Variable-Polarization Skin Imaging for Surface and Subsurface Analysis
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Solution Overview
Problem
Conventional cross-polarized and parallel-polarized skin imaging techniques provide only two-dimensional images without depth information, failing to differentiate between surface and subsurface features effectively.
Innovation Solution
A skin imaging apparatus and method utilizing variable polarization angles between 0 and 90 degrees, allowing capture of images with different polarization orientations to differentiate between surface and subsurface features by varying the angle between source and detection polarizers, enabling depth estimation and visualization of both superficial and subsurface skin features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cross-polarized and parallel-polarized imaging is used, then surface and subsurface features can be selectively captured, but depth information cannot be differentiated
Solution Approach 1:
The system dynamically varies the polarization angle between the light source and detector through rotational movement. The detector or polarizer rotates to change the angle of incidence and detection, enabling depth-resolved imaging without requiring complex mechanical structures. This dynamic adjustment transforms a static two-dimensional imaging system into a depth-capable system.
Solution Approach 2:
The invention adds a third dimension (depth) to the conventional two-dimensional skin imaging by utilizing the polarization angle as an additional degree of freedom. By varying the polarization angle, the system extracts depth information from scattered light, converting planar images into depth-resolved visualizations of skin features.
2Loss of information
If variable polarization angles are used to obtain depth information, then both superficial and subsurface features can be visualized, but the device complexity increases
Solution Approach 1:
The imaging system performs multiple functions using a single variable polarization mechanism. The same rotational mechanism that changes the polarization angle also serves to scan different depths, eliminating the need for separate depth-scanning hardware. This multi-functionality reduces overall device complexity despite adding polarization control capabilities.
Solution Approach 2:
The system utilizes the natural scattering properties of skin tissue to provide depth information. The scattered light itself carries depth-encoded polarization information, which the system extracts through angle variation. The tissue's optical properties serve the dual purpose of both the imaging target and the depth-encoding medium, reducing the need for additional depth-encoding components.
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 the visualization and analysis of both superficial and subsurface skin features by providing depth information through the use of variable polarization angles, enhancing diagnostic accuracy in skin imaging applications.
Implementation Method 1
The use of a polarizing filter in photography for reducing glare, managing reflections, and darkening skies is known. Light reflected from a non-metallic surface becomes polarized.
Implementation Method 2
A polarizer rotated to pass only light polarized in the direction perpendicular to the reflected light absorbs most of the reflected light and removes glare from the image.
Implementation Method 3
Light that enters the tissue undergoes scattering and absorption. Each photon that enters the tissue follows a random path, and due to scattering starts losing its incident polarization.
Implementation Method 4
Light that enters the tissue undergoes scattering and absorption.
Implementation Method 5
one or more of the detection polarizer and a source polarizer is rotatable so as to allow the angle between orientations of their polarizations to be varied
Data Source
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Figure 3A~3B
AI summary
Methods and apparatuses are disclosed for capturing and analyzing images of tissue, such as human skin, using variable polarization. Exemplary devices are described having a detection polarizer via which an area of tissue is imaged and one or more light sources whose emitted light is polarized with one or more source polarizers. In a first such device, one or more of the detection polarizer and a source polarizer is rotatable so as to allow the angle between their polarizations to be varied. An area of tissue can be imaged as the angle is varied. Another device has multiple fixed source polarizers of different polarization orientations, each source polarizer polarizing the light emitted by a corresponding group of light sources which can be selectively activated, thereby enabling the device to illuminate an area of tissue with polarized light of different orientations relative to the orientation of the detection polarizer. Images of an area of tissue captured with different polarizations provide information from different depths, allowing visualization of superficial as well as subsurface features.