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Rapid, nondestructive characterization techniques for evaluating the degree of crystallinity and phase segregation of organic semiconductor blend thin films are highly desired for in‐line, automated optoelectronic device fabrication facilities. Here, it is demonstrated that reflection polarized optical microscopy (POM), a simple technique capable of imaging local anisotropy of materials, is capable of determining the relative degree of crystallinity and phase segregation of thin films of polymer:fullerene blends. While previous works on POM of organic semiconductors have largely employed the transmission geometry, it is demonstrated that reflection POM provides 3× greater contrast. The optimal configuration is described to maximize contrast from POM images of polymer:fullerene films, which requires Köhler illumination and slightly uncrossed polarizers, with an uncrossing angle of ±3°. It is quantitatively demonstrated that contrast in POM images directly correlates with 1) the degree of polymer crystallinity and 2) the degree of phase segregation between polymer and fullerene domains. The origin of the bright and dark domains in POM is identified as arising from symmetry‐broken liquid crystalline phases (i.e., dark conglomerates), and it is proven that they have no correlation with surface topography. The use of reflection POM as a rapid diagnostic tool for automated device fabrication facilities is discussed. [ABSTRACT FROM AUTHOR]

Laser range-gated underwater imaging technology, by removing most of the backscattering noise, can effectively increase image contrast and extend the detection range. The optical signal captured by a range-gated imaging system primarily comprises reflected light from the object and backscattered light from the surrounding water. Consequently, surfaces with low reflectivity or highly turbid water environments substantially constrain the applicability of the range-gated imaging system. To enhance the detection capability of underwater laser range-gated imaging, this paper proposes the incorporation of underwater polarized light imaging technology as an enhancement method. Based on polarization differences, backscattered light and reflected light from an object can be distinguished. Experimental results indicate that, compared to images obtained using a conventional range-gated laser imaging system, those captured with a polarization-enhanced system exhibit an increase of up to 47% for the corresponding Enhancement Measure Evaluation (EME) index. The proposed approach, which integrates polarization imaging with range-gated laser imaging, has the potential to broaden the applicability of underwater laser imaging scenarios, such as deep-sea exploration and military applications. [ABSTRACT FROM AUTHOR]

Optical anisotropic (e.g., birefringent) crystals can manipulate the polarization of light and thus are widely applied in modern optical fields. Common birefringent crystals are almost exclusively limited to inorganic oxides with small birefringence. Here, a new 1D hybrid halide perovskite PZPbCl3 (PZ = phenazine) is reported, which consists of perfectly parallel Pb–Cl chains and PZ cations. Remarkably, polarized optical observations show that even a PZPbCl3 crystal with micrometer thickness can modulate the polarized light efficiently. Furthermore, PZPbCl3 exhibits exceptional birefringence up to 0.65@546 nm, which is significantly larger than that of commercial oxide crystals. According to first‐principles calculations and polarizability anisotropy analyses, it is found that this birefringence is mainly ascribed to the linear polymerization of π‐conjugated rings in PZ cations. Due to the rich physical properties and structural diversity of hybrid perovskites, it is believed that the introduction of excellent birefringence into the hybrid perovskites will bring unprecedented opportunities to the future explorations of polarization‐dependent functional materials. [ABSTRACT FROM AUTHOR]

