Retinal Scanning Polarization Compensation for Optical Retardance

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Solution Overview

Problem

Polarization-sensitive retinal scanning systems face interference from components with retardation, such as dichroic mirrors and beamsplitters, which alter the polarization state of light, complicating accurate measurement of retinal birefringence patterns.

Innovation Solution

The system employs compensating retarders in both the forward and return light paths to nullify the effect of unwanted retardance, using Mueller matrix measurements to calculate compensating waveplates that restore the polarization state to its original state, and incorporates variable compensator modules to account for individual patient's corneal birefringence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If components with retardation (dichroic mirrors, beamsplitters) are used in the optical system, then the system can perform retinal imaging functions, but the polarization state of light is altered which interferes with accurate measurement of retinal birefringence

Engineering Contradiction:

Improveretinal imaging functionVSAvoidpolarization state measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary anti-action by placing compensating retarders in the optical path before the light reaches the retina and after light returns from the retina. These compensating retarders are specifically designed to counteract the polarization-altering effects of other optical components (dichroic mirrors, beamsplitters), thereby nullifying their harmful influence on polarization state measurement while preserving the retinal imaging function.

Inventive Principle:

Principle #9Preliminary anti-action

2Measurement precision

If compensating retarders are added to nullify unwanted retardance, then polarization measurement accuracy is improved, but the device complexity increases

Engineering Contradiction:

Improvepolarization state measurement accuracyVSAvoidoptical system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses compensating retarders as intermediary elements that mediate between the polarization-altering optical components and the polarization-sensitive detection system. These retarders act as mediators that specifically counteract the unwanted polarization effects without disrupting the overall imaging function, thereby improving measurement accuracy while adding minimal complexity compared to complete system redesign.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If variable compensator modules are used to account for individual patient's corneal birefringence, then measurement precision is enhanced, but the ease of operation decreases

Engineering Contradiction:

Improveretinal birefringence detection precisionVSAvoidsystem operation simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent applies preliminary action by incorporating variable compensator modules that can be adjusted to account for individual patient characteristics (corneal birefringence) before the actual retinal imaging measurement is performed. This preliminary adjustment ensures that each patient's unique optical properties are compensated for in advance, thereby enhancing measurement precision while maintaining a relatively simple operational workflow.

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

This approach ensures accurate detection of retinal birefringence patterns by minimizing interference from optical components and corneal birefringence, enhancing the precision of retinal scanning systems.

Implementation Method 1

A compensating retarder provided in each of the forward and return light paths nullifies an effect of the unwanted retardance in each of the forward and return light paths

Methodology Applied

Scientific EffectRetardation: Birefringence

Implementation Method 2

analyzing changes in a polarization state of the reflected light from the retina as a measure of the retinal birefringence amount and orientation

Methodology Applied

Scientific EffectBirefringence: Birefringence

Data Source

PatentUS12446776B2Compensating for polarization changes introduced by components with retardation in polarization-sensitive retinal scanning systems

Publication Date: 2025.10.21 JOHNS HOPKINS UNIVERSITY

AI summary

An optical apparatus uses polarized light to interrogate birefringence properties of the retina to detect the fixation condition of the eye by sensing characteristic birefringence patterns of the retinal structures. Optical components, as well as optional additional components, interfere with the polarization measurements by introducing unwanted retardance which alters the polarization state of the light entering the eye and of the light reaching the detection system. Compensating retarders are provided to nullify the effect of unwanted retardance in the forward and return light paths so the polarization states of the light entering the eye and the light reaching the detection system are not contaminated by the effects of the unwanted retardance. Mueller matrices are used to mathematically calculate the parameters for the compensating retarders for the unwanted retardance. A variable retarder system may also be provided to compensate for the corneal birefringence of the eye via feedback control.