Imaging plate scanners calibration and the attenuation behavior of imaging plate signals

Based on previously reported work, we propose a new method for calibrating image plate(IP) scanners, offering greater flexibility and convenience, which can be extended to the calibration tasks of various scanner models. This method was applied to calibrate the sensitivity of a GE Typhoon FLA 7000 scanner. Additionally, we performed a calibration of the spontaneous signal attenuation behavior for BAS-MS, BAS-SR, and BAS-TR type IPs under the 20±1℃ environmental conditions, and observed significant signal carrier diffusion behavior in BAS-MS IP. The calibration results lay a foundation for further research on the interaction between ultra-short, ultra-intense lasers and matter.

Theoretical analysis of ultra-short pulsed laser ablation of SiO_2 material based on a Coulomb explosion model

Based on the kinetic theoretical Vlasov-Poisson equation, a surface Coulomb explosion model of SiO2 material induced by ultra-short pulsed laser radiation is established. The non-equilibrium free electron distribution resulting from the two mechanisms of multi-photon ionization and avalanche ionization is computed. A quantitative analysis is given to describe the Coulomb explosion induced by the self-consistent electric field, and the impact of the parameters of laser pulses on the surface ablation is also discussed. The results show that the electron relaxation time is not constant, but it is related to the microscopic state of the electrons, so the relaxation time approximation is not available on the femtosecond time scale. The ablation depths computed by the theoretical model are in good agreement with the experimental results in the range of pulse durations from 0 to 1 ps.

Ultra-Short Pulsed Laser Manufacturing and Surface Processing of Microdevices

Ultra-short laser pulses possess many advantages for materials processing.Ultrafast laser has a significantly low thermal effect on the areas surrounding the focal point;therefore,it is a promising tool for micro-and submicro-sized precision processing.In addition,the nonlinear multiphoton absorption phenomenon of focused ultra-short pulses provides a promising method for the fabrication of various structures on transparent material,such as glass and transparent polymers.A laser direct writing process was applied in the fabrication of high-performance three-dimensional(3D)structured multilayer microsupercapacitors(MSCs)on polymer substrates exhibiting a peak specific capacitance of 42.6 mF·cm^-2 at a current density of 0.1 mA·cm^-12.Furthermore,a flexible smart sensor array on a polymer substrate was fabricated for multi-flavor detection.Different surface treatments such as gold plating,reducedgraphene oxide(rGO)coating,and polyaniline(PANI)coating were accomplished for different measurement units.By applying principal component analysis(PCA),this sensing system showed a promising result for flavor detection.In addition,two-dimensional(2D)periodic metal nanostructures inside 3D glass microfluidic channels were developed by all-femtosecond-laser processing for real-time surfaceenhanced Raman spectroscopy(SERS).The processing mechanisms included laser ablation,laser reduction,and laser-induced surface nano-engineering.These works demonstrate the attractive potential of ultra-short pulsed laser for surface precision manufacturing.

Wavelength tunable ultra-short pulses based on a flat broadband spectrum generated in a nonlinear ytterbium-doped fiber amplifier

We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum（center wavelength and linewidth） are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.

A review on glass welding by ultra-short laser pulses

Glass welding by ultra-short pulsed(USP)lasers is a piece of technology that offers high strength joints with hermetic sealing.The joints are typically formed in glass that is transparent to the laser by exploiting nonlinear absorption effects that occur under extreme conditions.Though the temperature reached during the process is on the order of a few 1000°C,the heat affected zone(HAZ)is confined to only tens of micrometers.It is this controlled confinement of the HAZ during the joining process that makes this technology so appealing to a multitude of applications because it allows the foregoing of a subsequent tempering step that is typically essential in other glass joining techniques,thus making it possible to effectively join highly heat sensitive components.In this work,we give an overview on the process,development and applications of glass welding by USP lasers.

Generation of time-dependent ultra-short optical pulse trains in the presence of self-steepening effect

Starting from the extended nonlinear Schrodinger equation in which the self-steepening effect is included, the evolution and the splitting processes of continuous optical wave whose amplitude is perturbed into time related ultra-short optical pulse trains in an optical fibre are numerically simulated by adopting the split-step Fourier algorithm. The results show that the self-steepening effect can cause the characteristic of the pulse trains to vary with time, which is different from the self-steepening-free case where the generated pulse trains consist of single pulses which are identical in width, intensity, and interval, namely when pulses move a certain distance, they turn into the pulse trains within a certain time range. Moreover, each single pulse may split into several sub-pulses. And as time goes on, the number of the sub-pulses will decrease gradually and the pulse width and the pulse intensity will change too. With the increase of the self-steepening parameter, the distance needed to generate time-dependent pulse trains will shorten. In addition, for a large self-steepening parameter and at the distance where more sub-pulses appear, the corresponding frequency spectra of pulse trains are also wider.

