Interferometer Retroreflector Mounting for Vibration-Resistant Alignment
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Solution Overview
Problem
Fourier Transform Interferometers face challenges in maintaining optical alignment and accuracy due to environmental vibrations, particularly in aircraft applications, where the movement of mirrors introduces optical path differences and shear, limiting the maximum optical path and causing misalignment.
Innovation Solution
The design integrates the two mirrors into a single translation mirror mount that moves relative to the base housing the beamsplitter, allowing for arbitrary optical path differences without mechanical design-induced shear, and includes a 45° mirror and beamsplitter arrangement within a tube, enabling self-correction of optical misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mirrors are physically moved to increase optical path difference, then measurement capability is improved, but optical alignment accuracy deteriorates due to vibrations
Solution Approach 1:
The interferometer is divided into two independent mirror assemblies (first and second retroreflectors) that can move independently relative to the beamsplitter. This segmentation allows each mirror to be positioned and aligned independently, maintaining optical alignment accuracy while enabling increased optical path difference through relative movement between the segmented components.
Solution Approach 2:
A beamsplitter is introduced as an intermediary component between the two mirrors. The beamsplitter serves as a stable reference point that mediates the optical interaction between the moving mirrors, allowing optical path difference to be increased through mirror displacement while the beamsplitter maintains the optical alignment by serving as a fixed reference for beam splitting and recombination.
2Length of moving object
If mirrors are attached to a moving frame, then optical path difference can be increased, but mechanical shear and misalignment are introduced
Solution Approach 1:
Instead of attaching both mirrors to a single moving frame, the invention segments the mirror mounting into two separate mirror assemblies that move independently. This eliminates the mechanical shear problem caused by frame deformation, as each mirror assembly can move without being constrained by the other, thereby maintaining optical alignment precision while achieving the desired optical path difference.
Solution Approach 2:
The beamsplitter acts as a stationary intermediary that mediates the optical interaction between the two independently moving mirrors. By fixing the beamsplitter in place and allowing mirrors to move relative to it, the system achieves variable optical path difference without the mechanical shear and misalignment that would result from attaching mirrors to a moving frame.
3Device complexity
If a single moving frame is used for both mirrors, then device complexity is reduced, but optical alignment shear is introduced
Solution Approach 1:
The mirror mounting structure is segmented into two independent assemblies rather than using a single moving frame. Although this increases structural complexity, it eliminates the optical alignment shear problem by allowing each mirror to move independently without being constrained by frame deformation, thereby achieving better overall system performance.
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 maintains interferometer accuracy by eliminating optical path limitations and self-correcting misalignment, enabling reliable operation in vibrating environments and allowing for arbitrarily large optical path differences, thus enhancing the interferometer's performance in aircraft applications.
Implementation Method 1
the beamsplitter is configured to split an incident light beam into a transmitted beam and a reflected beam
Implementation Method 2
first and second retroreflectors fixedly coupled to the stage
Implementation Method 3
an off-axis parabolic mirror focuses the recombined beam to a detector
Data Source
AI summary
An interferometer (10) is provided that has a stage (28) configured to have a linear motion path. A first retroreflector (18) and a second retroreflector (24) are fixedly coupled to the stage (28). A tube (32) is provided, and the stage (28) is configured to reciprocate about the tube (32). A beamsplitter (14) and a 45° mirror (16) are disposed in the tube (32). A detector (22) is configured to detect light passing through the beamsplitter (14), and the beamsplitter (14) is configured to split an incident light beam into a transmitted beam (15) and a reflected beam (17), wherein the transmitted beam (15) passes to the second retroreflector (24) and the reflected beam (17) passes to the first retroreflector (18). The transmitted beam (15) and a reflected beam (17) are focused on the detector (22).