Grating Element Research Articles

Ergonomic Analysis of Small-Scale Palm Sugar Starch Processing Industry in Rancakalong Village, Sumedang Regency

Rancakalong village, Sumedang Regency, has been known for its small-scale palm sugar starch processing industry since 2013. This industry produces starch from palm trees, which is crucial for food and beverages. Generally, the processes involved in processing palm sugar starch include (i) splitting of the palm, (ii) grating, (iii) coarse fiber screening, (iv) fine fiber screening, (v) harvesting, and (vi) drying. Initial evaluations indicated that the workers experienced physical discomfort during their work. Therefore, this study aimed to analyze the ergonomic aspects of processing palm sugar starch, including the working posture, standard time, workload, noise, and vibration. Based on the analysis, the risk level for each work element in processing palm sugar starch fell into the high-risk (score 8-10) and very high-risk (score 11-15) categories. These risks cause discomfort due to inappropriate work posture and duration, necessitating significant changes. The standard time required for each work element was as follows: 212.88±28.43 seconds/kg (palm splitting), 363.45±12.90 seconds/kg (grating), 95.08±9.74 seconds/kg (coarse fiber screening), 192.05±21.27 seconds/kg (fine fiber screening), 35.57±5.78 seconds/kg (harvesting), and 1821.01±41.09 seconds/kg (drying). Regarding workload analysis, processing palm sugar starch activities fell into the moderate category with total energy cost (TEC) values ranging from 92.66±1.50 265.55±3.88 kcal/hour. Regarding noise and vibration analysis, the grating work element was identified as the station with the highest exposure, i.e., 96.00±0.82 dB and 1.6±0.05 m/s2, respectively. The results of this study could be used as a basis for developing more efficient work procedures, maintaining health, and improving safety in the processing of palm sugar starch.

The application of cumulating lattice to accelerate diffusion during thermal diffusion chromiing

The creation of coatings on parts with improved corrosion resistance, throughput at low and high temperatures, wear resistance makes it possible to expand the possibilities of using low and medium alloy steels. Traditional methods for creating protective coatings are various types of chemical-thermal treatment and thermal diffusion chromium plating, in particular. In recent decades, attempts have been repeatedly made to increase the efficiency of the process of thermal diffusion saturation of chromium metal, mainly due to complex saturation with vanadium, boron and other elements, as well as the use of external physical influences that accelerate diffusion. Previously, in the works of the authors, it was shown that the introduction of electron-emitter metal powder into the composition of the metal part of the filling ensures the acceleration of diffusion processes during thermal diffusion chromium plating due to the action of an internal emission field. A similar effect is also observed when replacing corundum in the separating part of the filling with powders of solid electrolytes (minerals such as serpentine and scheelite, which are emitters of electrons and anions of the oxygen when heated). An additional enhancement of the internal emission field was noted when cumula-tive nickel and molybdenum lattice were used, however, the effect of the geometric characteristics of these lattice on the magnitude of the thermal emission of electrons and oxygen anions and, as a result, the diffusion acceleration was not established. The paper presents the results of saturation of samples of steel X35CrNi2-3 at a temperature of 1000°C for 24 hours using cumulative lattice that differ in the density of holes per unit area: 20, 10 and 6 holes/cm2. The control of the elemental composition of the diffusion layer was carried out on transverse sections in the direction from the saturated surface to base metal of the sample using a JEOL JSM-6460LV universal scanning (scanning) electron microscope. X-ray phase analysis was performed on an Ultima IV diffractometer, the radiation used was Cu-Kα. The microstructure was studied using an optical microscope Axio Observer D1.m. The microhardness of the coatings was measured using an FM-800 microhardness tester. It has been established that the use of cumulative nickel lattices provides an increase in the depth of the diffusion layer in the base metal by at least 25% and additional alloying coating with a grating metal element with a hole density of 10 pieces/cm2 or more. At a lower density of perforating the lattice, the opposite effect is observed

Ultra-Precision Cutting and Characterization of Reflective Convex Spherical Blazed Grating Elements.

