scholarly journals A Dispersion Compensation Method Based on Resampling of Modulated Signal for FMCW Lidar

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 249
Author(s):  
Shuo Jiang ◽  
Bo Liu ◽  
Shengjie Wang
Keyword(s):  
Continuous Wave ◽  
Dispersion Compensation ◽  
Compensation Method ◽  
Laser Ranging ◽  
Full Width ◽  
Half Maximum ◽  
Optical Interferometers ◽  
Multiple Measurements ◽  
Reflected Signal ◽  
Reference Clock

In order to eliminate the nonlinearity in the laser modulation process, the dual-interferometers system is often adopted in the frequency modulation continuous wave (FMCW) laser ranging. However, the dispersion mismatch between the fiber reference interferometer and the measurement interferometer will lead to the decrease in ranging accuracy and resolution. In this paper, a dispersion compensation method based on resampling with a modulated signal is proposed. Since the beat signal of the end face of the delay fiber is not affected by dispersion mismatch, it can be modulated to generate a signal whose phase is proportional to that of the target spatial signal. Then, the modulated signal is regarded as the reference clock to sample the target spatial signal. Thereby, the influence of the dispersion mismatch between the two optical interferometers can be eliminated. In this article, simulation is performed to verify the effect of this method, and an experiment is carried out on the target at the distance of 2.4 m. Experiments show that the full width at half maximum (FWHM) of the distance spectrum after dispersion compensation is consistent with the reflected signal from the end face of the delay fiber, and the standard deviation of multiple measurements reached 10.12 μm.

Temperature-gradient analyzers for non-resonant inelastic X-ray scattering

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Daisuke Ishikawa ◽  
Alfred Q. R. Baron
Keyword(s):  
Temperature Gradient ◽  
Solid Angle ◽  
Dispersion Compensation ◽  
Full Width ◽  
Half Maximum ◽  
Sensitive Detector ◽  
X Ray ◽  
X Ray Scattering ◽  
Position Sensitive ◽  
And Performance

The detailed fabrication and performance of the temperature-gradient analyzers that were simulated by Ishikawa & Baron [(2010). J. Synchrotron Rad. 17, 12–24] are described and extended to include both quadratic and 2D gradients. The application of a temperature gradient compensates for geometric contributions to the energy resolution while allowing collection of a large solid angle, ∼50 mrad × 50 mrad, of scattered radiation. In particular, when operating relatively close to backscattering, π/2 − θB = 1.58 mrad, the application of a gradient of 1.32 K per 80 mm improves the measured total resolution from 60 to 25 meV at the full width at half-maximum, while when operating further from backscattering, π/2 − θB = 6.56 mrad, improvement from 330 to 32 meV is observed using a combination of a gradient of 6.2 K per 80 mm and dispersion compensation with a position-sensitive detector. In both cases, the operating energy was 15.8 keV and the incident bandwidth was 22 meV. Notably, the use of a temperature gradient allows a relatively large clearance at the sample, permitting installation of more complicated sample environments.

Observation of continuous KrCl excimer fluorescence in microwave discharges employing binary mixtures of Kr and Cl2

1991 ◽  
Vol 69 (6) ◽  
pp. 699-701 ◽  
Author(s):  
Scott B. Hassal ◽  
Edward A. Ballik
Keyword(s):  
Binary Mixture ◽  
Total Pressure ◽  
Full Width Half Maximum ◽  
Continuous Wave ◽  
Wavelength Region ◽  
Gas Composition ◽  
Full Width ◽  
Half Maximum ◽  
Excimer Fluorescence ◽  
Microwave Discharges

A novel apparatus was designed to couple 2.45-GHz microwave radiation into a gas discharge. Using this apparatus, continuous-wave 222-nm B → X fluorescence of the KrF excimer system was observed in a binary mixture of chlorine and krypton. The effects of gas composition and total pressure on the fluorescence intensity at a wavelength of 222 nm was investigated. Spectra over the wavelength region of 200–320 nm were recorded for various gas compositions near the optimum total pressures for excimer fluorescence. The 222-nm B → X KrCl excimer transition was apparent in all cases and had a full-width half-maximum (FWHM) of 3 nm. In addition, the 258-nm Cl2 excimer transition was also evident with a FWHM of 5 nm. Both the center frequencies and widths of these transitions were constant for the conditions tested.

