Amorphous Silicon Mirror Coating for Low-Roughness Reflective Surfaces
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Solution Overview
Problem
Existing mirrors face limitations due to substrate quality, requiring thin polishable layers that lead to imperfections, non-uniform adhesion, and long polishing times, restricting substrate choice and reflectivity, especially in concave or convex mirrors.
Innovation Solution
A mirror design featuring a machined layer of amorphous silicon with a root-mean-square roughness below 1 nm, applied via physical vapor deposition without radio frequency, sandwiched between a reflective layer and substrate, enhancing adhesion and allowing faster machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a thin polishable layer is applied on the substrate, then the polishing time is reduced, but the layer cannot cover substrate imperfections completely, creating non-uniform adhesion and imperfections in the mirror
Solution Approach 1:
The patent changes the material parameters of the intermediate layer by using amorphous silicon with specific deposition parameters (without radio frequency) to achieve a layer that is both thin enough for fast processing and thick/structured enough to cover substrate imperfections, resolving the contradiction between polishing time and surface uniformity
Solution Approach 2:
The patent introduces an amorphous silicon intermediate layer as a mediator between the substrate and the reflective layer. This intermediate layer serves as a buffer that covers substrate imperfections while providing a uniform surface for the reflective layer, eliminating the direct contact between the reflective layer and imperfect substrate surfaces
2Adaptability or versatility
If substrates that are difficult to be mechanically processed or less polishable are used, then the manufacturing flexibility is improved, but the polishable layer cannot achieve low root-mean-square roughness without defects
Solution Approach 1:
The amorphous silicon intermediate layer acts as an intermediary that decouples the substrate surface quality from the final mirror surface quality. It provides a uniform, defect-free surface for the reflective layer regardless of the substrate's inherent surface imperfections, enabling the use of diverse substrate materials without compromising surface roughness
Solution Approach 2:
The patent applies a locally optimized intermediate layer with specific material properties (amorphous silicon deposited without radio frequency) that is tailored to cover and compensate for local substrate imperfections, providing uniform surface quality across the entire mirror surface regardless of substrate variations
3Device complexity
If a thin polishable layer is used on concave or convex mirrors, then the manufacturing complexity is reduced, but the centering of the mirror curve to the middle point of the outer diameter cannot be achieved
Solution Approach 1:
The patent changes the physical and chemical parameters of the intermediate layer (amorphous structure, deposition method without radio frequency) to enable precise thickness control and uniform coverage, which is critical for achieving accurate centering of the mirror curve on concave or convex substrates while maintaining manufacturing simplicity
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 mirror achieves high reflectivity with reduced imperfections, lower heat absorption, and extended lifetime, suitable for various substrates including less polishable ones, and improved centering in concave or convex designs.
Implementation Method 1
the machinable layer (3') that was applied to the surface of the substrate (4) by physical vapor deposition without using radio frequency
Implementation Method 2
a reflective layer (2) configured to reflect radiation in a wavelength of more than 25 nm
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a mirror made on a substrate that is not limited by its surface quality. Said mirrors having no or minor imperfections between the surface of its substrate and the polishing layer, also in the case when an adhesive layer is applied between the surface of its substrate and the polishing layer; and said mirrors having improved reflectivity. Additionally, it relates to a method for producing said a mirror wherein the application of the polishable/machinable layer is carried out by an uncomplicated and therefore less costly process.