Polarized Near-Infrared Blood Flow Sensing for Surface Reflection Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing blood flow measurement devices suffer from low signal-to-noise ratio (SNR) and poor measurement accuracy due to the difficulty in distinguishing between near-infrared rays of the detection target and noise components, primarily caused by the scattering and reflection of near-infrared rays on body surfaces.
Innovation Solution
Incorporation of first and second polarizing elements made of liquid crystal compounds that change the polarization state of near-infrared rays, with configurations such as linear polarizers and λ/4 plates, to selectively filter out noise components and enhance the SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If near-infrared rays are irradiated for blood flow measurement, then blood flow information can be obtained, but the detected rays are weak and noise components from surface reflection reduce measurement accuracy
Solution Approach 1:
The patent changes the polarization state parameter of the near-infrared rays by introducing polarizing elements (linear polarizer and λ/4 plate) in the optical path. This parameter change allows the system to distinguish between scattered light from blood vessels and reflected light from body surfaces, thereby improving measurement accuracy while filtering out noise components.
2Measurement precision
If polarizing elements are added to filter noise, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent merges multiple optical components (linear polarizer and λ/4 plate) into a single integrated polarizing element assembly that can be positioned at one location in the optical path. This combining approach reduces the number of separate components and simplifies the overall device structure while still achieving the desired noise filtering effect.
Solution Approach 2:
The polarizing elements act as intermediary components between the light source and the detection target, and between the target and the detector. These intermediaries modify the polarization state of the light to enable discrimination between signal and noise without requiring complex mechanical or electronic systems.
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 device achieves improved measurement accuracy by effectively distinguishing between target and noise near-infrared rays, enhancing the SNR and reducing noise interference.
Implementation Method 1
a first polarizing element that is disposed on a front surface of the light source unit, includes a layer formed of a liquid crystal compound, and changes a polarization state of the near-infrared rays
Implementation Method 2
a second polarizing element that is disposed on a front surface of the light receiving section, includes a layer formed of a liquid crystal compound, and changes a polarization state of the near-infrared rays
Implementation Method 3
obtains information on a blood flow rate by detecting near-infrared rays that are scattered while being partially absorbed by the blood vessel (blood)
Data Source
AI summary
Provided is a blood flow measurement device having excellent measurement accuracy. The blood flow measurement device includes a light source unit that irradiates an object with near-infrared rays, and a light receiving section that receives scattered light generated by scattering of the near-infrared rays emitted from the light source unit by the object, the blood flow measurement device further including a first polarizing element that is disposed on a front surface of the light source unit, includes a layer formed of a liquid crystal compound, and changes a polarization state of the near-infrared rays, and a second polarizing element that is disposed on a front surface of the light receiving section, includes a layer formed of a liquid crystal compound, and changes a polarization state of the near-infrared rays.