Single Input State PS-OCT Retardance Measurement
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Solution Overview
Problem
Current Polarization Sensitive Optical Coherence Tomography (PS-OCT) systems require multiple input polarization states or complex recursive algorithms to measure depth-resolved birefringence, which limits imaging speed, increases system complexity, and costs, especially in catheter-based imaging.
Innovation Solution
A single input state PS-OCT scheme using a mirror state constraint and Stokes vector reasoning to determine retardance without the need for multiple input states, enabling depth-resolved birefringence imaging with a single illuminating polarization state, compatible with both fiber- and catheter-based systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple input polarization states are used in PS-OCT systems, then depth-resolved birefringence measurement accuracy is improved, but imaging speed decreases and system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the mirror state constraint relationship between input and output polarization states. Instead of acquiring multiple input states sequentially, the system uses a single input state and applies the mirror state constraint (Equation 1: S_out(λ) = M·S_in(λ)·M^T) to directly calculate depth-resolved birefringence, eliminating the need for sequential measurements and thereby improving imaging speed while maintaining measurement accuracy
Solution Approach 2:
The patent changes the measurement approach from acquiring multiple input polarization states to using a single input state with modified detection and processing parameters. By implementing the mirror state constraint and Stokes vector reasoning, the system transforms the measurement paradigm to achieve depth-resolved birefringence using only one input state, thus improving imaging speed without sacrificing precision
2Measurement precision
If multiple input polarization states are used in PS-OCT systems, then depth-resolved birefringence measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the polarization modulator component from the PS-OCT system. By applying the mirror state constraint and using Stokes vector reasoning with a single input state, the system achieves depth-resolved birefringence measurement without requiring complex polarization modulation hardware, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent uses mathematical modeling (mirror state constraint and Stokes vectors) to replace physical polarization modulation components. Instead of using multiple physical input states requiring complex hardware, the system creates virtual polarization state variations through computational methods, simplifying the physical device while preserving measurement capabilities
3Measurement precision
If polarization modulators are used in PS-OCT systems, then birefringence imaging accuracy is improved, but imaging speed decreases and system cost increases
Solution Approach 1:
The patent replaces the mechanical polarization modulator system with a computational approach based on mirror state constraint and Stokes vector analysis. By eliminating the need for physical polarization modulation and using mathematical relationships to derive birefringence from single-input-state measurements, the system achieves faster imaging speeds while maintaining birefringence imaging accuracy
4Measurement precision
If polarization modulators are used in PS-OCT systems, then birefringence imaging accuracy is improved, but system cost increases
Solution Approach 1:
The patent extracts and removes the polarization modulator component from the PS-OCT system architecture. By implementing the mirror state constraint and Stokes vector reasoning with a single input state, the system achieves birefringence imaging without requiring expensive polarization modulation hardware, thereby reducing system cost while maintaining imaging accuracy
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 allows for faster, lower-cost, and higher-resolution birefringence imaging without the need for polarization modulators, applicable in fields like ophthalmology, dermatology, and intravascular imaging, providing accurate local retardation maps.
Implementation Method 1
The light emitted from the source is divided and directed into different paths, usually called the 'reference arm' and the 'sample arm,' then redirected and combined again resulting in interference via a Michelson or Mach-Zehnder configuration
Implementation Method 2
Detecting, using a detector, the combined light along a first polarization state and a second polarization state
Implementation Method 3
Birefringence describes the difference in the refractive index experienced by light polarized along the fast and slow principal polarization state, or optic axis, respectively, of a birefringent medium. Birefringence results in retardation, i.e. delaying of the light polarized along the slow optic axis direction
Data Source
Figure 1
Figure 2A~3
Figure 4~5d
AI summary
A method for determining a retardance of a layer of a sample. The method includes: transmitting a first portion of a polarized light to a sample arm of an optical system and a second portion of the polarized light to a reference arm of the optical system; combining first return light returned from the sample arm and second return light from the reference arm; detecting, using a detector, the combined light along a first polarization state and a second polarization state to produce polarization data, the second polarization state being different from the first polarization state; determining, using a processor coupled to the detector, polarization states of light returning from upper and lower surfaces of a layer of the sample based on detecting the combined light; and determining, using the processor, a retardance of the layer of the sample based on the determined polarization states.