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In-situ measurement of surface relief induced by Widmanst?tten and bainitic ferrites in low carbon steel by digital holographic microscopy
摘要： In-situ measurement by digital holographic microscopy (DHM) was employed to clarify the difference between the surface relief effects of Widmanst?tten ferrite (WF) and bainitic ferrite (BF) associated with their transformations from austenite in a low-carbon steel. It was clarified that the evolution of the surface relief is totally different between WF and BF. Only in BF, the observed ratio of the relief height to the plate width converged instantly to the value predicted by the phenomenological theory of martensite crystallography (PTMC). The ratio gradually increased with increasing plate thickness and never reached the value predicted by PTMC in WF.
关键词： Digital holographic microscopy,Phase transformations,Surface relief,Phenomenological theory of martensite crystallography
更新于2025-09-23 15:21:21
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Selective Uropathogenic E. coli Detection Using Crossed Surface-Relief Gratings
摘要： Urinary tract infections (UTIs) are one of the major burdens on public healthcare worldwide. One of the primary causes of UTIs is the invasion of the urinary tract by uropathogenic Escherichia coli (UPEC). Improper treatment of bacterial infections like UTIs with broad-spectrum antibiotics has contributed to the rise of antimicrobial resistance, necessitating the development of an inexpensive, rapid and accurate detection of UPEC. Here, we present real-time, selective and label-free detection of UPEC using crossed surface-relief gratings (CSRGs) as nanometallic sensors incorporated into an optical sensing platform. CSRGs enable real-time sensing due to their unique surface plasmon resonance (SPR)-based light energy exchange, resulting in detection of a very-narrow-bandwidth SPR signal after the elimination of residual incident light. The platform’s sensing ability is experimentally demonstrated by the detection of bulk refractive index (RI) changes, with a bulk sensitivity of 382.2 nm/RIU and a resolution in the order of 10?6 RIU. We also demonstrate, for the ?rst time, CSRG-based real-time selective capture and detection of UPEC in phosphate-buffered saline (PBS) solution, in clinically relevant concentrations, as opposed to other UTI-causing Gram-negative bacteria. The platform’s detection limit is calculated to be 105 CFU/mL (concentration on par with the clinical threshold for UTI diagnosis), with a dynamic range spanning four orders of magnitude. This work paves the way for the development of inexpensive point-of-care diagnosis devices focusing on effective treatment of UTIs, which are a burden on public healthcare due to the rise in the number of cases and their recurrences in the recent past.
关键词： crossed surface-relief gratings,nanoplasmonics,surface plasmon resonance,urinary tract infection,biosensing,uropathogenic E. coli,surface-relief gratings
更新于2025-09-23 15:21:01
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Photoconstruction of a Microrelief in a Photochromic Crystalline Spirooxazine Film
摘要： In its crystalline form, spirooxazine does not usually exhibit photochromism. However, a crystalline spherulite spirooxazine film has been found to exhibit coloration upon irradiation with a continuous ultraviolet (UV) light and decoloration under the dark condition at room temperature, thereby indicating the occurrence of photochromism. The replicable microreliefs was construction of different successfully achieved by alternately irradiating with patterned UV light and heating the film to its melting point.
关键词： Spirooxazine,Surface relief,Spherulite
更新于2025-09-23 15:21:01
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Rapid label-free detection of intact pathogenic bacteria <i>in situ via</i> surface plasmon resonance imaging enabled by crossed surface relief gratings
摘要： The unique plasmonic energy exchange occurring within metallic crossed surface relief gratings (CSRGs) has recently motivated their use as biosensors. However, CSRG-based biosensing has been limited to spectroscopic techniques, failing to harness their potential for integration with ubiquitous portable electronics. Here, we introduce biosensing via surface plasmon resonance imaging (SPRi) enabled by CSRGs. The SPRi platform is fully integrated including optics and electronics, has bulk sensitivity of 613 Pixel Intensity Unit (PIU)/Refractive Index Unit (RIU), a resolution of 10?6 RIU and a signal-to-noise ratio of ～33 dB. Finite-Difference Time-Domain (FDTD) simulations confirm that CSRG-enabled SPRi is supported by an electric field intensity enhancement of ～30 times, due to plasmon resonance at the metal-dielectric interface. In the context of real-world biosensing applications, we demonstrate the rapid (<35 min) and label-free detection of uropathogenic E. coli (UPEC) in PBS and human urine samples for concentrations ranging from 103 to 109 CFU mL?1. The detection limit of the platform is ～100 CFU mL?1, three orders of magnitude lower than the clinical detection limit for diagnosis of urinary tract infection. This work presents a new avenue for CSRGs as SPRi-based biosensing platforms and their great potential for integration with portable electronics for applications requiring in situ detection.
