Mirror Material Research Articles

Analysis of Optical Diffraction Profiles Created by Phase-Modulating MEMS Micromirror Arrays.

This paper presents modeling and analysis of light diffraction and light-intensity modulation performed by an optical phased array (OPA) system based on metal-coated silicon micromirrors. The models can be used in the design process of a microelectromechanical system (MEMS)-based OPA device to predict its optical performance in terms of its field of view, response, angular resolution, and long-range transmission. Numerical results are derived using an extended model for the 1st-order diffracted light intensity modulation due to phase shift. The estimations of the optical characteristics are utilized in the designs of an OPA system capable of active phase modulation and an OPA system capable of array pitch tuning. Both designs are realized using the Multi-User MEMS Processes (PolyMUMPs) in which polysilicon is used as structural material for the MEMS-actuated mirrors. The experiments are performed to evaluate the optical performance of the prototypes. The tests show that the individually actuated micromirrors, which act as phase shifters, can transmit the most optical power along the 1st-order diffracted beam by actively changing their out-of-plane positions. In addition, the 1st-order diffracted beam with high optical intensity can be steered for distance measurement.

Modeling, experimental validation, and model order reduction of mirror thermal dynamics.

A large variety of optical systems and devices are highly sensitive to temperature variations and gradients induced by the absorption of thermal energy. Temperature gradients developed across optical elements, mounts, and supporting structures can lead to thermally induced wavefront aberrations and, consequently, to the reduction of optical performance. Consequently, modeling, estimation, and control of thermal dynamics are important problems that need to be carefully addressed by optical system designers. However, the development of accurate and experimentally validated models of thermal dynamics that are suitable for prediction, estimation, and control is a challenging problem. The main modeling challenges originate from model uncertainties, nonlinearities, and the fact that the thermal dynamics is inherently large-dimensional. In this manuscript, we present a synergistic modeling framework that combines first-principle heat transfer modeling, experimental validation, finite element techniques, and model order reduction techniques. We experimentally validate our approach on a recently developed 8-inch mirror prototype equipped with heaters and temperature sensors. We are able to accurately predict the temperature transients lasting for several hours. Furthermore, we apply our modeling approach to a parabolic mirror with an optimized honeycomb back structure. We investigate how the choice of mirror materials, such as aluminum, beryllium, Zerodur, and ULE, influence the ability to derive reduced-order models. Our results show that mirror thermal dynamics can be approximated by low-order state-space models. The modeling approach used in this manuscript is relevant for the prediction, estimation, and control of thermal dynamics and thermally induced aberrations in optical systems. MATLAB, COMSOL Multiphysics, and LiveLink codes used in this manuscript are available online.

Design High performance multilayers cold mirror

The optical design process includes a myriad of tasks that the designer must be performed and consider in the process of optimizing the performance of the optical system. In this article, a design based on four groups of materials for a multilayer dielectric cold mirror: V2O5 \\MgF2, Sic\\MgF2, TiO2\\MgF2, and Al As\\MgF2 where MgF2 represents low refractive index and other material in each group represent high refractive index. A cold mirrors are a special dielectric mirrors that reflects the entire visible wavelength band, while the transmitting infrared wavelength band. These systems of mirrors are constructed for an event angle from 0° to 45° and are modeled with interference filters-like multi thin layer dielectric coatings. The results of our work designed shows the mirror based on Al As/MgF2 is the most promising design for cold mirror with the highest reflection in the visible region and the highest Transition in the IR region. In the spectrum range of 400-800 nanometers, the average transmission is much less than 1 %, while the average transmission is 95 percent in the wave band 800-2500 nanometer.

Optical design and intensity interferometry simulations in support of the Kilometer Space Telescope.

