Self-Mixing Interferometry Sensor Module for Multilayer Depth Detection
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Solution Overview
Problem
Existing self-mixing interferometry (SMI) sensors struggle with multilayer target detection due to unclear photon travel paths and interference complexities, especially in layered structures like human skin, lacking precise depth information.
Innovation Solution
A self-mixing interferometry sensor module with spatially offset photodetection and an array of light detectors is used to measure photon travel depths and interference patterns, complemented by an electronic processing unit to determine depth profiles and layer contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If self-mixing interferometry is used for multilayer target detection, then interference patterns can be detected, but photon travel depth information remains unclear
Solution Approach 1:
The patent segments the detection function by introducing an array of light detectors with different spatial offsets from the light emitter. Each detector captures interference patterns from photons that have traveled different depths into the multilayer target, effectively dividing the depth detection task across multiple detection channels. This segmentation allows the system to resolve which photons traveled to what depth, overcoming the information loss in conventional SMI.
2Measurement precision
If conventional SMI sensors are used, then the device structure remains simple, but multilayer target detection precision deteriorates
Solution Approach 1:
The patent transitions from a single-point detection (0D/1D) to a spatially distributed detection array (2D/3D). By arranging multiple light detectors at different spatial offsets from the light emitter, the system adds a spatial dimension to the detection process. This dimensional expansion enables depth resolution in multilayer targets while maintaining a relatively compact sensor module structure.
3Measurement precision
If spatially offset photodetection is introduced, then photon travel depth can be resolved, but device complexity increases
Solution Approach 1:
The patent makes the light emitter and detector array serve multiple functions simultaneously. The light emitter not only provides illumination but also acts as a reference for interference measurement. The detector array not only captures interference patterns but also provides spatial information about photon travel paths. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device 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
Enables precise multilayer target detection by resolving photon travel depths and interpreting interference patterns, suitable for health monitoring and medical applications such as vital sign sensing and blood flow analysis.
Implementation Method 1
the light emitter undergoes self-mixing interference, SMI, which is caused by reflections of the emitted electromagnetic radiation from layers of different depths of a multilayer target
Implementation Method 2
the light emitter is configured to emit coherent light
Implementation Method 3
the array of light detectors comprises a number of light detectors... the light detectors of the array generate auxiliary output signals, which are indicative of a distribution of relative reflections
Data Source
AI summary
A self-mixing interferometry sensor module for multilayer target detection includes a light emitter, a detector unit and an array of light detectors. The light emitter is operable to emit coherent electromagnetic radiation out of the sensor module, and undergo self-mixing interference (SMI) caused by reflections of the emitted electromagnetic radiation from layers of different depths of a multilayer target to be placed outside the sensor module. The detector unit is operable to generate an SMI output signal indicative of the SMI of the light emitter. Light detectors of the array are operable to generate auxiliary output signals indicative of a distribution of relative reflections of the emitted electromagnetic radiation from layers of different depths.