Modulated Fabry-Perot Interferometer Actuator Strain Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Tunable Fabry-Perot filters with piezoelectric actuators face issues such as breakage, delamination, and short-circuiting due to high strain during repeated bending, limiting their lifespan and scan frequency, especially when trying to achieve high-frequency modulation for improved detection capabilities.
Innovation Solution
The use of separate actuators with lower strain, where one actuator adjusts the mirror distance and another modulates at a lower frequency, reducing strain and mechanical stress, and incorporating materials like PZT or electrostatic actuators to achieve high-frequency scanning while minimizing damage, along with vacuum packaging to reduce squeeze film effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single piezoelectric actuator is used for both wavelength scanning and modulation, then the device structure is simple, but the actuator experiences high strain leading to breakage and delamination
Solution Approach 1:
The patent divides the actuator system into two separate units: a first actuator for wavelength scanning and a second actuator for modulation. This segmentation allows each actuator to be optimized for its specific function, with the second actuator operating at lower strain levels to avoid the reliability issues of high-strain operation.
Solution Approach 2:
The patent applies different operational characteristics to different parts of the system. The first actuator handles large-scale wavelength scanning while the second actuator handles small-scale modulation at much lower strain levels. This local differentiation of functional requirements resolves the contradiction between structural simplicity and reliability.
2Productivity
If piezoelectric actuators operate at high frequency, then detection capability improves, but mechanical stress increases causing delamination and short circuiting
Solution Approach 1:
By separating the scanning function from the modulation function into two distinct actuators, the system allows the second actuator to operate at high modulation frequencies without bearing the mechanical stress of large-scale scanning movements. This enables high-frequency operation with improved reliability.
Solution Approach 2:
The patent changes the operational parameters of the two actuators differently: the first actuator operates at lower frequencies for scanning, while the second actuator operates at high frequencies for modulation but with much smaller displacement amplitudes, keeping strain levels manageable.
3Measurement precision
If the amplitude of modulation is increased to improve detection, then signal detection sensitivity improves, but the strain on piezoelectric material increases causing breakage
Solution Approach 1:
The patent separates the wavelength scanning function from the modulation function, allowing the second actuator to provide modulation with optimized amplitude that improves detection sensitivity without subjecting the piezoelectric material to excessive strain that would cause breakage.
Solution Approach 2:
The system applies different amplitude levels to different functions: large amplitude for scanning (first actuator) and optimized smaller amplitude for modulation (second actuator). This local optimization allows sufficient modulation amplitude for detection while keeping material strain within safe limits.
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 significantly increases the lifespan of the Fabry-Perot filter and allows for higher frequency scanning, reducing noise and improving the detection of weak signals in applications like photoacoustic gas analysis without generating offset signals from the filter walls.
Implementation Method 1
at least one of said actuator units comprising a piezoelectric material on said membrane
Implementation Method 2
Another alternative is making a second actuator with electrostatic modulation
Implementation Method 3
Fabry-Perot interferometer including two plane mirror surfaces mounted in a frame
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a Fabry-Perot interferometer including two plane mirror surfaces mounted in a frame and a system including the interferometer. The mirrors have a known distance between them, and at least one of the mirror surfaces is both partially reflective and partially reflective, where there are at least two actuator units, each including at least one actuator. The first actuator unit is adapted to adjust said distance between said mirrors and the second actuator unit is adapted to modulate said distance at a chosen frequency, both thus providing a variation over a range of mirror distances corresponding to a range of filtered wavelengths in said Fabry-Perot interferometer. At least one of said mirrors is related to the frame through a silicon membrane, at least one of said actuator units comprising a piezoelectric material on said membrane, thus constituting a bimorph or unimorph actuator unit.