Very large telescopes will be needed for the future of space science, space laser-com, and other interstellar or interplanetary applications. However, as telescopes' diameters increase, their weight and cost increase dramatically. An approximation for ground-based observatories is that their cost increases to the power of 2.7 of its diameter [SAO, Special Report #385 (1979), p. 9]. Large space-based telescopes become limited by the rocket size and power. Multiple telescopes are also needed for very long baseline interferometry (VLBI), which further increases cost. A solution to overcome these issues is the use of inflatable telescopes. A thin mirror material clearly has much lower mass; however, controlling its surface error or wavefront can be a challenge. Intensity interferometry is an imaging method that has a much looser sensitivity to wavefront error (WFE), and thus is an ideal match for very large inflatable telescopes. A spherical inflatable mirror is the most practical; however, it suffers from spherical aberration. This paper presents new optical designs and simulations for intensity interferometry in support of large inflatable spherical telescopes. The optical system design includes a novel five-mirror off-axis, free-form, spherical aberration corrector. The system design shown is a 10 m diameter f/1 spherical primary mirror with 1.2 arcmin (0.02°) field of view (FOV). MATLAB simulations of intensity interferometry combine signal with noise and WFE. Visibility-based VLBI image simulations are shown based on various telescope arrays. Simulations show that with a 1 GHz detector, a 1 cm RMS WFE is tolerable. So the challenge of the optical design is then more about gathering and concentrating the light down to a reasonable size detector. Further simulations of signal combined with noise indicate that the signal rate must be about 100 times higher than the noise rate for an adequate intensity interferometry measurement. Visibility-based image simulations reveal that many telescopes (5-20 per axis) are needed in a 2D array out to the first visibility minimum to adequately resolve unknown features of a distant object.

REFLECTIVE MATERIALS AND SEEDS FROM DIFFERENT PLANT POSITIONS FOR PRODUCTION OF ACHACHAIRU SEEDLINGS

The plant environment in the production of Achachairu (Garcinia humilis) seedlings aims to obtain quality plants for orchards' formation. The present study aimed to evaluate reflective materials on benches and fruit seeds harvested from different plant positions to produce Achachairu seedlings. The reflective materials used under the cultivation benches were aluminum foil, "fake sequin" fabric, mirror, and tetra pak®. The fruit collection positions in the plants were at the top, median and bottom. The largest seedlings were obtained on the bench with reflective material of Tetra Pak®; however, in this material, there was a greater relationship between the height and diameter of the seedlings' neck, which is not desired for quality seedlings. The largest number of sheets was observed on the benches with reflective material of Tetra Pak® and "false sequin" fabric. The lowest dry masses of the root system and the lowest Dickson quality indexes were obtained from seedlings grown on the bench with reflective mirror material, forming lesser quality seedlings. The fruit collection place in the matrix plant did not influence the seedlings' quality. The use of reflective material on the bench is not recommended for the cultivation of Achachairu seedlings.

PRODUCTION OF ORNAMENTAL PYRAMID PEPPER WITH REFLECTIVE MATERIAL ON BENCHES IN DIFFERENT ENVIRONMENTS

Pepper trees have great ornamental value due to the varied colors of their fruits. Thus, the objective was to evaluate the Pyramid cultivar's production in different cultivation environments using benches with reflective material. The experiment was carried out in two protected environments: a) agricultural greenhouse with 42-50% shade screen under the plastic film and b) agricultural screen with black monofilament screen with 18% shade. Inside the environments, the production system was tested with and without reflective material on the cultivation bench. The experiments were conducted in a completely randomized design, with four replicates and six plants per plot. Joint analysis was used to compare environments. At 45, 60, and 75 days after transplantation, plant height, stem diameter, number of leaves, canopy area, and number of fruits were evaluated. The agricultural greenhouse with a 42/50% shade screen under the plastic film provided the formation of higher plants with greater stem diameter, greater number of leaves and fruits, and greater top diameter than the screen with 18% shading. The reflective mirror material showed positive results only for plant height.

