Mirror Research Articles

Effect of Operation Time on the Performance and Accuracy of the Condor Reflectometer

This paper evaluates the potential effect that operation lifetime could have on the accuracy and reproducibility of the Condor reflectometer. For this purpose, three Condors with different operation lifetimes have been used and compared in this study. In addition to the device’s operation lifetimes, reproducibility and the repeatability of the measurements have also been evaluated. Silvered glass mirrors at different states have been used, e.g., clean, soiled and eroded in order to evaluate the effect of the surface properties on the difference reported using different devices. The obtained results have shown that the difference in specular reflectance reported by the three different Condors is more noticeable in case of soiled and eroded glass mirrors compared to clean sample. This could be linked to the surface roughness more than to the years of operation of the device itself.

A comparative study on the optical performance of retro-reflective coatings before and after the aging process

Retro-reflective (RR) materials are largely included among the strategies to mitigate Urban Heat Island (UHI) phenomenon in the urban spaces thanks to their optical directional properties. As materials potentially used in the building exterior envelope, RR materials are subjected to outdoor aging and soiling processes, which could alter their optical behaviour. In this perspective, the investigation focuses on the characterization of the optical performance of several types of RR plaster coatings after outdoor aging and soiling processes. The RR plaster coatings were previously developed and studied, before undergoing the outdoor exposure. The RR samples were developed covering the support with a reflective white paint and glass beads. Five different microsphere diameter ranges and three different microsphere superficial density ranges have been employed. In this paper, the RR plaster coatings were tested in terms of optical properties after outdoor aging and soiling and results were compared with data of the same plaster coatings pre-aging. Generally, all RR aged samples show a lower solar reflectance in the Vis region with respect to the pre-aging conditions. The RR behaviour is qualitatively maintained after aging and soiling. The RR sample made of glass beads of 200–300 μm diameter range could represent the best solution both in pre- and post-conditions and both in terms of solar reflectance and retro-reflective behaviour, regardless of the density of microspheres used.

Structural Analysis Technique and Its Validation for Large Range Mirror Refocusing System for Spaceborne Deployable Telescopes

Large aperture deployable telescopes with numerous onboard instruments are popular in the space industry for astronomy. Scientific data in various wavelength bands, from 0.6µ to 28µ, is provided by these instruments and is crucial for deep space exploration. The deployment mechanisms handle the alignment and functionality at the telescope level only. At instrument level, there is always a need for a refocusing system which can cater individual need of instrument for focusing independent to other instruments nearby. In this paper, we present a structural analysis technique for such a type of large range mirror refocusing mechanism, similar to the Near Infrared Spectrograph (NIRSpec) payload of the James Webb Space Telescope (JWST). The method relies on geometric non-linearity for large deflection, in which the structure's stiffness matrix changes as a function of loading. We have designed, analyzed structurally, and tested a 4mm range slider crank based compliant mechanism. The outcomes of linear and non-linear static analysis, computed numerically, have been compared. There are noticeable significant variations in one direction between the two analyses' results. The results are validated using appropriately designed and realized test setups, like measurements of displacement, changes in focus and image position of the optical system.

Strongly localized nanolaser based on the vertical dipole governed by bound states in the continuum

Ultrasmall mode volumes and strongly localized fields are crucial for the miniaturization and performance enhancement of nanolasers. Here, we demonstrate a nanolaser based on a vertical dipole resonance coupled to its mirror in a periodic array of nanopillars on an Ag mirror, governed by symmetry-protected bound states in the continuum (BICs), which possess extremely small mode volumes and high field enhancement. A nanolaser with a strongly localized field size of only ∼λ/300 (where λ is the resonant wavelength) can be explored by using this vertical dipole. Compared to a vertical dipole nanolaser without a silver mirror, the effective mode volume can be reduced by an order of magnitude, and the threshold can decrease from 5.85 to 0.337 μJ/mm2. Additionally, by controlling further investigated the angle of the incident light, we can also adjust the threshold of the nanolaser. When the incidence angle is adjusted from 9° to 1°, the threshold can be reduced from 1.43 to 0.299 μJ/mm2.