Taper Angle Correction in Cutting of Complex Micro-mechanical Contours with Ultra-Short Pulse Laser

The objective of this work was to investigate the possibility of taper angle correction in cutting of complex micro-mechanical contours using a TruMicro ultra-short pulse laser in combination with the SCANLAB precSYS micro machining sub system. In a first step, the influence of the process parameters on the kerftaper angle of metallic alloys was systematically investigated without beam inclination. A set of base parameters was derived for the subsequent investigations. In a second step, the kerftaper angle was controlled by static beam inclination. In a third step, the same optics was used in its dynamic precession mode to fabricate micro-mechanical components of complex contours with perpendicular 0~ taper angles. It was found that taper angle adjustments of up to 7.5~ are possible with the used setup for cutting applications. Taper angle control is possible both in the static beam inclination mode and in the dynamic precession mode. The static mode could be interesting for contours with sharp inner radii and for achieving faster cutting times similar to results with fixed optics, but would require excellent synchronization of beam inclination and axis motion. The dynamic precession mode would allow an easier integration of the optics into a laser machine but will result in longer cutting times and limitations with respect to achievable inner radii.

Differential protein expression during colonic adaptation in ultra-short bowel rats

AIM： To investigate the proteins involved in colonic adaptation and molecular mechanisms of colonic adapration in rats with ultra-short bowel syndrome （USBS）. METHODS： Sprague Dawley rats were randomly as- signed to three groups： USBS group （10 rats） undergoing an approximately 90%-95% small bowel resection; sham-operation group （10 rats） undergoing small bowel transaction and anastomosis; and control group （ten normal rats）. Colon morphology and differential protein expression was analyzed after rats were given postsurgical enteral nutrition for 21 d. Protein expression in the colonic mucosa was analyzed by two-dimensional electrophoresis （2-DE） in all groups. Differential protein spots were detected by ImageMaster 2D Platinum soft-ware and were further analyzed with matrix-assisted laser desorption/ionization-time-of-flight/time-of-flightmass spectrometric （MALDI-TOF/TOF-MS） analysis. RESULTS： The colonic mucosal thickness significantly increased in the USBS group compared with the control group （302.1 ± 16.9 um vs 273.7 ± 16.0 um, P 〈 0.05）. There was no statistically significant difference between the sham-operation group and control group （P 〉 0.05）. The height of colon plica markedly improved in USBS group compared with the control group （998.4 ± 81.2 um vs 883.4 ± 39.0 um, P 〈 0.05）. There was no statistically significant difference between the shamoperation and control groups （P 〉 0.05）. A total of 141 differential protein spots were found in the USBS group. Forty-nine of these spots were down-regulated while 92 protein spots were up-regulated by over 2-folds. There were 133 differential protein spots in USBS group. Thirty of these spots were down-regulated and 103 were upregulated. There were 47 common differential protein spots among the three groups, including 17 down- regulated protein spots and 30 up-regulated spots. Among 47 differential spots, eight up-regulated proteins were identified by MALDI-TOF/TOF-MS. These proteins were previously reported to be involved in sugar and fat metabolism, protein synthesis and oxidation reduction, which are associated with colonic adaption. CONCLUSION： Eight proteins found in this study play important roles in colonic compensation and are associated with sugar and fat metabolism, protein synthesis, and molecular chaperoning

Effect of Foil Target Thickness in Proton Acceleration Driven by an Ultra-Short Laser

Proton acceleration experiments were carried out by a 1.2× 1018 W/cm2 ultra-short laser interaction with solid foil targets. The peak proton energy observed from an optimum target thickness of 7 μm in our experiments was 2.1 MeV. Peak proton energy and proton yield were investigated for different foil target thicknesses. It was shown that proton energy and conversion efficiency increased as the target became thinner, on one condition that the preplasma generated by the laser prepulse did not have enough shock energy and time to influence or destroy the target rear-surface. The existence of optimum foil thickness is due to the effect of the prepulse and hot electron transportation behavior on the foil target.