Response sensitivity characteristics of ultra-high-speed isotriangular rotating mirror

On the basis of theory of dynamic modification and the finite element method, a numerical analysis modal of the response sensitivity of a mirror structure is established, and the influence of the random variables of the rotating mirror on the various order modals of the mirror is obtained. The structural size and material properties of the rotating mirror are used as random variables, and the rotating mirror feature value and feature vector are considered the response volumes. Results show that the radius R2 of axis segment 1 is the largest random variable that affects the first-order modal of the rotating mirror, the density D2 of the mirror body has the greatest influence on the first-order bending of the mirror, and the radius R3 of axis segment 2 has the greatest influence on the second-order bending of the mirror. The density of the spinning axis and mirror body are negatively correlated with each order modal, and R2 and R3 are positively correlated with the various order modals. Results provide theoretical guidance and basis for the selection of rotating mirror materials and the optimisation of the directional orientation of the dynamic parameters of a rotating mirror.

Neutronic analysis for the Edge Charge Exchange Recombination Spectroscopy in Equatorial Port of ITER

• Neutronics for Edge Charge Exchange Recombination Spectroscopy (CXRS-Edge). • CXRS-Edge Diagnostics installed in Equatorial Port #3 (EP3) of ITER. • New MCNP model of CXRS-Edge Diagnostic system in EP3 was created. • Personnel access to the Inter-Space Structure (ISS) the EP3 is evaluated. • Maps of local shutdown dose rate (SDDR) are shown in EP3 ISS with CXRS-Edge. The neutronic analysis results presented in this paper support the design development of the Edge Charge Exchange Recombination Spectroscopy (CXRS-Edge) system to be installed in Equatorial Port #3 (EP3) of ITER. That is an active optical diagnostic system with a dogleg labyrinth design of two optical pathways and a system of mirrors arranged in Diagnostic Shield Modules #1 and #2 (DSM #1 and #2) of EP3. The shielding performance of the CXRS-Edge system and the radiation effects of its mirror materials have been evaluated. To this end, a neutronic 3D model of the CXRS-Edge system has been created in the format of the MCNP code. The MCNP model of CXRS has been converted from the underlying CAD engineering model using the SuperMC code. Then the model has been integrated with the actual standard MCNP model of the ITER tokamak called “C-Model R181031 (Revision 190110)”. With this C-Model, neutron and photon fluxes, nuclear heating distributions and neutron damage in molybdenum, steel, and silicon carbide (SiC) materials have been calculated. Assessing the possibility of personnel access to the Inter-Space Structure (ISS) of EP3 with CXRS-Edge installed, a map of shutdown dose rate (SDDR) has been calculated using the local approach, without any other diagnostics systems shared by EP3. In conclusion, the suitability of CXRS Edge doglegs for necessary attenuations of neutron and photon fluxes, nuclear heating, and SDDR is demonstrated. As design work is progressing, this paper presents an initial contribution to the complete neutronic analysis.

What is in the Mirror? On Mirror Self-Recognition, Semiotics, and Material Engagement

What is in the Mirror? On Mirror Self-Recognition, Semiotics, and Material Engagement

Design methodology to develop an active optics system for a thin 1-m meniscus mirror

We investigate the design of an active support system for the thin primary mirror of a mid-sized telescope system used for optical satellite communication and space debris observation. To handle the complexity of this task, a general design methodology is proposed. The design for the axial and lateral support is separated into several subtasks to reduce the number of design variables in every design step. Due to the independence of mirror geometry and material, this methodology is also applicable to larger mirrors. Utilizing the proposed procedure, an active support for a 1-m meniscus mirror with 25 mm thickness and the requirement to achieve diffraction-limited optical performance is developed. The final system consists of 32 axial and 8 lateral actuators supporting the mirror with a maximal simulated RMS error of 8.8 nm and PV error of 48.0 nm when pointing to zenith. Simulations show that the obtained design ensures the required performance even under commonly occurring mirror deformations.

