Superlarge-Capacity Optical Disk with Multilayer Structure Fabricated Using a Photopolymer Sheet

We have been studying a multilayer disk in order to realize a 12-cm-diameter optical disk with the recording capacity of 100 GB or more. We tried to fabricate a multilayer disk using a photopolymer sheet. We developed a new sheet, and confirmed the performance of this sheet. A single layer disk made using this sheet had a value of 5.3%, and a 25 GB capacity. Then we fabricated a dual layer disk. The thickness variations from the disk surface to each recording layer were ±0.6 µm and ±0.7 µm. These results indicated the possibility of realizing a multilayer disk for a high-numerical-aperture (high-NA) system. We will evaluate the signals reproduced from the multilayer disk in the next step.