In this work, based on the diffraction principle of reflective blazed grating, the structure size of the convex spherical blazed grating unit is determined, the machining accuracy of the convex spherical blazed grating is formulated, the effects of tool nose radius and Poisson burr on the diffraction efficiency of the convex spherical blazed grating are analyzed, and the performances of cutting convex gratings with microcrystalline aluminum RSA6061 and RSA6061+ chemically plated NiP for two workpiece materials are compared. A convex spherical blazed grating with a radius of curvature R = 41.104 mm, substrate diameter 14 mm, grating density 53.97 line/mm, and blaze angle of roughly 3.8° is turned by a four-axis ultra-precision machining system by adjustment of the cutting tool, workpiece material, and cutting parameters, as well as modification of the layouts of the blazed grating on the convex sphere. The results of the testing of convex spherical blazed grating elements in both layouts show that the size error of the grating period is close for both layouts, the size error of grating height is smaller in the equal-along-arc layout, the blaze angle error in the equal-along-projection layout is only 0.74%, and the average roughness of the blazed surface is less than 5 nm to meet the processing quality requirements of the reflective convex spherical blazed grating. The greater the blaze angle accuracy of the blazed grating, the higher its diffraction efficiency, so the grating element with an equal-along-projection layout has a higher diffraction efficiency than the grating element with an equal-along-arc layout. RSA6061+ chemically plated NiP material is superior to RSA6061 material in Poisson burr height and blazed surface roughness, which is more suitable for Offner-type imaging spectrometers in the spectral range 0.95–2.5 μm (SWIR).

Development of an Optic Fiber-Based Torque Sensor With a Torsion-Translation Conversion Flexure

This work proposes a miniature and high-sensitivity torque sensor that mainly consists of a torque-sensitive flexure and one tightly suspended optic fiber with an inscribed Fiber Bragg Grating (FBG) element for application in minimally invasive surgery robots and multi-finger robotic hands. The proposed flexure can achieve a torsion-translation conversion with a linear measurement range and a solid resistance to moment loadings. It is implemented based on the hybrid design among the specially designed hyperboloid, hollow cruciform, and cross-beam structures. The mounted FBG fiber has been configured at the flexure’s central line with its two ends glued. This tight suspension configuration can improve resolution and sensitivity and avoid FBG chirping compared to the direct FBG-pasting methods. The flexure translational motion overlaps with the FBG fiber suspension direction, generating a large and uniform strain distribution on the suspended FBG. Design optimization has been performed based on finite element modeling (FEM) simulation for structural investigation and sensor sensitivity enhancement. The prototyped sensor achieved a high resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.295 {\mathrm {~N}} \cdot {\mathrm {mm}}$ </tex-math></inline-formula> within [−600, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$600 {\mathrm {~N}} \cdot {\mathrm {mm}}$ </tex-math></inline-formula> ] and exhibited excellent linearity with a small linearity error of 1.24%. The dynamic experiments demonstrated small crosstalk values of 1.6% and 3.4% for Mx and My moments. Furthermore, the proposed design supports convenient customization, and it can also achieve a resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.81 {\mathrm {~N}} \cdot {\mathrm {mm}}$ </tex-math></inline-formula> within [−2000, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2000 {\mathrm {~N}} \cdot {\mathrm {mm}}$ </tex-math></inline-formula> ] by structural modification.

High-Precise Fractional Orbital Angular Momentum Probing With a Fiber Grating Tip

Optical orbital angular momentum (OAM), carried by optical vortices, is a fundamental property of light that grabs broad interests. The detection of OAM modes, including fractional OAM is of great importance in diverse fields. Here, we firstly propose and develop the limited integer-component measurement method to determine the fractional topological charge (TC) of OAM states. This method indicates that a 2-integer-mode responsive device could be applied for the detection of fractional TC. An orthogonal long-period fiber grating (OLPFG) element is used as a fractional OAM TC probe to verify the Applicability. We experimentally demonstrate the fractional TC detection, ranging from −1 to 0, and recognize different fractional OAM modes with the minimum TC interval of 0.01. This scheme provides a concise, precise, continuous, and fiber-compatible fractional TC detection method that might have great potential in micro-detection, optical communication, quantum information, and chiral sensing applications.

Asymmetrical bidirectional optical wireless communication system based on a transmissive 1D LC-SLM for NG-PON2.