Electro-tunable optical cavity filters in near-infrared regime

The design, simulation, and fabrication of two electrically tunable Fabry-Perót (FP) microcavities filled with Twisted Nematic Liquid Crystal (TNLC), based on different mirror materials are demonstrated theoretically and experimentally in the near-infrared (NIR) regime. Owing to the polarization-independent property of TNLC, the wavelength-selection and tunable property of the Liquid Crystal Tunable Filter (LCTF) is independent on polarization state of incoming light beam in the tuning range. The experimentally measured full width at half maximum (FWHM) of the first aluminum mirrors device at a voltage of 10.39 V is ∼2.5 nm while the other device composed of gold mirrors showed ∼5.5 nm at an applied voltage of 12.72 V. An overall ∼53.6 nm spectral shift is observed in first device at 12.72 V with seven and five distinct spectral channels are found with an overall spectral shift of ∼27.9 nm at 15.29 V applied voltage in second device over the desired spectral band. The simulated work on LCTFs is found in complete agreement with experimental results.

Interference suppression of light backscattering through oblique deposition of high-reflectivity multilayers: a theoretical analysis.

We demonstrate a theoretical approach whereby light backscattering toward the incident beam can be suppressed entirely for a high-reflectivity, rough-surfaced multilayer mirror fabricated using oblique deposition, such that the interface relief is replicated at a certain angle β to the sample normal. The mirror comprises two parts: a main (lower) multilayer consisting of N identical bi-layers growing at the angle βML to the mirror normal, and an additional bi- or tri-layer forming the topmost section of the mirror, which grows at another angle βBL. We show that choosing appropriate growth angles βML and βBL results in a disappearance of backscattering toward the incident beam due to the destructive interference of waves scattered from the main multilayer and uppermost bi- or tri-layer. The conditions for the scattering suppression are formulated, and the suitability of different mirror materials is discussed.

A horizontal-axis spaceborne primarymirror design

The purpose of mounting a mirror is to maintain the correct position and control the deformation of the optical surface from external disturbance to allowable level. It is more difficult to mount a spaceborne large mirror in optical axis horizontal state than in vertical state on ground due to gravity. The design of a 1030 mm-diameter spaceborne primary mirror that is tested and aligned in laboratory with optical axis in horizontal state is described in this paper. A new kinematic mounting that is called three-spherical-joints mounting is proposed. Based on this new mounting concept, the primary mirror is lightweighted with Zerodur and ULE separately. ULE is selected finally as the material of primary mirror for it can be fabricated into sandwich structure which is the ideal structure for bending stiffness. The mass of lightweighted primary mirror is 50.5 kg. The detail mounting structure is described. This type of support offers the advantages of simple structure, ability of disturbance isolated and high natural frequency. Error budgets of surface figure are listed according to the developing processes. The primary mirror surface figure RMS error induced by environment disturbances are simulated. An aluminum dummy mirror assembly is made. Experiments show that the primary mirror has required static and dynamic performances which comply with simulations very well.

Description of Integrated Science Process Skills in Physics Education Students in Convex Mirror Practicum

This study aims to determine the description of students towards the use of ICT-based convex mirror material guidebooks. The population of this study was the students of the Jambi University physics education class program in 2018. The sampling technique used total sampling, so that the sample of this study was all physical education students at the University of Jambi with 105 students in class 2018 Indicators of observed process skills included the identification of variables, making tables data, Make a graph, Explain the relationship between variables, Obtain and process data, Analyze investigations, Make hypotheses, Identify variables by ovational, design experiments, and conduct experiments. Process skill data is measured through a basic physics practicum performance evaluation sheet, when practitioners conduct convex mirror practicum activities. Data were analyzed using descriptive statistics. The analysis shows that the average Science Process Skills are categorized as good and very good, this shows that students have mastered the integrated Science Process Skills. The results of this study are expected to be a consideration for physics study programs to conduct related studies for other practicum subjects.

