Composite Waveplate Calibration via Mueller Matrix Offset Extraction

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Solution Overview

Problem

Current Mueller matrix measurement systems face challenges in achieving high-speed, high-precision calibration of achromatic composite waveplates due to misalignment of optical axes, which affects polarization performance and requires a method to accurately account for alignment angle offsets.

Innovation Solution

A method and apparatus for calibrating composite waveplates by determining a first matrix characterizing the waveplate, establishing a theoretical relationship between light intensity and alignment angle offset, and using measured data to obtain a second matrix that eliminates unknowns, thereby improving precision and reducing calibration complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual alignment by experience or alignment by light extinction is used to align optical axes of single waveplates, then the alignment process is simple, but the alignment precision is insufficient and the alignment angle is always offset from the designed angle

Engineering Contradiction:

Improvealignment angle precisionVSAvoidcalibration process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent transforms the calibration problem from aligning multiple waveplates to measuring a single parameter (alignment angle offset). By representing the composite waveplate's polarization performance through a Mueller matrix and extracting the alignment angle offset as a key parameter, the system achieves high-precision calibration through parameter measurement rather than complex physical alignment procedures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces manual mechanical alignment methods (experience-based or light extinction methods) with an optical measurement system that uses Mueller matrix measurement and parameter extraction. This substitution eliminates the need for complex mechanical alignment operations while achieving superior alignment precision through optical characterization

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If composite waveplate is treated as ideal waveplate and only phase delay amount is calibrated, then the calibration process is simple, but the polarization performance has gaps from designed ideal Mueller matrix due to misalignment

Engineering Contradiction:

Improvepolarization performance accuracyVSAvoidcalibration efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent extracts the alignment angle offset as a separate measurable parameter from the composite waveplate's overall Mueller matrix. By identifying and measuring this specific parameter that causes deviation from ideal performance, the system can correct alignment errors without requiring complete recalibration of all waveplate parameters, thus maintaining both accuracy and efficiency

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements a feedback mechanism where the Mueller matrix measurement provides information about the actual polarization performance, which is then used to extract the alignment angle offset parameter. This feedback loop allows the system to identify and correct deviations from the designed Mueller matrix, ensuring high polarization performance accuracy

Inventive Principle:

Principle #23Feedback

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 approach significantly reduces the number of unknowns in calibration, simplifies the process, and enhances the precision of Mueller matrix measurements by accounting for alignment angle offsets, improving the overall accuracy and efficiency of the calibration.

Implementation Method 1

which includes an additional phase difference to the two vertical components of a polarized light, thereby changing or checking a polarized state of a light wave

Methodology Applied

Scientific EffectPhase difference:

Implementation Method 2

an achromatic composite waveplate, which is featured by a compact dimension, a simple structure, and an easily adjusted light path

Methodology Applied

Scientific EffectAchromatic:

Data Source

PatentUS10309834B2Calibrating method and device for broad-band achromatic composite wave plate and corresponding measurement system

Publication Date: 2019.06.04 RAINTREE SCI INSTR SHANGHAI

AI summary

The present disclosure discloses a calibrating method, apparatus, and corresponding measurement system for a composite waveplate. The calibrating method comprises: A. determining a first matrix characterizing the composite waveplate, the first matrix including at least one unknown number; B. determining a theoretical relationship between a light intensity and an alignment angle offset value of the composite waveplate based on the first matrix; and C. calibrating based on the theoretical relationship between a light intensity and an alignment angle offset value of the composite waveplate determined in step (B) and actually measured light intensity data to obtain a second matrix that may characterize the composite waveplate and does not contain the unknown number. The technical solution of the present disclosure may greatly reduce the amount of unknown numbers when calibrating a composite waveplate or a measuring system, thereby lowering the difficulty of calibration and improving the precision of calibration.