Non-invasive Optical Detection System Using Partially Balanced Interferometric Parallel Detection
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Solution Overview
Problem
Conventional optical interferometry systems face challenges in achieving high spatial resolution and depth penetration for non-invasive measurements, particularly in the brain, due to light scattering and limited data throughput, which restricts their ability to detect neural activity effectively.
Innovation Solution
A non-invasive optical detection system employing a multi-channel setup with an optical source that sweeps wavelengths, an interferometer, and an array of detectors to generate and analyze interference light patterns, using differential analog circuitry to suppress DC components and enhance AC signal detection, allowing for parallel processing and data compression to improve signal-to-noise ratio and depth penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical interferometry is used for non-invasive brain measurements, then the system can detect optical signals, but light scattering limits spatial resolution and depth penetration
Solution Approach 1:
The patent divides the detection into multiple channels, each detecting specific optical modes. The interferometer output is separated into multiple spatial channels that can be processed independently, allowing selective enhancement of signals from different depths and locations while suppressing scattered light contributions
Solution Approach 2:
The patent introduces spatial dimensionality by using an array of detectors to capture multiple optical modes simultaneously. This multi-dimensional detection approach allows differentiation between ballistic photons (which carry useful information) and scattered photons (which contribute noise), thereby improving spatial resolution despite light scattering
2Productivity
If a single optical detector is used to detect interference light, then the system is simple, but data throughput is limited
Solution Approach 1:
The detection system is segmented into multiple parallel channels, each with its own detector. This allows simultaneous detection of multiple optical modes, dramatically increasing data throughput. Each channel processes specific spatial frequencies or depth ranges, enabling parallel acquisition of information from different tissue depths
Solution Approach 2:
The multi-channel detection system serves multiple functions: it detects signals from different depths, captures multiple spatial frequencies, and provides redundant measurements for noise suppression. This universal detection approach handles various measurement requirements simultaneously, improving productivity without proportionally increasing complexity
3Measurement precision
If full balanced detection is used to suppress DC offset, then DC suppression is achieved, but the system complexity increases significantly
Solution Approach 1:
Instead of implementing full balanced detection across all channels, the patent applies partial balanced detection selectively to channels where DC suppression is most critical. This partial action approach achieves sufficient DC offset suppression for the measurement requirements while avoiding the complexity of complete balanced detection across the entire multi-channel system
Solution Approach 2:
The patent applies different detection strategies to different channels based on their specific requirements. Channels detecting optical modes with strong DC components receive balanced detection, while other channels use simpler detection. This local differentiation optimizes DC suppression where needed without unnecessarily complicating the entire system
4Measurement precision
If reference light intensity is increased to boost optical gain, then signal detection sensitivity improves, but noise from reference light fluctuations increases
Solution Approach 1:
The patent extracts and separates the reference light contribution from the total detected signal using the multi-channel detection approach. By detecting multiple optical modes and analyzing their interference patterns, the system can identify and remove the reference light noise component, retaining only the useful signal information
Solution Approach 2:
The patent uses the interference pattern itself as an intermediary to separate signal from noise. The interference between reference and sample light creates a pattern that encodes both the useful signal and the reference light fluctuations. Through multi-channel analysis, the system decodes this pattern to extract the signal while rejecting the noise
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 enables higher data throughput and signal-to-noise ratio, allowing for more accurate detection of neural activity at deeper depths within the brain, overcoming the limitations of conventional systems by suppressing DC offsets and enhancing AC signal detection.
Implementation Method 1
an optical source configured for generating source light having a range of optical wavelengths during each of at least one measurement period
Implementation Method 2
an interferometer configured for splitting the source light into sample light, which propagates along a sample arm of the interferometer, and reference light, which propagates along a reference arm of the interferometer... and combining, during each of the measurement period(s), the signal light and the reference light into an interference light pattern
Implementation Method 3
delivering the sample light into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample
Implementation Method 4
an array of optical detectors configured for respectively detecting different subsets of the plurality of optical modes of the interference light pattern, and respectively outputting a plurality of high-bandwidth analog signals
Implementation Method 5
differential analog circuitry configured for respectively subtracting pairs of the analog signals from each other, and respectively outputting a plurality of differential analog signals
Data Source
AI summary
Source light having a range of optical wavelengths is generated. The source light is split into sample light and reference light. The sample light is delivered into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample. The signal light and the reference light are combined into an interference light pattern having optical modes, each having a direct current (DC) component and at least one alternating current (AC) component. Different subsets of the optical modes of the interference light pattern are respectively detected, and analog signals representative of the optical modes of the interference light pattern are output. Pair of the analog signals are subtracted from each other, and differential analog signals are output. The sample is analyzed based on the differential analog signals.