Optimized algorithm for BDS/GPS RTK suitable for urban canyons with a low-cost receiver

Due to large noise, severe multi-path errors and the frequent rise and fall of satellites caused by propagation obstacles and mirror materials widespread in urban canyons with low-cost receivers produced with low-power design and restricted computing resources, the positioning accuracy in urban canyons with normal RTK has been heavily reduced with these large biased observations and discontinuous tracking satellites. Therefore it is not applicable to urban canyons without optimization. The C/N0-dependent exponential noise model for an urban canyon was designed to provide a balance between practical noises and the noise model adopted in the EKF filter. The accuracy of the fixed solution with this model was better than 0.5 m compared to the traditional elevation-dependent model for urban canyons, except for special circumstances, such as a deep urban canyon. So, an optimized empirical strategy for ambiguity resolution depending on posterior variance and the number of satellites available was also proposed for special local circumstances, such as a deep urban canyon. The results show that it has a heavily reduced proportion of incorrectly-fixed solutions; the accuracy of the fixed solution can be better than 0.10 m with a significant drop in incorrectly-fixed solutions, and the accuracy of the float solution can be better than 0.898 m with good reliability and stability, even if the ambiguity resolution failed. The proportion of correct-fixed solutions in a deep urban canyon was further reduced with the ambiguity resolution AR-AIM method, which was proposed to migrate the negative effect of the frequent rise of satellites on the ambiguity resolution.

Low energy sputtering of Mo surfaces

Surfaces of materials subject to irradiation will be affected by sputtering, which can be a beneficial effect, like in the coating industry where a material is sputtered and redeposited on to another material to coat it. However, in most cases sputtering is an unwanted side-effect, for instance in nuclear fusion reactors, where the wall material will be degraded. This effect needs to be understood in order to be able to predict its consequences. To understand the sputtering, on an atomistic level, we have thoroughly investigated molybdenum surface sputtering by computational means. Molybdenum was chosen as detailed experimental studies have been carried out on it and it is one candidate material for the diagnostic mirrors in ITER, facing the plasma. In this study, we thoroughly investigate the molybdenum samples of different surface orientations, and their response to low energy argon plasma irradiation, by molecular dynamics simulations. We find both a surface orientation and ion energy specific sputtering yield of the samples, and a very good agreement with the experiments available in the literature. A few different setups were investigated to observe differences as well as to understand the key features affecting the sputtering events. The different simulation setups revealed the optimal one to represent the experimental conditions as well as the mechanisms behind the observed discrepancies between different modelling setups.

RELATIONSHIP BETWEEN THE PERCEPTION AND SKILLS OF STUDENT BASIC SCIENCE PROCESS IN THE USE OF M-MODULE IN BASIC PHYSICS PRACTICUM

This study aims to determine the relationship between perception and basic science process skills through the use of the m-module in basic physics practicum II. This research is a quantitative study using correlational design. data collection instruments used in the form of perception questionnaire instruments and observation sheets to measure students' science process skills. This study used a sample of 36 physics students at Universitas Jambi. The results of the study will be analyzed using descriptive statistics and inferential statistics. The results of this study indicate that students give a good perception of the use of the m-module in basic physics practicum II. Flat mirror material is proven from the value of the perception of 63.9% in the good category according to a predetermined range. And the basic science process skills of students are in a good category with a percentage of 50.0%. Pearson correlation results show the number 0.756 and sig 0.05 which is 0.00, this shows that there is a strong relationship between perceptions and students' science process skills in using the m-module. This means that a high perception will result in high science process skills.

Strain-induced band modulation and excellent stability, transport and optical properties of penta-MP2 (M = Ni, Pd, and Pt) monolayers.

