Laser-assisted milling of silicon nitride ceramics and inconel

Laser-assisted machining (LAM

Ultrasound-Assisted Water-Confined Laser Micromachining

Systems and processes for improved laser machining, such as micro machining, of a workpiece. Systems and processes involve directing at a first surface of the workpiece a laser beam and wherein at least the laser-irradiated region of the first surface of the workpiece is immersed in a liquid, and delivering to the liquid-immersed and laser-irradiated workpiece surface region at least a first ultrasound output from a first ultrasound device. The ultrasound output and the laser beam desirably impact the workpiece first surface substantially simultaneously.Sponsorship: Illinois Institute of TechnologyUnited States Paten

A study on laser-fiber coupling efficiency and ablation rate in femtosecond laser deep microdrilling

Laser microdrilling is a common micromachining operation in many industrial applications. This paper presents a new laser microdrilling technique in which a hollow-core fiber is employed to transmit femtosecond laser pulses to the target position. The coupling efficiency between the laser and the fiber is investigated and found to be strongly related to pulse energy and pulse duration. A parametric study on the ablation rate indicates that in microdrilling of a stainless steel (type 303), the operating parameters including pulse energy, pulse duration, sample thickness, focal length and sample-fiber distance can affect the ablation rate. The experimental results show that the new technique developed in this study is feasible to conduct microdrilling of holes with high aspect ratio

Numerical modeling of metal heating using ultra-short pulsed lasers

This work is concerned with the comparative study on parabolic one-step (POS), parabolic two-step (PTS) and hyperbolic two-step (HTS) heat conduction models in two-dimensional numerical modeling of ultra-short pulse laser metal heating. --Abstract, page iv

Faraday effect optical temperature sensors

In this thesis, the realization of temperature sensing through Faraday effect, and the expected performance of the proposed sensors were investigated theoretically. --Introduction, page 1

Numerical modeling and analysis of laser-matter interactions in laser-based manufacturing and materials processing with short and ultrashort lasers

Short and ultrashort-pulsed lasers (with the duration of ~10 nanosecond or even less) have been developing rapidly in recent years, for which many competitive applications have been found and explored, such as laser shock peening, pulsed laser ablation for micromachining, and thin film deposition, etc. Although a lot of research has been carried out in literature, the numerical modeling work is far from being sufficient for many laser-matter interaction processes that are important for laser-based manufacturing and materials processing. The following models, although very important for the investigations of laser-matter interactions and the relevant laser materials processing applications, have been rarely reported in literature, and have been developed and described in this dissertation: 1. A complete and self-closed model for laser shock peening. 2. A low-fluence nanosecond laser ablation model with both rigorous boundary conditions at the liquid-vapor interface and plasma formation considerations. 3. A one-dimensional hydrodynamic model for the early-stage evolution of high-fluecne laser-induced metal plasma in air. 4. A two-stage and self-closed model for high-fluence nanosecond laser-induced metal plasma in vacuum. The model can simulate both the early stage evolution and the long-term behavior of the laser-induced plasma. 5. A simplified model for ultrashort laser ablation that is easy to apply and computationally efficient, while can still reflect the dominant physics in the process and produce reasonably accurate predictions. The above developed models have been compared with experimental measurements, and the agreements are reasonably good compared with the typical accuracy of models in literature for short and ultrashort pulsed laser-matter interactions. Preliminary experimental work has also been performed for laser shock peening and picosecond laser micromachining using a developed nanosecond laser processing system and a picosecond laser processing system, respectively

Magnetic Field Effects on Laser Drilling

A magnetic field-assisted laser drilling process has been studied, where nanosecond laser ablation is performed under an external magnetic field. The study shows that the magnetic field-assisted laser drilling process produces deeper drilling depth and generates more confined plasma plume and relative less residual, as compared with laser drilling without magnetic field. This phenomenon has been rarely reported in the literature. The magnetic field effects on laser ablation have been analyzed analytically and a hypothesized explanation has been proposed based on the effect of the magnetic field on the plasma produced during laser ablation

Laser Sintering Of Carbon Nanotube-Reinforced Ceramic Nanocomposites

The fabrication of carbon nanotube (CNT)-reinforced ceramic nanocomposites through laser sintering has been rarely studied, and the fabrication feasibility has been rarely tested. Laser sintering is a flexible, localized and high-precision process, which can also potentially produce coatings or parts with complicated shapes and/or spatially controlled compositions. Therefore, compared with other technologies laser sintering has its own advantages. Experimental investigations reported in this paper have confirmed the feasibility of fabricating CNT-reinforced ceramic nanocomposites through laser sintering of ceramic nanoparticles and CNTs. The studies show that laser sintering can induce the agglomeration of ceramic nanoparticles into a relatively more continuous ceramic phase, and during the sintering process CNTs are well preserved without any obvious quality degradation, and they are also bonded with the ceramic phase after laser sintering. © 2011 Copyright Taylor and Francis Group, LLC