Anodic Bonding for Optical Element Stability
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Solution Overview
Problem
Existing optical assemblies face challenges in maintaining stability and alignment when exposed to harsh chemical and thermal environments, particularly with alkali-metal vapor, and require expensive atomic-level polishing for optical contacting techniques.
Innovation Solution
The use of anodically bonded silicon wafers and borosilicate glass components with matched thermal expansion coefficients, allowing for vacuum-compatible and low-outgassing multi-pass cells that can operate at high temperatures without alignment changes, using anodic bonding to secure mirrors and windows within a vacuum-sealed enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesives are used to mount optical elements, then ease of manufacture is improved, but reliability deteriorates due to degradation in harsh thermal and chemical environments
Solution Approach 1:
The patent replaces chemical adhesive bonding with electrostatic anodic bonding, substituting a chemical system with an electrical/physical system. The anodic bonding process uses controlled electrochemical reactions to form strong ionic bonds between glass and metal surfaces, eliminating the need for organic adhesives that degrade in harsh environments while maintaining ease of manufacture through a standardized electrical bonding process.
Solution Approach 2:
The patent changes the bonding mechanism from chemical (adhesive) to electrochemical (anodic bonding), utilizing controlled electrical parameters (voltage, current, time) to create stable bonds. By applying specific electrical parameters during bonding and then operating in high-temperature environments, the system achieves both ease of manufacture and high reliability that cannot be obtained with traditional adhesives.
2Reliability
If optical contacting techniques are used to mount optical elements, then reliability is improved, but manufacturing precision requirements worsen due to need for atomic level polishing
Solution Approach 1:
The patent changes the bonding approach from direct optical contact requiring atomic-level surfaces to anodic bonding that tolerates conventional surface finishes. The electrochemical bonding process creates strong bonds through ionic interactions that do not require the same extreme surface precision as optical contacting, thereby reducing manufacturing precision requirements while maintaining bonding reliability.
Solution Approach 2:
The anodic bonding process introduces an electrochemical intermediary mechanism that mediates the bonding between optical elements and mounting surfaces. This intermediary electrochemical process allows bonding to occur with conventional surface preparations rather than requiring direct atomic-level contact, thus reducing the stringent surface precision requirements of traditional optical contacting.
3Loss of energy
If mirrors are placed inside vacuum-sealed enclosure, then optical performance is improved by eliminating losses, but device complexity worsens due to sealing and vacuum maintenance requirements
Solution Approach 1:
The patent merges the vacuum sealing function with the optical element mounting structure. The anodically bonded glass-to-metal seals serve dual purposes: they provide the vacuum-tight sealing required for vacuum operation and simultaneously provide the structural mounting for optical elements. This integration reduces device complexity by combining sealing and mounting functions into a single unified structure rather than requiring separate sealing mechanisms.
Solution Approach 2:
The anodic bonding process creates self-sealing joints that automatically maintain vacuum integrity. The electrochemically formed bonds between glass and metal create hermetic seals that self-maintain the vacuum environment without requiring additional active sealing mechanisms or complex vacuum control systems, thereby reducing overall device complexity while maintaining optical performance.
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
This solution provides a stable, cost-effective, and vacuum-compatible optical assembly capable of operating in harsh environments with minimal alignment changes and reduced outgassing, enabling efficient operation with alkali-metal vapor at elevated temperatures.
Implementation Method 1
The use of anodically bonded silicon wafers and borosilicate glass components with matched thermal expansion coefficients, allowing for vacuum-compatible and low-outgassing multi-pass cells that can operate at high temperatures without alignment changes, using anodic bonding to secure mirrors and windows within a vacuum-sealed enclosure
Implementation Method 2
anodically bonded silicon wafers and borosilicate glass components with matched thermal expansion coefficients, allowing for vacuum-compatible and low-outgassing multi-pass cells that can operate at high temperatures without alignment changes
Data Source
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AI summary
The disclosure provides an optical apparatus including at least one optical element including glass, at least one support including silicon and a housing including glass. Furthermore, the at least one optical element and the at least one support can be anodically bonded together, and the at least one support and the housing can be anodically bonded together. The disclosure further provides a method for fabricating optical components with durable bonds and incorporates active alignment.