Fourier Transform Spectrometer With Graphene Electrode Actuation
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Solution Overview
Problem
Existing spectrometers are bulky and costly, limiting their use outside laboratory settings, and miniaturization is hindered by issues such as manufacturing complexity, high costs, and limited optical frequency range in grating, Fabry-Perot, and Michelson interferometers.
Innovation Solution
A Fourier transform spectrometer with an interferometer design featuring parallel mirrors, a movable mirror, and an electrode, allowing for easier miniaturization and lower costs by decoupling the actuation of the movable mirror from the optical cavity, using silicon mirrors and a transparent graphene electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a grating, Fabry-Perot interferometer, or Michelson interferometer is used for miniaturization, then the spectrometer size can be reduced, but the manufacturing complexity increases and the optical frequency range is limited
Solution Approach 1:
The device separates the actuation mechanism (electrode and circuit) from the optical cavity, allowing independent optimization of each component. The movable mirror is actuated by an electrode positioned outside the optical cavity, decoupling the mechanical control system from the optical path.
Solution Approach 2:
A transparent graphene electrode serves as an intermediary between the electrical actuation system and the movable mirror. The graphene layer allows optical transmission while providing the necessary electrical field for mirror actuation, bridging the gap between electrical control and optical function.
2Measurement precision
If a Fabry-Perot interferometer with Bragg mirrors is used, then spectral resolution can be achieved, but the manufacturing cost increases and material choices are limited
Solution Approach 1:
The invention changes the material parameter from traditional Bragg mirror materials to silicon mirrors with specific reflective properties. This allows compatibility with standard MEMS processing techniques while maintaining the necessary spectral resolution through controlled reflectivity at the silicon-mirror interfaces.
Solution Approach 2:
The system uses a composite structure combining silicon mirrors with transparent graphene electrode material. This composite approach leverages the high reflectivity of silicon and the optical transparency of graphene to achieve both spectral resolution and ease of manufacture.
3Ease of manufacture
If standard MEMS processing techniques are used with Fabry-Perot interferometers, then manufacturing ease improves, but material choices are restricted
Solution Approach 1:
Silicon mirrors serve multiple functions: they provide the reflective surface for the interferometer, are compatible with standard MEMS processing techniques, and can be actuated using conventional MEMS fabrication methods. This universal material choice simplifies the manufacturing process while maintaining functional versatility.
4Use of energy by moving object
If the electrode is positioned within the optical cavity to actuate the movable mirror, then actuation efficiency improves, but the optical path is obstructed
Solution Approach 1:
The transparent graphene electrode acts as an intermediary that allows the electrical actuation field to pass through to the movable mirror while maintaining optical transparency. This enables efficient electrostatic actuation without blocking the optical path, as the graphene layer is sufficiently transparent to the wavelengths of interest.
Solution Approach 2:
The invention replaces mechanical actuation mechanisms with an electrostatic field-based system. The electrode generates an electric field that directly actuates the movable mirror through electrostatic forces, eliminating the need for mechanical linkages or moving parts within the optical cavity.
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
Enables a compact, cost-effective spectrometer with a broad wavelength range, high spectral resolution, and high signal-to-noise ratio, suitable for integration into mobile devices.
Implementation Method 1
The position of the side mirror 9 is adjustable, such that the optical path length for one part of the light can be changed and so introduce an optical path difference
Implementation Method 2
the circuit connected to the movable mirror and the electrode and operable to apply an electric field between them to move the movable mirror with respect to the fixed mirror
Implementation Method 3
part of the light received is reflected within the interferometer before exiting the optical cavity and takes at least two optical paths within and through the first and second mirrors
Implementation Method 4
the detector positioned and operable to detect light which has exited the optical cavity through a back of the second mirror of the mirrors and output an interferogram
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A Fourier transform spectrometer 100 comprising an interferometer 10 comprising a fixed mirror 11, a movable mirror 12 and a detector 101, wherein: the mirrors 11,12 are positioned parallel to each other and form an optical cavity; the movable mirror 12 is operable to move relative the fixed mirror 11 to change the size of the optical cavity; a first mirror of the mirrors is positioned such that light 14 received from a sample enters the optical cavity through a back of the first mirror; the detector 101 is positioned and operable to detect light which has exited the optical cavity through a back of the second mirror of the mirrors and output an interferogram; and the mirrors 11, 12 are distanced from each other such that the movable mirror is at or can move to a position where at least two paths 16, 31 to the detector 101 for received light 14 reflected within the interferometer are equal length.