Curved Reflector Beam Scanner for Near-Eye Displays
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Solution Overview
Problem
Existing near-eye display technologies face challenges in achieving a wide field of view (FOV) due to oblique angles of incidence on tiltable reflectors, leading to FOV reduction and distortion, which results in a cumbersome and uncomfortable user experience.
Innovation Solution
A scanning projector configuration that includes a tiltable reflector with a small opening and a curved reflector to allow near-normal incidence of the light beam, combined with a photonic integrated circuit (PIC) to focus and collimate the light beam, which is then propagated through a pupil-replicating lightguide to minimize beam walk-off and maintain a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a tiltable reflector is used in conventional near-eye displays, then the display can be compact, but the field of view is reduced and distorted due to oblique angles of incidence
Solution Approach 1:
The patent employs a curved reflector surface instead of a flat tiltable reflector. The curvature is specifically designed to compensate for the oblique angle of incidence effects, maintaining a wide field of view while keeping the optical path compact. The curved surface redirects light rays to correct for distortion and preserve the angular distribution of incoming light from the PIC across the entire field of view.
2Adaptability or versatility
If the tiltable reflector is positioned to achieve wide FOV, then FOV improves, but the device becomes larger and more cumbersome
Solution Approach 1:
The curved reflector surface enables the system to achieve a wide field of view within a compact form factor. By strategically designing the curvature radius and profile of the reflector, the patent accomplishes FOV expansion without proportionally increasing the overall device volume, thus resolving the trade-off between FOV and device size.
3Device complexity
If conventional light routing is used, then the optical path is simple, but beam walk-off occurs and image quality degrades
Solution Approach 1:
The patent introduces a curved reflector as an intermediary optical element between the PIC and the display optics. This curved reflector serves as a mediating component that redirects and recollimates light rays, correcting beam walk-off and maintaining image quality without requiring complex additional optical assemblies.
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 enables a wider FOV with reduced optical losses and a more compact, lightweight display, enhancing user comfort by maintaining image quality and reducing the size and weight of the display device.
Implementation Method 1
A scanning projector configuration that includes a tiltable reflector with a small opening and a curved reflector to allow near-normal incidence of the light beam, combined with a photonic integrated circuit (PIC) to focus and collimate the light beam
Implementation Method 2
The first reflector is tiltable upon application of a control signal and has an opening therein for receiving the first light beam out-coupled from the first waveguide. The second reflector is configured to at least partially reflect the first light beam back towards the first reflector
Implementation Method 3
A scanning projector configuration that includes a tiltable reflector with a small opening and a curved reflector to allow near-normal incidence of the light beam
Implementation Method 4
which is then propagated through a pupil-replicating lightguide to minimize beam walk-off and maintain a compact design
Data Source
AI summary
A beam scanner and a display device is based on a photonic integrated circuit coupling light to a pair of opposed reflectors. One reflector is tiltable and has an opening through which the light is coupled, and the other reflector is configured to focus light, e.g. a concave reflector. A polarization folding configuration is used to cause the focused light propagate through the opening in the first reflector, get collimated by the second reflector, get scanned by the first reflector, and propagate through the second reflector to a pupil-replicating lightguide which provides multiple laterally offset parallel portions of the scanned beam.