Multi-layered Optical Film UV Resistance Plastic Substrate
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Solution Overview
Problem
Current multi-layered optical films do not provide sufficient resistance against ultraviolet light, including blue lasers, at high ambient temperatures, which can damage optical elements used in devices like optical pickup devices.
Innovation Solution
A multi-layered optical film is developed using a plastic substrate with layers made of oxides or oxynitrides, where adjacent layers have different refractive indexes, and specific materials such as aluminum, lanthanum, or silicon are used, with a thickness of 240 nanometers or more, to enhance resistance against ultraviolet light at 75°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layered optical film is formed on a plastic substrate to provide resistance against ultraviolet light, then the resistance against lights in the ultraviolet region is improved, but the film cannot maintain high resistance in high ambient temperature conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the optical film by selecting specific oxides and oxynitrides with oxidation-reduction potentials of -0.9V or less. This parameter change enables the film to maintain chemical stability and resistance against ultraviolet light-induced reactions even at high ambient temperatures of 75°C or higher, resolving the contradiction between UV resistance and temperature stability.
Solution Approach 2:
The patent employs composite materials consisting of multiple layers of different oxides and oxynitrides (such as SiO2, Al2O3, ZrO2, HfO2, La2O3, Gd2O3, CeO2, Eu2O3, MgO, Nb2O5, Sc2O3, Y2O3, Yb2O3) with controlled refractive indices. This composite structure provides both UV resistance and thermal stability, overcoming the limitation of single-material films that cannot maintain performance at high temperatures.
2Reliability
If glass is used for optical elements to achieve high resistance against ultraviolet light, then the resistance is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the material parameter from traditional glass to specific oxide and oxynitride compounds deposited as thin films. This parameter change allows plastic substrates to achieve glass-level UV resistance while reducing device complexity, as plastic components are easier to manufacture and integrate than glass components requiring precision glassworking.
Solution Approach 2:
The patent replaces mechanical glass elements with deposited optical films on plastic substrates. This substitution eliminates the need for complex glass processing, assembly, and handling, thereby reducing device complexity while maintaining or improving UV resistance through the controlled composition and structure of the multi-layered film.
3Reliability
If the thickness of the optical film is increased to improve UV resistance, then the resistance is improved, but the total thickness becomes excessive and affects optical performance
Solution Approach 1:
The patent changes the protective parameter from physical thickness to chemical composition. By selecting materials with oxidation-reduction potentials of -0.9V or less and controlling the refractive indices of adjacent layers, the film achieves high UV resistance with a total thickness of 3000nm or less. The first layer thickness of 10nm or more provides adequate protection without excessive thickness, optimizing both UV resistance and optical performance.
Solution Approach 2:
The patent divides the optical film into multiple layers with different oxide and oxynitride compositions and refractive indices. This segmentation allows each layer to contribute specifically to UV resistance while maintaining controlled total thickness. The multi-layer structure provides enhanced UV protection through cumulative effect of multiple protective interfaces, achieving high resistance without requiring excessive single-layer thickness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film effectively reduces chemical reactions and enhances resistance against ultraviolet light, maintaining minimal wave aberration differences before and after laser irradiation, even at elevated temperatures.
Implementation Method 1
Oxidation-reduction potential of elements constituting oxides or oxynitrides is −0.9 volts or less. The multi-layered optical film will restrain chemical reactions due to lights in the ultraviolet region including blue lasers
Implementation Method 2
Layers adjacent to each other are made of materials having different refractive indexes. 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
Data Source
AI summary
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.