Effectiveness of fine-pitch lenticular lens arrays fabricated using projection lithography for improving resolution and clearness in switching of two pictures

摘要

It was verified that a lenticular lens array with a fine pitch of 100 μm was effective for improving resolution and clearness in switching of two images. Lenticular lens array patterns of negative resist SU-8 were fabricated on a 240-μm thin quartz plate, and they were directly used as lenticular lens arrays. The patterns were printed using 1:1 projection lithography under largely defocused conditions using a reticle with 50-μm line-and-space patterns. Because pattern images were made vague by the defocus, connected humpbacked patterns with a pitch of 100 μm were continuously formed without spaces. Cross section profiles of the patterns were almost circular, and the curvature radius was controllable in a range between 60 and 130 μm by adjusting exposure time. In the case of picture switching using conventional lenticular lens arrays with spatial frequencies of 40.1-00 lenses per inch, stitching lines appeared considerably clear between divided picture elements, and discontinuous steps were observed at inclined parts of figures. However, when the 100-μm pitch lens arrays were used, stitched steps became far finer and smoother, and scenes without notable stitching lines were obtained. Steps and discontinuities at inclined parts of figures were especially improved. Thus, fine pitch lenticular lens arrays are effective, and the new method for printing lenticular lens patterns would be useful for fabricating original molds of lenticular lens arrays.