Present situation of research on stereophonic lithography using a pair of parabolic mirrors

Abstract

As the present situation of stereophonic lithography using a pair of parabolic mirrors, a main subject of the research and challenges to solve it were discussed. Using a commercially available magic mirror system composed of a pair of parabolic mirrors, it was capable to make 3-dimensional real images of the original reflective objects placed on the lower mirror bottom at just above the upper mirror aperture. Utilizing this optics, and adding some ideas, stereophonic lithography on curved articles were enabled. At first, an aperture was opened at the bottom center of the lower mirror also. Next, transparent curved reticles were used instead of the original reflective objects. In addition, the transparent curved reticles were illuminated obliquely upward from the bottom using a collimated light from one side. Owing to these ideas, it was demonstrated that patterns on a curved spoon-shape reticles were successfully replicated on spoonshape articles with the same shape. However, the reticles were made by pasting transparent seals with emulsion illustrations. Such reticles were not desirable from the view point of accuracy and exposure homogeneity. To solve this important subject, a new idea was contrived further. That was the replication from the conventional flat reticle to curved articles using the same parabolic mirror optics. Because the focal redundancy was very large, patterns were replicable, though light intensity distributed, pattern shapes were distorted, and pattern widths were also distributed. However, it was thought feasible to utilize flat reticles by compensating the light intensity distribution and image distortions.