Multiple-Source Laser Display System Using VCSEL Arrays
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Solution Overview
Problem
Conventional laser-based display systems require high power for each color emitter, leading to inefficiencies and limitations in brightness and power consumption, especially in wearable display devices for augmented reality and mixed reality applications.
Innovation Solution
A system utilizing multiple low-power vertical-cavity surface-emitting lasers (VCSELs) for each color, optically coupled with efficient optics and a steering element, to form a substantially white image with a brightness of at least 1000 nits, where the optical combiner redirects light to an eyebox, achieving high brightness and efficient power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional high-power laser emitters are used for each primary color, then sufficient brightness can be achieved, but power consumption increases and system efficiency decreases
Solution Approach 1:
The patent divides the light source system into multiple low-power laser emitters (e.g., three blue VCSELs, three green VCSELs, three red VCSELs) instead of using a single high-power emitter per color. This segmentation allows the system to achieve sufficient total brightness through aggregation while maintaining low individual emitter power levels, thereby reducing overall power consumption and improving efficiency.
2Illumination intensity
If conventional high-power laser emitters are used for each primary color, then sufficient brightness can be achieved, but system complexity increases
Solution Approach 1:
The patent combines multiple low-power laser emitters of the same color into a unified optical system that shares common optical elements (such as combiners, scanners, and projection optics). This merging approach achieves the brightness of high-power systems while reducing complexity by eliminating redundant high-power driver circuits and simplifying thermal management requirements.
3Use of energy by moving object
If multiple low-power VCSELs are used for each color, then power efficiency improves, but achieving sufficient brightness becomes challenging
Solution Approach 1:
The patent transitions from a single-color projection approach to a multi-color sequential projection system using time-division multiplexing. By rapidly switching between red, green, and blue VCSEL arrays and utilizing persistent vision of the human eye, the system achieves full-color images with high brightness perception while maintaining low power consumption at each wavelength.
4Volume of moving object
If multiple low-power VCSELs are used for each color, then a compact design is enabled, but achieving high brightness requires sophisticated optical coupling
Solution Approach 1:
The patent implements a nested optical architecture where multiple VCSEL arrays are vertically stacked with shared optical paths. The blue, green, and red VCSEL arrays are nested within a compact housing, with each color's light path integrated through common combiners and scanning mirrors, achieving high brightness in a miniaturized form factor suitable for wearable devices.
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 solution enables high-brightness, efficient power usage, and improved chromaticity in wearable display systems, addressing the inefficiencies of conventional high-power laser emitters while maintaining a compact and efficient design.
Implementation Method 1
A display system includes at least two blue lasers, two green lasers, and two red lasers
Implementation Method 2
An optical element is optically coupled to the first array and the second array to form a light that impinges on a steering element
Implementation Method 3
The steering element is modulated in time to direct the light in an angular range in which it is optically coupled to the optical combiner
Implementation Method 4
The optical combiner is configured to redirect the light to an eyebox, where the light forms a substantially white image having a brightness of at least 1000 nits
Data Source
AI summary
A display system includes one or more low-power laser diodes, each producing an emission. The emissions are directed to an optical element that affects the direction or divergence of the emissions. The optical element redirects the emissions toward a steering element such as a MEMS-actuated mirror, or a combination of such mirrors. The steering element directs the emissions toward the incoupler of a waveguide acting as an optical combiner. The emissions propagate through the waveguide and are extracted by an outcoupler in the direction of an observer. By scanning the direction of the beam-steering element along one or several directions, an image may be formed.