Femtosecond laser micromachining has emerged in recent years as a new technique for micro/nano structure fabrication because of its applicability to virtually all kinds of materials in an easy one-step process that is scalable. In the past, much research on femtosecond laser micromachining was carried out to understand the complex ablation mechanism, whereas recent works are mostly concerned with the fabrication of surface structures because of their numerous possible applications. The state-of-the-art knowledge on the fabrication of these structures on metals with direct femtosecond laser micromachining is reviewed in this article. The effect of various parameters, such as fluence, number of pulses, laser beam polarization, wavelength, incident angle, scan velocity, number of scans, and environment, on the formation of different structures is discussed in detail wherever possible. Furthermore, a guideline for surface structures optimization is provided. The authors’ experimental work on laser-inscribed regular pattern fabrication is presented to give a complete picture of micromachining processes. Finally, possible applications of laser-machined surface structures in different fields are briefly reviewed.

https://www.mdpi.com/2072-666X/5/4/1219/pdf

Fabrication of Micro/Nano Structures on Metals by Femtosecond Laser Micromachining

We report on the fabrication of high resolution 3D scaffolds of polylactide-based materials using direct laser writing and we explore their use as neural tissue engineering scaffolds.

Direct Laser Writing of 3D scaffolds for neural tissue engineering applications

Laser beam drilling (LBD) is one of non contact type unconventional machining process that are employed in machining of stiff and high-strength materials, high strength temperature resistance materials such as; metal alloys, ceramics, composites and superalloys. Most of these materials are difficult-to-machine by using conventional machining methods. Also, the complex and precise holes may not be obtained by using the conventional machining processes which may be obtained by using unconventional machining processes. The laser beam drilling in one of the most important unconventional machining process that may be used for the machining of these materials with satisfactorily. In this paper, the attention is focused on the experimental and theoretical investigations on the pulsed Nd:YAG laser drilling of different categories of materials such as ferrous materials, non-ferrous materials, superalloys, composites and Ceramics. Moreover, the review has been emphasized by the use of pulsed Nd:YAG laser drilling of different materials in order to enhance productivity of this process without adverse effects on the drilled holes quality characteristics. Finally, the review is concluded with the possible scope in the area of pulsed Nd:YAG laser drilling. This review work may be very useful to the subsequent researchers in order to give an insight in the area of pulsed Nd:YAG laser drilling of different materials and research gaps available in this area.

Pulsed Nd:YAG laser beam drilling: A review

Laser-derived graphene: A three-dimensional printed graphene electrode and its emerging applications

Microchannels are primarily used in biomedical devices and microfluidic applications. Fabrication of microchannels has always been a tough task using conventional manufacturing technologies. Variou...

Fabrication of microchannels: A review

A brief review is given regarding ultrafast laser micromachining of materials. Some general experimental observations are first provided to show the characteristics of ultrafast laser micromachining. Apart from empirical research, mathematical models also appear to allow for a further and systematic understanding of these phenomena. A few fundamental ultrafast laser micromachining mechanisms are addressed in an attempt to highlight the physics behind the experimental observations and the mathematical models. It is supposed that a vivid view of ultrafast laser micromachining has been presented by linking experimental observations, mathematical models and the behind physics.

A review of ultrafast laser materials micromachining

Laser patterning is a key industrial process in the manufacturing of organic light emitting diode (OLED) displays, solid-state lighting foils and solar cells. Ultrafast lasers are of particular interest for this application as they may enable selective ablative removal of OLED layers with minimal energy density requirements on the target. Since sufficient laser output from commercial laser sources is currently exceeding single beam process requirements, parallel processing with multiple beams could provide a novel route for up-scaling processing speed and reduce manufacturing costs. In this paper, we propose the use of a reflective liquid crystal on silicon spatial light modulator, driven by fast computer-generated holograms, for splitting a parent laser beam into a number of beamlets and to digitally manipulate their position and laser intensity on the target. With successful blocking of the non-diffracted zero order beam and subsequent delivery of the SLM diffracted beams using a galvanometer scanner and flat-field f-theta lens, we demonstrate high throughput precision patterning of silicon and thin film electrodes (ITO anode and metal cathode) on flexible and glass substrates. It is additionally shown that, by carefully adjusting the number of beams per line, one can selectively remove different amount of materials simultaneously in adjacent locations all within a single scanning step. Microscopic examination with optical microscopy and white light interferomety revealed the extent of resolution, process quality and assisted quantification of the process speed gain. The benefits and current limitations of this technique are discussed in detail.

http://pcwww.liv.ac.uk/~kuang/Publications/Zheng%20Kuang%27s%20pulications_files/Proceeding-LAMP%20ps%20SLM%20paper.pdf

Ultrafast parallel laser processing of materials for high throughput manufacturing

Laser assisted direct write process with novel beam profiles

The laser assisted direct write (LADW) method can be used to generate electrical circuitry on a substrate by depositing metallic ink and curing the ink thermally by a laser. Laser curing has emerged over recent years as a novel yet efficient alternative to oven curing. This method can be used in situ, over complicated 3D contours of large parts (e.g. aircraft wings) and selectively cure over heat sensitive substrates, with little or no thermal damage.In previous studies, empirical methods have been used to generate processing windows for this technique, relating to the several interdependent processing parameters on which the curing quality and efficiency strongly depend. Incorrect parameters can result in a track that is cured in some areas and uncured in others, or in damaged substrates. This paper addresses the strong need for a quantitative model which can systematically output the processing conditions for a given combination of ink, substrate and laser source; transforming the LADW technique from a purely empirical approach, to a simple, repeatable, mathematically sound, efficient and predictable process.The method comprises a novel and generic finite element model (FEM) that for the first time predicts the evolution of the thermal profile of the ink track during laser curing and thus generates a parametric map which indicates the most suitable combination of parameters for process optimization. Experimental data are compared with simulation results to verify the accuracy of the model.

Shuo Shang

Papers

A review of ultrafast laser materials micromachining

Ultrafast parallel laser processing of materials for high throughput manufacturing

Laser assisted direct write process with novel beam profiles

A predictive thermal dynamic model for parameter generation in the laser assisted direct write process

Diffractive Multi-Beam Ultra-fast Laser Micro-processing using a Spatial Light Modulator