An asymmetric bidirectional optical wireless communication (B-OWC) system using optical fibers as the transmitter and receiver and capable of wavelength switching is proposed for next generation passive optical network stage two (NG-PON2) extension to home area network (HAN), without optical/electrical (O/E) and electrical/optical (E/O) conversions, which is based on a transmissive "floating" pixel size one-dimensional (1D) liquid crystal spatial light modulator (LC-SLM) at the access node (AN) and a modulated retroreflector (MRR) at the terminal user (TU). The utilization of a reflective grating element and a low-cost LC-SLM in the AN offers a high flexibility of beam steering and wavelength selection in the scenario of B-OWC. Instead of a light source used at conventional TU, a MRR was employed at a TU in order to improve the problems of the power consumptions, alignment difficulties, wavelength contentions, and cost of the TUs. Downlink and uplink data transmissions at a link speed over 2.5 Gbits/s, using wavelengths between 1590∼1603nm and 1524∼1544nm, respectively, corresponding to the downlink and uplink wavelengths specified by the NG-PON2 standard, have been experimentally demonstrated successfully, with quality factors (Q-factors) beyond the forward error correction limit (Q-factor=16.9dB, bit error rate=10-12).

Smartphone-Based Spectrometric Analyzer for Accurate Estimation of pH Value in Soil

This article demonstrates a cost-effective, compact, and handheld smartphone-based sensing tool for accurate estimation of pH values of agricultural farmlands. We develop a spectrometric tool with a resolution ability of 0.22 nm/pixel by utilizing 3D printing technology, regular optical components, a Digital Versatile Disc (DVD) as a grating element, and the rear camera of the phone. The sensor responses for standard pH samples within the pH range 4 to 10 are observed to be linear yet yield a sensitivity of 0.129 per pH unit. The resolution of the proposed sensor for the considered samples is observed to be 0.09 pH units. The results obtained from the designed tool while measuring the pH values of six field-collected soil samples are found to be accurate. The designed sensor’s performance has been evaluated by comparing the experimental data with the commercial-grade pH sensing tool. With the advantages of being a low-weight and data-sharing ability, we envision that the proposed sensing scheme could emerge as a promising alternative platform for in-field estimation of pH values of soil and water resources of our environment.

Preparation and characterization of carbon/epoxy towpreg composite material

Abstract Towpreg has steady and regular resin substance and high grating element to do non geodesic winding than wet winding and dealing with perspective is easy and clear-cut. The investigational characterization of carbon Fiber/Epoxy Towpreg composite material and its behavior is basically necessary for age of mechanical properties information for investigation, plan & creation of auxiliary parts. Also, the experimental information can be sufficiently meant hone and have vital ramifications for ideal outline of composites.

2D broadband beamsteering with large-scale MEMS optical phased array

Optical-phased arrays (OPAs) enable complex beamforming, random-access beam pointing, and simultaneous scan and tracking of multiple targets by controlling the phases of two-dimensional (2D) coherent emitters. So far, no OPA can achieve all desirable features including large 2D arrays, high optical efficiency, wideband operation in wavelengths, fast response time, and large steering angles at the same time. Here, we report on a large-scale 2D OPA with novel microelectro-mechanical-system (MEMS)-actuated phase shifters. Wavelength-independent phase shifts are realized by physically moving a grating element in the lateral direction. The OPA has 160×160 independent phase shifters across an aperture of 3.1 mm×3.2 mm. It has a measured beam divergence of 0.042°×0.031°, a field of view (FOV) of 6.6°×4.4°, and a response time of 5.7 μs. It is capable of providing about 25,600 rapidly steerable spots within its FOV. The grating phase shifters are optimized for the near-infrared telecom wavelength bands from 1200 to 1700 nm with 85% optical efficiency.

Single Chip-Based Nano-Optomechanical Accelerometer Based on Subwavelength Grating Pair and Rotated Serpentine Springs.

