What happens when a laser beam interacts with a material?

Question

Accepted Answer

The incident beam can be reflected, transmitted, scattered, or absorbed.

The incident beam can be reflected, transmitted, scattered, or absorbed. In most cutting, the absorbed energy heats the material until it melts or vaporizes; some ultraviolet and ultrashort-pulse lasers remove material in other, non-thermal ways. Assist air blows molten material out of the cut and the exhaust carries away fumes and debris, while some heat spreads into the surrounding workpiece. A laser beam can be reflected, scattered, transmitted or absorbed, and the absorbed part heats the material Two parts. On the left, a beam arrow comes down onto the surface of a slab seen from the side. From the spot, short arrows show the four things that can happen to the energy: reflected upward, scattered in several directions, transmitted out the bottom, and absorbed, shown as a shaded half circle just under the surface. A note says how the energy divides depends on the material and the conditions, and that settings are process records tied to conditions, not universal constants. On the right, a chain of boxes follows the absorbed part. Absorbed energy raises the local temperature. Depending on material and process, that can produce melting, vaporization, ablation, chemical decomposition, or a combination. Removed material is carried away by vapor pressure, assist flow and exhaust. A dashed box notes that some heat spreads into the surrounding workpiece. incident beam absorbed reflected scattered transmitted How the energy divides depends on the material and the conditions. Settings are process records tied to conditions, not universal constants. Absorbed energy raises the local temperature Depending on material and process: melting, vaporization, ablation, chemical decomposition, or a combination Removed material is carried away by vapor pressure, assist flow, exhaust Meanwhile, some heat spreads into the surrounding workpiece Conceptual, and the arrows are not to scale: how much goes each way depends on wavelength, optical properties, beam size and quality, energy over time, motion, focus, thickness, thermal properties and assist conditions. That is why two materials, or two batches of the same nominal material, can respond differently to the same nominal setting. The outcome depends on wavelength, optical properties, beam size and quality, delivered energy over time, motion, focus position, material thickness, thermal properties, and assist conditions. That is why two materials—or two batches of the same nominal material—can respond differently to an identical nominal setting. Treat settings as process records tied to conditions, not universal material constants.

Sources