Tunable MEMS Etalon with Electrostatic Gap Control
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Solution Overview
Problem
Conventional etalons are not suitable for sequential spectral imaging due to their narrow spectral transmission profiles and limited free spectral range, which results in significant chromatic aberrations and high manufacturing costs, making them unsuitable for wide spectral band applications like RGB color image acquisition and hyper spectral imaging.
Innovation Solution
A tunable Micro-Electro-Mechanical Systems (MEMS) etalon with a high aspect ratio between mirror width and gap distance, utilizing electrostatic actuation to adjust the gap between parallel mirrors to tens of nanometers, and incorporating a wide spectral transmission profile and large free spectral range, fabricated using Silicon on Insulator (SOI) or Glass on Silicon techniques to achieve low-cost mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional etalons are used for spectral filtering, then narrow spectral transmission profile is achieved, but chromatic aberrations increase and manufacturing costs rise
Solution Approach 1:
The patent implements a movable mirror that can dynamically adjust the gap distance between mirrors from tens of nanometers to micrometers, enabling the etalon to adapt its spectral transmission profile dynamically. This dynamic adjustment allows optimization of the spectral profile width to reduce chromatic aberrations while maintaining manufacturing feasibility through standard MEMS fabrication processes
Solution Approach 2:
The patent changes the gap distance parameter between mirrors by adjusting the applied voltage, which directly modifies the spectral transmission profile. By controlling the voltage, the system can tune the spectral bandwidth and free spectral range to achieve wide spectral transmission while minimizing chromatic aberrations, resolving the contradiction between narrow profile precision and aberration reduction
2Measurement precision
If conventional etalons are used for spectral filtering, then narrow spectral transmission profile is achieved, but manufacturing costs increase
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with electrostatic actuation, where voltage control directly adjusts the mirror position and gap distance. This substitution of mechanical systems with electrical control simplifies the manufacturing process, enables mass production through standard MEMS fabrication, and significantly reduces costs while maintaining precise spectral transmission control
Solution Approach 2:
The patent utilizes voltage parameter control to adjust the gap distance between mirrors, replacing complex mechanical positioning systems. This electrical parameter control approach simplifies the overall device structure, reduces manufacturing complexity, and enables cost-effective mass production while maintaining the ability to achieve desired spectral transmission profiles
3Measurement precision
If small gap distance between mirrors is used, then wide spectral transmission profile is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces mechanical gap control mechanisms with electrostatic actuation, where the gap distance is controlled by applied voltage rather than mechanical positioning. This substitution eliminates the need for high-precision mechanical fabrication of small gaps, as the gap can be dynamically adjusted electrical post-fabrication, significantly reducing manufacturing precision requirements while enabling wide spectral transmission profiles
Solution Approach 2:
The patent implements dynamic gap adjustment through movable mirror actuation, allowing the system to optimize the gap distance after fabrication. This dynamic capability enables achievement of wide spectral transmission profiles by adjusting the gap to tens of nanometers or micrometers as needed, without requiring extremely precise initial fabrication, thus reducing manufacturing precision requirements
4Adaptability or versatility
If large free spectral range is achieved, then wide spectral band filtering is enabled, but device complexity increases
Solution Approach 1:
The patent designs a universal etalon structure with movable mirror and electrostatic actuation that can achieve multiple functions: wide spectral transmission, adjustable free spectral range, and tunable spectral profile. This multi-functional design enables wide spectral band filtering while maintaining relatively simple device structure, as the same basic structure adapts to different spectral requirements through voltage control rather than requiring multiple specialized components
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 MEMS etalon provides wide dynamic filtering over a broad spectral band, reducing chromatic aberrations and enabling efficient sequential color imaging with high color fidelity, suitable for RGB and hyper spectral imaging applications, while being cost-effective for mass production.
Implementation Method 1
one or more regions of the actuation layer are electrically insulated from the functional layer. The displacement between said aperture mirror and the back mirror is adjustable by applying electric potential difference between the one or more regions of the actuation layer and the functional layer to cause said electrostatic forces between them
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
Disclosed herein is a novel a tunable Micro-Electro-Mechanical (MEMS) Etalon system including: a functional layer patterned to define a suspension structure for suspending a first mirror being an aperture mirror of the Etalon, an aperture mirror coupled to the suspension structure, and a back layer including a second mirror, being a back mirror of the Etalon. The functional layer may be located above the back layer and the back layer may include spacer structures protruding therefrom towards the aperture mirror to define a minimal gap between the aperture mirror and the back mirror and prevent collision between them. The aspect ratio between the width of the etalon/mirrors may be high (e.g. at least 500), and the minimal gap/distance between the mirrors may be small in the order of tens of nanometers (nm). Accordingly, in some implementations the parallelism between the aperture mirror and the back mirror is adjustable to avoid chromatic artifacts associated with spatial variations in the spectral transmission profile across the etalon.