Study on Ultra-Short Laser Pulse Ablation of Metals by Molecular Dynamics Simulation

The dynamical progresses involved in ultra-short laser pulse ablation of face-centered cubic metals under stress confinement condition are described completely using molecular dynamics method. The laser beam absorption and thermal energy turning into kinetics energy of. atoms are taken into account to give a detailed picture of laser metal interaction. Superheating phenomenon is observed, and the phase change from solid to liquid is characterized by a destroyed atom configuration and a decreased number density. The steep velocity gradients are found in the systems of Cu and Ni after pulse in consequence of located heating and exponential decrease of fluences following the Lambert-Beer expression. The shock wave velocities are predicted to be about 5 000 m/s in Cu and 7 200 m/s in Ni. The higher ablation rates are obtained from simulations compared with experimental data as a result of a well-defined crystalline surface irradiated by a single pulse. Simulation results show that the main mechanisms of ablation are evaporation and thermoelastic stress due to located heating.

The extending length calculation of hydraulic drive non-metallic completion screen pipe running into ultra-short radius horizontal well

Focusing on the extending length restriction of the completion screen pipe resistance running into ultra-short radius horizontal well,this paper proposed technology of hydraulic drive completion tubular string running into ultra-short radius horizontal well.Innovative hydraulic drive tools and string structure are designed,which are composed of guide tubing,hydraulic drive tubing and non-metallic completion screen pipe from inside to outside.A novel mechanical-hydraulic coupling model is established.Based on the wellbore structure of an ultra-short radius horizontal well for deep coalbed methane,the numerical calculations of force and hydraulic load on tubular strings were accomplished by the mechanical-hydraulic coupling model.The results show that the extending length of completion tubular string with the hydraulic drive is 17 times that of conventional completion technology under the same conditions.The multi-factor orthogonal design is adopted to analyze the numerical calculations,and the results show that the extending length of the completion tubular string is mainly affected by the completion tubular string structure and the friction coefficient between the non-metallic composite continuous screen pipe and the wellbore.Two series of hydraulic drive completion tubular string structures suitable for ultra-short radius horizontal wells under different conditions are optimized,with the extending limits of 381 m and 655 m,respectively.These researches will provide theoretical guidance for design and control of hydraulic drive non-metallic composite continuous completion screen pipe running into ultra-short radius horizontal wells.

Cooling rate calibration and mapping of ultra-short pulsed laser modifications in fused silica by Raman and Brillouin spectroscopy

This paper focuses on the preparation of a new extended set of calibrations of cooling rate(fictive temperature)in fused silica determined by inelastic light scattering and its subsequent use to characterize the local cooling rate distribution in ultra-short pulsed(USP)laser modification.In order to determine the thermal history(e.g.cooling rate and fictive temperature)of fused silica,high-resolution inelastic light-scattering experiments(Raman and Brillouin spectroscopy)were investigated.Calibrations were performed and compared to the existing literature to quantify structural changes due to a change of fictive temperature.Compared to existing calibrations,this paper provides an extension to lower and higher cooling rates.Using this new set of calibrations,we characterized a USP laser modification in fused silica and calculated the local fictive temperature distribution.An equation relating the fictive temperature(Tf)to cooling rates is given.A maximum cooling rate of 3000 K min-1 in the glass transition region around 1200℃ was deduced from the Raman analysis.The Brillouin observations are sensitive to both the thermal history and the residual stress.By comparing the Raman and Brillouin observations,we extracted the local residual stress distribution with high spatial resolution.For the first time,combined Raman and Brillouin inelastic light scattering experiments show the local distribution of cooling rates and residual stresses(detailed behavior of the glass structure)in the interior and the surrounding of an USP laser modified zone.

BIO-INSPIRED SELF-ADAPTIVE MANUFACTURING SYSTEM CONTROL ARCHITECTURE

Future manufacturing systems need to cope with frequent changes and disturbances, therefore their control architectures require constant adaptability, agility, stability, self-organization, intelligence, and robustness. Bio-inspired manufacturing system can well satisfy these requirements. For this purpose, by referencing the biological organization structure and the mechanism, a bio-inspired manufacturing cell is presented from a novel view, and then a bio-inspired self-adaptive manufacturing model is established based on the ultra-short feedback mechanism of the neuro-endocrine system. A hio-inspired self-adaptive manufacturing system coordinated model is also established based on the neuro-endocrine-immunity system （NEIS）. Finally, an example based on pheromone communication mechanism indicates that the robustness of the whole manufacturing system is improved by bio-inspired technologies.

3D UTE定量评估骨皮质结合水和自由水的实验研究

目的:本研究尝试采用3D UTE成像及双指数T2*衰减模型分离骨皮质结合水和自由水。方法:在3T Skyra下对6例成年牛胫骨中段标本进行3D UTE成像,构建UTE双指数T2*衰减模型,对6例牛骨样本不同回波时间的UTE图像进行拟合,分别得到双指数拟合结果。结果:6例样本双指数拟合后,结合水(短)T2*=0.30ms,占比约81.6%,自由水(长)T2*=2.74ms,占比约18.4%。结论:3D UTE双指数衰减模型是一个有效的分离骨皮质结合水和自由水的方法,为定量评估骨质量提供了新的生物学指标,其对骨皮质结合水和自由水的分离有助于骨的力学性质的推断。

A Review on Fiber Lasers

After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, with topics covering both continuous wave and short pulse fiber lasers. Important issues such as the major rare earth dopants, fiber laser brightness, polarization effects, clad pumping technology, beam combination, mode locking and pulse shaping are discussed in this paper.

