US 12,242,025 B2
Synthetic quartz glass substrate with antireflection film, window material, lid for optical element package, optical element package, and light irradiation device
Harunobu Matsui, Joetsu (JP); Daijitsu Harada, Joetsu (JP); and Masaki Takeuchi, Joetsu (JP)
Assigned to SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed by Shin-Etsu Chemical Co., Ltd., Tokyo (JP)
Filed on Mar. 10, 2021, as Appl. No. 17/197,444.
Claims priority of application No. 2020-047579 (JP), filed on Mar. 18, 2020.
Prior Publication US 2021/0293994 A1, Sep. 23, 2021
Int. Cl. G02B 1/115 (2015.01); F21V 3/06 (2018.01); F21V 3/10 (2018.01); G02B 5/02 (2006.01)
CPC G02B 1/115 (2013.01) [F21V 3/061 (2018.02); F21V 3/10 (2018.02); G02B 5/0294 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A synthetic quartz glass substrate with an antireflection film, comprising:
the synthetic quartz glass substrate; and
the antireflection film formed on a main surface of the synthetic quartz glass substrate, wherein
a contact angle of the main surface of the synthetic quartz glass substrate is within 5 degrees, the contact angle being defined by a sessile drop method of JIS R 3257:1999, and
the antireflection film includes a first layer containing Al2O3, a second layer containing HfO2, and a third layer containing MgF2 or SiO2 sequentially laminated on the main surface of the synthetic quartz glass substrate,
wherein the synthetic quartz glass substrate satisfies a relational expression of D99.9−D50<5 nm, where D50 is a median height and D99.9 is a height of 0.1% from a highest height in a height histogram obtained by measuring, with an atomic force microscope, in a 1 μm×1 μm area, which is randomly selected, on the main surface of the synthetic quartz glass substrate.