Waveplate Support Segmentation for FTIR Spectrometer Stability

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Solution Overview

Problem

Existing Fourier transform infrared spectrophotometers face challenges in obtaining stable power spectra due to temporal changes caused by variations in the orientation and position of mirrors, leading to inaccuracies in interferograms and power spectra measurements.

Innovation Solution

The implementation of a Fourier transform infrared spectrophotometer design that includes a main interferometer, a control interferometer, an infrared detector, a control light detector, a waveplate, and a support member with a released region to reduce thermal stress and conduction, allowing for accurate adjustment of mirror orientations and positions, thereby stabilizing the interferogram and power spectrum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the waveplate is fully supported by the support member, then the waveplate is mechanically stable, but thermal stress and refractive-index variations increase due to thermal conduction

Engineering Contradiction:

Improvemechanical stability of waveplateVSAvoidstability of power spectrum

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The support structure is segmented such that only a portion of the waveplate's outer perimeter is supported, while other portions are released. This partial support configuration reduces thermal conduction to the waveplate while maintaining sufficient mechanical stability, thereby decreasing thermal stress and refractive-index variations that cause power spectrum instability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the waveplate are treated differently: some regions are supported to maintain mechanical stability, while other regions are released to minimize thermal conduction. This local differentiation allows the system to balance mechanical support with thermal isolation, reducing thermal stress and improving power spectrum stability.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If mirrors are adjusted to correct orientation variations, then interferogram accuracy improves, but temporal changes and instability increase

Engineering Contradiction:

Improveinterferogram accuracyVSAvoidtemporal stability of power spectrum

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The waveplate is designed with a specific configuration (partial support with released regions) that beforehand cushions against thermal stress and refractive-index variations. This preventive design reduces temporal changes in the interferogram, allowing mirror adjustments to achieve accurate power spectra without introducing additional instability from thermal effects.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If thermal conduction to the waveplate is increased, then mechanical support is improved, but thermal stress and refractive-index variations increase

Engineering Contradiction:

Improvemechanical support of waveplateVSAvoidrefractive-index uniformity

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The support structure is segmented to provide mechanical support only at specific locations rather than full perimeter support. This segmentation maintains sufficient mechanical strength while creating thermal isolation zones that reduce thermal conduction to the waveplate, thereby preserving refractive-index uniformity and reducing thermal stress.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The support member acts as an intermediary that provides mechanical support while intentionally limiting thermal conduction to the waveplate. By controlling the contact area and configuration, the support member mediates between the need for mechanical strength and the need to minimize thermal stress and refractive-index variations.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design achieves a stable power spectrum with reduced temporal changes by minimizing thermal stress and refractive-index variations in the waveplate, enabling precise control of mirror positions and orientations, resulting in more accurate interferograms and power spectra measurements.

Implementation Method 1

a waveplate (27) disposed on an optical path of the control light beam (21)

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 2

a beam splitter (13), a fixed mirror (14), and a moving mirror (15)

Methodology Applied

Scientific EffectPartial reflection: Reflection

Implementation Method 3

A Fourier transform infrared spectrophotometer includes a main interferometer, a control interferometer... an infrared interference light beam that is generated by the main interferometer

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS11874172B2Fourier transform infrared spectrophotometer

Publication Date: 2024.01.16 SHIMADZU CORP

AI summary

A Fourier transform infrared spectrophotometer includes a main interferometer, a control interferometer, an infrared detector, a control light detector, a waveplate, and a support member. The waveplate is disposed on an optical path of a control light beam and between a fixed mirror or a moving mirror and a beam splitter. The support member supports the waveplate. An outer perimeter of the waveplate includes a supported region supported by the support member and a released region spaced apart from the support member.