N2 laser stereo-lithography

A number of pulsed and/or continuous wave lasers are applied in stereo-lithography. In particular, the He-Cd laser and Ar ion laser with a wavelength of 325 nm and 351/364 nm respectively are used as ultraviolet (UV) light source. Disadvantages of these lasers include inefficient output energy, which is less than 0.1%, large machine size, insufficient output power, and they are very expensive. In the near future, these lasers are expected to increasingly lack the requested performance for higher speed stereo-lithography systems. Moreover, there will be growing demands for lower cost apparatus. For the laser stereo-lithography, the N2 laser with cylindrical tube has been adopted to achieve a lower cost type UV light source. Because of its excellent output efficiency, it is expect to downsize the power supply and laser head, and allows air-cooling. Moreover we adopt an optical fiber system for its optics, because the N2 laser output beam divergence has an excessive. In view of this, attempts were made to develop a special design cylindrical tube as the UV light source. This paper reports the fundamental characteristics of this laser.