DIYode has a G.Weike model LG900 laser engraver. The laser is a 60Watt CO2 tube with 3 mirror flying optics setup and a 56mm final lens focal length.
The mirrors are 25mm in diameter and the lens is 20mm in diameter.
A very good place to start is KwartzLab's Wiki on their laser : Laser Cutter
Care and Feeding
Please visit ANSI Z136 Safe Use of Lasers and Copy of ANSI Z136.1 for general laser safety information. Further Reading
Focus on the surface, under the surface, or on the bottom surface.