# US 9,517,969 B2 · Method for manufacturing a porous glass film

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- Number: US 9,517,969 B2
- Document ID: US9517969B2
- Status: Granted
- Kind: B2
- Application number: 14/358,850
- Filed: 2012-10-18
- Published: 2014-10-16
- Granted: 2016-12-13
- Earliest claimed: 2011-11-18
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Naoyuki Koketsu; Zuyi Zhang; Yoshinori Kotani; Akiko Takei; Akira Sugiyama; Kenji Takashima
- Web page: https://patentgrep.com/patent/US9517969B2

## CPC

- C03C 11/005: {obtained by leaching after a phase separation step}
- C03C 17/006: {with materials of composite character}
- G02B 5/3008: {comprising dielectric particles, e.g. birefringent crystals embedded in a matrix}
- C03C 2217/425: consisting of a porous layer
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

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.

## Claims

### Claim 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 SiO2, B2O3, Na2O and Al2O3, 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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).