionally, the polarization state of reflected light can be utilized for surface normal estimation and 3D shape reconstruction. This paper presents a learning-based method for 3D shape reconstruction of underwater targets using shape from polarization techniques. To address the lack of publicly available datasets for underwater polarization 3D imaging, we have developed a data acquisition system that simulates Jerlov Type I water conditions, creating a dataset of underwater polarized images along with corresponding ground truth surface normal images. Furthermore, we propose a network framework based on Attention U2Net for the 3D reconstruction of underwater polarized images. This framework is designed to capture detailed texture information of underwater targets and incorporates an effective polarization representation to resolve azimuthal ambiguity, thus enhancing the accuracy of underwater 3D imaging. Experimental results demonstrate that our method effectively addresses azimuthal ambiguity, reduces texture loss during reconstruction, and improves the accuracy of surface normal estimation, achieving superior performance compared to existing methods.

Compact single-shot multispectral polarization imager through joint spectral-polarization encoding.

The technique of spectral polarization imaging (SPI) is a potent detection tool in various fields due to its ability to capture multi-dimensional information. However, existing SPI systems usually face challenges associated with architectural complexity and computational requirements, rendering them unsuitable for handheld, on-board, and real-time applications. Consequently, a compact single-shot multispectral polarization imager (CSMPI) is proposed, which employs a combined spectral-polarization encoding strategy to address the aforementioned issues. It incorporates a coded aperture for encoding multiple spectral channels together with linear polarization into a single measurement, enabling the simultaneous detection of up to nine light components with just one exposure. The resulting prototype consists solely of a color polarization detector and an imaging lens inserted with the small and easily fabricable coded aperture, which features compact dimensions of Φ5.5 cm × 21.5 cm and a light weight of approximately 670 g. This is particularly advantageous for application areas that require system miniaturization and rapid multi-dimensional detection.

Interferenceless coded aperture correlation holography for five-dimensional imaging of 3D space, spectrum and polarization

Abstract Interferenceless coded aperture correlation holography (I-COACH) is a robust imaging technique for recovering three-dimensional object information using incoherent holography without two-beam interference. In this study, five-dimensional (5D) imaging along 3D space, spectrum and polarization in I-COACH is proposed and experimentally demonstrated for the first time. The proposed technique exploits the polarization-dependent light modulation characteristics of spatial light modulators to record polarization-dependent intensity distributions, which are distinguished by significant blurring between orthogonal polarization states. 5D I-COACH is implemented by inter-connecting all five dimensions in a single frame, and image recovery is attempted from different configurations of recorded point spread intensity distributions and response-to-object intensity distributions along 5D using recently developed deconvolution techniques. The simulation and experimental results confirm the 5D imaging capabilities of I-COACH. The proposed technique can be a useful tool for birefringence microscopy, and functional and structural imaging applications.

Self-Assembled Piezoelectric Films from Aligned Lysozyme Protein Fibrils.

Piezoelectric organic polymers are promising alternatives to their inorganic counterparts due to their mechanical flexibility, making them suitable for flexible and wearable piezoelectric devices. Biological polymers such as proteins have been reported to possess piezoelectricity, while offering additional benefits, such as biocompatibility and biodegradability. However, questions remain regarding protein piezoelectricity, such as the impact of the protein secondary structure. This study examines the piezoelectric properties of lysozyme amyloid fibril films, plasticized by polyethylene glycol (PEG). The films demonstrated a measurable d33 coefficient of 1.4 ± 0.1 pCN-1, for the optimized PEG concentration, confirming piezoelectricity. The PEG was found to hydrogen-bond with the fibrils, likely impacting the piezoelectric response of the film. Polarization imaging revealed long-range alignment of the amyloid fibrils in a circumferential arrangement. These results demonstrate the potential of using amyloid fibrils, which can be formed from various proteins, to create bulk self-assembled piezoelectric materials.

PdSe2/NbSe2 Heterojunction Photodetector with Broadband Detection and Polarization Sensitivity.

