High sensitivity plated-wire sensor using second harmonic oscillation and its applications

1971 ◽  
Vol 7 (3) ◽  
pp. 436-437 ◽  
Author(s):  
S. Oshima ◽  
T. Watanabe ◽  
T. Fukui
Keyword(s):  
Second Harmonic ◽  
Harmonic Oscillation ◽  
High Sensitivity

scholarly journals Second harmonic generation correlation spectroscopy for characterizing translationally diffusing protein nanocrystals

2016 ◽  
Vol 72 (7) ◽  
pp. 849-859
Author(s):  
Ximeng Y. Dow ◽  
Christopher M. Dettmar ◽  
Emma L. DeWalt ◽  
Justin A. Newman ◽  
Alexander R. Dow ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Unit Volume ◽  
Second Harmonic ◽  
Incident Beam ◽  
High Sensitivity ◽  
Correlation Spectroscopy ◽  
Optical Process ◽  
Active Nanoparticles ◽  
Low Sensitivity

Second harmonic generation correlation spectroscopy (SHG-CS) is demonstrated as a new approach to protein nanocrystal characterization. A novel line-scanning approach was performed to enable autocorrelation analysis without sample damage from the intense incident beam. An analytical model for autocorrelation was developed, which includes a correction for the optical scattering forces arising when focusing intense, infrared beams. SHG-CS was applied to the analysis of BaTiO3nanoparticles ranging from 200 to ∼500 nm and of photosystem I nanocrystals. A size distribution was recovered for each sample and compared with the size histogram measured by scanning electron microscopy (SEM). Good agreement was observed between the two independent measurements. The intrinsic selectivity of the second-order nonlinear optical process provides SHG-CS with the ability to distinguish well ordered nanocrystals from conglomerates and amorphous aggregates. Combining the recovered distribution of particle diameters with the histogram of measured SHG intensities provides the inherent hyperpolarizability per unit volume of the SHG-active nanoparticles. Simulations suggest that the SHG activity per unit volume is likely to exhibit relatively low sensitivity to the subtle distortions within the lattice that contribute to resolution loss in X-ray diffraction, but high sensitivity to the presence of multi-domain crystals.

Real-Time System for Liquid Level Measurement

2013 ◽  
Vol 441 ◽  
pp. 356-359
Author(s):  
Wei Wei ◽  
Hai Ying Jiang ◽  
Qin Jian Sun ◽  
Qiang Huang ◽  
Zhi Wei Wang
Keyword(s):  
Harmonic Oscillation ◽  
High Sensitivity ◽  
Capacitive Sensor ◽  
Liquid Level ◽  
Capacitance Measurement ◽  
Measurement Circuit ◽  
Real Time System ◽  
Level Measurement ◽  
Sensor Structure ◽  
Level Height

A small level measurement system is designed by installing a compact capacitive level sensor in the small container. By analyzing the capacitive sensor structure, a sensor measurement circuit is designed with high sensitivity, measuring stability and good repeatability. Capacitance measurement circuit makes use of multiple harmonic oscillation principle. The microcomputer measures the oscillation frequency of the multivibrator, and calculates the liquid level height based on the monotonic function about the liquid level height and frequency.

scholarly journals Protein-crystal detection with a compact multimodal multiphoton microscope

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Qing-di Cheng ◽  
Hsiang-Yu Chung ◽  
Robin Schubert ◽  
Shih-Hsuan Chia ◽  
Sven Falke ◽  
...  
Keyword(s):  
Data Collection ◽  
Harmonic Generation ◽  
Diffraction Data ◽  
Second Harmonic ◽  
High Sensitivity ◽  
Protein Crystal ◽  
Third Harmonic ◽  
Increasing Demand ◽  
Biomolecular Crystallography ◽  
Nano Crystal

Abstract There is an increasing demand for rapid, effective methods to identify and detect protein micro- and nano-crystal suspensions for serial diffraction data collection at X-ray free-electron lasers or high-intensity micro-focus synchrotron radiation sources. Here, we demonstrate a compact multimodal, multiphoton microscope, driven by a fiber-based ultrafast laser, enabling excitation wavelengths at 775 nm and 1300 nm for nonlinear optical imaging, which simultaneously records second-harmonic generation, third-harmonic generation and three-photon excited ultraviolet fluorescence to identify and detect protein crystals with high sensitivity. The instrument serves as a valuable and important tool supporting sample scoring and sample optimization in biomolecular crystallography, which we hope will increase the capabilities and productivity of serial diffraction data collection in the future.

scholarly journals Large Nonlinear Kerr Angle in non-Centrosymmetric Fe/AlGaAs (001) Heterostructure

2006 ◽  
Vol 941 ◽  
Author(s):  
Haibin Zhao ◽  
Diyar Talbayev ◽  
Gunter Luepke ◽  
Aubrey Hanbicki ◽  
Connie Li ◽  
...  
Keyword(s):  
Second Harmonic ◽  
High Sensitivity ◽  
Harmonic Signal ◽  
Direct Consequence ◽  
Optical Effect ◽  
Kerr Rotation ◽  
Hard Axis ◽  
Magneto Optical Effect ◽  
Kerr Angle ◽  
Second Harmonic Signal

