| 摘要 |
<p>A precision press molding preform and a manufacturing method of optical element are provided to obtain a high-quality optical element in high productivity in precision press molding by controlling fluorine concentration on the surface and volatility of glass during process. A precision press molding preform consists of oxide glass comprising fluorine, and each of the light reflection factor and the surface free energy for both sides which face the opposite direction from the center of the precision molding preform each other, is different, respectively. The precision press molding preform has a axis of rotation symmetry, a primary curved surface having the axis and one of two intersection points on the surface, and a secondary curved surface having the axis and the other intersection point on the surface, and each of the surface face energy and the radius curvature for the primary curved surface and the secondary curved surface is different, respectively. A manufacturing method of optical element using the precision press molding preform comprises steps of: separating molten glass gob including the lower end of the molten glass flowed from pipe, and levitating the molten glass gob on the concave of the mold by wind pressure from gas spouted out of an outlet equipped in the concave in order to form preform while making no reversion of top and bottom, and the glass is oxide glass comprising fluorine. The light reflection factor is measured in an autocollimator having: a light controller(1), a sight controller(2), a collimator lens(3), a half-mirror(4), an objective lens(5) for a sample(6), a focusing lens(7), a half-prism(8), an ocular lens(9), a sight controller(10), a 2-dimensional cut filter(11), a diffraction grating(12), a mirror(13) and a line sensor(14).</p> |