1064 nm High-Power Broad Area Semiconductor Lasers with Electrode Pattern

2011 ◽  
Vol 84-85 ◽  
pp. 590-593
Author(s):  
Zhong Liang Qiao ◽  
Si Yu Zhang ◽  
Xin Gao ◽  
Peng Lu ◽  
Hui Li ◽  
...  
Keyword(s):  
Aluminum Nitride ◽  
Semiconductor Lasers ◽  
High Power ◽  
Continuous Wave ◽  
Far Field ◽  
Full Width ◽  
Half Maximum ◽  
Broad Area ◽  
Continuous Wave Output Power ◽  
Area Distribution

According to the principle of carrier diffusion, aluminum nitride (AlN) coating, and RIE deep etching technology are implemented, 1064 nm broad area distribution electrode lasers have been obtained exhibiting near single lobe near and far field. We report electrode pattern lasers emitting at 1064 nm with the minimal full width at half maximum (FWHM) horizontal angle of 2.7° while the maximum continuous-wave output power up to 3.65 W and slope efficiencies as high as 0.85 W/A.

Research of Angled 8° Integrated 808 nm Wavelength SLDs

2011 ◽  
Vol 84-85 ◽  
pp. 598-602
Author(s):  
Si Yu Zhang ◽  
Zhong Liang Qiao ◽  
Bao Xue Bo ◽  
Xin Gao ◽  
Yi Qu ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Output Power ◽  
Room Temperature ◽  
Continuous Wave ◽  
Seed Source ◽  
Full Width ◽  
Half Maximum

Integrated 808 nm wavelength super-luminescent diodes (SLDs) with a ring seed source and a tapered amplifier were fabricated tilted at 8° from the facet normal. Max-output power of 700 mW was obtained in continuous wave (CW) mode under room temperature, and the full width at half maximum (FWHM) of the emission spectrum is 36 nm.

High Performance 785 nm Wavelength Super-Luminescent Diodes

2011 ◽  
Vol 84-85 ◽  
pp. 594-597
Author(s):  
Si Yu Zhang ◽  
Zhong Liang Qiao ◽  
Xin Gao ◽  
Yi Qu ◽  
Guo Jun Liu ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Output Power ◽  
High Performance ◽  
Room Temperature ◽  
Continuous Wave ◽  
Ring Cavity ◽  
Maximum Output Power ◽  
Maximum Output ◽  
Full Width ◽  
Half Maximum

High-performance 785 nm wavelength super-luminescent diodes (SLDs) with ring cavity were fabricated. The maximum output power of 100 mW was obtained in continuous wave (CW) mode under room temperature. The full width at half maximum (FWHM) of the emission spectrum was 24 nm.

808 nm Semiconductor Lasers with Tailored Gain for Mode Shape

2011 ◽  
Vol 84-85 ◽  
pp. 603-606
Author(s):  
Zhong Liang Qiao ◽  
Bao Xue Bo ◽  
Si Yu Zhang ◽  
Xin Gao ◽  
Peng Lu ◽  
...  
Keyword(s):  
Semiconductor Lasers ◽  
Mode Shape ◽  
Continuous Wave ◽  
Hole Burning ◽  
Full Width ◽  
Half Maximum ◽  
Optical Mode ◽  
Continuous Wave Output Power ◽  
High Slope ◽  
Modal Behavior

We implement the concept of the distributed electrode, which allows to improve the modal behavior of lasers and to reduce spatial-hole burning effects by preferentially localizing current injection in the center of the structure, hence discriminating the optical mode. We report the first realization of distributed electrode lasers emitting at 808 nm with the measured full width at half maximum (FWHM) angle of the minimal horizontal angle as 3.8° while the maximum continuous-wave output power is up to 4 W and high slope efficiencies as high as 0.95 W/A.

scholarly journals Spectroscopic Studies of Laser-Based Far-Ultraviolet Plasma Light Source

2021 ◽  
Vol 11 (15) ◽  
pp. 6919
Author(s):  
Majid Masnavi ◽  
Martin Richardson
Keyword(s):  
Dense Plasma ◽  
Wavelength Region ◽  
Spectroscopic Studies ◽  
Radiation Hydrodynamics ◽  
Full Width ◽  
Half Maximum ◽  
Laser Plasmas ◽  
Series Of Experiments ◽  
Far Ultraviolet ◽  
Radiation Conversion

A series of experiments is described which were conducted to measure the absolute spectral irradiances of laser plasmas created from metal targets over the wavelength region of 123–164 nm by two separate 1.0 μm lasers, i.e., using 100 Hz, 10 ns, 2–20 kHz, 60–100 ns full-width-at-half-maximum pulses. A maximum radiation conversion efficiency of ≈ 3%/2πsr is measured over a wavelength region from ≈ 125 to 160 nm. A developed collisional-radiative solver and radiation-hydrodynamics simulations in comparison to the spectra detected by the Seya–Namioka-type monochromator reveal the strong broadband experimental radiations which mainly originate from bound–bound transitions of low-ionized charges superimposed on a strong continuum from a dense plasma with an electron temperature of less than 10 eV.

