Laser ablation

[5] Laser pulses can vary over a very wide range of duration (milliseconds to femtoseconds) and fluxes, and can be precisely controlled.

The simplest application of laser ablation is to remove material from a solid surface in a controlled fashion.

High power lasers clean a large spot with a single pulse.

One of the advantages is that no solvents are used, therefore it is environmentally friendly and operators are not exposed to chemicals (assuming nothing harmful is vaporized).

The process is gentler than abrasive techniques, e.g. carbon fibres within a composite material are not damaged.

Another class of applications uses laser ablation to process the material removed into new forms either not possible or difficult to produce by other means.

[7] The catalytic metal can consist of elements such as cobalt, niobium, platinum, nickel, copper, or a binary combination thereof.

The composite block is formed by making a paste of graphite powder, carbon cement, and the metal.

As the laser ablates the target, carbon nanotubes form and are carried by the gas flow onto a cool copper collector.

This process is used to manufacture some types of high temperature superconductor and laser crystals.

Laser ablation is also used to create pattern, removing selectively coating from dichroic filter.

This products are used in stage lighting for high dimensional projections, or for calibration of machine vision's instruments.

This process is used in industry to work-harden metal surfaces, and is one damage mechanism for a laser weapon.

Processes are currently being developed to use laser ablation in the removal of thermal barrier coating on high-pressure gas turbine components.

Due to the low heat input, TBC removal can be completed with minimal damage to the underlying metallic coatings and parent material.

Laser ablation in the liquid phase is an efficient method to exfoliate bulk materials into their 2-dimensional (2D) forms, such as black phosphorus.

By changing the solvent and laser energy, the thickness and lateral size of the 2D materials can be controlled.

Laser ablation sampling is detected by monitoring the photons emitted at the sample surface - a technology referred to as LIBS (Laser Induced Breakdown Spectroscopy) and LAMIS (Laser Ablation Molecular Isotopic Spectrometry), or by transporting the ablated mass particles to a secondary excitation source, like the inductively coupled plasma.

Some instruments combine both optical and mass detection to extend the analysis coverage, and dynamic range in sensitivity.

Laser ablation is used in science to destroy nerves and other tissues to study their function.

There are several laser types used in medicine for ablation, including argon, carbon dioxide (CO2), dye, erbium, excimer, Nd:YAG, and others.

Some of the most common procedures where laser ablation is used include LASIK,[18] skin resurfacing, cavity preparation, biopsies, and tumor and lesion removal.

[21] Laser ablation can be used on benign and malignant lesions in various organs, which is called laser-induced interstitial thermotherapy.

The main applications currently involve the reduction of benign thyroid nodules[22] and destruction of primary and secondary malignant liver lesions.

A well-established framework for laser ablation is called the two-temperature model by Kaganov and Anisimov.

This threshold depends on the wavelength of the laser, and can be simulated assuming the Lennard-Jones potential between the atoms in the lattice, and only during a particular time of the temperature evolution called the hydrodynamic stage.

For ultra-short pulses (which suggest a large fluence) it has been proposed that Coulomb explosion also plays a role [26] because the laser energy is high enough to generate ions in the ablation plume.

Anisimov's theory considered an elliptical gas cloud growing in vacuum.

In this model, thermal expansion dominates the initial dynamics, with little influence from the kinetic energy,[26] but the mathematical expression is subject to assumptions and conditions in the experimental setup.

Parameters such as surface finish, preconditioning of a spot on the target, or the angle of the laser beam with respect to the normal of the target surface are factors to take into account when observing the angle of divergence of the plume dynamics or its yield.