Optical member and image pickup apparatus

Patent metadata

Field	Value
Publication number	US-2016178806-A1
Application number	US-201414392283-A
Country	US
Kind code	A1
Filing date	May 23, 2014
Priority date	Jun 28, 2013
Publication date	Jun 23, 2016
Grant date	—

Abstract

There are provided an optical member having a low reflectance and a good dustproof property and an image pickup apparatus.
A plurality of projections are formed on a surface of a low-refractive-index layer disposed on a base and having a refractive index lower than that of the base so that a distance between peaks of the projections is 50 nm or more and 600 nm or less. An occupied area percentage at a depth of 15 nm in a direction toward the base from a peak farthest from the base among the peaks of the projections is 40% or less. An average of minor axis lengths of the projections at a depth of 5 nm or more and 15 nm or less in the direction is 15 nm or more.

First claim

1 . An optical member comprising:
a base; and a porous glass layer disposed on the base and having a refractive index lower than that of the base, wherein the porous glass layer has a plurality of projections on a surface opposite to a surface facing the base, distance between peaks of two adjacent projections is 50 nm or more and 600 nm or less, a percentage of a total cross-sectional area of the plurality of projections in a cross section parallel to the base at a depth of 15 nm from a peak farthest from the base in a direction toward the base per unit area is 40% or less, and an average of minimum distances among distances of straight lines that extend between any two points on a circumference of a projection and that pass through a center point in a cross section of the projection is 15 nm or more, the distances of straight lines being obtained in each of a plurality of cross sections parallel to the base at a depth of 5 nm or more and 15 nm or less from the peak farthest from the base in the direction toward the base.

2 . The optical member according to claim 1 , wherein a pore size of the porous glass layer is 5 nm or more and 20 nm or less.

3 . The optical member according to claim 1 , wherein a skeleton size of the porous glass layer is 5 nm or more and 20 nm or less.

4 . The optical member according to claim 1 , wherein a porous structure of the porous glass layer is derived from spinodal phase separation.

5 . The optical member according to claim 1 , wherein an average of minimum distances among distances of straight lines that extend between any two points on a circumference of the projection and that pass through a center point in a cross section of the projection is 60 nm or less, the distances of straight lines being obtained in each of a plurality of cross sections parallel to the base at a depth of 5 nm or more and 15 nm or less from the peak farthest from the base in the direction toward the base.

6 . An image pickup apparatus comprising:
the optical member according to claim 1 ; and an image pickup element.

7 . The optical member according to claim 1 , wherein the porous glass layer contains boron oxide.

8 . The optical member according to claim 1 , wherein the base is quartz glass or rock crystal.

9 . An optical member comprising:
a base; and a porous glass layer having pores whose size is 5 nm or more and 20 nm or less, disposed on the base and having a refractive index lower than that of the base, wherein the porous glass layer has a plurality of projections on a surface opposite to a surface facing the base, and a distance between peaks of two adjacent projections is 50 nm or more and 600 nm or less.

Assignees

• Canon Kk

Inventors

• Takei Akiko
• Sugiyama Akira
• Kakegawa Norishige
• Takashima Kenji
• Zhang Zuyi
• Kotani Yoshinori
• Koketsu Naoyuki

Classifications

• G02B1/118 Primary

  having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures · CPC title

• G02B1/14

  Protective coatings, e.g. hard coatings · CPC title

• G02B1/113

  using inorganic layer materials only · CPC title

• G02B1/18 Primary

  Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films (G02B1/16 takes precedence) · CPC title

• C03C3/06

  with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)} · CPC title