Wide Angle High Reflective Mirror with Dielectric Film Stack
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Solution Overview
Problem
Conventional wide angle reflective mirrors suffer from low abrasion resistance, poor environmental reliability, and limited lifetime due to the use of metallic film layers, while all-dielectric thin films provide better reliability but suffer from significant wavelength shift at increased incident angles, limiting their application range.
Innovation Solution
A wide angle high reflective mirror is designed with a reflection band overlapping the wavelength range of 800 to 4000 nm, comprising alternately stacked high refractive index film layers made of SiH, SiOxHy, or SiOxNy, and low refractive index film layers made of TiO2, Nb2O5, Ta2O5, SiO2, or their mixtures, ensuring high reflectance (>99%) over a large incident angle range (0 to 60 degrees).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If metallic film layers are used to meet wide angle application needs, then the mirror can be coated with metallic film, but the abrasion resistance is low, environmental reliability is poor, and lifetime is short
Solution Approach 1:
The patent uses a composite dielectric film structure consisting of multiple layers with different refractive indices (high refractive index layers of TiO2, Nb2O5, Ta2O5 alternated with low refractive index layers of SiO2, Al2O3). This composite structure achieves both wide angle reflectivity (>99% from 0-60 degrees) and high reliability by combining materials with complementary properties.
Solution Approach 2:
The patent changes the optical parameters of the film layers by selecting materials with specific refractive indices and controlling layer thicknesses (optical thickness of λ/4 or variations thereof). By adjusting these parameters, the reflection band is maintained across a wide angular range while achieving high reflectance, resolving the contradiction between wide angle capability and reliability.
2Reliability
If conventional oxide or fluoride all-dielectric materials are used, then environmental reliability and lifetime are excellent, but the center wavelength of the reflection band shifts significantly to the short wave as incident angle increases
Solution Approach 1:
The patent employs a composite dielectric structure with alternating high and low refractive index layers. The specific combination of materials (TiO2, Nb2O5, Ta2O5 with SiO2, Al2O3) and their optimized thicknesses creates a reflection band that remains stable across wide angular ranges, preventing the wavelength shift problem while maintaining all-dielectric reliability.
Solution Approach 2:
The patent addresses the angular dependency problem by designing a multi-layer structure where the optical path differences between layers compensate for angle-induced wavelength shifts. This dimensional approach to film structure design maintains consistent reflection characteristics across varying incident angles.
3Reliability
If hard dielectric thin films are added as enhanced protective layers to improve reliability, then reliability is improved, but there is still a large reliability gap with conventional all-dielectric thin film
Solution Approach 1:
The patent achieves high reliability through a composite all-dielectric structure that eliminates the need for metallic layers while maintaining wide angle performance. The combination of hard dielectric materials (TiO2, Nb2O5, Ta2O5, SiO2, Al2O3) in an optimized multi-layer configuration provides both protective functionality and optical performance, closing the reliability gap without requiring additional protective layers.
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 solution achieves high reflectance (>99%) over a wide incident angle range (0 to 60 degrees) while maintaining good reliability and lifetime, effectively addressing the limitations of conventional reflective mirrors.
Implementation Method 1
a plurality of high refractive index film layers and a plurality of low refractive index film layers alternately stacked
Implementation Method 2
each of the high refractive index film layers has a refractive index of greater than 3 in a wavelength range of 800 to 4000 nm
Data Source
AI summary
Provided is a wide angle application high reflective mirror having a reflection band partially overlapping in a wavelength range of 800-4000 nm. The mirror comprises a film system in which a plurality of high refractive index film layers and a plurality of low refractive index film layers that are alternately stacked, and the material of the high refractive index film layer is one of SiH, SiOxHy, or SiOxNy, or a mixture thereof. The highly reflective mirror can achieve a reflectance greater than 99% with an incident angle ranging from 0 to 60 degrees over a large angle range.