Optical coupling between subwavelength grating pairs allows for the precise measurement of lateral or vertical displacement of grating elements and gives rise to different types of displacement and inertial sensors. In this paper, we demonstrate a design for a nano-optomechanical accelerometer based on a subwavelength grating pair that can be easily fabricated by a single Silicon-on-insulator (SOI) chip. The parameters of the subwavelength grating pair-based optical readout, including period, duty cycle, thickness of grating and metal film, and the distance of the air gap, were optimized by combining a genetic algorithm and rigorous coupled wavelength analysis (RCWA) to obtain the optimal sensitivity to the displacement of suspended grating element and the acceleration. A corresponding mechanical design was also completed to meet the highly sensitive acceleration measurement requirement while considering the mechanical cross-axis sensitivity, dynamic range, bandwidth, and fabrication feasibility. This device was verified by both RCWA and finite-different-time-domain methods, and a tolerance analysis was also completed to confirm that it is able to achieve the extremely high optical displacement sensitivity of 1.8%/nm, acceleration-displacement sensitivity of 1.56 nm/mg, and acceleration measurement sensitivity of more than 2.5%/mg, which is almost one order of magnitude higher than any reported counterparts. This work enables a single SOI-based high performance accelerometer, and provides a theoretical basis and fabrication guides for the design.

Solution of the three-dimensional problem of plane wave diffraction by a two-period plane grating

Using the discrete source method, we develop an algorithm for solving the three-dimensional problem of wave scattering by a plane grating consisting of acoustically soft or acoustically stiff bodies. An efficient algorithm is proposed for determining the periodic Green’s function of the grating. Numerical results are obtained for different geometries of the grating elements. The fulfillment of the energy conservation law is verified along with the fulfillment of the boundary condition at the surface of the central grating element.

Mathematical Model for a Novel Cryogenic Flow Sensor Using Fibre Bragg Gratings

In this work, a mathematical model is presented for a newly developed cryogenic flow meter which is based on fibre Bragg grating (FBG) principle. The principle of operation is to use the viscous drag force induced by a flowing fluid on an optical fibre placed transverse to the flow. An optical fibre will have a 5mm long grating element inscribed in it and will be placed so that the sensor is at the centre of the pipe. The fibre will act as the bluff body, while the FBG sensor will pick up the bending strain induced in the fibre due to the drag force. The amount of bending strain which can be measured as a shift in Bragg wavelength can be calibrated to provide the mass flow rate. Here a mathematical model is being presented to predict the operation of the sensor and to calculate the sensor characteristics so that the sensor design can be optimised. The sensor exhibits an exponential relationship between sensitivity and mass flow rate. It is also seen that the sensitivity depends greatly on the fluid properties such as density and viscosity.

Fiber Bragg Grating Sensors for Distributed Torsional Strain Measurements in a (RE) BCO Tape

Fiber Bragg grating (FBG) sensors were used to measure the torsional strain distribution in a second-generation (rare-earth) Ba2Cu3Oy high-temperature superconducting sample tape (SST) at 77 K. Two SST samples were prepared. A slit was fabricated in each sample to allow an optical fiber to be embedded. In the first sample, a 10-mm-long single grating element was inserted into the slit. In the second sample, three grating elements of 10-mm length each were put into the slit. These grating elements were fabricated along a single-mode fiber and could be addressed individually using the wavelength division multiplexing (WDM) technique. Finally, the samples were recoated with a primary and secondary coating to form an embedded sensing system. When the high-temperature superconducting (HTS) tape is subjected to torsion, there is a strain induced in the FBG sensor, which varies the grating period accordingly. It was interrogated using a tunable laser in a WDM scheme. Based on the wavelength shift and the photoelastic properties of the FBG sensor embedded to the HTS tape, the torsional deformation of the HTS tape can be obtained. In this paper, the design and technology requirements to embed the single and WDM FBG sensors into the coated conductors are presented. Initial experiments to measure the torsional strain distribution at 77 K are reported.

Wavelength division multiplexing based optical backplane with arrayed waveguide grating passive router

A wavelength division multiplexing (WDM)-based optical backplane architecture is introduced. It is a tunable transmitter fixed receiver (TT-FR) architecture incorporating an N×N arrayed waveguide grating (AWG) element for passive data routing between the nodes, which in conjunction with star couplers, offers both unicast and multicast capabilities. The data and control plane of the network are implemented on a high-speed field programmable gate array (FPGA), and a four-node demonstrator is built up. Three different types of AWG routing elements implemented in different technologies are employed, and bit error rate (BER) versus incident power on the receiver measurements are presented for a data rate of 10 Gbps per link. A total switching time as low as 500 ns is achieved, permitting packet switching operation with more than 95% efficiency when the packet length is greater than 10 kbytes.

