Method for manufacturing a porous glass film
The present invention provides an optical member having a high transmittance, wherein a composition change of a phase-separable base material glass film is suppressed. A method for manufacturing an optical member provided with a porous glass film on the base member includes the steps of forming a glass powder film containing a glass powder on the base member, forming a phase-separable base material glass film on the base member by heating and fusing the glass powder film in an atmosphere having an oxygen concentration of more than 20%, forming a phase-separated glass film on the base member by heating the base material glass film, and forming a porous glass film on the base member by subjecting the phase-separated glass film to an etching treatment.
1. A method for manufacturing an optical member provided with a porous glass film on a base member, comprising the steps of:
forming a glass powder film containing a glass powder on the base member;
forming a phase-separable base material glass film on the base member by heating and fusing the glass powder film;
forming a phase-separated glass film on the base member by heating the base material glass film; and
forming a porous glass film on the base member by subjecting the phase-separated glass film to an etching treatment,
wherein the glass powder comprises SiO 2 , B 2 O 3 , Na 2 O and Al 2 O 3 , and
wherein the step of forming a phase-separable base material glass film on the base member by heating and fusing the glass powder film is performed in an atmosphere having an oxygen concentration of 50% or more.
2. The method for manufacturing an optical member, according to claim 1 , wherein the forming of the base material glass film is performed by heating at a temperature higher than or equal to the glass transition temperature and lower than or equal to the crystallization temperature.
3. The method for manufacturing an optical member, according to claim 1 , wherein the forming of the base material glass film is performed by heating at a temperature from 500 degrees (Celsius) to 800 degrees (Celsius).