Compact Wavelength Variable Interference Filter With Bonded Diaphragm Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wavelength variable interference filters face an issue of increased size due to the formation of a curved surface portion on the diaphragm portion, which is formed by wet etching, leading to a larger relative size compared to the planar size of the movable portion.
Innovation Solution
A configuration where the second substrate includes a diaphragm substrate with uniform thickness and a support substrate bonded to it, featuring a movable portion and a support portion with a hole portion exposing the diaphragm substrate, allowing the second reflective film to be displaced without increasing the planar size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a recessed groove is formed by wet etching to create a diaphragm portion, then the first mirror can be displaced toward the second mirror, but a curved surface portion is formed by side etching which increases the overall size of the interference filter
Solution Approach 1:
The second substrate is divided into a diaphragm substrate and a support substrate that are bonded together. The diaphragm substrate provides the flexible diaphragm portion for mirror displacement, while the support substrate provides structural support. This segmentation allows the diaphragm to be thin and flexible without requiring large curved surface portions that would increase overall device size.
Solution Approach 2:
The diaphragm substrate is designed with non-uniform thickness, having a thinner central portion and thicker peripheral portions. This local quality variation allows the central region to be highly flexible for mirror displacement while the peripheral regions provide structural support, eliminating the need for large curved surface portions that would increase the overall footprint of the device.
2Area of stationary object
If the size of the wavelength variable interference filter is fixed to a predetermined size, then it is necessary to reduce the size of the movable portion, but this reduces the cross-sectional area available for optical regions
Solution Approach 1:
The invention transitions from a planar single-substrate structure to a three-dimensional stacked structure with diaphragm substrate and support substrate bonded together. This dimensional change allows the movable portion to maintain sufficient cross-sectional area for optical regions while the overall device footprint is controlled by the support substrate's outer peripheral edge.
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 reduces the overall size of the interference filter by minimizing the need to reduce the movable portion's size, maintaining sufficient cross-sectional area for optical regions and ensuring stable bonding strength, thus facilitating miniaturization of devices incorporating the filter.
Implementation Method 1
by bending the diaphragm, the first mirror can be displaced toward the second mirror
Implementation Method 2
a first reflective film provided on a surface of the first substrate facing the second substrate, and a second reflective film provided on the second substrate and facing the first reflective film via a gap
Implementation Method 3
wavelength variable interference filter
Data Source
AI summary
A wavelength variable interference filter includes a first substrate, a second substrate facing the first substrate, a first reflective film provided on the first substrate, and a second reflective film provided on the second substrate and facing the first reflective film via a gap. The second substrate includes a diaphragm substrate having a uniform thickness in a Z direction and a support substrate bonded to the diaphragm substrate. The support substrate includes a movable portion overlapping the first reflective film and the second reflective film, and a support portion provided along an outer peripheral edge of the second substrate, and a hole portion for exposing the diaphragm substrate is provided between the movable portion and the support portion.