Tunable Fabry-Perot Interferometer for Multi-Band Spectral Analysis
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Solution Overview
Problem
Current MEMS Fabry-Perot interferometers have limited usable spectral range due to mirror working range, tuning range limitations, and multiple order transmission issues, restricting their applications and measurement selectivity and sensitivity.
Innovation Solution
An electrically tunable Fabry-Perot interferometer system that allows simultaneous detection of multiple pass bands without band-limiting filters, enabling a detection range greater than a single free spectral range and relaxing mechanical scanning range limitations, thereby enhancing the usable wavelength range and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single MEMS FPI element is used, then the device complexity is reduced and footprint is minimized, but the usable spectral range is limited
Solution Approach 1:
The patent segments the spectral detection by using multiple discrete MEMS FPI elements, each optimized for a specific wavelength range or pass band. This allows the system to cover a broader spectral range while keeping each individual element simple and compact.
Solution Approach 2:
The patent creates a universal spectrometer system that can detect multiple wavelength ranges by combining multiple MEMS FPI elements. Each element serves a specific function for its optimized range, but together they provide multi-functional spectral coverage across a wide range.
2Adaptability or versatility
If the mirror gap is increased to expand the spectral range, then the detection range is improved, but the pull-in phenomenon limits the mechanical movement to about 1/3 of the nominal gap
Solution Approach 1:
Instead of relying on a single MEMS mirror to cover the entire spectral range through large mechanical movement, the patent segments the spectral coverage across multiple discrete FPI elements. Each element operates within its reliable mechanical range while collectively providing extended spectral detection.
Solution Approach 2:
The patent uses electrostatic tuning to dynamically adjust the mirror gap in each MEMS FPI element, allowing each element to be tuned to its optimal operating point within the safe mechanical range, avoiding the pull-in phenomenon while maintaining detection capability across different wavelengths.
3Adaptability or versatility
If multiple order transmission is allowed, then the spectral coverage is increased, but signal ambiguity arises from colors separated by one free spectral range
Solution Approach 1:
The patent assigns specific transmission orders and wavelength ranges to different MEMS FPI elements. By segmenting the spectral detection across multiple elements with defined wavelength assignments, the system avoids signal ambiguity while maintaining broad spectral coverage through coordinated operation of the elements.
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 approach significantly expands the detection range, allowing simultaneous measurement of multiple transmission peaks, increasing the usable wavelength range by a factor of three and maintaining analysis accuracy without the need for additional band-limiting filters, thus improving the system's sensitivity and selectivity.
Implementation Method 1
A Fabry-Perot interferometer is based on two mirrors, i.e. an input mirror and an output mirror arranged facing the input mirror via a gap... The pass band wavelength can be controlled by adjusting the distance between the mirrors... The Fabry-Perot interferometer may provide a narrow transmission peak
Data Source
AI summary
According to an example aspect of the present invention, there is provided a method for analysing a chemical composition of a target, the method comprising placing an electrically tunable Fabry-Perot interferometer in a path of radiation emitted by a radiation source, and detecting the radiation, which has passed the Fabry-Perot interferometer and which has passed or was reflected by the target, by means of a detector, and wherein detection is made such that multiple pass bands are allowed to be detected simultaneously.