METHOD AND APPARATUS FOR FORMING OPTICAL ELEMENT, SUBSTRATE AND FORMING DIE

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for the thermal forming of an optical element where gas sealing at thermal forming can be efficiently prevented, the occurrence of a crater-like structure caused by it is controlled and the optical element can be produced more precisely and at an efficient cost. SOLUTION: The surface of a die 1 is shaped to be a recessed cavity 3 and a substrate 10, for example a glass preform, is shaped to be a projected and curved part 16. The curvature radius of the recessed cavity 3 is longer than that of the projected and curved part 16. The die 1 and the substrate 10 are pressed each other at the thermal forming and the interface between the substrate and the die and a process gas moves gradually from a central part 11 to the die 1 and the substrate 10 and then all process gases are exhausted from an annular gap between the die 1 and the substrate 10. The crater-like structure caused by the gas sealing at the thermal forming does not exist on the projected and curved surface 21 at the optical element 20. COPYRIGHT: (C)2006,JPO&NCIPI