Movable Mirror Elastic Support for FTIR Sensitivity
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Solution Overview
Problem
The size limitation of movable mirrors in optical modules on silicon-on-insulator (SOI) substrates restricts the sensitivity of Fourier Transform Infrared (FTIR) analyzers, as the degree of deep cutting on the substrate is limited to approximately 500 μm, hindering the improvement of mirror size for enhanced sensitivity.
Innovation Solution
An optical module design featuring a support layer, a device layer with a mounting region for the movable mirror, and elastic support regions that sandwich the mounting region, allowing for stable movement of the mirror, along with an optional intermediate insulating layer and a configuration that includes a beam splitter and light incident/emission units to form an interference optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the degree of deep cutting with respect to an SOI substrate is increased to maximize the size of a movable mirror, then the sensitivity of an FTIR is improved, but the degree of completion of deep cutting is limited to approximately 500 μm, which restricts further increase in mirror size
Solution Approach 1:
The device layer is divided into a mounting region for the movable mirror and a driving region connected to it, with the mounting region disposed between a pair of elastic support regions. This segmentation allows the mirror size to be determined by the overall device layer area rather than the limited deep cutting depth, enabling larger mirrors while maintaining manufacturing feasibility.
Solution Approach 2:
The patent transitions from a single-layer deep cutting approach to a multi-layer SOI substrate structure with device layer, intermediate layer, and support layer. By utilizing the lateral dimensions and multiple layers, the movable mirror can achieve larger area without being constrained by the vertical deep cutting limit of 500 μm.
2Area of moving object
If a separately formed movable mirror is mounted in the device layer to overcome the deep cutting limitation, then the size of the movable mirror can be increased, but the reliability of mirror movement becomes uncertain
Solution Approach 1:
The movable mirror is integrated with the device layer through mounting, and the device layer is supported by the support layer through elastic support regions. This merging of components ensures that the large movable mirror maintains reliable movement by combining it with the robust support structure of the SOI substrate.
Solution Approach 2:
The device layer has different functional regions: a mounting region for the movable mirror and a driving region for actuation. The mounting region is specifically designed to support the mirror while the driving region provides the actuation mechanism, with elastic support regions providing localized support. This local differentiation ensures reliable movement by optimizing each region for its specific function.
3Device complexity
If the mounting region is supported by an elastic support region extending from it, then the structure is simplified, but the mounting region cannot be stably moved
Solution Approach 1:
The device layer is configured with asymmetric support: the mounting region is supported by elastic support regions that are part of the driving region, rather than being self-supported or supported by simple extensions. This asymmetric configuration, where the support structure is integrated into the driving region, provides both stability and controlled movement capability.
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 configuration enables reliable and stable movement of the movable mirror, improving the sensitivity of the FTIR analyzer and allowing for a more compact, high-accuracy setup.
Implementation Method 1
The mounting region is disposed between a pair of elastic support regions included in the driving region and is supported by the pair of elastic support regions
Data Source
AI summary
An optical module includes a support layer, a device layer which is provided on the support layer, and a movable mirror which is mounted in the device layer. The device layer has a mounting region in which the movable mirror is mounted, and a driving region which is connected to the mounting region. A space corresponding to at least the mounting region and the driving region is formed between the support layer and the device layer. The mounting region is disposed between a pair of elastic support regions included in the driving region and is supported by the pair of elastic support regions.