Spread Spectrum Optical Spectroscopy for Faster DOS Acquisition
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Solution Overview
Problem
Existing diffuse optical spectroscopy (DOS) techniques, particularly Time-Domain DOS (TD-DOS), face challenges with long acquisition times due to the use of time-correlated single photon counters (TC-SPCs) and pulsed lasers, which require extensive averaging and stabilization, leading to inefficiencies and high costs in commercial systems.
Innovation Solution
The implementation of incoherent spread spectrum optical spectroscopy using a coherent CW laser modulated with a pseudo-random bit sequence (PRBS) and time-multiplexed coding schemes, coupled with frequency, spatial, and polarization multiplexing, allows for faster acquisition of point spread functions (PSFs) by demultiplexing and multiplexing optical signals, enabling efficient detection and processing in diffuse media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-correlated single photon counters (TC-SPCs) and pulsed lasers are used in TD-DOS, then measurement precision and temporal resolution are improved, but acquisition time increases significantly
Solution Approach 1:
The patent replaces the mechanical time-gating system of TC-SPCs with an all-optical spread spectrum modulation and detection system. Instead of using pulsed lasers and time-correlated single photon counting, the invention uses continuous wave lasers modulated with pseudo-random binary sequences and optical code division multiplexing, eliminating the need for mechanical time-gating and extensive photon accumulation, thereby reducing acquisition time while maintaining temporal resolution
Solution Approach 2:
The patent changes the fundamental operating parameters from pulsed laser excitation with time-gated detection to continuous wave laser excitation with frequency-modulated detection. By spreading the spectral content across a broad frequency range and using code-division multiplexing, the system achieves high temporal resolution through frequency domain analysis rather than time domain photon counting, significantly reducing measurement acquisition time
2Measurement precision
If pulsed lasers and TC-SPCs are used for high temporal resolution, then sensitivity is improved, but system complexity and cost increase
Solution Approach 1:
The patent replaces complex time-correlated single photon counting electronics and pulsed laser systems with a simpler all-optical spread spectrum system using continuous wave lasers and optical modulators. The detection is performed using standard photodetectors and frequency domain analysis, eliminating the need for complex time-gating electronics and reducing overall system complexity and cost
Solution Approach 2:
The patent creates a multi-functional system where a single continuous wave laser source can simultaneously provide excitation for multiple wavelengths through frequency modulation, and a single detector can analyze multiple spectral components through code-division multiplexing. This universal approach replaces the need for multiple specialized components (pulsed lasers, TC-SPCs, time-gating electronics) with a unified spread spectrum platform that achieves the same functionality with reduced complexity
3Measurement precision
If extensive averaging is performed to achieve high signal-to-noise ratio, then measurement precision is improved, but acquisition time increases
Solution Approach 1:
The patent employs periodic pseudo-random binary sequence modulation at high frequencies, where the known modulation pattern allows for coherent integration and correlation detection. By spreading the signal energy across a broad frequency spectrum and using matched filtering with the known code sequence, the system achieves high signal-to-noise ratio through frequency domain correlation rather than time domain averaging, dramatically reducing the number of measurements required
Solution Approach 2:
The patent replaces time-domain photon accumulation and averaging with frequency-domain spread spectrum correlation detection. The known pseudo-random modulation code enables coherent integration of signal energy across the broadened spectral bandwidth, achieving high signal-to-noise ratio through frequency domain processing rather than repeated time domain measurements, thereby reducing acquisition time while maintaining measurement precision
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 significantly reduces acquisition time and improves temporal resolution and sensitivity in DOS, making it more efficient and cost-effective compared to traditional TD-DOS systems, while maintaining high signal-to-noise ratio (SNR) and enabling better estimation of tissue properties.
Implementation Method 1
a laser source that generates a coherent light
Implementation Method 2
launches a set of optical signals into a target medium... receiving a second set of optical signals from the target medium
Implementation Method 3
Diffuse optical spectroscopy (DOS) is a known method of optical imaging where an optical signal is transmitted through a turbid or diffusing media
Implementation Method 4
obtaining a set of electrical signals based on one or more measurements of one or more optical fields of the one or more multiplexed signals
Data Source
AI summary
Aspects of the subject disclosure may include, for example, generating a first set of optical signals, demultiplexing the first set of optical signals to generate demultiplexed signals, launching the demultiplexed signals into a medium, receiving from the medium a second set of optical signals, multiplexing at least a portion of the second set of optical signals to generate one or more multiplexed signals, obtaining one or more electrical signals according to one or more measurements of one or more optical fields of the one or more multiplexed signals, and generating one or more point spread functions from the one or more electrical signals. Other embodiments are disclosed.