Double-Pass Photonic Laser Scanning for Compact AR and LiDAR
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Solution Overview
Problem
Existing laser-scanning light engines and LiDAR systems for augmented reality glasses face challenges in miniaturization, complexity, and performance limitations due to MEMS mirrors, leading to trade-offs between field of view, spatial resolution, and frame rate, with complex packaging and alignment issues.
Innovation Solution
Employing photonic integrated circuits with visible-light and NIR capabilities, combined with scanning mirrors and lenses in a double-pass configuration, to create compact, multi-beam laser-scanning systems for augmented reality displays and LiDAR functionalities, utilizing edge couplers and waveguides to emit and detect light efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MEMS mirrors are used for laser scanning, then field of view and spatial resolution can be achieved, but device complexity and packaging difficulty increase
Solution Approach 1:
The patent combines multiple functional components (laser sources, modulators, beam combiners, and scanning mirrors) into an integrated photonic chip. This merging eliminates the need for complex free-space optical packaging and alignment, while maintaining high spatial resolution through on-chip waveguide structures and edge couplers.
Solution Approach 2:
The patent implements a nested structure where multiple laser beams and optical paths are integrated within a single chip substrate. The waveguides and edge couplers are nested within the chip architecture, allowing compact integration of complex optical functions without increasing external packaging complexity.
2Productivity
If higher mirror frequencies are used, then frame rate improves, but beam diameter must be reduced compromising resolution
Solution Approach 1:
The patent replaces the mechanical scanning mirror system with a photonic integrated circuit that uses optical switching and beam steering within waveguides. This substitution eliminates the mechanical frequency-resolution trade-off by achieving fast scanning through optical means rather than mechanical motion, maintaining both high frame rates and beam quality.
3Ease of operation
If multiple free-space optical components are used, then laser scanning functionality is achieved, but system size and alignment complexity increase
Solution Approach 1:
The patent merges multiple free-space optical components (lasers, modulators, beam combiners, scanners) into a single photonic chip with integrated waveguides. This consolidation maintains full laser scanning functionality while eliminating alignment complexity, as all components are pre-aligned during chip fabrication.
4Manufacturing precision
If beam diameter is increased for high resolution, then spatial resolution improves, but mirror frequency must be reduced limiting frame rate
Solution Approach 1:
The patent replaces the mechanical mirror system with an integrated photonic scanning system that uses optical switching and waveguide-based beam steering. This allows maintaining large effective beam diameters for high resolution while achieving fast scanning rates through electronic control of optical paths, breaking the traditional frequency-resolution trade-off.
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 high-resolution and wide-field-of-view displays with reduced mechanical and electronic complexity, allowing for scalable manufacturing and improved performance by alleviating trade-offs in mirror frequencies and laser modulation rates.
Implementation Method 1
guided by total internal reflection (TIR) at the interfaces of the waveguide combiner 108
Implementation Method 2
edge couplers, integrated into the curved bridge, to couple the light into free space
Implementation Method 3
waveguides, connecting the lasers to the edge couplers, to guide the light from the lasers to the edge couplers
Data Source
AI summary
A set of laser-scanning systems for augmented reality glasses displays and LiDAR (light detection and ranging) uses photonic integrated circuits to generate multiple modulated laser beams, one or more lenses to collimate and/or focus light from the photonic integrated circuits, scanning mirrors (e.g., microelectromechanical systems (MEMS) mirrors) to scan the laser beams along two axes, and a double-pass configuration to reduce the overall size of the system and enable an inline geometry. The photonic chip has emitters distributed along a thin and narrow bridge, which may be curved. This bridge is inserted into the path of optical system, enabling the double-pass configuration with small amounts of scattering or diffraction of light that passes through/by the bridge on the second pass.