Abstract This study introduces a novel approach in the realm of liquid biopsies, employing a 3D Mueller-matrix (MM) image reconstruction technique to analyze dehydrated blood smear polycrystalline structures. Our research centers on exploiting the unique optical anisotropy properties of blood proteins, which undergo structural alterations at the quaternary and tertiary levels in the early stages of diseases such as cancer. These alterations manifest as distinct patterns in the polycrystalline microstructure of dried blood droplets, offering a minimally invasive yet highly effective method for early disease detection. We utilized a groundbreaking 3D MM mapping technique, integrated with digital holographic reconstruction, to perform a detailed layer-by-layer analysis of partially depolarizing dry blood smears. This method allows us to extract critical optical anisotropy parameters, enabling the differentiation of blood films from healthy individuals and prostate cancer patients. Our technique uniquely combines polarization-holographic and differential MM methodologies to spatially characterize the 3D polycrystalline structures within blood films. A key advancement in our study is the quantitative evaluation of optical anisotropy maps using statistical moments (first to fourth orders) of linear and circular birefringence and dichroism distributions. This analysis provides a comprehensive characterization of the mean, variance, skewness, and kurtosis of these distributions, crucial for identifying significant differences between healthy and cancerous samples. Our findings demonstrate an exceptional accuracy rate of over $$90\%$$ 90 % for the early diagnosis and staging of cancer, surpassing existing screening methods. This high level of precision and the non-invasive nature of our technique mark a significant advancement in the field of liquid biopsies. It holds immense potential for revolutionizing cancer diagnosis, early detection, patient stratification, and monitoring, thereby greatly enhancing patient care and treatment outcomes. In conclusion, our study contributes a pioneering technique to the liquid biopsy domain, aligning with the ongoing quest for non-invasive, reliable, and efficient diagnostic methods. It opens new avenues for cancer diagnosis and monitoring, representing a substantial leap forward in personalized medicine and oncology.

The article discusses stains from water and reagents, as well as false structures that occur on the surface of metal and alloy samples during metallographic sample preparation and etching. The appearance of such artifacts under bright‑field illumination and when using optical contrasting techniques such as dark‑field and polarized light is demonstrated.

Polarization detection plays an essential role in a wide range of fields, including target identification, 3D reconstruction, and robotic vision. Self‐driven on‐chip full‐Stokes photodetectors are urgently required to meet the trend of miniaturization and integration. Nevertheless, how to fulfill efficient circular and linear polarimetry simultaneously with sufficient recognition effectiveness in a compact device is a great challenge. Herein, a patterned chiral perovskite film is fabricated by imprinting strategy, and vertically‐structured self‐driven Stokes photodetector is demonstrated, which can recognize various polarization states at 0 V. Through patterned design of the chiral perovskite film by integrating circle and nanowire structure, flexible tuning of circular and linear polarization components within the detector is achieved, enabling the detector to strike a balance between circular and linear polarization detection ability when recognizing arbitrary polarization light. The maximum circular polarization sensitivity factor and linear polarization ratio can reach 0.125 and 1.5, respectively. By optimizing well‐defined patterned shape, the resultant detector can recognize polarized light with an average recognition error <7%. This work opens an avenue toward the fabrication of self‐driven filterless Stokes detectors based on patterned chiral perovskite film for accurate detection of arbitrary polarization states. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach in the realm of liquid biopsies, employing a 3D Mueller-matrix (MM) image reconstruction technique to analyze dehydrated blood smear polycrystalline structures. Our research centers on exploiting the unique optical anisotropy properties of blood proteins, which undergo structural alterations at the quaternary and tertiary levels in the early stages of diseases such as cancer. These alterations manifest as distinct patterns in the polycrystalline microstructure of dried blood droplets, offering a minimally invasive yet highly effective method for early disease detection. We utilized a groundbreaking 3D MM mapping technique, integrated with digital holographic reconstruction, to perform a detailed layer-by-layer analysis of partially depolarizing dry blood smears. This method allows us to extract critical optical anisotropy parameters, enabling the differentiation of blood films from healthy individuals and prostate cancer patients. Our technique uniquely combines polarization-holographic and differential MM methodologies to spatially characterize the 3D polycrystalline structures within blood films. A key advancement in our study is the quantitative evaluation of optical anisotropy maps using statistical moments (first to fourth orders) of linear and circular birefringence and dichroism distributions. This analysis provides a comprehensive characterization of the mean, variance, skewness, and kurtosis of these distributions, crucial for identifying significant differences between healthy and cancerous samples. Our findings demonstrate an exceptional accuracy rate of over 90 % for the early diagnosis and staging of cancer, surpassing existing screening methods. This high level of precision and the non-invasive nature of our technique mark a significant advancement in the field of liquid biopsies. It holds immense potential for revolutionizing cancer diagnosis, early detection, patient stratification, and monitoring, thereby greatly enhancing patient care and treatment outcomes. In conclusion, our study contributes a pioneering technique to the liquid biopsy domain, aligning with the ongoing quest for non-invasive, reliable, and efficient diagnostic methods. It opens new avenues for cancer diagnosis and monitoring, representing a substantial leap forward in personalized medicine and oncology. [ABSTRACT FROM AUTHOR]

