Optical Phantom Using Delay Lines for Photon Time-of-Flight Simulation
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Solution Overview
Problem
Current methods for testing measuring devices for time-resolved diffuse optical spectroscopy face challenges in accurately mimicking the photon time-of-flight distribution of biological tissue, particularly for cerebral tissue oximetry, due to the complexity of physical phantoms and the difficulty in reproducing results for multiple tissue layers and structures.
Innovation Solution
An optical phantom system comprising a light source, spatial light modulator, and optical delay line with varying fiber lengths is used to produce a time-resolved diffuse reflectance spectrum that mimics the photon time-of-flight distribution of biological tissue, allowing for the testing of measuring devices without in vivo measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical phantoms are used to test measuring devices, then the testing can be performed with real tissue-like structures, but the complexity of creating and reproducing multiple tissue layers and structures increases significantly
Solution Approach 1:
The patent uses optical copying by generating light pulses that traverse optical paths with different lengths to create a photon time-of-flight distribution that copies the statistical properties of biological tissue. Instead of physically replicating tissue layers, the invention creates an optical copy of the photon transport behavior through controlled path length variations in a turbid medium.
Solution Approach 2:
The patent changes the parameter of optical path length in the turbid medium to control the photon time-of-flight distribution. By varying the path lengths that light pulses traverse through the scattering medium, the system can reproduce different tissue layer configurations and optical properties without physically constructing those layers.
2Measurement precision
If physical phantoms with multiple tissue layers are constructed, then realistic tissue modeling is achieved, but the ease of manufacture and reproduction of results decreases
Solution Approach 1:
The system achieves different tissue layer models by changing the optical path lengths in the turbid medium rather than constructing different physical layers. This parameter-based approach allows easy reproduction of results by adjusting optical path configurations rather than manufacturing new physical phantoms for each tissue type.
Solution Approach 2:
The patent employs a dynamic approach where the optical path lengths can be varied and adjusted to simulate different tissue configurations. This dynamic parameter adjustment provides flexibility in modeling various tissue types without requiring separate static physical phantoms for each case.
3Measurement precision
If conventional light sources are used, then the system is simpler, but the time resolution of the waveform cannot achieve picosecond precision
Solution Approach 1:
The patent uses periodic pulsed light sources operating at high repetition rates (e.g., 80 MHz) to achieve precise time resolution. The periodic nature of the pulses allows for accurate time-of-flight measurements by correlating pulse emission times with detected photon arrival times, enabling picosecond-level temporal precision.
Solution Approach 2:
The patent replaces mechanical timing mechanisms with optical and electronic timing methods. By using precisely timed optical pulses and electronic correlation techniques to measure photon arrival times, the system achieves picosecond time resolution without relying on mechanical timing devices, which would be too slow and imprecise.
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
The optical phantom system provides a controlled waveform with picosecond time resolution, enabling the simulation of photon time-of-flight distributions for various physiological conditions, such as blood oxygenation in cerebral tissue, thereby validating the performance of measuring devices like cerebral oximeters with high accuracy and reproducibility.
Implementation Method 1
an optical delay line comprising a plurality of optical fibers that includes a first delay fiber and a second delay fiber, such that: a first optical entrance of the first delay fiber is disposed in the first light path and receives the first photon flux from the spatial light modulator; a second optical entrance of the second delay fiber is disposed in the second light path and receives the second photon flux from the spatial light modulator
Implementation Method 2
a spatial light modulator comprising a plurality of mirrors arranged in an array, the mirrors being independently controlled to reflect the first light in a plurality of light paths comprising a first light path and a second light path
Data Source
AI summary
An optical phantom produces a time-resolved diffuse reflectance spectrum and includes: a light source; a spatial light modulator; and an optical delay line including optical fibers of different length that produce different time-of-flight distributions, such that different time-of-flight distributions are combined and produce phantom light having the time-resolved diffuse reflectance spectrum.