Dielectric Mirror With Niobium Oxide Layers
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Solution Overview
Problem
Conventional mirrors require metallic reflective layers like Al or Ag, which is undesirable, and existing dielectric mirrors do not achieve the desired visible reflection and transmission values without these metals.
Innovation Solution
A dielectric mirror design using niobium oxide and silicon oxide layers with a NiCr symmetry adjusting layer, eliminating metallic reflective layers and achieving visible reflection of 50-90% and transmission of 10-50% by optimizing refractive index and thickness differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metallic reflective layer (Al or Ag) is used, then high visible reflection is achieved, but the mirror contains undesirable metallic materials
Solution Approach 1:
The patent removes the metallic reflective layer (Al or Ag) from the mirror structure and replaces it with a dielectric coating system consisting of alternating high and low refractive index layers. This extraction eliminates the harmful metallic materials while maintaining the reflective function through optical interference in the dielectric layers.
Solution Approach 2:
The patent changes the optical parameters by using dielectric materials with different refractive indices (high index layers of TiO2 or Nb2O5 and low index layers of SiO2) instead of metallic materials. By optimizing the thickness and sequence of these dielectric layers, the mirror achieves high visible reflection without metals, and can also control visible transmission in the 10-50% range.
2Object-generated harmful factors
If dielectric layers are used without metallic reflective layer, then metallic materials are eliminated, but desired visible reflection and transmission values are not achieved
Solution Approach 1:
The patent employs a composite dielectric coating structure with alternating layers of high refractive index materials (TiO2, Nb2O5) and low refractive index materials (SiO2). This composite structure creates optical interference effects that produce high visible reflection (50-90%) and controlled visible transmission (10-50%) without requiring any metallic materials.
Solution Approach 2:
The patent optimizes the thickness parameters of individual dielectric layers to control the optical performance. By adjusting layer thicknesses and refractive indices, the mirror achieves the target visible reflection of 50-90% and visible transmission of 10-50%, demonstrating that parameter optimization can replace metallic materials while maintaining desired optical characteristics.
3Ease of manufacture
If symmetric dielectric layers are used, then manufacturing is simplified, but asymmetric reflectance control is limited
Solution Approach 1:
The patent introduces asymmetry into the dielectric coating structure by making the first high refractive index layer (closest to the substrate) thicker than the third and fifth high refractive index layers. This asymmetric design enables independent control of glass side reflectance and film side reflectance, allowing the mirror to achieve glass side reflectance at least 30% different from film side reflectance, thereby enhancing adaptability for different application requirements.
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 dielectric mirror achieves high visible reflection and transmission values without metallic layers, suitable for various applications including consumer and digital signage, with the option for heat treatment and asymmetric reflectance adjustment.
Implementation Method 1
a first transparent dielectric high refractive index layer comprising niobium oxide and/or titanium oxide, the first transparent dielectric high refractive index layer having a thickness of from about 70-140 nm; a second transparent dielectric low refractive index layer comprising silicon oxide
Implementation Method 2
a first transparent dielectric high refractive index layer comprising niobium oxide and/or titanium oxide... a second transparent dielectric low refractive index layer comprising silicon oxide
Implementation Method 3
a symmetry adjusting layer located between the third transparent dielectric high refractive index layer and the fifth transparent dielectric high refractive index layer. The symmetry adjusting layer comprises NiCr
Data Source
Figure 1
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AI summary
A dielectric mirror includes a coating having alternating high and low index layers. The high index layers comprise niobium oxide and/ or titanium oxide, and the low index layers comprise silicon oxide. The mirror coating has no metallic reflective layer of Al or Ag in certain example embodiments, and may have film side and/or glass side visible reflection of from about 50-90% (more preferably from about 60-80% and most preferably from about 65-75%) and visible transmission of from about 10-50% (more preferably from about 10-40% or 20-40%) in certain example embodiments. The thicknesses and relative thicknesses of the layers, as well as their refractive indices, are specified. Asymmetry of reflectance between the glass substrate side and the film side is achieved.