Polarized photodetectors based on anisotropic two-dimensional (2D) materials display great potential applications in communications and optoelectronics. However, the existence of high dark current, low anisotropic ratio, and response speed limits their development. In this paper, a broadband polarization angle-dependent photodetector based on the PdSe2/NbSe2 van der Waals (vdW) heterojunction has been constructed. Characterization results show that the PdSe2/NbSe2 heterojunction photodetector can suppress the dark current effectively (NbSe2 ∼4 orders of magnitude and PdSe2 ∼1 order of magnitude compared with individual material). Meanwhile, the device exhibits a broadband detection capability ranging from 405 to 980 nm. The device shows a superior responsivity of 27 mA/W, a considerable detectivity of 9.8 × 107 Jones, a large external quantum efficiency of 528%, and an ultrafast rise/decay time of 1.6/1.9 μs at 1 V bias under 638 nm laser wavelength. The photodetector also achieves a high polarization-sensitive anisotropic ratio of ∼2.62 under 638 nm laser irradiation. In addition, the heterojunction device shows outstanding polarization imaging capabilities, which can be used as the image sensor. This work proposed a PdSe2/NbSe2 vdW heterojunction device with low dark current, broadband polarized detection, and polarized visual imaging, which will promote the development and practicality of polarization-sensitive photodetectors.

High reflectivity surface highlight removal technology based on light field polarization imaging.

This paper proposes an imaging technique to remove strong reflections from specular surfaces using polarization characteristics combined with light field imaging. Firstly, the correct strong reflection region is found by studying the reflected light characteristics, and the strong reflection region highlights are filtered out using Stokes parameters based on polarization information. Then, a system of microlens arrays with different transmittances was built for imaging, and the system was image-corrected to enable more information about the scene to be captured. Finally, the color statistics are corrected according to the color characteristics, and then the color adjustment is performed to enhance the local color transfer results to obtain a high-quality true color image. The results of the experiment suggest that the method proposed in this paper is effective in restoring the actual texture contours of large highlight regions on strongly reflective surfaces.

Quantitative fiber orientation analysis of carbon fiber sheet molding compounds using polarization imaging and X-ray computed tomography

Quantitative fiber orientation analysis of carbon fiber sheet molding compounds using polarization imaging and X-ray computed tomography

Underwater polarization de-scattering imaging independent of target-free regions

Underwater optical imaging technology presents broad application prospects in fields such as marine resource exploration, underwater ecological environment monitoring, and seabed topography detection. The technology employs the polarization characteristics of light, particularly those of the background and target, to achieve a clear image. However, the traditional methods rely on target-free regions to compute the backscattered light information, which is infrequently present in the actual scene captured by the camera. Then the full-space resolution of target information light and backscattered light information are required. At this time, the traditional methods may be difficult to adapt in practical application.<br>In this paper, an underwater polarization de-scattering method independent of target-free regions is proposed by combining active polarization imaging and transmittance de-scattering model. Initially, the total light intensity within the camera's field of view is decomposed into its polarized and unpolarized components. By removing the backscattered light with polarized and unpolarized information from the total light intensity, a clear underwater target can be obtained. Based on the active polarization imaging model, the backscattered light with polarization information is calculated, in which the polarization angle of the backscattered light is considered as zero in the full-space. Thus, the polarization degree of the target information light occupying the camera's entire field of view can be derived. According to the polarization correlation, the polarization degree of the backscattered light can be characterized, and the intensity of the backscattered light with polarization information in the camera's entire field of view can also be obtained. Then the unpolarized component is calculated using the minimum intensity image with Stokes vector transformation. Finally, the underwater scene is obtained by combining the transmittance de-scattering principle and introducing adjustment parameters.<br>Experimental and real-world underwater imaging results demonstrate that the proposed method can effectively remove the majority of the backscattered light and improve the image contrast and entropy, irrespective of the presence of target-free regions. Additionally, it offers a certain rate advantage, which can facilitate the real-time complex underwater imaging technology.

Polarization Imaging Method for Detection of Lung Cancer Based on Symmetrical Single LCVR

ABSTRACTLung cancer ranks among the three most prevalent cancers worldwide. Polarization imaging technology can effectively distinguish between cancerous and normal tissues. The most commonly applied method for cancer detection is the dual‐rotating wave plate polarization imaging system (DWRPIS), which is cumbersome and prone to significant error due to 60 mechanical rotations. To address this, our experiment leveraged the stability of the Liquid Crystal Variable Retarder (LCVR) and, based on existing theoretical foundations for simplifying the use of LCVRs, designed a symmetric single‐LCVR polarization imaging system (SSLPIS) for the first time to detect lung cancer images. The SSLPIS is easy to operate, completing the entire acquisition process in just 150 s, with effective Mueller matrix imaging and an overall accuracy rate of over 90%, offering a faster and more precise detection method. This new approach provides an innovative pathway for the rapid detection of lung cancer.