Optical IRF Monitoring with Reference Detection for Tissue Measurement
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Solution Overview
Problem
Time domain-based optical measurement devices face inaccuracies due to changes in instrument response function (IRF) caused by environmental and system conditions, leading to inaccurate measurement and analysis of tissue properties.
Innovation Solution
Incorporating a reference detector to measure the instrument response function (IRF) in real-time, allowing for accurate accounting of changes and improving the determination of tissue characteristics by generating more precise histograms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a time domain-based optical measurement device is used to measure tissue properties, then the measurement capability is provided, but the measurement accuracy deteriorates due to changes in instrument response function caused by environmental and system conditions
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements to establish a baseline instrument response function before actual tissue measurements are taken. This baseline is stored and used for subsequent corrections, allowing the system to pre-compensate for systematic variations in the optical path and detector response.
Solution Approach 2:
The patent implements feedback by continuously monitoring the instrument response function using a reference detector that measures the laser pulse shape and timing. This monitored information is fed back to correct measurements in real-time, compensating for drifts caused by temperature changes, humidity, and component aging.
2Measurement precision
If periodic calibration is performed to maintain baseline shape, then measurement accuracy is improved, but the time required for calibration and operation increases
Solution Approach 1:
The patent applies continuity of useful action by performing instrument response function measurements continuously or at frequent intervals during normal operation, rather than requiring separate periodic calibration sessions. The reference detector operates concurrently with tissue measurements, allowing the system to maintain an up-to-date baseline without interrupting the primary measurement function.
Solution Approach 2:
The system performs a preliminary calibration measurement to establish a baseline instrument response function before actual tissue measurements begin. This initial calibration creates a reference that can be used for subsequent corrections, reducing the need for frequent re-calibration and minimizing overall calibration time.
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
Enhances the accuracy of tissue property measurements by compensating for IRF changes, resulting in more reliable biological property assessments.
Implementation Method 1
A time domain-based optical measurement device (e.g., a near-infrared spectroscopy (TD-NIRS) device) may be configured to perform an optical measurement by emitting picosecond pulses of light into tissue (e.g., brain, muscle, finger, etc.) and detecting arrival times of single photons at nearby detectors.
Data Source
AI summary
An illustrative optical measurement system may include a module comprising a light source configured to emit light directed at a target, a plurality of detectors configured to detect target photon arrival times of target photons of the light after the light is scattered by the target, a reference detector configured to detect reference photon arrival times of reference photons of the light after the light is reflected within the module, and a waveguide configured to direct the light reflected within the module through a plurality of channels of the waveguide to the reference detector. The system may further include a controller configured to determine, based on an output from the reference detector, an instrument response function (IRF) of the module.