Transfer Optic for Waveguide Light Coupling in Wearable Displays
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Solution Overview
Problem
In wearable heads-up displays (WHUDs), the limited space and the double-bounce effect in waveguides lead to light loss, reducing image brightness and user experience due to the need for compact yet efficient light transmission from scan mirrors to incouplers.
Innovation Solution
The use of a transfer optic, such as a prism, to direct light from the scan mirror close to the waveguide, minimizing the incoupler size and reducing light loss by consolidating the cone of propagation, allowing for a smaller incoupler and potentially smaller scan mirrors, which reduces power consumption and increases operating time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between the scan mirror and the waveguide is reduced to minimize device size, then the device becomes more compact, but light loss increases due to the double-bounce effect
Solution Approach 1:
A transfer optic is introduced as an intermediary component between the scan mirror and the waveguide. This transfer optic receives light from the scan mirror and directs it to the waveguide, enabling compact configuration while maintaining efficient light coupling and minimizing the double-bounce effect through optimized optical path design
Solution Approach 2:
The optical parameters (such as numerical aperture, beam convergence angle, and coupling efficiency) are optimized to minimize light loss in the compact configuration. By adjusting these parameters, the system achieves effective light transmission despite the reduced distance between components
2Volume of moving object
If a smaller incoupler is used to reduce device size, then the device becomes more compact, but light transmission efficiency decreases
Solution Approach 1:
The incoupler is designed with optimized optical parameters including numerical aperture and acceptance angle that are specifically tailored for compact configurations. These parameter optimizations enable the smaller incoupler to maintain high light transmission efficiency by maximizing light capture within the reduced aperture
Solution Approach 2:
The system replaces mechanical enlargement of the incoupler with optical design optimizations. Through careful control of beam convergence and angular distribution, the system achieves efficient coupling with a compact incoupler without relying on increased physical dimensions
3Loss of energy
If larger scan mirrors are used to improve light collection, then light transmission improves, but power consumption increases
Solution Approach 1:
The scan mirror is designed with optimized angular parameters and scanning range that maximize light collection efficiency. By optimizing the scanning angles and beam distribution, the system achieves effective light coupling without requiring oversized mirrors, thereby reducing the power needed for mirror actuation
Solution Approach 2:
The system replaces mechanical enlargement of the scan mirror with optimized optical path design and angular control. Through precise control of beam direction and convergence, the system achieves efficient light collection with a compact scan mirror, reducing the mechanical work and power consumption required
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
This configuration minimizes light loss through the double-bounce effect, enhances image brightness, and allows for a more compact and power-efficient WHUD design without compromising the field of view or image quality.
Implementation Method 1
a transfer optic configured to direct light from the optical engine to the first scan mirror and transmit light reflected from the first scan mirror to one of a second scan mirror or the incoupler
Implementation Method 2
The transfer optic is a prism having at least one surface configured to reflect light received from the optical engine and a second surface configured to receive light reflected from the first scan mirror
Implementation Method 3
at least one scan mirror, that scans (or reflects) the laser light emitted from the laser light sources in at least one direction
Implementation Method 4
the waveguide, which transmits the light representing the images to a user's eye
Data Source
AI summary
Systems and methods for incoupling light into a waveguide. A system includes a transfer optic and an optical scanner being configured to receive light from an optical engine. The optical scanner includes a first scan mirror positioned close to the transfer optic. The system further includes a waveguide with an incoupler positioned close to the transfer optic, which is configured to direct the light from the optical engine to the first scan mirror and to transmit light reflected from the first scan mirror to one of a second scan mirror or the incoupler of the waveguide.