OAM Metasurface Sensing for Compact Polarization-Aware 3D Mapping
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Solution Overview
Problem
Conventional Time-of-Flight (ToF) devices are bulky, costly, and high-power consuming, and metalens-based ToF devices face efficiency issues due to polarization limitations, affecting the accuracy of 2D/3D map reconstruction.
Innovation Solution
An optical device utilizing orbital angular momentum (OAM) with metasurfaces to generate and capture OAM light beams, incorporating polarizers and metasurfaces to convert and focus light beams, enabling simultaneous capture of intensity and polarization information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional bulky lenses and structured light illuminators are used in ToF devices, then the device can capture light intensity, but the device becomes bulky, costly, and high-power consuming while losing polarization information
Solution Approach 1:
The patent replaces conventional bulky mechanical optical components (lenses, illuminators) with metasurfaces that manipulate light through subwavelength nanostructures. This substitution enables polarization-sensitive ToF imaging in a compact form factor by using geometric phase modulation instead of traditional optical elements
Solution Approach 2:
The patent employs metasurfaces composed of anisotropic nanostructures that combine multiple optical functions (beam shaping, polarization modulation, OAM generation) in a single integrated component. This composite material approach allows simultaneous capture of intensity and polarization information while maintaining device compactness
2Loss of information
If metalenses are designed to detect multiple polarization orientations, then the device can capture polarization information, but the efficiency is divided by the number of polarization orientations reducing accuracy
Solution Approach 1:
The patent designs the metasurface with anisotropic nanostructures that can generate and detect multiple OAM modes and polarization states simultaneously through a single unified structure. This multi-functional design eliminates the need for separate metalenses for each polarization orientation, maintaining high efficiency while capturing comprehensive polarization information
Solution Approach 2:
The patent changes the structural parameters of the metasurface nanostructures (shape, orientation, size) to achieve geometric phase modulation that is independent of wavelength and polarization orientation. This parameter optimization allows the same metasurface to efficiently handle multiple polarization states without dividing efficiency among them
3Loss of information
If OAM beams with different topological charges are used, then the device can capture data across various time scales and generate unique facial fingerprints, but the device complexity increases
Solution Approach 1:
The patent segments the optical detection process into multiple temporal measurements, where each measurement captures a specific OAM mode reflected from the facial surface. By sequentially measuring different topological charges over time, the system builds a comprehensive fingerprint database without requiring all OAM modes to be detected simultaneously, thus managing complexity
Solution Approach 2:
The patent employs periodic modulation of the illumination source to sequentially excite and measure different OAM modes at different time scales. This periodic action allows the system to capture multi-dimensional facial information across time, generating robust fingerprints while using a relatively simple optical configuration
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
Enhances data capture with greater design freedom, allowing for more accurate 2D/3D mapping and facial recognition by collecting unique facial fingerprints with phase singularities and various time scales.
Implementation Method 1
optical device and module using orbital angular momentum for sensing an object
Implementation Method 2
a first metasurface configured to receive at least one reflected OAM light beam by the object and convert the at least one reflected OAM light beam into at least one Gaussian light beam
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An optical device and an optical module using orbital angular momentum (OAM) for sensing an object are provided. The optical device includes a light source configured to emit at least one light beam to the object; an OAM generator configured to generate at least one OAM light beam according to the at least one light beam emitted by the light source and transmit the at least one OAM light beam to the object; a first metasurface configured to receive the at least one reflected OAM light beam reflected by the object and convert the at least one reflected OAM light beam into at least one Gaussian light beam; a second metasurface configured to focus the at least one Gaussian light beam transmitted by the first metasurface on a sensor; and the sensor configured to receive the at least one Gaussian light beam.