Multi-Function Projector Using Metasurfaces for Thin Dual-Mode Illumination
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Solution Overview
Problem
Conventional structured light and ToF sensors use diffractive optical elements (DOEs) that result in a thick structure and are unable to switch between light patterns and flood illumination.
Innovation Solution
A multi-function projector employing a multi-wavelength laser source and metasurfaces to diffract laser beams into either light patterns or flood illumination, utilizing thinner metasurfaces instead of DOEs, and optionally using two laser sources and metasurfaces to switch between these modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diffractive optical element (DOE) combined with a lens is used to form light patterns, then the structured light sensor can obtain depth data, but the device structure becomes thick
Solution Approach 1:
The patent changes the optical parameter (wavelength) to resolve the contradiction. By using a multi-wavelength laser source and designing the metasurface with wavelength-specific diffraction patterns, the system achieves effective light pattern projection at specific wavelengths while maintaining a thin overall structure. The metasurface is optimized to diffract specific wavelengths to form light patterns, allowing depth measurement without requiring the thick DOE+lens combination of conventional systems.
2Measurement precision
If a conventional structured light sensor uses a fixed light pattern projection method, then depth measurement can be performed, but the system cannot switch to flood illumination mode
Solution Approach 1:
The patent implements multi-functionality by designing a metasurface that can perform multiple illumination functions. The metasurface is configured with specific diffraction patterns that enable it to project structured light patterns for depth measurement while also being capable of flood illumination mode. This universal design allows the same optical component to serve both structured light projection and uniform illumination purposes, eliminating the need for separate components for different illumination modes.
Solution Approach 2:
The patent introduces dynamic switching capability between different illumination modes. By using a multi-wavelength laser source where different wavelengths correspond to different diffraction patterns in the metasurface, the system can dynamically switch between structured light pattern projection and flood illumination by changing the active wavelength. This dynamic control enables adaptability without requiring mechanical moving parts or multiple fixed components.
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 projector achieves a thinner structure and the ability to switch between light patterns and flood illumination, enhancing flexibility and reducing thickness compared to conventional systems.
Implementation Method 1
The metasurface is disposed on a path of the laser beam and configured to diffract the laser beam onto a projected surface
Data Source
AI summary
A multi-function projector includes a multi-wavelength laser source, a metasurface, and a light sensor. The multi-wavelength laser source is configured to emit a laser beam, wherein a wavelength of the laser beam is capable of being switched to a first wavelength or a second wavelength. The metasurface is disposed on a path of the laser beam and configured to diffract the laser beam onto a projected surface. The metasurface is configured to diffract the laser beam with the first wavelength to form a light pattern on the projected surface, and the metasurface is configured to diffract the laser beam with the second wavelength to form flood illumination on the projected surface. The light sensor is disposed beside the metasurface and configured to sense the projected surface.