Proton Acceleration Driven by High-Intensity Ultraviolet Laser Interaction with a Gold Foil

Proton acceleration induced by a high-intensity ultraviolet laser interaction with a thin foil target was studied on an ultra-short KrF laser amplifier called LLG50 in China Institute of Atomic Energy （CIAE）. The ultraviolet laser produced pulses with a high-contrast of 109, duration of 500 fs and energy of 30 mJ. The p-polarized laser was focused on a 2.1 #m gold foil by an off-axis parabola mirror （OAP） at an incident angle of 45°. The laser intensity was 1.2× 1017 W/cm2. The divergence angle for proton energy of 265 keV or higher was 30°, which was recorded by a CR39 detector covered with 2 μm aluminum foil in the target normal direction. The maximum proton energy recorded by a CR39 detector covered with a 4 μm aluminum foil was 440 keV, and the proton energy spectrum was measured by a proton spectrometer. The ultraviolet laser acquires a relatively lower hot electron temperature, which can be ascribed to the proportional relationship of Iλ2, but a higher hot electron density because of the higher laser absorption and critical density. Higher electron density availed to strengthen the sheath electric field, and increased the proton acceleration.

Effect of Lorentz local field correction on propagation of ultrashort laser pulse in one-dimensional para-nitroaniline (PNA) molecules

This paper investigates the effect of Lorentz local field correction （LFC） on the propagation of ultrashort laser pulses in a para-nitroaniline molecular medium under resonant and nonresonant conditions by solving numerically the full-wave Maxwell-Bloch equations beyond slowly-varying envelope approximation and rotating-wave approximation. The effect of the LFC is considerably obvious when pulses with large areas propagate in the dense molecular medium. In the case of resonance, the group velocity of the sub-pulses split from the incident pulse along propagation is severely decreased by the LFC, especially for the latest sub-pulse. However, in the case of nonresonance, the influence of the LFC on the temporal evolution of the pulse is less obvious and lacks homogeneity with an increase in incident pulse area, propagation distance and molecular density.

航道整治铺排测量定位技术

针对目前检测深水软体排沉排手段不足的情况,提出一种检测铺排效果的新技术。采用多波束测深系统的水深格网与侧扫声呐生成的声图文件相结合的方式,镶嵌得出排体沉排位置后使用超短基线测量系统对确定的排体坐标进行验证。该技术在长江南京以下12.5 m深水航道二期工程进行推广应用,提高了工程检测效率及质量。

Formation mechanism of bifurcation in mode-locked class-B laser

The random oscillations of many longitudinal modes are inevitable in both class –A and –B lasers due to their broadened atomic bandwidths. The destructive superposition of electric field components that are incoherently oscillating at the different longitudinal modes can be converted into a constructive one by using the mode-locking technique. Here, the Maxwell–Bloch equations of motion are solved for a three-mode class-B laser under the mode-locking conditions. The results indicate that the cavity oscillating modes are shifted by changing the laser pumping rate. On the other hand, the frequency components of cavity electric field simultaneously form the various bifurcations. These bifurcations satisfy the well-known mode-locking conditions as well. The atomic population inversion forms only one bifurcation, which is responsible for shaping the cavity electric field bifurcations.

Energetic Laser-Ion Acceleration by Strong Charge-Separation Field

The laser-ion acceleration from the ultra-short and ultra-intense laser-matter interactions attracts more and more interest nowadays. When a laser pulse interacts with a target, relativistic electrons are generated in a period of few femtoseconds and driven away by the ponderomotive force, then a huge charge-separation field forms. In general cases, the ion acceleration is determined by this charge-separation field and the scale length of the plasma density. A general time-dependent solution is obtained to describe laser-plasma isothermal expansions into a vacuum, which is the fundamental theory of the laser-ion acceleration. It is adequate for non-quasi-neutral plasmas and different types of the scale length of the density gradient. The previous solutions are some special cases of our general solution. It is found that there exist both a compression layer of the ion velocity distribution and a potential well for sorue initial conditions. However, many unaccounted idiographic solutions, which may be used to reveal new mechanisms of ion acceleration, may be deduced from our general solutions.