Sealed FTIR Optical Module Layout for Larger Movable Mirrors
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Solution Overview
Problem
The size of the mirror surface in existing optical modules is limited by deep drilling on the SOI substrate, leading to sensitivity limitations and potential deterioration in movable performance due to increased mirror size, which also enlarges the entire module.
Innovation Solution
The optical module incorporates a mirror unit with a movable mirror and a fixed mirror disposed in an airtight space, where the movable mirror's surface is parallel to the base, and the drive unit is isolated from external environments, allowing for enlargement of the mirror surface while maintaining compact dimensions and high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mirror surface of the movable mirror is enlarged to improve FTIR sensitivity, then the sensitivity of the FTIR is improved, but the movable performance of the movable mirror deteriorates and the entire module increases in size
Solution Approach 1:
The patent applies the inert atmosphere principle by creating a sealed cavity that isolates the movable mirror from the external environment. This sealed environment prevents dust, humidity, and other contaminants from affecting the mirror's movement, thereby maintaining reliable movable performance even when the mirror surface is enlarged to improve FTIR sensitivity.
2Measurement precision
If the mirror surface of the movable mirror is enlarged to improve FTIR sensitivity, then the sensitivity of the FTIR is improved, but the entire module increases in size
Solution Approach 1:
The patent applies the dimensionality change principle by reconfiguring the optical path arrangement from a traditional linear layout to a folded optical path within a sealed cavity. This allows the movable mirror to have a larger surface area for improved sensitivity while the overall module maintains compact dimensions through three-dimensional spatial optimization.
3Measurement precision
If the mirror surface of the movable mirror is enlarged, then the sensitivity of the FTIR is improved, but the movable performance of the movable mirror deteriorates
Solution Approach 1:
The patent applies the inert atmosphere principle by creating a sealed cavity that isolates the movable mirror from the external environment. This sealed environment prevents dust, humidity, and other contaminants from affecting the mirror's movement, thereby maintaining reliable movable performance even when the mirror surface is enlarged to improve FTIR sensitivity.
4Area of moving object
If deep drilling on the SOI substrate is increased to accommodate larger mirror surface, then the mirror surface size is increased, but the drilling depth limitation of 500 μm prevents further improvement
Solution Approach 1:
The patent applies the dimensionality change principle by transitioning from a vertical drilling approach to a horizontal/planar integration approach within the sealed cavity. This allows the movable mirror to achieve a larger surface area without requiring deeper drilling into the SOI substrate, thereby overcoming the 500 μm drilling depth limitation while maintaining manufacturability.
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 suppresses deterioration in movable performance and reduces the module's size while enhancing sensitivity and accuracy by isolating the drive unit and maintaining optical path alignment within an airtight space.
Implementation Method 1
a movable mirror 11 which includes a mirror surface 11a following a plane parallel to the main surface 12a of the base 12
Implementation Method 2
the beam splitter unit 3, the movable mirror 11, and the fixed mirror 21 constitute an interference optical system I1 for measurement light L0
Data Source
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AI summary
An optical module includes a mirror unit and a beam splitter unit. The mirror unit includes a base with a main surface, a movable mirror, a first fixed mirror, and a drive unit. The beam splitter unit constitutes a first interference optical system for measurement light along with the movable mirror and the first fixed mirror. A mirror surface of the movable mirror and a mirror surface of the first fixed mirror follow a plane parallel to the main surface and face one side in a first direction perpendicular to the main surface. The movable mirror, the drive unit, and at least a part of an optical path between the beam splitter unit and the first fixed mirror are disposed in an airtight space.