Angularly Separated Laser Beams in Near-Eye Displays
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Solution Overview
Problem
Conventional laser projection systems face challenges in reducing form factor and improving image quality, particularly in near-eye display systems, due to the need for large scan mirrors to accommodate angularly separated laser beams and the occurrence of optical aberrations from dust or reflective surface imperfections.
Innovation Solution
The system employs angularly separated laser light beams that converge at specific pupil planes, allowing for a reduced size of the second scan mirror and placement of the first exit pupil plane at the second scan mirror instead of the incoupler, which minimizes the impact of optical aberrations by positioning the first entrance pupil plane between the first scan mirror and the optical relay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional laser projection systems use large scan mirrors to accommodate angularly separated laser beams, then the system can handle multiple laser inputs, but the form factor increases and device size becomes larger
Solution Approach 1:
The patent positions pupil planes at different locations in the optical path (between scan mirrors, at scan mirrors, or at the incoupler) to spatially separate the handling of angularly separated laser beams. This dimensional arrangement in optical space allows multiple beams to be processed without requiring proportionally larger mirror surfaces, thus reducing the form factor while maintaining adaptability.
Solution Approach 2:
The patent introduces pupil planes as intermediary reference points in the optical path where angularly separated laser beams are positioned at controlled locations. These pupil planes act as mediators that organize the spatial arrangement of multiple laser beams, enabling compact optical design by providing structured positions for beam convergence and separation without requiring oversized components.
2Device complexity
If the first exit pupil plane is positioned at the incoupler, then the optical path is simplified, but optical aberrations from dust or reflective surface imperfections increase
Solution Approach 1:
The patent extracts the exit pupil plane from the incoupler location and repositions it at intermediate locations in the optical path (between scan mirrors or at scan mirrors). This extraction removes the vulnerability of the incoupler surface from direct exposure to angularly separated beams, thereby reducing the impact of dust and surface imperfections on optical quality while maintaining acceptable optical path complexity.
Solution Approach 2:
The patent performs preliminary positioning of the exit pupil plane at optimized locations before the light reaches the incoupler. By pre-establishing the pupil plane position in the optical path, the system proactively minimizes the exposure of critical surfaces to harmful factors like dust, preventing optical aberrations before they occur rather than correcting them afterward.
3Measurement precision
If the first entrance pupil plane is positioned at the first scan mirror, then the optical alignment is simplified, but the impact of reflective surface imperfections on image quality increases
Solution Approach 1:
The patent introduces intermediate pupil plane positions (between scan mirrors or at the second scan mirror) as mediators that decouple the alignment requirements from the scan mirror surface quality requirements. By positioning entrance and exit pupil planes at intermediate locations, the system separates the alignment function from the reflective surface, allowing each to be optimized independently without compromising the other.
Solution Approach 2:
The patent segments the optical path into distinct sections with pupil planes positioned at different locations (first entrance pupil plane, first exit pupil plane, second entrance pupil plane, second exit pupil plane). This segmentation allows independent optimization of each section's alignment and surface quality requirements, reducing the coupled impact of scan mirror imperfections on overall image quality while maintaining alignment precision.
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 reduces the size of the laser projection system, enhances image quality by minimizing optical aberrations, and allows for a wider variety of form factors in display systems, including wearable heads-up displays.
Implementation Method 1
an optical engine of the laser projection system generates two or more angularly separated light beams having an angular separation that causes the angularly separated laser light beams to converge to one or more pupil planes at one or more MEMS mirrors of the laser projection system or at an intermediate location between one of the MEMS mirrors and an optical relay of the laser projection system
Data Source
AI summary
Display systems, such as near eye display systems or wearable heads up displays, may include a laser projection system having an optical engine and an optical scanner. Light output by the optical engine may be directed into the optical scanner as two angularly separated laser light beams. The angularly separated laser light beams may overlap at an entrance pupil plane along a first dimension at a first scan mirror of the optical scanner, or at a location between the first scan mirror and an optical relay of the optical scanner. The angularly separated laser light beams may overlap at an exit pupil plane along the first dimension at a second scan mirror of the optical scanner or at an incoupler of the laser projection system.