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Laser range-gated underwater imaging technology, by removing most of the backscattering noise, can effectively increase image contrast and extend the detection range. The optical signal captured by a range-gated imaging system primarily comprises reflected light from the object and backscattered light from the surrounding water. Consequently, surfaces with low reflectivity or highly turbid water environments substantially constrain the applicability of the range-gated imaging system. To enhance the detection capability of underwater laser range-gated imaging, this paper proposes the incorporation of underwater polarized light imaging technology as an enhancement method. Based on polarization differences, backscattered light and reflected light from an object can be distinguished. Experimental results indicate that, compared to images obtained using a conventional range-gated laser imaging system, those captured with a polarization-enhanced system exhibit an increase of up to 47% for the corresponding Enhancement Measure Evaluation (EME) index. The proposed approach, which integrates polarization imaging with range-gated laser imaging, has the potential to broaden the applicability of underwater laser imaging scenarios, such as deep-sea exploration and military applications.

Chironomid nonbiting midges are common in many waterbodies, occurring at high densities in sediment and also when flying adults emerge. Although important for food webs and ecosystem processes, the mass emergences of chironomid adults make some species nuisance pests. As part of an effort to develop "push–pull" strategies for managing midge populations, we investigated the importance of visual and chemical cues used by gravid females when selecting sites for oviposition. Field and laboratory oviposition choice tests with Chironomus riparius (Meigen) were used to assess the attractiveness of dark container colors and polarized light for females seeking water for egg laying. Females were not sensitive to increased intensity of polarized light, but they laid fewer eggs in containers with white color above the water's edge but black below the surface. A disruptive pattern of vertical black and white stripes at the water's edge reduced egg laying to a similar degree as white. To investigate the importance of olfactory or gustatory cues in oviposition decisions, we tested 3 potential chemical repellents (damaged larvae simulating predator presence, azadiractin, and picaridin) and 5 potential attractants (a tannin–molasses mixture, leaf detritus, live Hydrilla plants, periphyton, and fermented alfalfa infusions used to bait mosquito oviposition traps). Chemical cues appeared to play a weak role, if any, in oviposition choices. Onlyazadiractin (0.02 and 0.11 ppm) reduced the number of egg ropes deposited, but the mechanism may have been from mechanical trapping and drowning, not deterrence. [ABSTRACT FROM AUTHOR]

In organic solar cells, the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state. Therefore, the ratio of the singlet and triplet excitons directly affects the photocurrent. Many methods were used to optimize the performance of the low-efficiency solar cell by improving the ratio of triplet excitons, which shows a long diffusion length. Here we observed that in high-efficiency systems, the proportion of singlet excitons under linearly polarized light excitation is higher than that of circularly polarized light. Since the singlet charge transfer state has lower binding energy than the triplet state, it makes a significant contribution to the charge carrier generation and enhancement of the photocurrent. Further, the positive magnetic field effect reflects that singlet excitons dissociation plays a major role in the photocurrent, which is opposite to the case of low-efficiency devices where triplet excitons dominate the photocurrent.

Brands and products counterfeiting, and falsification are global problems for the development and distribution of high‐tech industrial and food products, which affect world economies. One way to solve these problems is to develop original packaging with protection elements and labeling against counterfeiting, which excludes the possibility of replication and forgery by printing or other methods. The most reliable way to protect packaging from counterfeiting is the use of new materials with unique optical properties and constantly updated technologies for packaging manufacturing and labeling. This paper proposes a new multi‐level technology for the design, manufacture and hidden labeling of polymer packaging made from several layers of transparent polymer films. The design and marking of the multilayer films are combined with perforation, thermal treatment and heat sealing of the package. The reliability of the proposed markings is based on the characterization of optical pleochroism effects in transparent multilayer polymer materials with shape memory. The thermomechanical and optical properties of films made of bulk thermoplastics (polypropylene, polystyrene, polyvinyl chloride and polyethylene) were characterized in polarized light. The modification and combination of these films provide a high color difference and sufficient contrast of hidden markings, allowing to identify genuine products by bar codes formed from shape memory films in sealing seams of flexible polymer packaging. [ABSTRACT FROM AUTHOR]

