Lightguide Prism and Scanning Mirror Layout for Compact Near-Eye Displays
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Solution Overview
Problem
Existing lightguide-based displays face challenges in achieving compactness, ergonomic design, and efficiency when injecting a scanning laser beam directly into a lightguide.
Innovation Solution
An optical system comprising a lightguide with a prism and a fast-scanning mirror, where the laser beam is injected via a prism and scanned to generate an angular field of view, with an optical cutoff edge trimming the beam edges, and optionally using mirrors to redirect the beam, ensuring compact and ergonomic implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a laser beam is injected directly into a lightguide for compactness, then the device size is reduced, but achieving ergonomic design and efficiency becomes difficult
Solution Approach 1:
A scanning mirror is introduced as an intermediary component between the laser source and the lightguide. The mirror enables the laser beam to be scanned across the lightguide entrance aperture, allowing compact integration while maintaining ergonomic design through proper beam steering and angular field of view generation.
2Ease of operation
If a scanning mirror is added to enable ergonomic design, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The scanning mirror is optically integrated with the lightguide system, merging the scanning function into the existing optical path. The mirror is positioned and oriented to work seamlessly with the lightguide geometry, reducing the need for additional separate components and simplifying the overall system architecture.
3Adaptability or versatility
If the beam is scanned to generate an angular field of view, then the field of view is expanded, but chromatic dispersion increases
Solution Approach 1:
The optical cutoff edge is designed to trim the beam edges at specific angles corresponding to the extremities of the angular field of view. This geometric parameter adjustment reduces chromatic dispersion by eliminating peripheral beam portions that contribute most to color separation, while preserving the desired angular field of view.
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 system achieves a highly compact and efficient optical system suitable for near-eye displays, minimizing chromatic dispersion and allowing ergonomic design without protruding hardware.
Implementation Method 1
a lightguide formed from transparent material and having a pair of mutually parallel surfaces for supporting propagation of light within the lightguide by internal reflection at the pair of surfaces
Implementation Method 2
a fast-scanning mirror in facing relation to the scanner interface surface, the fast scanning mirror performing a scanning motion about at least one axis, wherein the prism and the fast-scanning mirror are arranged such that a laser beam introduced via the input surface passes through the prism and exits from the scanner interface surface so as to impinge on the fast-scanning mirror to generate a scanned reflected beam that scans an angular field of view
Data Source
AI summary
An optical system includes a prism (36) having a planar input surface (38, 44a, 44b, 54) for injection of a laser beam, the prism integrated with a lightguide (10, 220). A fast-scanning mirror (32) is deployed in facing relation to a scanner interface surface (12) of the prism. A laser beam introduced via the input surface passes through the prism and the scanner interface surface, impinging on the fast-scanning mirror to generate a scanned reflected beam that scans an angular field of view, passing through the prism so as to enter the lightguide. One side of the lightguide entrance aperture has an optical cutoff edge (24a) that trims an edge of the scanned reflected beam for both a first beam direction (102) at a first extremity of the angular field of view and for a second beam direction (104) at a second extremity of the angular field of view.