Optical Filter Device Peripheral Fixing Suppresses Reflective Film Warping
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Solution Overview
Problem
Existing optical filter devices face issues with warping of reflective films due to differences in thermal expansion coefficients between the interference filter and the base substrate, leading to affected optical characteristics.
Innovation Solution
An optical filter device design where the second substrate is fixed to the base substrate in a specific configuration, excluding the region where the reflective film is provided, using a fixing member to minimize stress and warping, and an actuator is included to adjust the inter-reflective film gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the interference filter is fixed to the base substrate using an adhesive, then the interference filter can be securely mounted, but the reflective film warps due to adhesive contraction during hardening
Solution Approach 1:
The patent extracts the harmful effect of adhesive contraction by removing the adhesive from the optical path area. The adhesive is applied only in peripheral regions away from the reflective films, so the contraction force does not warp the reflective films while still providing secure mounting of the interference filter to the base substrate.
Solution Approach 2:
The patent applies different fixing strategies to different regions: the peripheral regions use adhesive for secure mounting, while the central optical path region remains free of adhesive to prevent warping of the reflective films. This local differentiation of fixing quality resolves the contradiction between overall fixing strength and local film flatness.
2Strength
If the interference filter and base substrate are fixed by welding or bonding, then the structural connection is strong, but the reflective film warps due to difference in thermal expansion coefficients
Solution Approach 1:
The patent removes the bonding or welding process from the optical path area, applying adhesive only in peripheral regions. This extraction of the harmful thermal process from the critical optical region prevents warping while maintaining structural connection through the peripheral adhesive bonding.
Solution Approach 2:
Different connection methods are applied to different regions: peripheral regions use adhesive bonding for structural strength, while the central region containing the reflective films remains free of thermal processes to maintain film flatness and optical precision.
3Stability of the object's composition
If the second substrate is fixed in multiple dispersed places, then the mounting is stable, but stress is distributed across the reflective film causing warping
Solution Approach 1:
The patent extracts the fixing points from the optical path area, concentrating adhesive application only in peripheral regions. This removes the source of stress on the reflective films while maintaining mounting stability through the peripheral fixation points.
Solution Approach 2:
The patent implements local differentiation of fixing density: high fixing density in peripheral regions provides mounting stability, while zero fixing density in the central optical region preserves reflective film flatness by eliminating stress distribution across the films.
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 effectively suppresses warping of the reflective films, maintaining the optical characteristics and allowing for a variable wavelength interference filter with reduced size and improved manufacturing quality.
Implementation Method 1
An interference filter in which reflective films are arranged to be opposed to each other across a predetermined gap on opposed surfaces of a pair of substrates
Implementation Method 2
A fixing member for fixing the second substrate to the base substrate is arranged between the second substrate and the base substrate
Data Source
AI summary
An optical filter device includes an interference filter and a housing. The interference filter includes a fixed substrate, a movable substrate joined to the fixed substrate, a fixed reflective film provided on the fixed substrate, and a movable reflective film provided on the movable substrate and opposed to the fixed reflective film across an inter-reflective film gap. The housing includes a base substrate on which the interference filter is arranged. A fixing member is arranged between the movable substrate and the base substrate. The movable substrate is fixed to the base substrate by the fixing member in one place excluding a region where the movable reflective film is provided.