scholarly journals Terahertz Displacement and Thickness Sensor with Micrometer Resolution and Centimeter Dynamic Range

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5249 ◽  
Author(s):  
Dae-Hyun Han ◽  
Lae-Hyong Kang
Keyword(s):  
Beam Splitter ◽  
Dynamic Range ◽  
Measurement Range ◽  
Terahertz Wave ◽  
Initial Position ◽  
Time Difference ◽  
Peak Time ◽  
Medical Electronic ◽  
Thickness Error ◽  
Time Information

Measuring distance and thickness simultaneously is important in biological, medical, electronic, and various industries. Herein, we propose a method for simultaneously measuring the displacement and thickness of transparent materials using a pulsed terahertz wave. For this technique, a beam splitter was used to design the optical path such that the terahertz wave would incident the specimen vertically to achieve centimeter measurement range and micrometer resolution. The measured terahertz waveform carries peak time information reflected from the upper and lower surfaces of the sample, and the thickness can be calculated using the time difference between the first and second reflected peaks. The displacement can also be calculated using peak time difference when the sample moves from the initial position to the changed position. For validation, an experimental test was performed using aluminum, acrylic, and glass plates. The results confirmed a measurement range of 1 cm with an error of less than 23 μm, and the thickness error was less than 8 μm.

scholarly journals In-Process Diameter Measurement Technique for Micro-Optical Fiber with Standing Wave Illumination

2021 ◽  
Author(s):  
Masaki Michihata ◽  
Zhao Zheng ◽  
Daiki Funaiwa ◽  
Sojiro Murakami ◽  
Shotaro Kadoya ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Standing Wave ◽  
Dynamic Range ◽  
Scattered Light ◽  
High Dynamic Range ◽  
Measurement Range ◽  
Diameter Distribution ◽  
Process Measurement ◽  
Air Turbulence ◽  
Tapered Optical Fiber

AbstractIn this paper, we propose an in-process measurement method of the diameter of micro-optical fiber such as a tapered optical fiber. The proposed technique is based on analyzing optically scattered light generated by standing wave illumination. The proposed method is significant in that it requires an only limited measurement range and does not require a high dynamic range sensor. These properties are suitable for in-process measurement. This experiment verified that the proposed method could measure a fiber diameter as stable as ± 0.01 μm under an air turbulence environment. As a result of comparing the measured diameter distribution with those by scanning electron microscopy, it was confirmed that the proposed method has a measurement accuracy better than several hundred nanometers.

scholarly journals Expanding Assay Dynamics: A Combined Competitive and Direct Assay System for the Quantification of Proteins in Multiplexed Immunoassays

2008 ◽  
Vol 54 (6) ◽  
pp. 956-963 ◽  
Author(s):  
Michael Hartmann ◽  
Monika Schrenk ◽  
Anette Döttinger ◽  
Sarah Nagel ◽  
Johan Roeraade ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Protein Microarray ◽  
Measurement Range ◽  
Multiplex Assay ◽  
Competitive System ◽  
Direct Immunoassay ◽  
Sandwich Configuration ◽  
Readout Channel ◽  
Autoantibody Detection ◽  
Detection And Quantification

Abstract Background: The concurrent detection and quantification of analytes that vary widely in concentration present a principal problem in multiplexed assay systems. Combining competitive and sandwich immunoassays permits coverage of a wide concentration range, and both highly abundant molecules and analytes present in low concentration can be quantified within the same assay. Methods: The use of different fluorescence readout channels allows the parallel use of a competitive system and a sandwich configuration. The 2 generated assay signals are combined and used to calculate the amount of analyte. The measurement range can be adjusted by varying the competitor concentration, and an extension of the assay system’s dynamic range is possible. Results: We implemented the method in a planar protein microarray–based autoimmune assay to detect autoantibodies against 13 autoantigens and to measure the concentration of a highly abundant protein, total human IgG, in one assay. Our results for autoantibody detection and IgG quantification agreed with results obtained with commercially available assays. The use of 2 readout channels in the protein microarray–based system reduced spot-to-spot variation and intraassay variation. Conclusions: By combining a direct immunoassay with a competitive system, analytes present in widely varying concentrations can be quantified within a single multiplex assay. Introducing a second readout channel for analyte quantification is an effective tool for spot-to-spot normalization and helps to lower intraassay variation.

scholarly journals Time Difference of Arrival (TDoA) Localization Combining Weighted Least Squares and Firefly Algorithm

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2554 ◽  
Author(s):  
Peng Wu ◽  
Shaojing Su ◽  
Zhen Zuo ◽  
Xiaojun Guo ◽  
Bei Sun ◽  
...  
Keyword(s):  
Least Squares ◽  
Firefly Algorithm ◽  
Weighted Least Squares ◽  
Initial Position ◽  
Time Difference ◽  
Sensor Nodes ◽  
Passive Location ◽  
Search Region ◽  
Time Difference Of Arrival ◽  
Location Methods

Time difference of arrival (TDoA) based on a group of sensor nodes with known locations has been widely used to locate targets. Two-step weighted least squares (TSWLS), constrained weighted least squares (CWLS), and Newton–Raphson (NR) iteration are commonly used passive location methods, among which the initial position is needed and the complexity is high. This paper proposes a hybrid firefly algorithm (hybrid-FA) method, combining the weighted least squares (WLS) algorithm and FA, which can reduce computation as well as achieve high accuracy. The WLS algorithm is performed first, the result of which is used to restrict the search region for the FA method. Simulations showed that the hybrid-FA method required far fewer iterations than the FA method alone to achieve the same accuracy. Additionally, two experiments were conducted to compare the results of hybrid-FA with other methods. The findings indicated that the root-mean-square error (RMSE) and mean distance error of the hybrid-FA method were lower than that of the NR, TSWLS, and genetic algorithm (GA). On the whole, the hybrid-FA outperformed the NR, TSWLS, and GA for TDoA measurement.

