Copper-Vapor Lasers Make Cents
Elizabeth K. Illy and James A. Piper
The miniaturization of mechanical and electronic components is revolutionizing modern biomedical, aerospace and industrial products. Laser micromachining is emerging as a critical manufacturing process for these components especially when dealing with polymers and ceramics. UV sources are best suited to the micromachining of these materials because short wavelengths, and therefore high optical resolution, and the fact that most polymers and ceramics of interest absorb strongly in the UV, resulting in ?clean? photodecomposition of the target material.
Frequency-doubled copper vapor lasers represent an attractive alternative to excimer lasers for many applications. Although the pulse energies (~0.2 mJ) are typically less than excimer lasers, they have relatively high-spatial coherence and low divergence. Indeed, the structures micro-machined with this system are identical in quality to those machined by excimer lasers . Also, whereas excimer lasers are generally restricted to operating at repetition frequencies less than 1kHz, frequency-doubled copper vapor lasers can operated at elevated repetition frequencies of up to 20kHz.