Home-Built Carbon Dioxide (CO2) Laser

The carbon dioxide (CO2) laser is the powerhouse for high tech industrial cutting and welding of metals and many other materials. Small CO2 lasers are used for marking of metal, wood, and composites, and in medicine and surgery. Even a `small` CO2 laser produces 10s of watts of beam power and the largest are in the 100 kW range! Its output is at 1

0. 6 um (10, 600 nm) or mid-IR. This wavelength is about 10 to 30 times longer than the other lasers under discussion and often considered a source of a heat beam than a light beam. At this wavelength, normal glass and plastic optics are either too lossy or totally opaque so alternatives must be found both for the end-mirrors and any other mirrors, lenses, or prisms required by the external optical setup. Divergence/diffraction effects are also increased by this same factor so obtaining a collimated beam is also more difficult. Many common materials including wood, paper, plastics, composites, and properly prepared metal surfaces absorb quite well at this wavelength so the CO2 laser makes an effective marking, cutting, welding, and heat treating tool. It is possible for an amateur to construct a working axial flow CO2 laser (non-sealed, see the chapter: Carbon Dioxide Lasers ) in the 10 to 50 W range without too much difficulty - at least compared to some of the other types of lasers described in this chapter. A vacuum system is needed but the range of operating vacuum is modest - 10 to 100 Torr. And while several gases are needed, the purity of the final gas fill isn`t nearly as critical as for, say, the HeNe laser, and pre-mixed gas is readily available. See the section: More on Obtaining Gases. With a bit of resourcefulness, no fancy glass work is needed. The power supply can be just a neon sign transformer on a Variac....

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