Natural scene analysis has been extensively used to understand how the invariant structure of the visual environment may have shaped biological image processing strategies. This paper deals with four crucial, but hitherto largely neglected aspects of natural scenes: (1) the viewpoint of specific animals; (2) the fact that image statistics are not independent of the position within the visual field; (3) the influence of the direction of illumination on luminance, spectral and polarization contrast in a scene; and (4) the biologically relevant information content of natural scenes. To address these issues, I recorded the spatial distribution of light in a tropical mudflat with a spectrographic imager equipped with a polarizing filter in an attempt to describe quantitatively the visual environment of fiddler crabs. The environment viewed by the crabs has a distinct structure. Depending on the position of the sun, the luminance, the spectral composition, and the polarization characteristics of horizontal light distribution are not uniform. This is true for both skylight and for reflections from the mudflat surface. The high-contrast feature of the line of horizon dominates the vertical distribution of light and is a discontinuity in terms of luminance, spectral distribution and of image statistics. On a clear day, skylight intensity increases towards the horizon due to multiple scattering, and its spectral composition increasingly resembles that of sunlight. Sky-substratum contrast is highest at short wavelengths. I discuss the consequences of this extreme example of the topography of vision for extracting biologically relevant information from natural scenes. [ABSTRACT FROM AUTHOR]

The colorization of electrochromic displays (ECDs) has become an intriguing hotspot with fast‐growing demands for the development of displays. Reported colorful inorganic ECDs incorporating optical nanocavity or metal‐dielectric stacks sacrifice transparency and have intrinsic structural color, thus confining plenty of applications as transparent displays. Additionally, most transparent ECDs adopt plane alignments of EC materials that can only show one or several kinds of colors under electrical stimuli. Herein, vertically stacked viologen‐based ECDs integrating cholesteric liquid crystal (CLC) are proposed. By applying voltage, rotation, and changing chiral dopants' concentration, the combined ECDs show enlarged color palette and multi‐mode color modulation. Moreover, red, blue, and green viologen gels are also synthesized by producing dioctyl‐, diethyl‐, and diphenyl‐substituted dipyridyl, which exhibit outstanding performance in terms of high optical variation, fast response speed, long cyclability, etc. Furthermore, the palette area of the CLC layers is dramatically expanded about 5 times more than reported by introducing a birefringent film. The vertically stacked ECDs integrate merits of both CLCs (high color purity and rich hues) and viologens (large variation and low voltage response), which will likely encourage attempts at three‐dimensional colorful EC displays and broaden its applications. [ABSTRACT FROM AUTHOR]

Many insects use patterns of polarized light in the sky to orient and navigate. Here, we functionally characterize neural circuitry in the fruit fly, Drosophila melanogaster, that conveys polarized light signals from the eye to the central complex, a brain region essential for the fly's sense of direction. Neurons tuned to the angle of polarization of ultraviolet light are found throughout the anterior visual pathway, connecting the optic lobes with the central complex via the anterior optic tubercle and bulb, in a homologous organization to the 'sky compass' pathways described in other insects. We detail how a consistent, map-like organization of neural tunings in the peripheral visual system is transformed into a reduced representation suited to flexible processing in the central brain. This study identifies computational motifs of the transformation, enabling mechanistic comparisons of multisensory integration and central processing for navigation in the brains of insects.

Scarring is one of the biggest areas of unmet need in the long-term success of glaucoma filtration surgery. Quantitative evaluation of the scar tissue and the post-operative structure with micron scale resolution facilitates development of anti-fibrosis techniques. However, the distinguishment of conjunctiva, sclera and the scar tissue in the surgical area still relies on pathologists' experience. Since polarized light imaging is sensitive to anisotropic properties of the media, it is ideal for discrimination of scar in the subconjunctival and episcleral area by characterizing small differences between proportion, organization and the orientation of the fibers. In this paper, we defined the conjunctiva, sclera, and the scar tissue as three target tissues after glaucoma filtration surgery and obtained their polarization characteristics from the tissue sections by a Mueller matrix microscope. Discrimination score based on parameters derived from Mueller matrix and machine learning was calculated and tested as a diagnostic index. As a result, the discrimination score of three target tissues showed significant difference between each other (p < 0. 0 0 1). The visualization of the discrimination results showed significant contrast between target tissues. This study proved that Mueller matrix imaging is effective in ocular scar discrimination and paves the way for its application on other forms of ocular fibrosis as a substitute or supplementary for clinical practice. [ABSTRACT FROM AUTHOR]

