Thin Near-Infrared Blood Flow Optics Using Light Guide Plates
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Solution Overview
Problem
Existing blood flow measurement devices are difficult to thin due to the necessity of positioning light sources and light receiving sections directly above the measurement site, and configurations using optical fibers result in a large optical system that impedes thickness reduction.
Innovation Solution
The device incorporates light guide plates and diffraction elements, including liquid crystal diffraction elements with helically twisted liquid crystal layers, to guide and diffract near-infrared rays, allowing for a thinner design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light source and light receiving section are disposed directly above the measurement site, then measurement accuracy is maintained, but device thickness cannot be reduced
Solution Approach 1:
The patent introduces optical fibers as intermediary elements to transmit light between the light source/receiving section and the measurement site. This allows the light source and detector to be positioned away from the measurement site while maintaining optical coupling, thereby reducing device thickness without compromising measurement accuracy
Solution Approach 2:
The patent transitions from a direct vertical arrangement (light source directly above measurement site) to a configuration using optical fibers that can route light through additional spatial dimensions. This dimensional change allows the optical path to be separated from the direct measurement axis, enabling thinner device design while preserving measurement capability
2Length of stationary object
If optical fibers are used to space the light source and light receiving section from the measurement site, then device thickness can be reduced, but the optical system becomes large
Solution Approach 1:
The patent integrates the optical fibers within the existing device structure, nesting them inside the housing or along the device body. This nesting approach allows the optical transmission path to be incorporated without significantly increasing the overall device envelope, thus reducing thickness while controlling optical system size
Solution Approach 2:
The device structure is designed to serve multiple functions: the housing not only provides mechanical support but also serves as a routing path for the optical fibers. This multi-functionality reduces the need for separate dedicated spaces for optical components, thereby reducing device thickness without proportionally increasing optical system complexity
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 configuration enables a significant reduction in device thickness while maintaining accurate blood flow measurement capabilities.
Implementation Method 1
an irradiation unit light guide plate that guides the near-infrared rays emitted from the light source
Implementation Method 2
an irradiation diffraction element for emitting the near-infrared rays guided in the irradiation unit light guide plate from the irradiation unit light guide plate
Implementation Method 3
a liquid crystal layer having a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating along at least one in-plane direction
Data Source
AI summary
An object of the present invention is to provide a thin blood flow measurement device. The object is accomplished by providing a blood flow measurement device that measures a blood flow by irradiating an object with near-infrared rays and measuring scattered light by the object, in which the blood flow measurement device includes at least one of a first configuration including an irradiation unit light guide plate that guides near-infrared rays emitted from a light source and an irradiation diffraction element that emits the near-infrared rays from the irradiation unit light guide plate, and a second configuration including a light receiving section light guide plate that guides the scattered light and a light receiving diffraction element that causes the scattered light by the object to be incident on the light receiving section light guide plate.