scholarly journals Initial Time Difference Stability of Causal Differential Systems in terms of Lyapunov Functions and Lyapunov Functionals

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Coşkun Yakar ◽  
Mustafa Bayram Gücen
Keyword(s):  
Differential System ◽  
Lyapunov Functions ◽  
Lyapunov Functional ◽  
Initial Position ◽  
Time Difference ◽  
Initial Time ◽  
Qualitative Behavior ◽  
Lyapunov Functionals ◽  
Comparison Result ◽  
Differential Systems

We investigate the qualitative behavior of a perturbed causal differential equation that differs in initial position and initial time with respect to the unperturbed causal differential equations. We compare the classical notion of stability of the causal differential systems to the notion of initial time difference stability of causal differential systems and present a comparison result in terms of Lyapunov functions. We have utilized Lyapunov functions and Lyapunov functional in the study of stability theory of causal differential systems when establishing initial time difference stability of the perturbed causal differential system with respect to the unperturbed causal differential system.

Design of terahertz wave polarizing beam splitter

Optik ◽  
2013 ◽  
Vol 124 (23) ◽  
pp. 6089-6092
Author(s):  
Wenliang Wang ◽  
Xiaohong Rong
Keyword(s):  
Beam Splitter ◽  
Terahertz Wave ◽  
Polarizing Beam Splitter

Optical Distance Meter Using a Pulsed Laser Diode and Fast Avalanche Photo Diodes for Measurements of Molten Steel Levels

1996 ◽  
Vol 118 (4) ◽  
pp. 800-803 ◽  
Author(s):  
Tsutomu Araki ◽  
Haruhiko Yoshida
Keyword(s):  
Light Source ◽  
Laser Diode ◽  
Molten Steel ◽  
Dynamic Range ◽  
Pulsed Laser ◽  
Casting Process ◽  
Measurement Range ◽  
Steel Mold ◽  
Optical Distance ◽  
Fast Rise

An optical distance meter with a wide dynamic range, is proposed for measuring the level of molten steel in a steel mold. The meter operates by measuring the flight time of a short optical pulse that is propagated between the light source and the target. A pulsed laser diode with a fast rise time is utilized as a light source, and two avalanche photo-diodes are used as detectors. The optical distance meter performs at a measurement range and a standard deviation of the measurement error of 1 m and 1 mm for the black paper target, respectively. To test its reliability, the distance meter is used to monitor the level of molten steel during a continuous casting process. The results obtained were compared with those obtained using an eddy current sensor and a γ-ray sensor. The measurement range of the optical method is ten times those attained using other two sensors. Continuous monitoring of the steel level can be done from the initiation of the casting process with the proposed distance meter.

scholarly journals In-Situ Wireless Pressure Measurement Using Zero-Power Packaged Microwave Sensors

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1263 ◽  
Author(s):  
Julien Philippe ◽  
Maria De Paolis ◽  
Dominique Henry ◽  
Alexandre Rumeau ◽  
Antony Coustou ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Pressure Sensors ◽  
Measurement Range ◽  
Full Scale ◽  
Remote Measurement ◽  
Reverberant Environments ◽  
Indoor Wireless ◽  
Measurement Results ◽  
Radar Imagery ◽  
First Time

This paper reports the indoor wireless measurement of pressure from zero-power (or passive) microwave (24 GHz) sensors. The sensors are packaged and allow the remote measurement of overpressure up to 2.1 bars. Their design, fabrication process and packaging are detailed. From the measurement of sensor scattering parameters, the outstanding sensitivity of 995 MHz/bar between 0.8 and 2.1 bars was achieved with the full-scale measurement range of 1.33 GHz. Moreover, the 3D radar imagery technique was applied for the remote interrogation of these sensors in electromagnetic reverberant environments. The full-scale dynamic range of 4.9 dB and the sensitivity of 4.9 dB/bar between 0.7 and 1.7 bars were achieved with radar detection in a highly reflective environment. These measurement results demonstrate for the first time the ability of the radar imagery technique to interrogate fully passive pressure sensors in electromagnetic reverberant environments.

Resonant cavity enhanced waveguide transmission for high-efficiency Terahertz polarization beam splitter

2021 ◽  
Vol 35 (05) ◽  
pp. 2150089
Author(s):  
Xiao-Fei Jiao ◽  
Zi-Heng Zhang ◽  
Yun Xu ◽  
Guo-Feng Song
Keyword(s):  
Beam Splitter ◽  
High Efficiency ◽  
Resonant Cavity ◽  
Transverse Magnetic ◽  
Terahertz Wave ◽  
Polarization Beam Splitter ◽  
Optical Systems ◽  
Metal Insulator Metal ◽  
Polarization Splitting ◽  
Easy Integration

In this study, a design for the high-efficiency transmissive terahertz polarization beam splitter is proposed. Based on the metal–insulator–metal waveguide array structure, it is found that the phase change between the transverse-electric (TE) and transverse-magnetic (TM) modes of terahertz wave transmission depends greatly on the medium width. According to this phenomenon, our designed devices can achieve polarization splitting of TE and TM modes in the frequency range 0.8–2.4 THz, and the transmittance can be maintained above 85%. In addition, through judicious design, polarization splittings with 93% transmittance at 1 THz and 95% transmittance at 1.5 THz are obtained, and polarization splitting at different angles is achieved according to variable periods. Compared with the traditional polarization beam splitter, this design has the advantages of adjustable frequency, high efficiency, and easy integration, thus having potential application in terahertz optical systems.

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