모방 유사도를 통해 살펴본 한·일 방제경의 성격 — 원삼국(야요이 후기~고훈 개시기)시대 자료를 중심으로

The purpose of this paper is to undertake a classification of the imitation bronze mirrors of the the Korean Peninsula and the Japanese Archipelago of the Proto-Three Kingdoms period (Yayoi-Kofun period) according to the degree of difference between them and the original bronze mirrors, and to consider the distinctive nature of the different types of imitation bronze mirrors. However, the term ‘imitation bronze mirror’ does not fully en-compass the diversity of these mirrors; in addition, it contains the meaning of ‘not’ being an original bronze mirror or ‘not’ being a bronze mirror bestowed upon local communities, and is seen to suggest a specific production location. Regarding this aspect, a preliminary review of the character of the bronze mirrors and the degree of imitation that reflects the intention of the subject who used it is necessary in order to fully understand the meaning of such mirrors that were created through acts of imitation. First, the practices of production associated with cases of imitation confirmed in the Korean Peninsula and the Japanese Archipelago during the period when imitation bronze mirrors were popular were identified, and based on similarities and dissimilarities of prac-tice, three types of imitation were established. Applying this to the actual artifacts, imitation bronze mirrors were broadly classified into three types (five in detail). Attempts were made to interpret the derived types by looking at their period of existence, as well as focusing on the period from the turn of the millennium to the late Proto-Three Kingdoms period when imitation bronze mirrors were most diverse in both regions. It was assumed that, when imitating the targeted original mirror, the value or character of the imitation mirror would be associated with the degree of similarity with the object of imitation. Since imitation bronze mirrors appeared for different purposes depending on the social background in the Korean Peninsula and the Japanese Archipelago, differences could be observed in terms of the degree of finishing and technique depending on the region. Accordingly, the higher the degree of imitation of he imitation of targeted mirror, the more similar their uses or characteristics appear. Conversely, as the characteristics change, they come to have various meanings depending on the needs of the local society.

Development and Evaluation of Insulation Materials for Deepwater Cementing.

Marine oil and gas resources are abundant in deepwater regions, where the shallow seabed harbors natural gas hydrate layers due to the cold temperature and high-pressure environment. Hydrates are prone to thermal decomposition, which can compromise the integrity of cement sealing and even lead to accidents like blowouts. While current low-hydrated heat cement systems mitigate hydrate decomposition from cement hydration heat during the waiting period for cementing, they do not address heat transfer from deep strata to shallow hydrate layers through fluid circulation in the tubing during deep oil and gas development. Rather than utilizing costly pipe insulation technology, adjusting the thermal conductivity of well cement emerges as a cost-effective approach to prevent heat loss in the wellbore to the hydrate layer and thus inhibit hydrate decomposition. The critical aspect lies in utilizing insulation functional materials. This study delves into the functional and structural design of insulation materials suitable for cement slurry systems in well cementing, outlining the preparation methods and processes for two insulation materials (SDBW and SDBW-II) tailored for deepwater well cementing. SDBW and SDBW-II are both nuclear shell structural materials. The core is made of high-strength hollow microspheres, produced by using a reverse suspension polymerization method to form spheres followed by high-temperature sintering. The shell consists of a wear-resistant BPA epoxy resin layer, with the surface of SDBW-II also containing highly reflective glass microspheres. Incorporating 20% of material SDBW into the cement reduces the thermal conductivity of the cement stone from 0.8 to 0.31 W·(m·K)-1 while achieving a compressive strength of 6 MPa after 24 h at 20 °C. Material SDBW-II offers both thermal resistance and reflection functions, increasing reflectivity (R) from 0.3 to 0.5. By adding 20% of this material to the cement, under the same conditions, although the compressive strength decreases to 4.2 MPa, the thermal conductivity can be reduced to 0.27 W·(m·K)-1. Furthermore, there is no significant change within 180 days, demonstrating long-term thermal insulation stability. These developed insulation materials can effectively improve the thermal insulation performance of the cement sheath, thereby maintaining the stability of the upper natural gas hydrate layer in the oil and gas production process of deepwater wells, providing an innovative solution for the long-term operation of deepwater oil and gas wells.

Arc-shaped air layer bioinspired by ginkgo nut to resist high humidity environment for PET fabrics

Developing simple processes and significant effect modification method for polyester (PET) fabrics to resist hygrothermal aging is a formidable challenge. In this study, inspired by the silver mirror phenomenon of natural ginkgo nut, we utilized the pea pod-shaped nanoparticles that zinc oxide (ZnO) was encapsulated in polyhedral oligomeric silsesquioxane (ZnO@POSS), and polydimethylsiloxane (PDMS) to construct stabilized arc-shaped air layer on the PET fabric surface to resist high humidity environment. The round belly structures of pea pod-shaped ZnO@POSS and interlaced physical networks assisted by PDMS on the PET fabrics surface served as the crucial roles to capture and retain air, resulting in the capacity of the arc-shaped air layer was significantly larger than other microstructures underwater. The water vapor was prevented from entering the fabric interstices that the self-catalytic hydrolysis behavior of PET macromolecular chains was efficiently restrained, and the strength retention of PET fabric was significantly improved from 45 % to 89 % after accelerated hygrothermal aging test (60 °C, 80 % RH, 600 h). This work represents a simple and effective approach to improve the durability for PET fabrics in high humidity environments.

