If you look up Pyrography, you will find this answer:
Pyrography or pyrogravure is the art of decorating wood or other materials with burn marks resulting from the controlled application of a heated object such as a poker. It is also known as pokerwork or wood burning.
The term means "writing with fire", from the Greek pur (fire) and graphos (writing). It can be practiced using specialized modern pyrography tools, or using a metal implement heated in a fire. "Pyrography dates from the 17th century and reached its highest standard in the 19th century. In its crude form it is pokerwork."
A new process, which has come to be known as Solar Pyrography, focuses the power of the sun through a magnifying lens onto the wood to create the designs. There are several Solar Pyros out there from myself in Northern California, to Florida's Key West, to England and France, Canada and even the Philippines. Solar Pyros are everywhere.