Polarization Measuring Device With Continuous Spectral Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polarization measurement methods in industrial quality control are time-consuming and prone to vibrations due to stepwise polarization modulation, limiting their widespread adoption in applications like imaging ellipsometry.
Innovation Solution
Simultaneously and continuously perform polarization and spectral modulation, allowing intensity measurements to be taken at different constellations of polarization and spectral states during a single monotonic variation, reducing measurement time without compromising quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stepwise polarization modulation is used to perform intensity measurements at different polarization states, then measurement precision is improved, but measurement time increases and vibrations occur
Solution Approach 1:
The patent applies periodic action by using a rotating compensator that continuously varies the polarization state at constant speed, creating periodic modulation of the measuring beam's polarization. This allows multiple intensity measurements to be taken during a single rotation cycle, capturing data at different polarization states without stopping or stepwise adjustments, thereby reducing total measurement time while maintaining precision through synchronous detection of the periodic signal
Solution Approach 2:
The patent implements continuity of useful action by maintaining continuous rotation of the compensator throughout the measurement process, eliminating idle time between discrete measurements. The polarization modulation proceeds continuously without interruption, and the detector continuously records intensity variations, ensuring that the useful measurement action is performed without gaps or pauses that would increase total measurement time
2Measurement precision
If stepwise polarization modulation is used to perform intensity measurements at different polarization states, then measurement precision is improved, but vibrations are generated
Solution Approach 1:
The patent eliminates vibrations by replacing stepwise positioning with continuous periodic rotation of the compensator. The smooth periodic motion avoids the acceleration and deceleration phases inherent in stepwise movement, which are the primary sources of mechanical vibrations. The continuous rotational motion maintains constant speed, preventing the shock and vibration that occur when the modulator starts, stops, or changes position discretely
Solution Approach 2:
The patent substitutes the mechanical stepwise positioning system with a continuous rotational mechanical system driven by a motor. This replacement eliminates the need for repeated starting, stopping, and positioning operations that generate vibrations. The continuous rotation driven by a well-controlled motor provides smooth motion without the mechanical shocks and vibrations associated with stepwise actuation mechanisms
3Measurement precision
If multiple intensity measurements are performed at different polarization and spectral states, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the polarization modulation function and spectral modulation function into a single integrated measurement system. The rotating compensator simultaneously modulates both polarization state and spectral content, allowing intensity measurements to be taken at different combinations of polarization and spectral states during continuous operation. This consolidation reduces device complexity by combining multiple modulation functions into one coordinated system rather than requiring separate independent modulation mechanisms
Solution Approach 2:
The patent implements multi-functionality by designing the measurement system to simultaneously perform polarization modulation and spectral modulation through a single integrated approach. The rotating compensator serves multiple functions: it modulates polarization state, enables spectral selection through its angular position, and provides the temporal reference for synchronous detection. This universal component performs what would otherwise require multiple separate devices, reducing overall system complexity
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
Accelerates the measurement process significantly while minimizing vibrations, enhancing the quality and accuracy of imaging ellipsometric measurements.
Implementation Method 1
a polarization-sensitive analyzer disposed between the sample and the intensity detector and adapted to select light components of predetermined polarization states
Data Source
AI summary
A polarization measuring device is operated by passing light having a predetermined input polarization state to a sample for a potentially polarization changing interaction and from the sample through a polarization selective analyzer and to an intensity detector. The method proceeds by varying an angle between the output polarization state of the light emanating from the sample and the analyzer. The wavelength of the light reaching the intensity detector is varied, and a plurality of intensity measurements are performed successively at different constellations of polarization. Spectral modulation states and corresponding intensity values are stored together with polarization and spectral values representing the corresponding constellation. The polarization modulation and the spectral modulation are performed simultaneously and continuously, and during a single, monotonic variation of the polarization modulation state, the spectral modulation state is varied plural times and during each spectral modulation period (τλ) plural successive intensity measurements are performed.