MULTI-LAYERED OPTICAL FILM AND METHOD FOR PRODUCING THE SAME

• US 20130176615A1
• Filed: 10/11/2012
• Published: 07/11/2013
• Est. Priority Date: 01/10/2012
• Status: Active Grant

• Current Assignee: Nalux Co., Ltd (Nalux Holdings Corp.)
• Original Assignee: Nalux Co., Ltd (Nalux Holdings Corp.)
• Inventors: INOUE, Yasuaki, UEFUJI, Hiroaki
• Granted Patent: US 9,459,388 B2
• Time in Patent Office: Days
• US Class Current: 359/359
• CPC Class Codes: G02B 1/113 using inorganic layer materials only
• CPC Class Codes: G02B 5/28 Interference filters
• CPC Class Codes: G02B 5/283 designed for the ultraviolet

Abstract

A multi-layered optical film formed on a plastic substrate, which has high resistance against lights in the ultraviolet region including blue lasers in a high ambient temperature is disclosed. Each layer of the multi-layered optical film is made of an oxide or an oxynitride, layers adjacent to each other are made of materials having different refractive indexes, oxidation-reduction potential of elements constituting oxides or oxynitrides is −0.9 volts or less, thickness of a first layer adjacent to the substrate is 10 nanometers or more, an absolute value of a difference in refractive index between a material of the substrate and a material of the first layer is 0.2 or less, an absolute value of a difference in refractive index between two kinds of materials of layers adjacent to each other is 0.45 or less and total thickness of the multi-layered optical film is 3000 nanometers or less.

Claims

1. A multi-layered optical film formed on a plastic substrate, wherein each layer of the multi-layered optical film is made of an oxide or an oxynitride, layers adjacent to each other are made of materials having different refractive indexes, oxidation-reduction potential of elements constituting oxides or oxynitrides is −

0.9 volts or less, thickness of a first layer adjacent to the substrate is 10 nanometers or more, an absolute value of a difference in refractive index between a material of the substrate and a material of the first layer is 0.2 or less, an absolute value of a difference in refractive index between two kinds of materials of layers adjacent to each other is 0.45 or less and total thickness of the multi-layered optical film is 3000 nanometers or less.

2. A multi-layered optical film according to claim 1, wherein at least one kind of pair of layers in which a layer made of a material having a higher refractive index and a layer made of a material having a lower refractive index are alternately stacked is stacked to form the multi-layered optical film and an absolute value of a difference between the higher refractive index and the lower refractive index is 0.45 or less.

3. A multi-layered optical film according to claim 1, wherein material with the highest refractive index among materials constituting the multi-layered optical film includes one of aluminium, lanthanum, gadolinium, zirconium, calcium, cerium, europium, hafnium, magnesium, niobium, scandium, yttrium and ytterbium.

4. A multi-layered optical film according to claim 1, wherein material constituting the first layer of the multi-layered optical film includes silicon or aluminium.

5. A multi-layered optical film according to claim 1, wherein the multi-layered optical film includes two kinds of materials.

6. A multi-layered optical film according to claim 1, wherein the multi-layered optical film includes three kinds of materials.

7. A multi-layered optical film according to claim 1, wherein total thickness of the multi-layered optical film is 240 nanometers or more.

9. An optical element including a plastic substrate and a multi-layered optical film formed on the plastic substrate according to claim 1 or claim 8.

8. A multi-layered optical film formed on a plastic substrate, which has resistance against lights in the ultraviolet region including blue lasers in an ambient temperature of 75°

C., wherein each layer of the multi-layered optical film is made of an oxide or an oxynitride, layers adjacent to each other are made of materials having different refractive indexes, oxidation-reduction potential of elements constituting oxides or oxynitrides is −

0.9 volts or less, thickness of a first layer adjacent to the substrate is 10 nanometers or more, an absolute value of a difference in refractive index between a material of the substrate and a material of the first layer is 0.2 or less, an absolute value of a difference in refractive index between two kinds of materials of layers adjacent to each other is 0.45 or less and total thickness of the multi-layered optical film is 3000 nanometers or less.

10. A method for forming a multi-layered optical film on a plastic substrate, wherein the multi-layered optical film includes at least one kind of pair of layers in which a layer made of a material having a higher refractive index and a layer made of a material having a lower refractive index are alternately stacked, each layer of the multi-layered optical film is made of an oxide or an oxynitride, oxidation-reduction potential of elements constituting oxides or oxynitrides is −

0.9 volts or less, thickness of a first layer adjacent to the substrate is 10 nanometers or more, an absolute value of a difference in refractive index between a material of the substrate and a material of the first layer is 0.2 or less, an absolute value of a difference between the higher refractive index and the lower refractive index is 0.45 or less and total thickness of the multi-layered optical film is 3000 nanometers or less, the method comprising the steps of

determining materials, thickness and the number of the layers in the above-described conditions in such a way that the multi-layered optical film has a required optical performance; and

adjusting the determined materials, thickness and the number of the layers in the above-described conditions in such a way that the multi-layered optical film has a required resistance against lights in the ultraviolet region including blue lasers in an ambient temperature of 75°

C.