METHOD FOR MANUFACTURING POROUS GLASS, AND METHOD FOR MANUFACTURING OPTICAL ELEMENT

摘要

A method for manufacturing a porous glass includes: forming a phase-separated glass by heating at a temperature in a range of 300 to 500 degrees Celsius for 3 to 50 hours for phase separation of a glass body in which the concentration of SiO2 is 50 to 70 percent by weight, the concentration of B2O3 is 15 to 40 percent by weight, the concentration of Li2O is 1.0 to 8.0 percent by weight, the concentration of Na2O is 2.0 to 8.0 percent by weight, the concentration of K2O is 0.3 to 5.0 percent by weight, the total concentration of Li2O, Na2O, and K2O is 3.5 to 15 percent by weight, and the ratio of the concentration of K2O to the total concentration of Li2O, Na2O, and K2O is 0.10 to 0.30; and forming a porous glass by etching the phase-separated glass.