Guo et al. (1995) were the first to report the use of a laser to ablate a block of graphite mixed with catalytic metal. The catalytic metal can consist of elements such as Co, Nb, Pt, Ni, Cu, or a binary combination thereof. The composite block is formed by making a paste of graphite powder, carbon cement, and the metal. The paste is next placed in a cylindrical mold and baked for several hours. After solidification, the graphite block is placed inside an oven with a laser pointed at it, and Ar gas is pumped along the direction of the laser point. The oven temperature is approximately 1200° C. As the laser ablates the target, carbon nanotubes form and are carried by the gas flow onto a cool copper collector. Like carbon nanotubes formed using the electric-arc discharge technique, carbon nanotube fibers are deposited in a haphazard and tangled fashion.

Laser ablation is currently finding industrial applications. CO2 or Nd-YAG pulsed lasers can be used to clean surfaces or to key them ready for paint. High power lasers clean a large spot with a single pulse. Lower power lasers use many small pulses which may be scanned across an area. The advantages are:

-No solvents are used, so it is environmentally friendly and operators are not exposed to chemicals.

-It is possible to automate the system, e.g. by using robots.

-The running costs are lower than dry media or CO2 ice blasting, (However the capital investment costs are much higher).

-The surface is gentler than abrasive techniques, e.g. carbon fibres within a composite material are not damaged.

-The surface is vaporised, but the energy is so low that the heating of the target is minimal.

Sources

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Guo, T., et al., Chemical Physics Letters 243:49 (1995).

Link to SLCR web site, Germany

Link to Clean Lasersysteme web site, Germany

Laser ablation has biological applications and can be used to destroy nerves and other tissues. For example, a species of pond snails, Helisoma trivolvis can have their sensory neurons laser ablated off when the snail is still an embryo to prevent use of those nerves (Kuang, et al., 2002)

Source: Kuang, S., et al., 2002, J Neurobiol 52:73-83