Fabry-Perot Mirror Assembly With Spacer-Defined Parallel Gap
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Solution Overview
Problem
The current FPI assembly process relies on epoxy shrinkage for setting the gap between mirrors, which is unreliable due to variable factors like epoxy quantity and shelf life, leading to inconsistent and low yield of good devices.
Innovation Solution
The use of precise production processes and additional spacer mesas to establish a repeatable and parallel initial gap, eliminating reliance on epoxy shrink rate, ensuring consistent mirror alignment and gap dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy is used to set the gap between mirrors during assembly, then the mirrors can be bonded together, but the gap dimension and parallelism become unreliable due to epoxy shrinkage during cure
Solution Approach 1:
The patent applies preliminary action by pre-establishing the gap dimension through mechanically precision-ground mirror surfaces and support structures before epoxy bonding. The mirrors and their supports are fabricated with precise dimensions and alignments, and the gap is mechanically set prior to applying the epoxy adhesive. This ensures that the critical gap dimension is determined by precision mechanical fabrication rather than by epoxy shrinkage during curing.
2Reliability
If epoxy quantity and shelf life are controlled, then bonding consistency can be improved, but the process remains inherently unreliable for achieving consistent gap dimensions
Solution Approach 1:
The patent applies the extraction principle by removing the epoxy shrinkage mechanism from the gap-setting function. The gap dimension determination is extracted from the epoxy bonding process and assigned to separate precision mechanical fabrication processes for the mirrors and their support structures. This decoupling ensures that gap dimension repeatability is achieved through controlled mechanical dimensions rather than through epoxy material properties or application variables.
3Manufacturing precision
If active alignment is performed to achieve parallelism, then mirror alignment can be optimized, but the final gap still depends on unpredictable epoxy shrinkage
Solution Approach 1:
The patent applies preliminary action by establishing the parallelism and gap dimension through precision mechanical fabrication of the mirrors and their support structures before epoxy bonding. The support structures are fabricated with precise dimensions and orientations that mechanically define the gap and parallelism. Active alignment procedures can then be performed on these pre-positioned components, and the assembly is bonded in this pre-aligned state, ensuring that the final gap consistency is maintained by the rigid mechanical structure rather than being altered by epoxy shrinkage.
Data Source
AI summary
A system includes a top mirror, a bottom mirror, a top spacer mesa, a bottom spacer mesa, and an adhesive. The top mirror is added to a top substrate. The bottom mirror is added to a bottom substrate. The top spacer mesa is added to the top substrate. The bottom spacer mesa is added to the bottom substrate. The adhesive is affixed between a) the top substrate or a top support element and b) the bottom substrate or a bottom support element or a piezo actuator.