AbstractA large nonlinear magneto-optical effect is observed in a non-centrosymmetric Fe/AlGaAs (001) heterostructure. This effect is a direct consequence of interference between second-harmonic optical waves of magnetic and crystallographic origin, generated at ferromagnetic Fe interface and bulk AlGaAs, respectively. The longitudinal nonlinear Kerr rotation is measured to be 1.6° along the [1-10] hard axis, about two orders of magnitude stronger than the linear equivalent. The rotational second-harmonic signal shows large magnetic contrast along all the in-plane directions, demonstrating a high sensitivity to the magnetization of an anisotropic interface in the longitudinal geometry.

scholarly journals Influence of Electric Field Coupling Model on the Simulated Performances of a GaN Based Planar Nanodevice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
K. Y. Xu ◽  
Z. N. Wang ◽  
Y. N. Wang ◽  
J. W. Xiong ◽  
G. Wang
Keyword(s):  
Electric Field ◽  
3D Model ◽  
Second Harmonic ◽  
Strong Electric Field ◽  
Three Dimensional ◽  
Harmonic Oscillation ◽  
Two Dimensional ◽  
Dc Bias ◽  
Simulation Results ◽  
2D Model

The performances of a two-dimensional electron gas (2DEG) based planar nanodevice are studied by a two-dimensional-three-dimensional (2D-3D) combined model and an entirely 2D model. In both models, 2DEGs are depicted by 2D ensemble Monte Carlo (EMC) method. However electric field distributions in the devices are obtained by self-consistently solving 2D and 3D Poisson equations for the 2D model and the 2D-3D model, respectively. Simulation results obtained by both models are almost the same at low bias while showing distinguished differences at high bias. The 2D model predicts larger output current and slightly higher threshold voltage of Gunn oscillations. Although the fundamental frequencies of current oscillations obtained by both models are similar, the deviation of wave shape from sinusoidal waveform obtained by the 2D model is more serious than that obtained by 2D-3D model. Moreover, results obtained by the 2D model are more sensitive both to the bias conditions and to the change of device parameters. Interestingly, a look-like second harmonic oscillation has been observed at DC bias. We contribute the origin of divergences in simulation results to the different coupling path of electric field in the two models. And the second-harmonic oscillations at DC bias should be the result of the appearance of concomitant oscillations beside the channel excited by strong electric-field effects.

Spectrum Absorption Methane Gas Sensor with Optical Fiber Based on Frequency Harmonic Detection Mechanism

2011 ◽  
Vol 383-390 ◽  
pp. 2907-2911
Author(s):  
Jiu Long Wang
Keyword(s):  
Optical Fiber ◽  
Light Source ◽  
Electromagnetic Interference ◽  
Near Infrared ◽  
Dynamic Range ◽  
Second Harmonic ◽  
High Sensitivity ◽  
Detection Mechanism ◽  
Methane Gas ◽  
Safe Production

Methane is an easily burning and exploding gas. It is the primary component of many gas fuels such as mine gas and natural gas and so on. In the coal mine accidences of our country, the casualties caused by gas explosion covers over 50% in all great casualties, and it becomes the largest obstruction of safe production. Incident online detecting methane gas density has important significance for mine and plant safe production and personal safety. Based on the near infrared spectral absorption of methane, a system using absorption type optical fiber for high sensitivity methane detection is demonstrated in this paper. DFB LD is adopted as light source in this paper. Modulating the light source, methane gas is detected by second harmonic. The ratio of the fundamental and second harmonic signal can be used for eliminating the interference owing to light power changing. The mathematical model of gas concentration harmonic measurement is built up. The result of methane concentration is also shown. The system overcomes the defect of great interference of available instruments by light route. It has advantages such as high sensitivity, quick response speed, large dynamic range, preventing electromagnetic interference, preventing burning and explosion, not easily being poisoned and so on. The probe can be put in condition of easily burning and exploding, being poisonous being high temperature and so on that man and instrument can not easily enter. It can realize online continuous telecontrol and telemeter.

scholarly journals Ultra-Highly Sensitive Hydrogen Chloride Detection Based on Quartz-Enhanced Photothermal Spectroscopy

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3563
Author(s):  
Yufei Ma ◽  
Ziting Lang ◽  
Ying He ◽  
Shunda Qiao ◽  
Yu Li
Keyword(s):  
Hydrogen Chloride ◽  
Continuous Wave ◽  
Second Harmonic ◽  
Modulation Depth ◽  
High Sensitivity ◽  
Integration Time ◽  
Wavelength Modulation ◽  
Photothermal Spectroscopy ◽  
Highly Sensitive ◽  
Hcl Concentration

Combining the merits of non-contact measurement and high sensitivity, the quartz-enhanced photothermal spectroscopy (QEPTS) technique is suitable for measuring acid gases such as hydrogen chloride (HCl). In this invited paper, we report, for the first time, on an ultra-highly sensitive HCl sensor based on the QEPTS technique. A continuous wave, distributed feedback (CW-DFB) fiber-coupled diode laser with emission wavelength of 1.74 µm was used as the excitation source. A certified mixture of 500 ppm HCl:N2 was adapted as the analyte. Wavelength modulation spectroscopy was used to simplify the data processing. The wavelength modulation depth was optimized. The relationships between the second harmonic (2f) amplitude of HCl-QEPTS signal and the laser power as well as HCl concentration were investigated. An Allan variance analysis was performed to prove that this sensor had good stability and high sensitivity. The proposed HCl-QEPTS sensor can achieve a minimum detection limit (MDL) of ~17 parts per billion (ppb) with an integration time of 130 s. Further improvement of such an HCl-QEPTS sensor performance was proposed.

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