ANTI-REFLECTION COATING, OPTICAL MEMBER, EXCHANGE LENS UNIT AND IMAGING DEVICE

• US 20090168184A1
• Filed: 12/23/2008
• Published: 07/02/2009
• Est. Priority Date: 12/27/2007
• Status: Active Grant

• Current Assignee: PENTAX RICOH IMAGING COMPANY, LTD.
• Original Assignee: Hoya Corporation
• Inventors: NAKAYAMA, Hiroyuki, YAMADA, Kazuhiro, SUZUKI, Mineta
• Granted Patent: US 8,199,404 B2
• Time in Patent Office: Days
• US Class Current: 359/601
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick

Abstract

An anti-reflection coating comprising first to seventh layers formed on a substrate in this order, the first layer being an alumina-based layer, the seventh layer being a porous, silica-based layer, and each of the first to seventh layers having predetermined refractive index and optical thickness in a wavelength range of 400-700 nm.

Claims

1. An anti-reflection coating comprising first to seventh layers formed on a substrate in this order, said first layer being an alumina-based layer, said seventh layer being a porous, silica-based layer, and in a wavelength range of 400-700 nm,

said substrate having a refractive index of 1.60-1.95,

said first layer having an optical thickness of 37.5-112.5 nm,

said second layer having a refractive index of 1.95-2.25 and an optical thickness of 35.5-60.0 nm,

said third layer having a refractive index of 1.35-1.50 and an optical thickness of 24.5-41.5 nm,

said fourth layer having a refractive index of 1.95-2.25 and an optical thickness of 210.5-250.0 nm,

said fifth layer having a refractive index of 1.35-1.50 and an optical thickness of 12.5-32.5 nm,

said sixth layer having a refractive index of 1.95-2.25 and an optical thickness of 27.5-45.0 nm, and

said seventh layer having an optical thickness of 108.0-138.0 nm.

2. The anti-reflection coating according to claim 1, wherein said second layer, said fourth layer and said sixth layer are made of at least one material selected from the group consisting of Ta₂O₅, ZrO₂, HfO₂, CeO₂, SnO₂, In₂O₃ and ZnO, and said third layer and said fifth layer are made of MgF₂ and/or SiO₂.

3. The anti-reflection coating according to claim 1, wherein said first layer has a refractive index of 1.59-1.69.

4. The anti-reflection coating according to claim 1, wherein said seventh layer having a refractive index of 1.25-1.30.

5. The anti-reflection coating according to claim 1, which has reflectance of 0.5% or less to incident light at 0°

in a wavelength range of 450-600 nm, and reflectance of 1.0% or less to incident light at 300 in a wavelength range of 400-650 nm.

11. The anti-reflection coating according to claim 1, wherein said seventh layer is a silica aerogel layer.

12. The anti-reflection coating according to claim 1, wherein a fluororesin layer as thick as 0.4-100 nm having water repellency or water/oil repellency is formed on said seventh layer.

13. The anti-reflection coating according to claim 1, wherein said seventh layer is formed by a sol-gel method.

14. An optical member having the anti-reflection coating recited in claim 1.

15. An exchange lens unit comprising the optical member recited in claim 14.

16. An imaging device comprising the optical member recited in claim 14.

6. An anti-reflection coating comprising first to seventh layers formed on a substrate in this order, said first layer being an alumina-based layer, said seventh layer being a porous, silica-based layer, and in a wavelength range of 400-700 nm,

said substrate having a refractive index of 1.50-1.70,

said first layer having an optical thickness of 24.5-200.0 nm,

said second layer having a refractive index of 1.93-2.25 and an optical thickness of 24.5-50.5 nm,

said third layer having a refractive index of 1.33-1.50 and an optical thickness of 14.0-30.0 nm,

said fourth layer having a refractive index of 2.00-2.16 and an optical thickness of 131.5-200.5 nm,

said fifth layer having a refractive index of 1.33-1.50 and an optical thickness of 20.0-31.5 nm,

said sixth layer having a refractive index of 2.04-2.17 and an optical thickness of 50.0-62.5 nm, and

said seventh layer having an optical thickness of 122.5-142.5 nm.

7. The anti-reflection coating according to claim 6, wherein said second layer, said fourth layer and said sixth layer are made of at least one material selected from the group consisting of Ta₂O₅, ZrO₂, HfO₂, CeO₂, SnO₂, In₂O₃ and ZnO, and said third layer and said fifth layer are made of MgF₂ and/or SiO₂.

8. The anti-reflection coating according to claim 6, wherein said first layer has a refractive index of 1.57-1.72.

9. The anti-reflection coating according to claim 6, wherein said seventh layer has a refractive index of 1.23-1.32.

10. The anti-reflection coating according to claim 6, which has reflectance of 0.3% or less to incident light at 0°

in a wavelength range of 450-600 nm.

17. The anti-reflection coating according to claim 6, wherein said seventh layer is a silica aerogel layer.

18. The anti-reflection coating according to claim 6, wherein a fluororesin layer as thick as 0.4-100 nm having water repellency or water/oil repellency is formed on said seventh layer.

19. The anti-reflection coating according to claim 6, wherein said seventh layer is formed by a sol-gel method.

20. An optical member having the anti-reflection coating recited in claim 6.

21. An exchange lens unit comprising the optical member recited in claim 20.

22. An imaging device comprising the optical member recited in claim 20.