An optical memory element.

摘要

An optical memory element comprising a substrate with grooves functioning as grooves for, for example, controlling the position of a laser beam, has the substrate formed from a glass containing SiO₂ in the range of <Bold>51</Bold> to <Bold>71</Bold>% by weight, Na₂O in the range of <Bold>10</Bold> to <Bold>18</Bold>% by weight, K₂O in the range of <Bold>0</Bold> to <Bold>8</Bold>% by weight, Al₂O₃ in the range of <Bold>12</Bold> to <Bold>22</Bold>% by weight, and B₂O₃ in the range of <Bold>0</Bold> to <Bold>9%</Bold> by weight.