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- 实验方案
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Fabrication of frequency selective metamaterial structure using low-cost laser writer
摘要： Tailoring the metamaterial structure using Laser writer lithography system offers a feasible way to accomplish the fine cross grating structures. The main focus of this work is to fabricate a metamaterial for absorption in the far infrared (far-IR) spectrum. Fabrication was carried out using homemade laser writer working at 405 nm in S1813 photoresist coated upon chromium on glass followed by its etching in the exposed regions. A 40 ? 40 array of unit cells with dimension in the order of 28 μm ? 1 μm were achieved. The structural characterization was carried out using scanning electron microscope (SEM) and Optical Microscope. We could observe clear absorption in the far-IR region. The results here would be favorable for the development of devices based on artificial material whose properties are not readily accessible in nature (metamaterials).
关键词： Optical microscope,FTIR,Laser writer,Metamaterial,SEM
更新于2025-09-23 15:19:57
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A Preamplifier for a CdHgTe Photodetector
摘要： A preamplifier for operation with an HgCdTe-based nitrogen-cooled IR photodetector (600 nm–15 μ m) is described. The preamplifier operates in the photoconductivity mode. The use of modern microcircuits made it possible to increase the bandwidth of the response to 2 MHz at a noise level of 0.5 nV/Hz1/2, which is close to the fundamental limit that is specified by the resistance of the photosensitive element. The preamplifier was used in an aperture-free scanning near-field optical microscope.
关键词： HgCdTe,IR photodetector,scanning near-field optical microscope,photoconductivity,preamplifier
更新于2025-09-23 15:19:57
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Active control of chiral optical near fields on a single metal nanorod
摘要： Chiral optical fields (typified by circularly polarized light) localized on the nanoscale enhance the chiral light-matter interaction, which may provide novel potential applications. This property enables the development of an ultrasensitive method for characterization of chiral molecules and nanoscale magnetic control realized by an all-optical method to interconnect spintronic nano-optical devices. A local chiral light source with switchable handedness or controllable chirality is indispensable for building such applications for practical use. In the current major method used for local chiral light generation, the handedness of the light is controlled by the handedness of the nanomaterial, which is not convenient when we need to change the handedness of the light. We experimentally achieve here generation and active control of a highly chiral local optical field by using a combination of an achiral gold nanorod and achiral linearly polarized optical field. By tilting the azimuth angle for the incident linear polarization relative to the axis of the nanorod, either left- or right-handed circularly polarized local optical fields can be generated. Our work may give us a chance to pioneer analytical applications of chiral optical fields and novel spintronic nano-optical devices.
关键词： near-field optics,chiral plasmonics,scanning near-field optical microscope,nanomaterial,polarimetry
更新于2025-09-19 17:15:36
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Unrevealing Charge Carrier Selective Layer in Silicon Heterojunction Solar Cells via Multifunctional Atomic Force Probes
摘要： The current silicon solar cell with a record efficiency is based on heterojunction contacts that offer carrier selectivity as well as surface passivation simultaneously. One remaining challenge with heterocontacts is the balance between carrier extraction and surface passivation. Here, it is demonstrated that the heterojunction of n-type silicon (N–Si) with the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) removes this trade-off, utilizing the strong depletion of PEDOT:PSS to realize the excellent carrier selectivity. The near-field optical contrast and surface potential distributions of the PEDOT:PSS/N–Si heterojunction via multifunctional atomic force probes are mapped for the first time. Interestingly, a low dielectric value region is observed in N–Si by using scattering-type scanning near-field optical microscopy on the junction cross-section. A special PEDOT:PSS slope is further fabricated to characterize the dielectric value and surface potential in the PEDOT:PSS side. By combining s-SNOM and scanning Kelvin probe microscopy, a special region in PEDOT:PSS is observed with a sharp surface potential drop and low dielectric value. The results suggest the existence of space charge regions both in N–Si and PEDOT:PSS at the interface. These findings contribute the understanding of the physical properties of the silicon heterojunction and promise potential routes to enhance device efficiency.
