Magnified Images of Laser Engraving on Wood, Acrylic, and Mild Steel.
Each small dot in this magnified image is a single “pulse.” More frequent pulses result in a tighter array and a finer surface finish.
Materials that are sensitive to thermal damange, like acrylic and rubber, are suited to higher-frequency engraving.
Do you want to take a look for yourself? USB Microscopes are available for public use in Small Hall Room 224.
The initial blast of the laser vaporizes all of the material in its path. Once it breaks through to the other side, it can begin following the cutting route. Oftentimes the laser creates a small fire on the underside of the material during the initial blast.
The materials above are acrylic, wood, and metal. As you can see, the more thermally sensitive material, the acrylic, has a slightly melted edge on the reverse side. The metal piece also has some visible melting.