Research and development of an accurate 3D shape measurement system based on fringe projection: Model analysis and performance evaluation

In this paper, the research and development of an accurate 3D shape measurement system based on fringe projection is presented. This system utilizes a sliding projection unit to project the desired encoding fringe patterns onto the object and the object shape can be obtained by analyzing the images captured with a camera for each projection. The sliding projection unit uses a high precision grating element fabricated by electron beam lithography to produce the accurate encoding fringe patterns thus to reduce the projection error. And a method based on gray-code and phase-period edge detection is developed to align the grating element with its sliding direction to guarantee the alignment between the projected patterns. The influence of the lens distortion of both the projection unit and the camera is also studied and an improved nonlinear system model is developed based on triangulation. This model gives a more accurate mathematical representation of the shape measurement system and thus improves the system measurement accuracy. The experimental results show that an overall measurement error of 0.04 mm with a variability of ±0.035 mm can be obtained for the developed system.

An accurate three-dimensional scanning system with a new phase error compensation method

An accurate three-dimensional scanning system based on fringe projection and active triangulation is presented. The structured light projection is implemented by using a special grating element fabricated by electron beam lithography which ensures the phase-shifting accuracy and continuous intensity. The phase error caused by non-sinusoidal phase-shifting patterns is reduced significantly by a new compensation method, and an average 62.5% improvement of the vibration error is revealed. The experimental results indicate that the measurement error of the system is lower than 0.04 mm, with a variability of about 0.03 mm. The registration of multi-view test results indicates registration standard deviation can be lower than 0.1 mm. The system promises a favourable future for industrial application, especially in reverse engineering of free form surfaces.

大型超精密鏡面加工システム“N-aou-VEL”による大型赤外用回折格子“ゲルマニウムイマージョングレーティング”加工

大型超精密鏡面加工システム“N-aou-VEL”による大型赤外用回折格子“ゲルマニウムイマージョングレーティング”加工

Analysis of directional grating-coupled radiation in waveguide structures

Radiation scattered from diffraction gratings on the surface of waveguides is analyzed using the volume current method. This technique allows the interpretation of the grating elements as scattering centers of the underlying waveguide mode, and radiating sources for the diffracted fields. The framework allows separation of the effects of the grating array global periodicity and the effects of the specific shape of the individual grating elements. A straightforward analogy between the effects of the grating element shape and the behavior of phased-antenna array systems allows a clear and intuitive understanding of the effects of blazed gratings on the directionality of grating-coupled radiation. The analysis is applied to some specific geometries.

Micro V-Groove Grinding Technique of Large Germanium Immersion Grating Element for Mid-Infrared Spectrograph

The 8.2m SUBARU large space telescope in Hawaii requires a mid-infrared high dispersion spectrograph with a resolution of 200000 at 10µm which employs a Germanium Immersion Grating (GIG) element. For this, the GIG element with a large number of sharp and smooth micro V-grooves must be fabricated. Previous studies were focused on the fabrication of a prototype GIG element. The grinding system developed however was not applicable for the fabrication of practical larger GIG element due to insufficient machining space and fast wear of the small grinding wheel used. The ultimate goal of this project was therefore to develop a new grinding system capable of fabricating larger GIG elements for practical use. This paper discusses the results achieved in the first phase of the research, which focused on the principle of the grinding process and grinding system, as well as describes results of micro-truing and micro-grinding experiments using a #4000 metal bonded diamond grinding wheel. Wear variation of the grinding wheel and its effects on the corner radius of micro V-grooves are also discussed. The minimum wheel tip radius of 8.2µm was achieved using this #4000 grinding wheel by micro-truing, and V-groove corner radiuses ranging from 15µm to 25.8µm were also achieved using the same grinding wheel.

204 Micro V-grooves Grinding Technique of Large Germanium Immersion Grating Element for Mid-infrared Spectrograph

204 Micro V-grooves Grinding Technique of Large Germanium Immersion Grating Element for Mid-infrared Spectrograph