Laser Display Coherence Artifact Suppression
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Solution Overview
Problem
Laser-based light sources in compact display systems suffer from coherence-related image artifacts due to optical interference, which hinders their application in miniature near-eye displays, leading to overheating and reduced image quality.
Innovation Solution
Operating laser sources in a short-pulse mode with spectral broadening, using multi-emitter laser chips emitting at different wavelengths, and employing pupil-replicating waveguides with antireflection coatings to reduce optical interference and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If laser sources are used in compact display systems, then energy efficiency and compactness are improved, but coherence-related image artifacts and optical interference worsen
Solution Approach 1:
The patent applies parameter changes by operating the laser source in pulsed mode rather than continuous wave mode. This temporal parameter change broadens the spectral width and reduces coherence length, thereby suppressing optical interference artifacts while maintaining the energy efficiency benefits of laser sources in compact display systems.
Solution Approach 2:
The patent employs periodic pulsed operation of the laser source instead of continuous illumination. By delivering light in short pulses with appropriate duty cycles, the system achieves spectral broadening that reduces coherence artifacts, while the periodic nature allows for thermal management in the compact form factor.
2Object-generated harmful factors
If laser sources are operated in short-pulse mode with spectral broadening, then coherence artifacts are suppressed, but device complexity increases
Solution Approach 1:
The patent utilizes the self-service principle by leveraging the inherent spectral broadening effect that occurs when laser sources are operated in pulsed mode. The system naturally achieves coherence artifact suppression through the physics of pulsed laser operation without requiring additional external components or complex control mechanisms to broaden the spectrum.
3Weight of moving object
If miniature display devices are used in near-eye displays, then weight and size are reduced, but heat dissipation capability worsens
Solution Approach 1:
The patent applies periodic pulsed operation to the laser source, which reduces the average power consumption and heat generation compared to continuous operation. This temporal modulation allows the miniature display device to maintain lower operating temperatures while still delivering sufficient light output for near-eye display applications.
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 approach effectively suppresses coherence artifacts, improves image quality, and reduces overheating in miniature near-eye displays, enabling more efficient and compact laser-based display systems.
Implementation Method 1
Operating laser sources in a short-pulse mode with spectral broadening
Implementation Method 2
coherence-related image artifacts due to optical interference
Implementation Method 3
Laser-based light sources in compact display systems
Implementation Method 4
coherence artifacts due to optical interference, which hinders their application in miniature near-eye displays
Implementation Method 5
employing pupil-replicating waveguides with antireflection coatings to reduce optical interference
Data Source
AI summary
A display device including a laser-based light engine is disclosed. Optical interference effects due to the coherent nature of a laser light source are mitigated by shortening a coherence length of the laser source. The coherence length shortening is achieved by at least one of the following: providing a multiple longitudinal mode laser source, pulsing a laser source to achieve spectral broadening, or providing multi-emitter laser source(s) with emission wavelength varying from emitter to emitter.