Curved Waveguide Collimates Light for Slim HUDs
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Solution Overview
Problem
The design of head-up displays (HUDs) faces challenges in compact size and optical train length to provide virtual imagery at the same distance as the real-world scene, limiting cockpit instrumentation in aircraft and other applications.
Innovation Solution
A novel optical waveguide design with a coupler and combiner, featuring a multifaceted waveguide that confines and collimates input beams to produce an image in infinity, minimizing mechanical profile and optimizing imagery projection without the need for large relay lenses or diffractive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional optical train design is used to provide virtual imagery at infinity, then the optical path length is sufficient, but the mechanical profile becomes too large for constrained cockpit spaces
Solution Approach 1:
The waveguide employs curved surfaces including a curved bottom surface and curved top surface to reflect and collimate light beams. The curvature enables compact folding of the optical path within a thin planar structure, achieving both sufficient optical path length and reduced mechanical profile suitable for constrained cockpit environments
Solution Approach 2:
The optical path is folded multiple times within the planar waveguide structure by utilizing reflections from curved surfaces. This transforms a linear optical path into a multi-dimensional folded path, achieving extended optical length within a compact two-dimensional footprint
2Manufacturing precision
If relay lenses are used to collimate the beam, then the beam can be projected to infinity, but the device becomes bulky and complex
Solution Approach 1:
The patent removes traditional relay lenses and diffractive optical elements from the system. Instead, the waveguide's curved surfaces directly perform the collimation function through geometric reflection, eliminating bulky corrective components while maintaining beam collimation quality
Solution Approach 2:
The curved surfaces of the waveguide perform multiple functions simultaneously: they reflect the beam, collimate the beam, and define the optical path. This multi-functionality eliminates the need for separate relay lenses and simplifies the overall optical system
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 compact, low-cost HUDs with a wide field of view and reduced parallax, suitable for constrained spaces, such as aircraft cockpits, by simplifying the optical beam path and eliminating the need for bulky corrective components.
Implementation Method 1
a waveguide, configured to confine an input beam within the structure of the waveguide
Implementation Method 2
A curved bottom surface of the wave guide can be shaped such that the surface will reflect and simultaneously collimate the input beam
Data Source
AI summary
A waveguide can include a first portion configured to confine an input beam within the structure of the waveguide, and a second portion configured to collimate the beam to be projected through a combiner, to produce an image in infinity. A method of constructing an optical system for a head-up-display can include shaping a first waveguide element such that a first portion of the waveguide is configured to confine an input beam within the structure of the waveguide, and a second portion is configured to collimate the input beam. The method can include coupling the waveguide to a combiner.