Wavelength Variable Interference Filter Gap Stability
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Solution Overview
Problem
Existing wavelength variable interference filters face challenges in maintaining a consistent gap between mirrors due to external factors like vibrations, leading to inaccuracies in selecting specific wavelengths.
Innovation Solution
The design incorporates two substrates with movable portions and linkage portions that shift in unison to maintain a consistent gap, using electrostatic attraction to control the gap length, with the substrates and linkage portions made of the same material and shape to minimize variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the diaphragm thickness is decreased or area is increased to achieve larger displacement, then the movable portion shifts more, but the gap becomes sensitive to external vibrations
Solution Approach 1:
The single diaphragm structure is divided into two separate diaphragms (first diaphragm on first substrate, second diaphragm on second substrate). Each diaphragm supports one mirror, and both diaphragms work together to control the gap. This segmentation allows each diaphragm to be thicker and more rigid while achieving the required total displacement through coordinated movement of both substrates.
Solution Approach 2:
The invention uses a dual-substrate configuration where both substrates actively participate in gap control. When external vibrations occur, both substrates can respond in a coordinated manner to counteract the disturbances, effectively canceling out the harmful effects of vibrations on gap stability.
2Device complexity
If only one substrate has a diaphragm to simplify structure, then manufacturing is easier, but the gap varies due to vibrations from the other substrate
Solution Approach 1:
The system is segmented into two independent but coordinated substrates, each with its own diaphragm and mirror assembly. This allows vibration isolation where each substrate's vibrations are independently managed by its own diaphragm structure, preventing transmission of vibrations to the gap region.
Solution Approach 2:
The diaphragms act as intermediary elements between the substrates and mirrors, providing mechanical compliance while isolating the optical gap from substrate vibrations. The flexible diaphragm structure absorbs vibrational energy before it can affect the mirror positioning.
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 allows for precise control of the gap length, reducing variations caused by external factors and enabling accurate selection of desired wavelengths, improving the filter's performance and manufacturing simplicity.
Implementation Method 1
A gap varying unit varies the length of the gap by shifting the first movable portion and the second movable portion relative to each other... the diaphragm bends by the force of electrostatic attraction generated in response to voltage applied to the pair of the electrodes
Data Source
AI summary
A wavelength variable interference filter includes: a first movable mirror disposed on a first substrate; a second movable mirror disposed so as to be opposed to the first movable mirror with a predetermined gap interposed therebetween; and an electrostatic actuator which varies the length of the gap between the mirrors. The first substrate has a first movable portion on which the first movable mirror is disposed, and a first linkage portion which holds the first movable portion in such a manner that the first movable portion can shift in the thickness direction of the substrate. The second substrate has a second movable portion on which the second movable mirror is disposed, and a second linkage portion which holds the second movable portion in such a manner that the second movable portion can shift in the thickness direction of the substrate.