Exposure Time Variation Method Using DMD for Microstereolithography

Abstract

In stereolithography, parts are fabricated by curing photopolymeric resins with light. The application of stereolithography can now be extended to a very small scale. The process, called microstereolithography, can fabricate parts on a microscale without any further consideration of geometry complexity. In particular, projection-type microstereolithography can perform quite rapid fabrication that cures a specific cross section in one exposure to light without movement. However, in the case where the light source has a nonuniform intensity or an aberration caused by its optics, the part might have some distortion, and this is commonly the case. Because the material experiences shrinkage when it is cured, the light intensity over the entire cross section should be uniform. This study utilizes a Dynamic Mirror Device, which is mainly used for beam shaping, to control the beam intensity also. This control makes the beam intensity profile flat and reduces the distortion to a great degree. This paper presents the concept of an exposure time control method that makes the beam intensity uniform, and it also presents some experimental results.

Microstereolithography

“…Many micro-SLA machines were built by different research teams using the DMD technology as dynamic mask [4,[36][37][38][39][40]. The first has been developed by Bertsch et al [41] in 1998.…”

Rapid Fabrication of Hydrogel Microstructures Using UV-Induced Projection Printing

“…A generalized schematic of the DMD-based hydrogel microstructures fabricating system used is shown in Figure 1, which contains five basic components: UV laser (Changchun Femtosecond Technology Ltd, Changchun, China, model MW-UV-375), the DMD (Texas Instruments Ltd, Dallas, TX, USA) [34,35], projection optics, a XYZ three-axes stage (Thorlabs Inc, Newton, NJ, USA), and a charge-coupled device (CCD) camera. We adopted an ultraviolet (UV) laser coupled with adjustable power (maximum intensity is 50 mW) and a wavelength of 375 nm as the light source to enhance the accuracy of the optical path.…”