Multi-Wavelength Metasurface Projector for Thin Pattern and Flood 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 limited to forming either dot or line patterns, lacking the ability to switch to 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 with lenses, 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 extracts the lens component from the traditional DOE-lens combination, using only the DOE to form light patterns. This removes the thick lens element while retaining the depth measurement capability, directly resolving the contradiction between measurement precision and device thickness.
Solution Approach 2:
The patent employs a thin-film DOE structure that replaces the bulky lens-based optical system. The DOE is deposited as a thin film on a substrate, maintaining optical functionality while dramatically reducing the z-direction thickness of the projector assembly.
2Adaptability or versatility
If a conventional structured light sensor uses a DOE to form dot or line patterns, then depth sensing is enabled, but the device cannot switch to flood illumination mode
Solution Approach 1:
The patent introduces a movable DOE component that can be dynamically repositioned between different locations. By moving the DOE to a first position, dot or line patterns are formed for depth sensing. By moving it to a second position, flood illumination is achieved. This dynamic repositioning enables mode switching without adding complex optical components.
Solution Approach 2:
The single DOE component serves multiple functions: it can form dot patterns, line patterns, and flood illumination by changing its position. This multi-functionality is achieved through the movable DOE mechanism, allowing one component to replace what would traditionally require multiple fixed optical elements.
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 dynamically switch between light patterns and flood illumination, enhancing versatility 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
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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.