REFRACTION OF E.T.A. HOFFMANN’S ROMANTIC TRADITIONS IN THE SHORT STORY “THE SILVER MIRROR” BY ARTHUR CONAN DOYLE

The article examines the influence of the German writer E.T.A. Hoffman on English neo-Romanticism using the example of the short story “The Silver Mirror” by Arthur Conan Doyle. The question of topicality of the question of the continuity of the German romantic tradition in English neo-Romanticism is raised. The features of Hoffman’s poetics in Doyle’s short story are considered in the form of an ideological and thematic complex inherent in Hoffman’s work (‟Hoffman complex”), which manifests itself in understanding the following problems: the two worlds (the real world – the unreal world), the mechanisation of man and society (realised in the romantic opposition of the inanimate (pragmatic worldview) – living (romantic worldview)), duality (represented by a ‟mirror complex” (mirror, eyes)) and psychologism (analysis of the mental state that occurs at a time of strong emotional stress (‟reasonable” insanity)). In conclusion, the article concludes that Hoffman’s tradition is refracted in Doyle’s work: instead of a hero with a romantic worldview in the core of the neo– romantic text, the hero is a pragmatist who is devoid of creative vision and is able to see a new world only in a state of ‟reasonable” madness.

SU-8-meta-phenylenediamine-conjugated thin film for temperature sensing.

Polymers have distinctive optical properties and facile fabrication methods that have been well-established. Therefore, they have immense potential for nanophotonic devices. Here, we demonstrate the temperature-sensing potential of SU8-meta-phenylenediamine (SU8-mPD), produced by epoxy amination of the SU-8 polymer. Its properties were examined through a series of molecular structural techniques and optical methods. Thin layers have demonstrated optical emission and absorption in the visible range around 420 and 520 nm, respectively, alongside a strong thermal responsivity, characterized by the 18 ppm °C-1 expansion coefficient. A photonic chip, comprising a thin 5-10 μm SU8-mPD layer, encased between parallel silver and/or gold thin film mirrors, has been fabricated. When pumped by an external light source, this assembly generates a pronounced fluorescent signal that is superimposed with the Fabry-Pérot (FP) resonant response. The chip undergoes mechanical deformation in response to temperature changes, thereby shifting the FP resonance and encoding temperature information into the fluorescence output spectrum. The time response of the device was estimated to be below 1 s for heating and a few seconds for cooling, opening a new avenue for optical sensing using SU8-based polymers. Thermoresponsive resonant structures, encompassing strong tunable fluorescent properties, can further enrich the functionalities of nanophotonic polymer-based platforms. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'.

Terahertz Meta-Mirror with Scalable Reflective Passband by Decoupling of Cascaded Metasurfaces

Electromagnetic metasurfaces have been playing exotic roles in the construction of ultracompact and versatile metadevices for wave–matter interactions. So far, multiple metasurfaces cascaded with intercouplings have been intensively investigated for extraordinary wavefront control and broadband spectral regulations. However, most cases face high structural complexity and little attention is paid to cascaded metasurfaces without interlayer couplings. In this paper, we demonstrate one type of terahertz Bragg mirror with ideally high reflectivity and ultra-broad bandwidth by simply resorting to decoupled metasurfaces. Cascaded metasurfaces with decoupled mode control prove practically straightforward for analytical design and easy to fabricate for engineering purpose in our scheme. Essentially, by flexibly tuning the decoupled metasurface mode, the middle Fabry–Perot mode that behaves like a defect mode inside the reflective passband can be eliminated for substantial band expanding. Fundamental analyses and rigorous calculations are performed to confirm the feasibility of our metasurface-based THz Bragg mirror with scalable bandgap. In comparison, our meta-mirror provides superior spectral performance of a larger bandgap and higher in-band reflectivity over that composed by ten layers of alternate dielectrics (Rogers 3003 and 3005). Finally, our analytical methodology and numerical results provide a promising way for the rapid design and fabrication of a Bragg mirror in the optical regime.

