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What is laser engraving?

Posted August 2, 2010

Laser engraving is the practice of using lasers to engrave, etch, or mark an object.

The technique can be very complex, and often a computer system is used to drive the movements of the laser head. Despite this complexity, very precise and clean engravings can be achieved at a high rate. The technique does not involve tool bits which contact the engraving surface and wear out. This is considered an advantage over alternative engraving technologies where bit heads have to be replaced regularly.

In situations where physical alteration of a surface by engraving is undesirable, an alternative such as “marking” is available. This is a generic term that covers a broad spectrum of surfacing techniques, including printing and hot-branding. In many instances, laser engraving machines are able to do marking that would have been done by other processes.

A laser engraving machine can be thought of as three main parts: a laser, a controller, and a surface. The laser is like a pencil in that the beam emitted from it allows the controller to trace patterns onto the surface. The controller (usually a computer) determines the direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The surface is picked to match what the laser can act on.

The point where the laser touches the surface should be on the focal plane of the laser’s optical system, and is usually synonymous with its focal point. This point is typically small, perhaps less than a fraction of a millimeter (depending on the optical wavelength). Only the area inside this focal point is significantly affected when the laser beam passes over the surface. The energy delivered by the laser changes the surface of the material under the focal point. It may heat up the surface and subsequently vaporize the material, or perhaps the material may fracture (known as “glass” or “glass up”) and flake off the surface. This is how material is removed from the surface to create an engraving.

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