Membranes are important sites of intermolecular interactions in biological systems. However, they present significant analytical challenges as they contain multiple analytes and are dynamic in nature. In this work, we show how a Jasco J‐1500 circular dichroism spectropolarimeter can be used with a microvolume Couette flow cell and appropriate cut‐off filters to measure excitation fluorescence detected linear dichroism (FDLD) of fluorophores embedded in liposomal membranes. The result is a spectrum that selectively probes the fluorophore(s) and eliminates the scattering that is apparent in the corresponding flow linear dichroism (LD) spectrum. The FDLD spectrum is opposite in sign from the LD spectrum with relative magnitudes modified by the quantum yields of the transitions. FDLD thus enables analyte orientations to be identified in a membrane. Data for a membrane peptide, gramicidin, and two aromatic analytes, anthracene and pyrene, are presented. Issues with the "leakage" of photons by the long pass filters used is also discussed. [ABSTRACT FROM AUTHOR]

It has been established that in order to obtain a high-quality image of a surface structure in polarized light with crossed nicols and to accurately quantify the bainitic fraction in Kh2G2S2MF grade structural steel, alongside with the LePera reagent, Nital reagent can be used. It has been established that the brightness level of martensite in polarized light does not depend on the etching time of 22Kh2G2S2MF and 44Kh2G2S2MF grade steel being at the background level. [ABSTRACT FROM AUTHOR]

In this study, the effect of a magnetic field on a Flint Glass for optical isolator applications has been reported. A flint glass and a laser light source with a wavelength of 650nm were used as a medium and a light source, respectively. The magnetic field was produced by applying a current through a coil. The linearly polarized light was passed through the medium in the presence of a magnetic field, and the angle of rotation was measured. The angle of rotation was plotted versus magnetic field strength and fitted linearly. The experimental results showed that the flint glass becomes optically active in the presence of a magnetic field because it rotates the plane of linearly polarized light, and this rotation increases with respect to the magnetic field linearly. The Verdet constant was calculated 10.46 𝑟𝑎𝑑 𝑇-1𝑚-1 for 650nm, which is a large coefficient for the rotation of the plane of polarized light. [ABSTRACT FROM AUTHOR]

The article considers etch pits that appear in metals and alloys during metallographic etching as an artifact. The optical contrasting tools capabilities, such as dark field, polarized light, and differential interference contrast in detecting etch pits, are demonstrated.

This study is aimed at the design, calibration, and development of a near-infrared (NIR) liquid crystal multifunctional automated optical polarimeter, which is aimed at the study and characterization of the polarimetric properties of polymer optical nanofilms. The characterization of these novel nanophotonic structures has been achieved, in terms of Mueller matrix and Stokes parameter analyses. The nanophotonic structures of this study consisted of (a) a matrix consisting of two different polymer domains, namely polybutadiene (PB) and polystyrene (PS), functionalized with gold nanoparticles; (b) cast and annealed Poly (styrene-b-methyl methacrylate) (PS-PMMA) diblock copolymers; (c) a matrix of a block copolymer (BCP) domain, PS-b-PMMA or Poly (styrene-block-methy methacrylate), functionalized with gold nanoparticles; and (d) different thicknesses of PS-b-P2VP diblock copolymer functionalized with gold nanoparticles. In all cases, backscattered infrared light was studied and related to the polarization figures-of-merit (FOM). The outcome of this study indicates that functionalized polymer nanomaterials, depending upon their structure and composition, exhibit promising optical characteristics, modulating and manipulating the polarimetric properties of light. The fabrication of technologically useful, tunable, conjugated polymer blends with an optimized refractive index, shape, size, spatial orientation, and arrangement would lead to the development of new nanoantennas and metasurfaces. [ABSTRACT FROM AUTHOR]