Macro and Nano Experimental Facts Verifying the Colloidal Process in Silver Mirror Reaction

Macro and Nano Experimental Facts Verifying the Colloidal Process in Silver Mirror Reaction

Improved axial confinement in the open trap by the combination of helical and short mirrors

The paper presents experimental results from the SMOLA device, which was built in the Budker Institute of Nuclear Physics for the verification of the helical mirror confinement idea. This concept involves active control of axial losses from the confinement zone in an open magnetic trap through the use of multiple mirrors that move in the plasma frame of reference. The discussed experiments focused on determining the cumulative effect of a helical mirror system in combination with a short segment of a stronger magnetic field. Combination of these two methods of axial flow suppression results in higher efficiency compared with each method individually. Different combinations of the mirrors were tested. The most effective flow suppression was observed if the short mirror was placed between the confinement region and the helical mirror. In this configuration, an effective mirror ratio of $R_{{\rm eff}} = 32.6\pm 7.8$ was achieved, along with a more than three-fold increase in plasma density within the confinement region. The possibility of a cumulative effect of different types of magnetic mirrors offers a way to improve the confinement performance of the reactor-grade mirror confinement devices.

Silver Mirror Reaction at School Chemistry Workshop

Silver Mirror Reaction at School Chemistry Workshop

Honeycomb network structure constructed by silver nanoparticles achieving negative permittivity at low percolation threshold

Continuous conductive network is associated with the percolation effect, yet the method of fabricating network structure at low content is still a challenge. Herein, this work proposed a “honeycomb” structure via hot pressing to realize weak negative permittivity at low percolation threshold. By polydopamine (PDA) self-polymerization and silver mirror reaction plating, Ag nanoparticles coated polystyrene (PS) microsphere (PS@PDA@Ag) was prepared. Through hot pressing, the microspheres were compressed into “honeycomb”. The percolation threshold was reduced because the thin silver layer oscillated at low frequency plasma. Besides, by controlling the slivering time, weak negative permittivity in the range of −139 to −95 was observed and the percolation threshold was merely 2.23 vol%. The ac conductivity increased by four orders of magnitude and the thermal conductivity enhanced 79.08 %. The electric field and power loss density were simulated by finite element method. More than 100 V/m of electric field mode and 3 × 1011 W/m3 of power loss density were presented, explaining the generation of negative permittivity and the enhancement of dielectric loss. This work presented a method of achieving weak negative dielectric via honeycomb structure, and provided a novel perspective for the development of metal-based metacomposites.

Comparative Assessment of the Durability of Glass and Polymer Mirrors for Concentrated Solar Thermal Technologies

This paper describes experimental work that has been carried out to assess the durability of glass and polymer mirrors against erosion and soiling phenomena. Both outdoor and indoor tests have been performed and the results show that polymer mirrors are quickly degraded in comparison to glass. Soiling deposition has been simulated using a soiling test rig developed for laboratory use. Results show that polymer mirrors, due to their high roughness and their surface energy properties, can accumulate more soiling on their surface generating a higher drop in specular reflectance compared to glass mirrors. Contact cleaning processes have also been simulated on polymer mirrors and the results show that using a hard brush, even at low speed with rotational motion, causes significantly more degradation than a soft brush.

Performance of a Prototype Heliostat Having a Twisting Mechanism to Maintain Focus Throughout the Day

A prototype heliostat has been designed and built with a rectangular reflector whose shape is altered automatically through the day, to maximize concentration at the receiver. The shape changes needed to form solar disc images, which give the highest possible concentration, can be realized by twisting the reflector from its corners, provided that a target-oriented, dual-axis mount is used. Then a cam mechanism connected to the second (cross) axis drive, turning with the angle of incident sunlight, may be used to twist the reflector as needed. Our prototype reflector comprises a single glass mirror, 2.4 m x 3.3 m, attached to a steel frame. Four diagonal back struts extend from the central mechanism out to the rectangular frame corners. The glass mirror of the prototype is attached to the steel frame by 58 screw actuators. Before twisting the frame, the glass shape is adjusted to the biconic shape needed to form a 1 m diameter disc image on a 113 m distant target when sunlight is incident at 60°. To form disc images over the full range of angles of incidence from 0° (normal incidence) to 70°, the struts push the corners up and down by up to 17 mm. A reflectometry metrology system has been used to set the 58 adjustment screws for the initial shape to an accuracy of ≤ 0.6 mrad, and to measure the accuracy of the different twisted shapes. The prototype will be tested at NSTTF early next year.

