Glossary · Processes

Laser

Diode laser

The cheapest and, among hobbyists, most common type of laser: small semiconductor chips produce blue light that engraves wood, leather or paper and cuts thin material.

Explained in more detail

Diode lasers use semiconductor laser diodes, in the hobby sector almost always with a wavelength of around 445 to 455 nm (visible blue). High-power modules combine several diodes, and 10 to 40 W of optical power is common at present. The beam spot is usually more rectangular than round and, depending on the module, about 0.1 to 0.2 mm in size. Wood, leather, cardboard and dark acrylic absorb blue light well, whereas clear and white acrylic, glass and bare metal hardly absorb it. As open gantry machines, almost all diode lasers fall into laser class 4.

Where does the term come from?

Diode comes from Greek: di = two, hodos = way, so a component with two terminals. A laser diode is a semiconductor diode that emits coherent light when current flows. Laser is the abbreviation for Light Amplification by Stimulated Emission of Radiation.

In practice

• Look at the optical power in watts, not the electrical consumption: only the optical power tells you what reaches the material.
• Clear acrylic, white material and glass let the blue light through almost unhindered. Dark masking or marking spray helps when engraving.
• With 10 W optical you usually cut 3 mm plywood in one pass; thicker wood needs several passes and air assist.
• The lens sits close to the material and quickly gets dirty from smoke. Check it regularly and clean it with lens tissues and isopropyl alcohol.

Not to be confused

Not to be confused with infrared modules, which can also use diodes but work at 1064 nm. A diode laser at 450 nm marks bare stainless steel only to a very limited extent.

Frequently asked questions

Can a diode laser engrave metal?

Bare metal reflects most of the blue light. Anodised or painted aluminium is easy to process, and on stainless steel you need marking spray or a laser with 1064 nm.

How thick a wood can a diode laser cut?

That depends on power, type of wood and passes. With 10 W optical, 3 to 5 mm plywood is usual; machines with 20 to 40 W manage 10 mm and more in several passes.