scholarly journals Analytic Design of Segmented Phase Grating for Optical Sensing in High-Precision Alignment System

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3805
Author(s):  
Guanghua Yang ◽  
Jing Li ◽  
Yu Wang ◽  
Minxia Ding ◽  
Lina Zhong
Keyword(s):  
Design Method ◽  
Signal To Noise Ratio ◽  
Diffraction Theory ◽  
Stray Light ◽  
Analytical Relationship ◽  
Phase Grating ◽  
Grating Structure ◽  
Analytic Design ◽  
Segmented Grating ◽  
Diffraction Signal

Ultra-precision measurement systems are important for semiconductor manufacturing processes. In a phase grating sensing alignment (PGA) system, the measurement accuracy largely depends on the intensity of the diffraction signal and its signal-to-noise ratio (SNR), both of which are associated with the grating structure. Although an equally segmented grating structure could increase the signal of a high odd order, it could also strengthen the signals at the zeroth and even orders which are the main contributors of stray light. This paper focuses on the practical problem of differently responding diffraction orders but in one grating structure. An analytical relationship has been established between the diffraction efficiency and the segment structure of phase grating. According to this analytic model, we then propose a design method to increase the diffraction signal at high odd orders and, meanwhile, to decrease it at the zeroth and even orders. The proposed method provides a fast and effective way to obtain the globally optimal grating structure in the valid scope. Furthermore, the design examples are also verified by means of numerical simulation tool–rigorous coupled-wave analysis (RCWA) software. As a result, the proposed method gives insight into the diffraction theory of segmented grating and the practical value to greatly improve the design efficiency.

scholarly journals The Improvement on the Performance of DMD Hadamard Transform Near-Infrared Spectrometer by Double Filter Strategy and a New Hadamard Mask

Micromachines ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 149 ◽  
Author(s):  
Zifeng Lu ◽  
Jinghang Zhang ◽  
Hua Liu ◽  
Jialin Xu ◽  
Jinhuan Li
Keyword(s):  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Nonuniform Distribution ◽  
Stray Light ◽  
Spectral Energy ◽  
Hadamard Transform ◽  
Digital Micromirror Device ◽  
Infrared Spectrometer ◽  
Near Infrared Spectrometer ◽  
The Impact

In the Hadamard transform (HT) near-infrared (NIR) spectrometer, there are defects that can create a nonuniform distribution of spectral energy, significantly influencing the absorbance of the whole spectrum, generating stray light, and making the signal-to-noise ratio (SNR) of the spectrum inconsistent. To address this issue and improve the performance of the digital micromirror device (DMD) Hadamard transform near-infrared spectrometer, a split waveband scan mode is proposed to mitigate the impact of the stray light, and a new Hadamard mask of variable-width stripes is put forward to improve the SNR of the spectrometer. The results of the simulations and experiments indicate that by the new scan mode and Hadamard mask, the influence of stray light is restrained and reduced. In addition, the SNR of the spectrometer also is increased.

Median Morphological Filter Design Based on the PSO Algorithm

2011 ◽  
Vol 128-129 ◽  
pp. 181-184
Author(s):  
You Lian Zhu ◽  
Cheng Huang
Keyword(s):  
Filter Design ◽  
Design Method ◽  
Signal To Noise Ratio ◽  
Pso Algorithm ◽  
Morphological Operations ◽  
Morphological Filter ◽  
Signal To Noise ◽  
Noise Ratio ◽  
The Cost ◽  
Filter Design Method

Design of morphological filter greatly depends on morphological operations and structuring elements selection. A filter design method used median closing morphological operation is proposed to enhance the image denoising ability and the PSO algorithm is introduced for structural elements selecting. The method takes the peak value signal-to-noise ratio (PSNR) as the cost function and may adaptively build unit structuring elements with zero square matrix. Experimental results show the proposed method can effectively remove impulse noise from a noisy image, especially from a low signal-to-noise ratio (SNR) image; the noise reduction performance has obvious advantages than the other.

Analytic Design Method Based on Homothetic Shape of Magnetic Cores for High-Frequency Transformers

2007 ◽  
Vol 22 (5) ◽  
pp. 2070-2080 ◽  
Author(s):  
FranÇois Forest ◽  
Eric Laboure ◽  
Thierry Meynard ◽  
Mohand Arab
Keyword(s):  
High Frequency ◽  
Design Method ◽  
Magnetic Cores ◽  
Analytic Design ◽  
Analytic Design Method

An Analytic Method and Application on Design Planar Six-Bar Mechanisms with an Approximately Equal Velocity Ratio Transmission

2012 ◽  
Vol 157-158 ◽  
pp. 1380-1383
Author(s):  
Shu Nü An ◽  
Hong Xin Wang
Keyword(s):  
Design Method ◽  
Velocity Ratio ◽  
Optimization Method ◽  
Transmission Characteristics ◽  
Basic Functions ◽  
Analytic Design ◽  
Derivatives Of ◽  
Analytic Design Method ◽  
Ratio Transmission ◽  
Better Than

An analytic design method on an approximately equal velocity ratio transmission mechanism is presented. The mathematical principle is that a compound function produced by two basic functions, let its one order differential is equal to an assigned constant on the special point, and then two to three order derivatives of the compound function are all zeroes, thus one algebraic equation is got, its solution defines the mechanism dimensions. This a principle not only sets up a new design method on approximately equal velocity ratio mechanisms but approximately equal velocity is independently designed. A design example shows that this method is simpler and transmission characteristics are better than optimization method.

scholarly journals Analytic design method for optimal imaging: coupling three ray sets using two free-form lens profiles

