Enhanced histotripsy induced by hundreds of microsecond pulses and dual-frequency second harmonic superimposition: A preliminary study

2017 ◽  
Author(s):  
Yujiao Li ◽  
Rui Wang ◽  
Mingzhu Lu ◽  
Dan Han ◽  
Yanshan Liu ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Dual Frequency ◽  
Preliminary Study

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

Adjusting the phase of the signals transmitted from dual frequency probe for reducing second harmonic during propagation

2008 ◽  
Vol 123 (5) ◽  
pp. 3695-3695
Author(s):  
Pasovic Mirza ◽  
Christian Cachard ◽  
Guillaume Matte ◽  
René Van Der Steen ◽  
Nico De Jong ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Dual Frequency

Asymmetrical Diphenylpolyene Pendant Polymers for Nonlinear Optical Activity

1990 ◽  
Vol 214 ◽  
Author(s):  
Linda S. Sapochak ◽  
David W. Polis ◽  
Larry R. Dalton ◽  
Charles W. Spangler
Keyword(s):  
Nonlinear Optical ◽  
Second Harmonic ◽  
Damage Threshold ◽  
Laser Damage Threshold ◽  
Device Development ◽  
High Laser ◽  
Nlo Materials ◽  
Donor Acceptor ◽  
Recent Activity ◽  
Preliminary Study

ABSTRACTRecent activity in the development of nonlinear optical (NLO) materials with high second order susceptibilities has prompted the development of a wide variety of pendant polymers which possess desirable properties for device development, including high Tg minimal relaxation of the poled matrix, and high laser damage threshold. Ideal candidates for such systems are asymmetrically substituted oligomers of polyacetylenes such as dimethylaminonitrostilbene (DANS) and corresponding higher order oligomers. We report here a preliminary study of the synthesis of asymmetrically substituted donor/acceptor diphenyl-capped polyenes and thienylene vinylene oligomers attached as pendant moieties on polyvinylphenol (PVP) for second harmonic generation.

scholarly journals EXTERIOR ORIENTATION OF HYPERSPECTRAL FRAME IMAGES COLLECTED WITH UAV FOR FOREST APPLICATIONS

2016 ◽  
Vol XL-3/W4 ◽  
pp. 45-50
Author(s):  
A. Berveglieri ◽  
A. M. G. Tommaselli
Keyword(s):  
Dual Frequency ◽  
Image Block ◽  
Weighted Constraints ◽  
Spectral Bands ◽  
Ground Control Points ◽  
Bundle Block Adjustment ◽  
Aerial Vehicle ◽  
Camera Position ◽  
Preliminary Study ◽  
Image Orientation

This paper describes a preliminary study on the image orientation acquired by a hyperspectral frame camera for applications in small tropical forest areas with dense vegetation. Since access to the interior of forests is complicated and Ground Control Points (GCPs) are not available, this study conducts an assessment of the altimetry accuracy provided by control targets installed on one border of an image block, simulating it outside a forest. A lightweight Unmanned Aerial Vehicle (UAV) was equipped with a hyperspectral camera and a dual-frequency GNSS receiver to collect images at two flying strips covering a vegetation area. The assessment experiments were based on Bundle Block Adjustment (BBA) with images of two spectral bands (from two sensors) using several weighted constraints in the camera position. Trials with GCPs (presignalized targets) positioned only on one side of the image block were compared with trials using GCPs in the corners. Analyses were performed on altimetry discrepancies obtained from altimetry checkpoints. The results showed a discrepancy in Z coordinate of approximately 40 cm using the proposed technique, which is sufficient for applications in forests.

scholarly journals EXTERIOR ORIENTATION OF HYPERSPECTRAL FRAME IMAGES COLLECTED WITH UAV FOR FOREST APPLICATIONS

2016 ◽  
Vol XL-3/W4 ◽  
pp. 45-50 ◽  
Author(s):  
A. Berveglieri ◽  
A. M. G. Tommaselli
Keyword(s):  
Dual Frequency ◽  
Image Block ◽  
Weighted Constraints ◽  
Spectral Bands ◽  
Ground Control Points ◽  
Bundle Block Adjustment ◽  
Aerial Vehicle ◽  
Camera Position ◽  
Preliminary Study ◽  
Image Orientation

This paper describes a preliminary study on the image orientation acquired by a hyperspectral frame camera for applications in small tropical forest areas with dense vegetation. Since access to the interior of forests is complicated and Ground Control Points (GCPs) are not available, this study conducts an assessment of the altimetry accuracy provided by control targets installed on one border of an image block, simulating it outside a forest. A lightweight Unmanned Aerial Vehicle (UAV) was equipped with a hyperspectral camera and a dual-frequency GNSS receiver to collect images at two flying strips covering a vegetation area. The assessment experiments were based on Bundle Block Adjustment (BBA) with images of two spectral bands (from two sensors) using several weighted constraints in the camera position. Trials with GCPs (presignalized targets) positioned only on one side of the image block were compared with trials using GCPs in the corners. Analyses were performed on altimetry discrepancies obtained from altimetry checkpoints. The results showed a discrepancy in Z coordinate of approximately 40 cm using the proposed technique, which is sufficient for applications in forests.

scholarly journals Electron heating modes and frequency coupling effects in dual-frequency capacitive CF4 plasmas

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Aranka Derzsi ◽  
Edmund Schüngel ◽  
Zoltán Donkó ◽  
Julian Schulze
Keyword(s):  
Control Parameter ◽  
Second Harmonic ◽  
Low Frequency ◽  
Dual Frequency ◽  
Electron Heating ◽  
Particle In Cell ◽  
Sheath Edge ◽  
Separate Control ◽  
Frequency Coupling ◽  
Coupling Mechanisms

AbstractTwo types of capacitive dual-frequency discharges, used in plasma processing applications to achieve the separate control of the ion flux, Гi, and the mean ion energy, <Ei>, at the electrodes, operated in CF4, are investigated by particle-in-cell simulations: (i) In classical dual-frequency discharges, driven by significantly different frequencies (1.937 MHz + 27.12 MHz), <Ei> and Гi are controlled by the voltage amplitudes of the low-frequency and high-frequeny components, ΦLF and ΦHF, respectively. (ii) In electrically asymmetric (EA) discharges, operated at a fundamental frequency and its second harmonic (13.56 MHz + 27.12 MHz), ΦLF and ΦHF control Гi, whereas the phase shift between the driving frequencies, θ, is varied to adjust <Ei>.We focus on the effect of changing the control parameter for <Ei> on the electron heating and ionization dynamics and on Гi. We find that in both types of dual-frequency strongly electronegative discharges, changing the control parameter results in a complex effect on the electron heating and ionization dynamics: in classical dual-frequency discharges, besides the frequency coupling affecting the sheath expansion heating, additional frequency coupling mechanisms influence the electron heating in the plasma bulk and at the collapsing sheath edge; in EA dual-frequency discharges the electron heating in the bulk results in asymmetric ionization dynamics for values of θ around 45°, i.e., in the case of a symmetric applied

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