Refrigerative Stereolithography Using Sol-Gel Transformable Photopolymer Resin and Direct Masking

The authors have been studying a new fabrication method termed “refrigerative stereolithography” which uses a gel resin layer instead of a liquid layer used in conventional stereolithography. In this paper, we propose the “direct masking method” in which a masking pattern is drawn directly on a gel layer surface to block harmful light exposure of photopolymer resin. With such masks, we can avoid surplus growth only in the regions where it is unnecessary to improve height direction accuracy and resolution. The possibility of surplus growth in the width direction caused by light reflection from the mask surface is pointed out, and the effect is analyzed and confirmed by simulation and experiment. This new surplus growth is termed “reflective surplus growth”. Also, we can solidify the required section shape selectively using the masks and a lamp instead of laser scan patterns. The effectiveness of refrigerative stereolithography with the direct masking method is discussed and confirmed by some experimental results.