Interference Filter with Segmented Pressure Zones
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Solution Overview
Problem
Existing interference filters face challenges in maintaining spectral accuracy due to substrate flexure caused by pressure differences, leading to noise in wavelength dispersion, especially in near-infrared applications.
Innovation Solution
The interference filter design includes a configuration where the first substrate with a first reflection film is sandwiched between two inner spaces maintained at reduced pressures, and the second substrate with a second reflection film is similarly sandwiched, using elastic layers and metal bonding to maintain high airtightness and prevent substrate flexure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the first substrate is subjected to atmospheric pressure on one side and reduced pressure on the other side to improve drive responsiveness, then the drive responsiveness is improved, but the first substrate flexes due to pressure difference causing spectral accuracy to deteriorate
Solution Approach 1:
The first substrate is divided into a light-receiving region and a pressure-receiving region. The light-receiving region maintains atmospheric pressure to prevent flexure and maintain spectral accuracy, while the pressure-receiving region is subjected to reduced pressure to improve drive responsiveness. This spatial segmentation resolves the contradiction by allowing different pressure conditions in different functional areas.
Solution Approach 2:
Different pressure conditions are applied to different regions of the first substrate based on their functional requirements. The light-receiving region has atmospheric pressure for optical stability, while the pressure-receiving region has reduced pressure for actuation performance. This local differentiation of pressure quality enables both spectral accuracy and drive responsiveness.
2Manufacturing precision
If the gap dimension between the first reflection film and the second reflection film is reduced to improve wavelength dispersion precision, then the wavelength half-width narrows, but the substrate flexure effect is increased causing more noise
Solution Approach 1:
The first substrate is segmented into a light-receiving region with atmospheric pressure (preventing flexure) and a pressure-receiving region with reduced pressure (improving actuation). This allows the gap to be small for precise wavelength dispersion while the light-receiving region remains stable without flexure-induced noise.
3Device complexity
If a single bonding structure is used to seal the inner space, then the device complexity is reduced, but the airtightness and pressure control capability are insufficient
Solution Approach 1:
The bonding structure is segmented into a first bonding structure sealing the light-receiving region and a second bonding structure sealing the pressure-receiving region. This dual-bonding approach ensures high airtightness and independent pressure control for each functional region, resolving the contradiction between simplicity and reliability.
Solution Approach 2:
A partition wall is introduced as an intermediary structure between the light-receiving region and pressure-receiving region. This partition enables independent pressure control and sealing in each region, allowing the system to maintain high airtightness without excessive complexity by clearly separating the two functional zones.
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 enhances drive responsiveness and precise wavelength dispersion, maintaining high spectral accuracy and reducing contamination of unwanted wavelengths, while also allowing for miniaturization of the filter and its applications.
Implementation Method 1
an interference filter has been known that includes a first substrate provided with a first reflection film, and a second substrate provided with a second reflection film, and the first substrate and the second substrate are disposed facing each other and bonded to each other, such that the first reflection film and the second reflection film face each other via a gap. Such an interference filter can emit light having a desired wavelength from incident light
Implementation Method 2
a movable portion held by a diaphragm or the like is provided at the second substrate, the movable portion is provided with the second reflection film, the movable portion is displaced toward the first substrate by a driving means such as an electrostatic actuator
Implementation Method 3
a first bonding portion configured to bond the first inner surface and the second inner surface to each other, the first bonding portion sealing a first inner space between the first substrate and the second substrate
Data Source
AI summary
An interference filter includes a transmissive first substrate including a first inner surface and a first outer surface facing each other, in which the first inner surface is provided with a first reflection film, a transmissive second substrate including a second inner surface and a second outer surface facing each other, in which the second inner surface is provided with a second reflection film, a first bonding portion configured to bond the first inner surface and the second inner surface to each other, and seal a first inner space between the first substrate and the second substrate, a transmissive third substrate facing the first outer surface, a second bonding portion configured to bond the first outer surface and the third substrate to each other, and seal a second inner space between the first substrate and the third substrate, a transmissive fourth substrate facing the second outer surface, and a third bonding portion configured to bond the second outer surface and the fourth substrate to each other, and seal a third inner space between the second substrate and the fourth substrate, wherein the first inner space, the second inner space, and the third inner space are lower in pressure than atmospheric pressure.