2012 ◽  
Vol 20 (5) ◽  
pp. 5576 ◽  
Author(s):  
Fabian Duerr ◽  
Pablo Benítez ◽  
Juan C. Miñano ◽  
Youri Meuret ◽  
Hugo Thienpont
Keyword(s):  
Design Method ◽  
Free Form ◽  
Analytic Design ◽  
Analytic Design Method ◽  
Optimal Imaging

TH-C-19A-01: Analytic Design Method to Make a 2D Planar, Segmented Ion Chamber Water-Equivalent for Proton Dose Measurements

2014 ◽  
Vol 41 (6Part32) ◽  
pp. 547-547
Author(s):  
W Harris ◽  
R Hollebeek ◽  
B Teo ◽  
R Maughan ◽  
D Dolney
Keyword(s):  
Design Method ◽  
Ion Chamber ◽  
Analytic Design ◽  
Dose Measurements ◽  
Analytic Design Method ◽  
Proton Dose

Forward Degenerate Four-Wave Mixing as a Detection Method in Liquid Separation Systems: Improving Detection Limits by Means of a Fabry—Perot Interferometer

1997 ◽  
Vol 51 (7) ◽  
pp. 1008-1011 ◽  
Author(s):  
Gerard Ph. Hoornweg ◽  
Tjipke De Beer ◽  
Nel H. Velthorst ◽  
Cees Gooijer
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Four Wave Mixing ◽  
Laser Wavelength ◽  
Stray Light ◽  
Concentration Limit ◽  
Wave Mixing ◽  
Fabry Perot ◽  
Degenerate Four Wave Mixing

A simple, small, and low-resolution confocal Fabry–Perot interferometer (CFP) has been developed to improve the signal-to-noise ratio (S/N) in forward degenerate four-wave mixing (F-D4WM) detection, coupled to high-performance liquid chromatography (HPLC). Its appropriateness is based on the difference in coherence between the F-D4WM signal and the background stray light. A detailed description of the specially designed CFP and its performance is presented. The improvement in S/N was calculated from the chromatographic peaks recorded after an HPLC separation of 1- and 2-aminoanthraquinone. The concentration limit of detection (LOD) was improved by a factor of 30; for 1-aminoanthraquinone it was 2 × 10−8 M injected (corresponding to about 3 × 10−9 M in the detector cell), which is quite favorable in view of its low molar extinction coefficient being 2000 M−1 cm−1 at the utilized laser wavelength (514.5 nm).

Wave Rotor Design Method With Three Steps Including Experimental Validation

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Shining Chan ◽  
Huoxing Liu ◽  
Fei Xing ◽  
Hang Song
Keyword(s):  
Experimental Method ◽  
Experimental Validation ◽  
Cfd Simulation ◽  
Design Method ◽  
Flow Characteristics ◽  
Design Procedure ◽  
Wave Rotor ◽  
Rotor Design ◽  
Design Function ◽  
Analytic Design

This paper adapted and extended the preliminary two-step wave rotor design method with another step of experimental validation so that it became a self-validating wave rotor design method with three steps. First, the analytic design based on unsteady pressure wave models was elucidated and adapted to a design function. It was quick and convenient for a first prediction of the wave rotor. Second, the computational fluid dynamics (CFD) simulation was adapted so that it helped to adjust the first prediction. It provided detailed information of the wave rotor inner flow. Thirdly, an experimental method was proposed to complement the validation of the wave rotor design. This experimental method realized tracing the pressure waves and the flows in the wave rotor with measurement on pressure and temperature distributions. The critical point of the experiment is that the essential flow characteristics in the rotor were reflected by the measurements in the static ports. In all, the three steps compensated for each other in a global design procedure, and formed an applicable design method for generic cases.

scholarly journals Characterization, Biocompatibility, and Optimization of Electrospun SF/PCL/CS Composite Nanofibers

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1439
Author(s):  
Hua-Wei Chen ◽  
Min-Feng Lin
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Applied Voltage ◽  
Composite Nanofibers ◽  
Fiber Diameter ◽  
Design Method ◽  
Signal To Noise Ratio ◽  
L929 Cell ◽  
Mouse Fibroblast ◽  
Cytotoxicity Test

In this study, composite nanofibers (SF/PCL/CS) for the application of dressings were prepared with silk fibroin (SF), polycaprolactone (PCL), and chitosan (CS) by electrospinning techniques, and the effect of the fiber diameter was investigated using the three-stage Taguchi experimental design method (L9). Nanofibrous scaffolds were characterized by the combined techniques of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), a cytotoxicity test, proliferation tests, the antimicrobial activity, and the equilibrium water content. A signal-to-noise ratio (S/N) analysis indicated that the contribution followed the order of SF to PCL > flow rate > applied voltage > CS addition, possibly owing to the viscosity and formation of the beaded fiber. The optimum combination for obtaining the smallest fiber diameter (170 nm) with a smooth and uniform distribution was determined to be a ratio of SF to PCL of 1:2, a flow rate of 0.3 mL/hr, and an applied voltage of 25 kV at a needle tip-to-collector distance of 15 cm (position). The viability of these mouse fibroblast L929 cell cultures exceeded 50% within 24 hours, therefore SF/PCL/CS could be considered non-toxic according to the standards. The results proposed that the hydrophilic structure of SF/PCL/CS not only revealed a highly interconnected porous construction but also that it could help cells promote the exchange of nutrients and oxygen. The SF/PCL/CS scaffold showed a high interconnectivity between pores and porosity and water uptake abilities able to provide good conditions for cell infiltration and proliferation. The results from this study suggested that SF/PCL/CS could be suitable for skin tissue engineering.

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