Add-on Imaging Module for Off-axis Polarization Recording
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Solution Overview
Problem
Off-axis holographic imaging systems face challenges with coherence noise and sensitivity to external variations due to the use of monochromatic light and double-path configurations, which affect the accuracy and cost-effectiveness of holographic image reconstruction.
Innovation Solution
An add-on imaging module utilizing a polarization sensitive beam splitter, such as a geometric-phase grating, for directional separation of polarization coded waves, allowing off-axis recording with a common-path configuration and low-coherence light, which reduces coherence noise and enhances system robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monochromatic light with long coherence length is used to achieve sufficient interference, then coherence noise increases strongly decreasing performance, but if low-coherence light is used then interference capability is insufficient
Solution Approach 1:
The patent changes the polarization state parameter of light beams to achieve beam separation. By converting linearly polarized beams to circularly polarized beams and then separating them based on handedness, the system enables off-axis holography with low-coherence light without suffering from coherence noise, resolving the contradiction between interference capability and coherence noise
2Ease of operation
If a double-path configuration is used to achieve different angular inclination of beams, then off-axis holography is enabled, but sensitivity to vibrations and external variations increases
Solution Approach 1:
The patent merges the reference and object beams into a common optical path after they have been separated by the polarization-sensitive beam splitter. This common-path configuration reduces sensitivity to vibrations and external variations while maintaining the off-axis beam inclination needed for holographic imaging
Solution Approach 2:
The polarization-sensitive beam splitter acts as an intermediary device that separates and recombines beams based on their polarization states. This mediator enables the system to achieve off-axis configuration without requiring physically separate optical paths, thereby reducing sensitivity to external disturbances
3Measurement precision
If achromatic phase-shifting methods are used to reconstruct true holographic image, then phase accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical phase-shifting devices with a polarization-based optical system. By using polarization-sensitive beam splitting and circular polarization conversion, the system achieves phase information extraction without mechanical scanning or complex phase-modulation devices, reducing system complexity while maintaining measurement precision
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 single-shot reconstruction of true holographic images with improved accuracy and reduced sensitivity to external variations, using low-coherence light and a common-path configuration, thus enhancing the efficiency and cost-effectiveness of holographic imaging.
Implementation Method 1
a polarization sensitive beam splitter, such as a geometric-phase grating, for directional separation of polarization coded waves
Implementation Method 2
The geometric-phase grating is an optical component capable of directional separation of the light beams according to their polarization states
Implementation Method 3
The interference record created by the signal and reference waves (hologram) is composed of three terms
Data Source
Figure 1~4
Figure 5~7
AI summary
The invention relates to an add-on imaging module for the off-axis recording of polarization coded waves, that might be connected to any polarization adapted interferometric system, and which incorporates the first polarization sensitive beam splitter, the first optical system of the module and the detector, wherein the first optical system of the module includes the first imaging system and the linear polarizer.