CO2 laser focus lens

CO2 laser focus lens is an important parts , for CO2 laser engraving machine, CO2 laser cutting machine. In general, one set CO2 laser cutter, with one laser path. It is made up of one piece laser focus lens, 3 pieces reflective mirrors.

ZnSe is very important materials for laser focus lens. Made in China, imported from Singapore , or America.

Usually, CO2 laser focus lens is with diameter of 18mm, 19mm , 20mm. But it has many different focus length. such as 1.5inch, 2 inch, 2.5 inch, 3inch, 4 inch. In practice for China laser engraving cutting machine, 2 inch, 2.5 inch are more popular. Then there is a new problem. what is the focus length?

Focus length measurement