Delayed-focus micro-angle measurement optical system based on structural segregation

In this paper, we propose a delayed-focusing type micro-angle measurement optical system based on the Cassegrain structure (cassette structure), analyze the basic cassette structure and the Galilean laser beam expanding system, and determine the primary and secondary mirror structure as a reflective focusless system as a determining module. This focusless system emits and receives parallel light, and the light source and detector separated by the beam splitter are designed as replaceable modules. Additionally, the imaging quality of the system can be optimized, or the effect of meeting different imaging requirements can be achieved, by changing the number and type of corrective mirrors and the parameters of the specific glass elements in the replaceable modules. After the final optimization, the radius of the imaging spot of the combined mirror group can be limited to 6.1 µm; the modulation transfer function is better than 0.6 at 100 lp/mm; the difference between the meridian and the arc-vector curves is less than 0.1; and the theoretical angular accuracy reaches 0.2″. The delayed-focusing system structure is analyzed under different temperature fields to provide guidance for the design of the subsequent structure temperature control. Comparison and analysis with commonly used angle measurement optical systems are also made. It is concluded that the structure meets the requirements for use in the on-orbit environment, completes the reuse of the established structural modules, and further saves the manufacturing cost, which provides a feasible solution to the problem of monitoring the small angular changes in the field of space.

Cermin Diri dan Cermin Kristen: Dalam Membantu Seseorang Mengenali Diri Sendiri dan Mengembangkan Hubungan dengan Tuhan

The purpose of this research is to explore the role of self-mirrors and Christian mirrors in helping someone recognize themselves and develop a relationship with God. This research is qualitative research with data search techniques through secondary sources, namely through the latest journals as part of the latest research. The important findings of this research indicate that both types of mirrors can be an effective means of strengthening self-awareness and deepening one's spiritual connection with God, providing deeper insight into one's identity and strengthening spiritual beliefs. This research makes an important contribution to the understanding of how self-mirrors and Christian mirrors can be used as tools for self-development and spirituality.

Laboratory Demonstration of Grating Embedded Mirrors for Single-Shot Heliostat Optical Metrology

Abstract Concentrated solar power (CSP) plants need to monitor the surface slope error of thousands of heliostats with sub-milliradian accuracy. Large numbers of heliostats installed in harsh environments mean that measurement speed and durability are key design considerations for metrology systems. We present a compact, accurate, and high-speed heliostat slope error metrology system that is robust to the harsh environmental conditions at CSP plants. The system is composed of (1) grating embedded mirrors (GEMs), which have multiple different phase diffraction gratings written within a glass mirror substrate, and (2) a compact optical system, the diffractive auto-stigmatic Hartmann camera (DASHCam). Using focused ultrafast laser pulses, we write phase gratings within second-surface float glass mirror without damaging the reflective coating on the backside. The gratings direct a small fraction of incident light to non-specular directions, which the DASHCam senses from a virtual center of curvature to measure the mirror slopes at each grating patch. In a CSP plant, each heliostat mirror would be a GEM, and the DASHCam would rapidly measure slope and canting errors during heliostat manufacturing, installation, or operation. We fabricated 0.1 meter-diameter GEMs with 24 grating patches, built a prototype DASHCam system, and tested the system repeatability and accuracy by comparing against a Fizeau interferometer. Our results show, in a laboratory environment, 24μrad root mean square (RMS) measurement repeatability and 47μrad RMS accuracy, with single-shot image capture. The combination of GEMs and DASHCam is a promising metrology approach that could lead to improved optical accuracy of heliostats throughout their life cycle. This work serves as a proof of principle for this system.

Dual-functional TiO2/Ag/NF SERS substrate with 3D channel structures for organic pollutant trace detection and degradation

Surface-enhanced Raman scattering (SERS) substrates are essential to realizing the SERS effect. Meanwhile, these substrates often get contaminated after testing and cannot be reused. Herein, the nickel foam (NF) skeleton was modified with TiO2 and Ag to synthesize TiO2/Ag/NF three-dimensional (3D) SERS substrates via dip-assisted spin coating combined with a silver mirror reaction. The substrates exhibited the outstanding SERS activity with a limit of detection (LOD) of 10−8 M for rhodamine 6G (R6G) and crystal violet (CV), as well as the enhancement factor are 1.18 × 106 and 1.39 × 106, respectively. Besides that, the signal attenuation was only about 19 % after 30 days of exposure to the natural environment. Moreover, the adsorbed dyes (10−4 M) were successfully degraded under ultraviolet light irradiation for 180 min, and about 70 % of the signal was still retained after three degradation cycles, which demonstrated excellent self-cleaning performance. Additionally, the substrates also showed good sensitivity and degradation ability for CV in river water, at a LOD of 10−7 M. The degradation time of CV (10−4 M) was 210 min, and the high SERS activity was still retained after three cycles. Thus, the proposed 3D TiO2/Ag/NF dual-functional SERS substrates have great potential for rapid monitoring and degradation of organic pollutants in wastewater.