Fabry-Perot Filter Voltage-Wavelength Control via Temperature Correction

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Solution Overview

Problem

In Fabry-Perot interference filters, the relationship between applied voltage and transmission wavelength varies among individual objects, requiring lengthy measurement times to achieve high accuracy for each object, as the generalized relationship between voltage and wavelength is not well-defined.

Innovation Solution

A filter controlling expression derivation method and system that includes a light measurement system and control method for a Fabry-Perot interference filter, using a filter control program to derive and apply a relational expression between applied voltage and transmission wavelength, incorporating temperature corrections to accurately control the inter-mirror distance and thus the transmission wavelength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If measurement is performed for each individual object to acquire accurate relationship between applied voltage and transmission wavelength, then measurement precision is improved, but measurement time increases

Engineering Contradiction:
Improveaccuracy of voltage-wavelength relationshipVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent introduces temperature as an additional parameter to characterize the voltage-wavelength relationship. By measuring at multiple temperatures and deriving temperature correction terms, the system creates a generalized expression that accounts for environmental variations, reducing the need for repeated measurements under different conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the measured transmission wavelength is used to verify and refine the voltage-wavelength relationship expression. The system measures actual transmission wavelengths, compares them with predicted values from the expression, and uses this feedback to ensure accuracy while maintaining efficiency.

Inventive Principle:
Principle #23Feedback

2Productivity

If generalized relationship between voltage and wavelength is established, then measurement efficiency is improved, but accuracy for individual objects deteriorates

Engineering Contradiction:
Improvemeasurement efficiencyVSAvoidaccuracy of voltage-wavelength relationship
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent transforms the relationship from a simple voltage-wavelength correlation to a multi-parameter expression incorporating temperature. This allows the generalized expression to adapt to different environmental conditions while maintaining accuracy across individual objects through the temperature correction mechanism.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary measurements at multiple temperatures to establish the temperature correction terms in advance. These pre-derived correction terms are then applied in subsequent measurements, allowing efficient operation without sacrificing accuracy when individual object characteristics are considered.

Inventive Principle:
Principle #10Preliminary action

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

Enables the efficient and accurate acquisition of the relationship between applied voltage and transmission wavelength, reducing measurement time and improving control accuracy across various environmental temperatures.

Implementation Method 1

the transmission wavelength is controlled by changing the gap by controlling the voltage applied between the fixed mirror portion and the movable mirror portion

Methodology Applied
Scientific EffectElectrostatic actuation: Electrostatics

Implementation Method 2

Fabry-Perot interference filter having a fixed mirror portion and a movable mirror portion

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP3637168B1Filter controlling expression derivation method, light measurement system, control method for fabry-perot interference filter, and filter control program
Publication Date: 2022.04.06 HAMAMATSU PHOTONICS KK
  • EP3637168B1 patent drawingFigure 1
  • EP3637168B1 patent drawingFigure 2
  • EP3637168B1 patent drawingFigure 3

AI summary

Provided is a filter controlling expression derivation method including: a preparation step of preparing a Fabry-Perot interference filter of which distance between a fixed mirror portion and a movable mirror portion is controlled by balancing an electrostatic force and an elastic force; a first derivation step of deriving a relational expression between a deflection amount and an elasticity index in which the elasticity index of the movable mirror portion is described as a quadratic or higher-order polynomial with the deflection amount of the movable mirror portion as a variable by performing predetermined measurement; and a second derivation step of deriving a relational expression between a transmission wavelength of light transmitted through the Fabry-Perot interference filter and the voltage as a filter controlling expression based on the relational expression between the deflection amount and the elasticity index and a relational expression between the electrostatic force and the elastic force, wherein, in the first derivation step, the transmission wavelength of light transmitted through the Fabry-Perot interference filter is measured in a state where each of a plurality of different voltages is applied as the voltage.