• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.3
• /
• pp.171-179
• /
• 2004

Micro-stereolithography technology has made it possible to fabricate a freeform 3D microslructure. This technology is based on conventional stereolithography, in which a UV laser beam irradiates the open surface of a UV-curable liquid photopolymer, causing it to solidify. In micro-stereolithography, a laser beam of a few $\mu m$ diameter is used to solidify a very small area of the photopolymer. This is one of the key technological elements, and can be achieved by using a focusing lens. Thus, the solidification phenomena of the liquid photopolymer must be carefully investigated. In this study, the photopolymer solidification phenomena in response to variations in the scanning pitch of a focused laser beam was investigated experimentally. The effect of layer thickness on the solidification width and depth was also examined. These studies were conducted under the conditions of relatively lower laser power and relatively higher scanning speed. Moreover, the photopolymer solidification phenomena for the relatively higher laser power and lower scanning speed was investigated, too. In this case, comparing to the case of lower laser power and higher scanning speed, the photopolymer absorbed large amount of irradiation energy of the laser beam. These results were compared with those obtained from a photopolymer solidification model. From these results, a new laser-scanning scheme was proposed according to the shape of the 3D model. Samples by each method were fabricated successfully.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.1015-1016
• /
• 2009

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.8
• /
• pp.98-104
• /
• 2010

It has been reported that the photopolymer solidification in the stereolithogrpahy process is mainly depend on the laser exposure conditions such as laser power and scanning speed. However, these researches were focused on the vertical laser exposure onto the surface of the photopolymer. In this research, we developed a mathematical model for the photopolymer solidification under the inclined laser beam exposure. Using the developed mathematical model, the photopolymer solidifications were simulated varying inclined laser exposure conditions. Developed mathematical model was in good agreement with the experimental result. This research can be applied to improve the surface roughness in the stereolithogrpahy process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.10a
• /
• pp.525-526
• /
• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.1037-1040
• /
• 2002

In micro-stereolithography technology, fabrication conditions that include laser power, laser scan speed, laser scan pitch, and material property of photopolymer such as penetration depth and critical exposure are considered as major process variables. But the existing scan path generation methods based only on CAD model have not taken them into account, which has resulted in cross-section dimension of low accuracy. Thus, to enhance cross-section dimensional accuracy, the physical resin solidification n phenomena should be reflected in laser scan path generation and stage operating code. In this paper, multi-line experiments based on single line solidification model are performed. And the method for improving cross-section dimensional accuracy is presented, which is to apply the database based on experimental results to laser scan path generation.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.12 s.189
• /
• pp.117-121
• /
• 2006

Generally, micro-stereolithography technology uses laser and complex optical system as light source and light delivery system, respectively. In this research, a novel micro-stereolithography technology that uses UV lamp that is more economical than UV laser as light source and optical fiber that is simpler than previous light delivery system has been developed. Furthermore, precise control system that is composed of 3-axis linear stage and shutter has been used to fabricate truly three dimensional micro-structure. For confirming the feasibility of developed micro-stereolithography apparatus, the solidification experiments were conducted. The solidification widths and depths datum of photopolymer as varying scanning speed of the UV light have been obtained. Using developed apparatus, some micro structures were fabricated successfully.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.2
• /
• pp.186-194
• /
• 2004

Micro-stereolithography is a newly proposed technology as a means that can fabricate a 3D micro-structure of free form. It makes a 3D micro-structure by dividing the shape into many slices of relevant thickness along horizontal surfaces, hardening each layer of slice with a focused laser beam, and stacking them up to a desired shape. In this technology, differently from the conventional stereolithography, scale effect is dominant. To realize micro-stereolithography technology, we developed the micro-stereolithography apparatus which is composed of an Ar+ laser, x-y-z stages. controllers. optical devices and scan path generation software. Related processes were developed, too. Using the system, a number of micro-structures were successfully fabricated. Some of these samples are shown for prove this system. Laser scan path generation algorithm and software considering photopolymer solidification phenomena as well as given 3D model were developed. Sample fabrication of developed software shows relatively high dimensional accuracy compared to the uncompensated result.