laserablation

Laser ablation is the removal of material from a solid surface by irradiation with a focused laser beam. The absorbed laser energy can rapidly heat the surface, causing melting, vaporization, and ejection of material in the form of a plume or ejecta. The outcome depends on laser parameters and the surrounding environment, and can range from shallow surface modification to complete material removal.

The dominant ablation mechanisms are photothermal, photomechanical, and, in some cases, photochemical. Photothermal effects raise the local temperature until the material vaporizes or explosively expands. Shorter pulse durations can produce high peak powers that generate plasma at the surface, which absorbs additional laser energy and reinforces material removal. Photomechanical effects involve rapid pressure transients that fracture the material. The presence of a plasma plume can influence ablation efficiency and the quality of the surface after processing.

Key parameters include pulse duration (from femtoseconds to nanoseconds), wavelength, pulse energy, fluence, repetition rate, and beam spot size. There is a threshold fluence below which ablation does not occur; shorter pulses generally reduce heat-affected zones. Common laser sources include CO2, Nd:YAG, excimer, ultrafast Ti:sapphire and fiber lasers, among others. The surrounding medium (air, vacuum, or liquids) also affects the process and the properties of ejected material.

Applications span materials processing (micromachining, surface structuring, thin-film deposition by pulsed laser deposition), nanoparticle synthesis (laser ablation in liquids), and analytical sciences (LIBS and LA-ICP-MS). In medicine, laser ablation enables precise tissue and tumor removal with minimal collateral damage. Safety concerns include laser hazards, fumes, and particulates, requiring appropriate containment and ventilation.