关键词： crossed surface relief gratings,portable electronics,biosensing,pathogenic bacteria detection,surface plasmon resonance imaging
更新于2025-09-23 15:19:57
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Enhancement of the Power Conversion Efficiency of Organic Solar Cells by Surface Patterning of Azobenzene Thin Films
摘要： Nanoscale-patterned azobenzene thin films were incorporated in organic solar cells to scatter incident light, thus increasing the optical path length of photons inside the active area. This ultimately led to significant power conversion efficiency (PCE) enhancements in the active layer. Specifically, the azobenzene thin films were patterned with two-dimensional crossed surface relief gratings inscribed via laser interference lithography. The patterned films were then bleached and thermally stabilized by exposure to strong ultraviolet light before being incorporated in P3HT:PC61BM and PTB7:PC61BM solar cells. The fabricated solar cells exhibited a PCE enhancement of 133%, from 1.37 to 3.19%, for P3HT:PC61BM solar cells, and a PCE enhancement of 302%, from 0.53 to 2.13%, for PTB7:PC61BM solar cells.
关键词： azobenzene thin films,laser interference lithography,organic solar cells,power conversion efficiency,surface relief gratings
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Retrievieng the Surface Relief of the Smooth Objects by the Digital Holography
摘要： A new method for the surface relief study using digital holography is presented. This method includes an approach for digital refocusing and elimination of optical aberrations. Experimental study of the standard roughness sample allowed estimation of the error of the proposed method. The practical application for solving real tasks of materials science is shown.
关键词： aberration elimination,Digital holography,surface relief,digital refocusing,nondestructive testing
更新于2025-09-12 10:27:22
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Reversible Polarization Recording in As2S3–Se Multilayer Nanostructures
摘要： Polarization holographic recording of diffraction gratings and their subsequent erasure have been investigated on As2S3–Se multilayer nanostructures. The work investigates how preexposure to actinic laser radiation up to complete photoinduced changes in the optical properties affects the formation of diffraction gratings in the studied structure. It is shown that the preexposure of an As2S3–Se multilayer nanostructure (MNS) leads to photobleaching, and the maximum achievable diffraction efficiency (DE) of 35% does not change; however, the required exposure value is increased. It is also shown that exposure using one laser beam results in complete erasure of the diffraction grating recorded up to the maximum. Seven recording–erasure cycles show that the kinetics of the increase in diffraction efficiency and its maximum value do not change, which indicates that the As2S3–Se multilayer structure is capable of reversible holographic recording under orthogonal circular polarization. Study of the gratings recorded with an atomic-force microscope shows that the main factor determining the diffraction efficiency value is modulation of the relief, the depth of which is greater than 200 nm.
关键词： reversible holographic recording,chalcogenide multilayer nanostructures,diffraction efficiency,direct surface relief formation
更新于2025-09-10 09:29:36
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41.5: Head-mounted Display Based on Surface Relief Grating for Augmented Reality
摘要： A see-through head-mounted display (HMD) is demonstrated in the paper, which can present the user with information such as virtual symbols or images superimposed over real-world image. To meet the human eyes’ visual requirements under different situations, a large exit pupil of 2 to 5 times of the pupil size (about 2.4 mm) is required. To solve the problem, the HMD presented in the paper is a combination of micro-display of LCoS, imaging eyepiece and an exit pupil expander based on planar waveguide with slanted surface relief grating. Both transmission and reflection gratings are applied in the HMD design. Two system schemes are presented which expand the light only along one direction and two orthogonal directions, respectively. The system configuration and principle of operation are described in the paper.
关键词： exit pupil expander,augmented reality,surface relief grating,head-mounted display
更新于2025-09-10 09:29:36
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Surface relief gratings in azo-polymers revisited
摘要： We use the concept of vectorial photochemical tweezing to rationalize the experimental observations of surface relief gratings in azo-polymers, e.g., the photochemically induced motion of the polymer in a one-dimensional intensity gradient produced by two-laser beam interference. Vectorial motion of matter occurs when photochemically active, polarization sensitive molecules are photo-selected in a gradient of light intensity. Directional motion is imposed parallel to the gradient vector with an efficiency that depends on the respective orientations of the vectors of light polarization and intensity gradient. Different combinations of polarizations of the interfering beams leading to differing efficiencies of matter motion are revisited and discussed. We show that the magnitude of photoisomerization force dictates the efficiency of the observed matter motion. We also show that the spatial distribution of the photo-moved matter is Gaussian, the height and width of which exhibit an intensity dependence which is predicted by the theory of photochemical vectorial tweezing; both theory and experiments indicate that the photoisomerization force, which acts on thin films of azo-polymers, is in the mN range.
关键词： photoisomerization force,vectorial motion,photochemical tweezing,azo-polymers,surface relief gratings
更新于2025-09-09 09:28:46