First principle calculations utilizing density functional theory were carried out to investigate the electronic, transport and optical properties of penta-MP2 (M = Ni, Pd and Pt) monolayer compounds under applied uniaxial and biaxial tensile strains. With an optimum magnitude of applied strain, we found band gap transitions in penta-MP2 monolayers from zero/narrow to the semiconductor regime, wherein band gaps were noticed to be firmly dependent on the applied uniaxial and biaxial tensile strains. In this study, the PBE approach was used primarily to evaluate electronic properties, from where the identified architectures of penta-MP2 with maximum obtained bandgaps under respective optimum strains were assessed through the HSE06 method of calculation for better estimation of band gaps and optical properties. Prior to HSE calculations, we affirmed our assessment for the stability and reliability of the compounds under uniaxial and biaxial strains of up to 15% through phonon spectrum and elastic calculations. A distinct transition was also noted from semiconductor to metal for all compounds after the applied optimum uniaxial and biaxial strains. The optical absorption spectra in all the stretched penta-MP2 compounds reached the order of 106 cm−1, with significant peaks belonging to the IR and visible regions; this indicates promising applications of these materials in high-performance solar energy and good hot mirror materials. The enhanced I–V responses under uniaxial and biaxial tensile strains using the non-equilibrium Green's function (NEGF) approach confirm the usefulness of the strained state of the considered penta-MP2 monolayers. The results show that tuning electronic properties, I–V characteristics and optical properties of stretched penta-MP2 compounds under tensile strain merits significant future applications in optoelectronic devices and as good hot mirror materials.

Diagnostic mirrors for ITER: research in the frame of International Tokamak Physics Activity

Mirrors will be used as first plasma-viewing elements in optical and laser-based diagnostics in ITER. Deterioration of the mirror performance due to e.g. sputtering of the mirror surface by plasma particles or deposition of impurities will hamper the entire performance of the affected diagnostic and thus affect ITER operation. The Specialists Working Group on First Mirrors (FM SWG) in the Topical Group on Diagnostics of the International Tokamak Physics Activity (ITPA) plays an important role in finding solutions for diagnostic first mirrors.Sound progress in research and development of diagnostic mirrors in ITER was achieved since the last overview in 2009. Single crystal (SC) rhodium (Rh) mirrors became available. SC rhodium and molybdenum (Mo) mirrors survived in conditions corresponding to ~200 cleaning cycles with a negligible degradation of reflectivity. These results are important for a mirror cleaning system which is presently under development. The cleaning system is based on sputtering of contaminants by plasma. Repetitive cleaning was tested on several mirror materials. Experiments comprised contamination/cleaning cycles. The reflectivity SC Mo and Rh mirrors has changed insignificantly after 80 cycles. First in situ cleaning using radiofrequency (RF) plasma was conducted in EAST tokamak with a mock-up plate of ITER edge Thomson Scattering (ETS) with five inserted mirrors. Contaminants from the mirrors were removed. Physics of cleaning discharge was studied both experimentally and by modeling.Mirror contamination can also be mitigated by protecting diagnostic ducts. A deposition mitigation (DeMi) duct system was exposed in KSTAR. The real-time measurement of deposition in the diagnostic duct was pioneered during this experiment. Results evidenced the dominating effect of the wall conditioning and baking on contamination inside the duct. A baffled cassette with mirrors was exposed at the main wall of JET for 23,6 plasma hours. No significant degradation of reflectivity was measured on mirrors located in the ducts.Predictive modeling was further advanced. A model for the particle transport, deposition and erosion at the port-plug was used in selecting an optical layout of several ITER diagnostics. These achievements contributed to the focusing of the first mirror research thus accelerating the diagnostic development. Modeling requires more efforts. Remaining crucial issues will be in a focus of the future work of the FM SWG.

Sub-picometer dynamic measurements of a diffuse surface.

Future space observatory missions are forecasting the need for sensing and controlling wavefront error and system alignment stability to picometer scale. Picometer stability performance demands precision knowledge of the mirror and metering structure materials to the same degree. A high-speed electronic speckle pattern interferometer was designed and built to demonstrate measurements of both static and dynamic responses of picometer amplitudes in materials of diffuse surface subjected to very low energy disturbances. This paper describes the details of a test to impart a dynamic disturbance of picometer scale and measure the response of a composite material. The results of the test are also reported and show conclusively that sub-picometer scale effects can be accurately measured in an open test environment outside a vacuum chamber.