Dual Input Interferometer Beamsplitter Tilt Control

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Solution Overview

Problem

Conventional FTIR interferometers face challenges with maintaining optical flatness and stability due to rigid mounting, which induces external stresses and tilts, leading to degraded light signals and operational issues, especially during shipping and temperature changes.

Innovation Solution

A dual tilt control system incorporating a soft flexure beamsplitter assembly with resilient membranes and magnetic movement means, combined with a wide range tilt control system that uses both auto-collimation and laser phase measurement for precise alignment and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If rigid mounting is used to support the beamsplitter, then structural stability is improved, but optical flatness is degraded due to induced external stresses and tilts

Engineering Contradiction:
Improvestructural stabilityVSAvoidoptical flatness
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent employs a flexible membrane mounting structure to support the beamsplitter, replacing rigid mounting mechanisms. This flexible membrane allows the beamsplitter to be supported without inducing external stresses that would compromise optical flatness, while still providing sufficient structural stability during operation and temperature changes.

Inventive Principle:
Principle #30Flexible shells and thin films

2Manufacturing precision

If soft flexure mounting is used to protect optical flatness, then manufacturing precision is improved, but device stability deteriorates due to increased susceptibility to tilt errors

Engineering Contradiction:
Improveoptical flatnessVSAvoiddevice stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent incorporates tilt control electronics that continuously monitor the beamsplitter orientation and provide feedback signals to adjustment mechanisms. This feedback system automatically corrects tilt errors caused by the soft flexure mounting, maintaining device stability while preserving the optical flatness benefits of the flexible mounting structure.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts mounting parameters through electronically controlled actuators that modify the mechanical properties of the flexure mounting in real-time. This allows the system to adapt to temperature changes and other environmental factors, maintaining both optical flatness and device stability under varying conditions.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If mechanical adjustments are made during shipping to maintain alignment, then manufacturing precision is improved, but device complexity increases due to additional adjustment mechanisms

Engineering Contradiction:
Improvealignment precisionVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements self-aligning features in the flexure mounting design that automatically maintain optimal optical alignment during shipping and handling. The flexible membrane structure inherently compensates for minor misalignments through its flexibility, eliminating the need for complex mechanical adjustment mechanisms while preserving alignment precision.

Inventive Principle:
Principle #25Self-service

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 protects optical flatness, allows for larger tilt error correction, and maintains instrument stability, enabling reliable data collection even under significant tilt errors and temperature changes, with improved ruggedness and reduced operational costs.

Implementation Method 1

a resilient membrane configured coupled about the periphery of the beamsplitter substrate and further coupled to a support structure; wherein the resilient membrane minimises induced external stresses directed through the support structure

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a plurality of magnetic means coupled to a predetermined surface of the beamsplitter substrate; and a plurality of coils configured to couple matched and/or mismatched predetermined magnetic forces with the plurality of magnetic means

Methodology Applied
Scientific EffectMagnetic force: Magnetic Field

Data Source

PatentEP2638369B1Dual input interferometer beamsplitter tilt control system and flexure mounting
Publication Date: 2020.12.23 THERMO ELECTRONICS SCI INSTR LLC
  • EP2638369B1 patent drawingFigure 1A~1D
  • EP2638369B1 patent drawingFigure 1C~3B
  • EP2638369B1 patent drawingFigure 2

AI summary

A novel soft beamsplitter mounting system as part of an interferometer to protect the beamsplitter substrate from external stresses and thus preserve optical flatness is introduced. The soft mounting system enables such protection by being more flexible that the beamspitter substrate so external forces deforms the mount rather than the beamsplitter. Although the soft beamsplitter mounting configurations disclosed herein protects the beamsplitter, the interferometer itself is less stable because the mounts of the present invention allows the beamspltter to tilt more easily than other components held in the interferometer. The improved tilt control embodiments of the present invention turns this seemingly deleterious effect into a cost saving benefit by using the inexpensive soft mounting system as a flexure to allow an improved active control system to maintain tilt alignment in a system that is more rugged than conventional interferometers.