关键词： poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate)/n-type silicon interface,scanning Kelvin probe microscopy,carrier redistribution,infrared scattering-type scanning near-field optical microscope
更新于2025-09-11 14:15:04
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Optimal methods to fix fish sperm for optical microscopic observation: comparisons among different fixative solutions using sperms of copulatory and non-copulatory marine fishes
摘要： Sperm fixation in better conditions is a requisite for the examination of sperm morphology using optical microscopes. Here, we investigated the effects of different fixatives on sperm morphological characteristics in four marine fishes: copulatory sculpins Pseudoblennius marmoratus and Radulinopsis taranetzi, and non-copulatory sculpin Icelus mororanis and dragonet Repomucenus beniteguri. We found that a 2.5% glutaraldehyde solution is optimal for observing sperm morphology in these fishes. Furthermore, the low concentrations (2.5%) of formalin could be useful, but the solvent for diluting formalin should be changed depending on the species: seawater in copulatory and non-copulatory sculpins and isotonic solution in the non-copulatory dragonet.
关键词： Sperm morphology,Fixative,Optical microscope,Copulation,Fish
更新于2025-09-10 09:29:36
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[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || A Facile Synthesis of Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) by Electrochemical Exfoliation of Battery Electrode
摘要： Graphene is a two-dimensional allotrope of carbon, in which carbon atoms are arranged in a hexagonal structure. All carbon atoms in graphene are sp2 hybridized due to which three atoms are bonded to neighboring atoms and one electron is unbounded. Here, we have demonstrated a facile and low-cost technique to synthesize the graphene oxide and reduced graphene oxide from readily available battery graphite by means of an electrochemical method using liquid electrolyte. The graphite in the battery electrode has been expanded using acid for effective exfoliation. This is used to increase the interlayer spacing of graphite causes the van der Waals forces to cease. Graphene oxide and reduced graphene oxide (reduction using ascorbic acid) have been synthesized using this technique. The optical microscope image has shown few layer ?akes and X-ray powder diffraction (XRD) demonstrated the reduction of oxygen content. The proposed setup is cheap and environmentally benign in nature.
关键词： Graphene oxide,Optical microscope,Electrochemical technique,Reduced graphene oxide,XRD
更新于2025-09-09 09:28:46
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Implementing a Stereo Image Correction Method for 3D Surgery Microscopes
摘要： Recently 3D scenes are used in various industrial fields such as medical applications, computer games, surface examinations, biology and others. 3D optical microscopes can show extremely precise details in 3D. To reconstruct the 3D images of an optical microscope, two cameras are mounted on the optical microscope. Incoming images through an object lens of an optical microscope are projected on sensors of mounted cameras by using refraction mirrors. Two cameras capture the left and right images to reconstruct the final 3D images. In this paper, we correct the 3D reconstruction errors with the SURF algorithm. We also design a hardware system to correct wrong mirror positions using servo motors. In addition, we propose the surgical system with HMD and wireless communications. This system would be helpful for doctors due to make doctors comfortable and it can be used to educate surgery procedures.
关键词： Stereo Image,Optical Microscope,SURF,Medical Device,Computer Vision
更新于2025-09-09 09:28:46
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Inverse photonic design of functional elements that focus Bloch surface waves
摘要： Bloch surface waves (BSWs) are sustained at the interface of a suitably designed one-dimensional (1D) dielectric photonic crystal and an ambient material. The elements that control the propagation of BSWs are defined by a spatially structured device layer on top of the 1D photonic crystal that locally changes the effective index of the BSW. An example of such an element is a focusing device that squeezes an incident BSW into a tiny space. However, the ability to focus BSWs is limited since the index contrast achievable with the device layer is usually only on the order of Δn≈0.1 for practical reasons. Conventional elements, e.g., discs or triangles, which rely on a photonic nanojet to focus BSWs, operate insufficiently at such a low index contrast. To solve this problem, we utilize an inverse photonic design strategy to attain functional elements that focus BSWs efficiently into spatial domains slightly smaller than half the wavelength. Selected examples of such functional elements are fabricated. Their ability to focus BSWs is experimentally verified by measuring the field distributions with a scanning near-field optical microscope. Our focusing elements are promising ingredients for a future generation of integrated photonic devices that rely on BSWs, e.g., to carry information, or lab-on-chip devices for specific sensing applications.
关键词： focusing elements,scanning near-field optical microscope,integrated photonic devices,Bloch surface waves,photonic design
更新于2025-09-04 15:30:14