| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a preform lot where the mixing of foreign matters is prevented, where characteristic variations by volatilization are suppressed and where an optical element is stably supplied by precision press molding under a definite condition. <P>SOLUTION: The preform lot is constituted of a plurality of preforms for precision press molding comprising fluorophosphate glass containing phosphorus, oxygen and fluorine as glass components. The fluorophosphate glass has a molar ratio O<SP>2-</SP>/P<SP>5+</SP>of the content of O<SP>2-</SP>to the content of P<SP>5+</SP>of 3.5 or more. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