scholarly journals Time to peak and full width at half maximum in MR perfusion: valuable indicators for monitoring moyamoya patients after revascularization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam Huang ◽  
Chung-Wei Lee ◽  
Hon-Man Liu
Keyword(s):  
Study Data ◽  
Unknown Etiology ◽  
Dynamic Susceptibility ◽  
Full Width ◽  
Half Maximum ◽  
Mr Perfusion ◽  
Dynamic Susceptibility Contrast ◽  
Time To Peak ◽  
Mr Perfusion Imaging ◽  
Outcome Monitoring

AbstractMoyamoya disease (MMD) is a chronic, steno-occlusive cerebrovascular disorder of unknown etiology. Surgical treatment is the only known effective method to restore blood flow to affected areas of the brain. However, there are lack of generally accepted noninvasive tools for therapeutic outcome monitoring. As dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) is the standard MR perfusion imaging technique in the clinical setting, we investigated a dataset of nineteen pediatric MMD patients with one preoperational and multiple periodic DSC MRI examinations for four to thirty-eight months after indirect revascularization. A rigid gamma variate model was used to derive two nondeconvolution-based perfusion parameters: time to peak (TTP) and full width at half maximum (FWHM) for monitoring transitional bolus delay and dispersion changes respectively. TTP and FWHM values were normalized to the cerebellum. Here, we report that 74% (14/19) of patients improve in both TTP and FWHM measurements, and whereof 57% (8/14) improve more noticeably on FWHM. TTP is in good agreement with Tmax in estimating bolus delay. Our study data also suggest bolus dispersion estimated by FWHM is an additional, informative indicator in pediatric MMD monitoring.

Preparation of highly c-axis oriented AlN thin films on Hastelloy tapes with Y2O3 buffer layer for flexible SAW sensor applications

2016 ◽  
Vol 09 (02) ◽  
pp. 1650023 ◽  
Author(s):  
Bin Peng ◽  
Jianying Jiang ◽  
Guo Chen ◽  
Lin Shu ◽  
Jie Feng ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Smooth Surface ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Mean Square ◽  
Full Width ◽  
Half Maximum ◽  
Sensor Applications ◽  
Saw Sensor ◽  
Y2o3 Buffer Layer

Highly c-axis oriented aluminum nitrade (AlN) films were successfully deposited on flexible Hastelloy tapes by middle-frequency magnetron sputtering. The microstructure and piezoelectric properties of the AlN films were investigated. The results show that the AlN films deposited directly on the bare Hastelloy substrate have rough surface with root mean square (RMS) roughness of 32.43[Formula: see text]nm and its full width at half maximum (FWHM) of the AlN (0002) peak is [Formula: see text]. However, the AlN films deposited on the Hastelloy substrate with Y2O3 buffer layer show smooth surface with RMS roughness of 5.46[Formula: see text]nm and its FWHM of the AlN (0002) peak is only [Formula: see text]. The piezoelectric coefficient d[Formula: see text] of the AlN films deposited on the Y2O3/Hastelloy substrate is larger than three times that of the AlN films deposited on the bare Hastelloy substrate. The prepared highly c-axis oriented AlN films can be used to develop high-temperature flexible SAW sensors.

scholarly journals Research of the anti-resonance pulse forming network and its application in the Marx generator

2016 ◽  
Vol 34 (4) ◽  
pp. 675-686 ◽  
Author(s):  
Z.-L. Pan ◽  
J.-H. Yang ◽  
X.-B. Cheng
Keyword(s):  
Equivalent Circuit ◽  
Rise Time ◽  
Pulse Width ◽  
Marx Generator ◽  
Full Width ◽  
Half Maximum ◽  
Compact Structure ◽  
Fall Time ◽  
Pulse Forming Network ◽  
Load Pulse

AbstractAn anti-resonance pulse forming network (PFN) has been designed, analyzed, and tested for its application in generating quasi-square pulses. According to the circuit simulations, a compact generator based on two/three-section network was constructed. Two-section network is applied in the generator due to its compact structure, while three-section network is employed for generating pulses with higher quality. When two-section network is applied in the generator, the full-width at half-maximum of the load pulse is 400 ns, at the same time, its rise time, flat top and fall time are 90, 180 and 217 ns, respectively. When the three-section network is applied with the same pulse width of the load pulse, the rise time of the output decreases to 60 ns, while the flat top increases to 240 ns and the fall time reduces to 109 ns. Meanwhile, this kind of network could be used to shape the output pulses of generators whose equivalent circuit is LC series discharge network, such as MARX generator, into quasi-square pulses. And the preliminary experiment demonstrates that anti-resonance network could work well on four-stage Marx generators. A sine pulse generated by the four-stage Marx generator is shaped into a quasi-square pulse with voltage of 11.8 kV and pulse width about 110 ns based on two-section anti-resonance network.

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