Coherent 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 inefficient measurement processes.
Innovation Solution
Implementing coherent spread spectrum optical spectroscopy using a coherent CW laser modulated with a pseudo-random bit sequence and high-bandwidth coherent detection, combined with frequency-domain multiplexing and time-multiplexed coding schemes, to enhance signal processing and reduce measurement time.
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 counting system (TC-SPC) with an optical interference system. Instead of detecting individual photons through time-correlated counting, the system uses coherent light interference patterns to encode temporal information, eliminating the need for slow statistical accumulation of photon counts while maintaining temporal resolution.
Solution Approach 2:
The patent employs continuous wave (CW) lasers instead of pulsed lasers, enabling continuous measurement without the repetition and averaging required by pulsed systems. The spread spectrum modulation continuously encodes temporal information in the optical field, allowing real-time acquisition without the intermittent nature of pulsed operation.
2Productivity
If pulsed lasers with fast repetition rates are used, then acquisition time is reduced, but the lasers require extensive warm-up and stabilization time
Solution Approach 1:
The patent uses spread spectrum modulation with pseudo-random binary sequences to periodically encode information in the optical field. This periodic modulation structure allows for coherent integration and correlation processing that rapidly converges to the correct measurement, eliminating the need for extended laser stabilization while maintaining high measurement speed.
3Measurement precision
If TC-SPC with time-gating is used to ensure accurate histogramming, then measurement precision is improved, but acquisition time increases due to the pile-up effect
Solution Approach 1:
The patent replaces the histogramming mechanism with an optical correlation mechanism. Instead of accumulating photon counts in time bins, the system uses coherent detection and correlation with the known spread spectrum code to directly extract temporal information, achieving accurate measurements without the pile-up effect that limits histogram-based methods.
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 allows for faster acquisition of point spread functions and improved temporal resolution, enabling more efficient and cost-effective diffuse optical imaging with enhanced sensitivity and spatial resolution.
Implementation Method 1
generating one or more first optical signals by modulating light to form a broad substantially-coherent optical spectrum
Implementation Method 2
mixing the second optical signal with a third optical signal to generate one or more mixed signals
Implementation Method 3
obtaining one or more electrical signals from the mixed signal
Data Source
AI summary
Aspects of the subject disclosure may include, for example, generating one or more first optical signals, launching the first optical signal into a medium, receiving from the medium one or more second optical signals, mixing the one or more second optical signals with one or more third optical signals to generate one or more mixed signals, obtaining one or more electrical signals from the mixed signal, and generating one or more point spread functions from the one or more electrical signals. Other embodiments are disclosed.