J. Tang

Numerical Simulation on the Temperature Field of Water-Jet Guided Laser Micromachining

Water-jet guided laser micromachining is the new development orientation of laser machining. This paper set up the numerical model on the action between the water-jet guided laser and the material. By using the software ANSYS, simulated the processing of the water-jet guided laser micromachining. This paper gave the investigation on the machining laws and the distributing of temperature fielding in processing of water-jet guided laser micromachining. And the results of the correlative experiment prove the model aright. The result provided the theoretical foundation for the next research on the water-jet guided laser machining.

Analysis on the Coupling Error of Laser and Water-Jet in Water-Jet Guided Laser Micromachining

Water-jet guided laser micromachining (WJGLM) is the new development of laser machining. It couples the focal laser beam of particular wavelength (low absorptivity of water) with the high speed water-jet which works as the multimode fiber. This paper investigated the necessary condition of coupling of laser and water-jet, and gave the fundamental research on the coupling error of laser coupling into the water-jet. On base of the analysis, the coupling unit is design for the WJGLM, the experimental results show that good cutting quality of Si wafer can be acquired by WJGLM with the coupling unit.

Simulation on the Effects of Misaligned Coupling on the Output Intensity Distribution in Water-Jet Guided Laser

Water-jet guided laser machining is a kind of material processing technology using water optical waveguide which is formed by coupling a high energy laser beam into variable-length water jet. In order to design the coupling unit and form the effective energy-jet, the research on the distribution of output intensity is beneficial to understand the structure of the coupling unit and improve the coupling efficiency of laser energy. This paper lists the different coupling misalignments in the coupling unit when laser couplings into water-jet. In this paper, the distribution of energy output intensity in water-jet guided laser is simulated with the ray trace theory under several different types of coupling misalignments with ZEMAX software, the results show that misaligned coupling provide various morphology of energy output intensity distribution: center peak morphology, ring peak morphology, and uniform peak morphology, which provides a method to optimize the energy output intensity distribution of water-jet guided laser.

Surface Quality of Pulsed Laser Cutting of Difficult to Machine Steel

This paper presented the experiments of Nd:YAG pulsed laser cutting of titanium alloy, super-alloy and stainless steel sheet, and investigated the influences of different laser cutting parameters on the surface quality factors focusing surface morphology. In comparison with air-, argon- and nitrogen-assisted laser cutting, argon-assisted laser cutting comes with unaffected surface quality and is suitable for laser cutting with subsequent welding requirement. With analyzing the interaction between pulses overlapping rate and energy, the results show that medium pulse overlapping rate and lower pulse rate helps to improve the surface roughness with pulsed laser cutting. And the results would be beneficial to find optimum cutting parameters for good separation surface.

Space Design of Business Buildings Base on the Different Gender Shopping Behavior

This paper discussed the different shopping behavior of gender in commercial building. On the base of the previous research on the physiological and shopping psychological characteristic of gender, summarize the difference of the shopping frequency, shopping time, choosing alternatives place, purchasing mode and behavior pattern of gender in commercial building, and give the dissimilarity on the requirement of the denoting system in commercial building. Through lots of the accessing records, observing shopping behavior, investigating questionnaires and testing on the physical environment, analyzes the data by using the statistical software STATISTICS and SPSS in the research. By using the physical instruments to test the indoor environments of commercial building, the paper gives the scientific attestations for the research results. The research provides the new ideas for the designing the commercial building, and make the commercial building vary humanness.

Analysis of the Nanoscale Manipulation Using Near-Field Optical Tweezers Combined with AFM Probe

In recent years, optical manipulators based on forces exerted by enhanced evanescent field close to near-field optical probes have provided the access to nonintrusive manipulation of nanometric particles. However, the manipulation capability is restricted to the intensity enhancement of the probe tip due to low emitting efficiency. Here a near-field optical trapping scheme using the combination of an optical fiber probe and an AFM metallic probe is developed theoretically. Calculations are made to analyze the field distributions including tip interaction and the trapping forces in the near-field region by applying a direct calculation of Maxwell stress tensor using three-dimensional FDTD. The results show that the scheme is able to trap particle at the nanoscale with lower laser intensity than that required by conventional near-field optical tweezers.

Nano-Particle Manipulated with Near-Field Optical Tweezers

By applying the direct calculation of Maxwell stress tensor using three-dimensional finite difference time domain method, the feasibility of using a metal-coated fiber probe to create near-field optical tweezers is investigated. Numerical results indicate that these schemes are able to trap nano-particles with lower laser intensity than that required by conventional optical tweezers. The near-field optical trapping systems that are more flexible than conventional optical tweezers are built. In experiments, 120-nm polystyrene particles are trapped in a multi-circular shape with a minimum size of 400 nm. The realization of trapping particles in the range of tens of nanometers largely promotes the role of near-field optical manipulation at the nanometer scale.

Numerical and Experimental Research on Water-Jet Guided Laser Micromachining

Water-jet guided laser micromachining is the new development of laser machining. This paper analysis the action mechanism of the plasma shock wave and hollow erode effects in water-jet guided laser machining processing, on the base of the thermal effects of the laser and water-jet. And the numerical model on the action effects between the water-jet guided laser and the material was founded. Using the software ANSYS, the processing of the water-jet guided laser micromachining was simulated. This paper gave the investigation on the distributing of temperature field in processing of water-jet guided laser micromachining. And the results of the correlative experiment correspond with the simulation results.

Laser and Water-Jet Fiber Coupling Technology for Water-Jet Guided Laser Micromachining

The processing effect using water-jet guided laser micromachining technology is determined by the accurate coupling of focused laser and high speed water-jet. In order to realize the effective coupling, based on the analysis and calculation, a coupling unit with special structures was designed. The maximum angle of incidence was researched, which determined whether the total reflection occurred when laser transported in the water-jet. By the aid of fluid dynamical simulation, the coupling unit with uniform distribution of inner-cavity fluid field was designed. The attenuation of laser energy in water-jet fiber was investigated. Using appropriate laser wavelength, pulse energy and filtered and de-ionized water, energy attenuation in fiber was reduced. Experimental results showed that applying this coupling technology, perfect water-jet guided laser micromachining can be achieved.

Experimental Research on UV Laser and High-Pressure Water-Assisted YAG Laser Dicing SiC Wafer

In this paper, the comparative experimental research on DPSS UV laser (wavelength is 355nm) and high-pressure water-assisted YAG laser dicing SiC wafer was done. The results show that is strict with the performance of laser source and the dicing technique parameters in UV laser dicing the SiC wafer, and the dicing surface of good quality can be obtained only when the parameters of laser source and dicing technology vary in a narrow range. Contrarily, the SiC wafer dicing technology using high-pressure water-assisted YAG laser has a perfect flexibility with the laser source and dicing apparatus, and the good dicing surface can be obtained even if the process parameters vary in a wide range.