Post-scan optics for infinite focus projector distortion
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Solution Overview
Problem
Laser-based scanned beam display systems face challenges in maintaining infinite focus while correcting scanning distortions, as distortion correction optics placed after the scanning platform can affect focus properties and introduce stray light artifacts, and achieving smaller form factors is crucial for projector design.
Innovation Solution
The use of post-scan correction optics and collimating optics in combination, where the curvature of post-scan optics corrects distortions and the focal length of collimating optics controls the expansion rate of the output beam to match the image pixel expansion, maintaining infinite focus and minimizing form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distortion correction optics are placed after the scanning platform, then scanning distortion is corrected, but the infinite focus property is adversely affected and stray light artifacts are introduced
Solution Approach 1:
A beam expander is introduced as an intermediary component between the scanning platform and the distortion correction optics. This beam expander modifies the beam characteristics to enable the distortion correction optics to function without compromising the infinite focus property, effectively mediating between the conflicting requirements of distortion correction and focus maintenance
Solution Approach 2:
The patent replaces traditional mechanical distortion correction methods with a combination of beam expansion and optimized optical correction. Instead of using complex mechanical adjustment systems that would further compromise focus, the solution uses controlled beam expansion followed by simplified distortion correction, substituting mechanical complexity with optical parameter control
2Manufacturing precision
If distortion correction optics are placed after the scanning platform, then scanning distortion is corrected, but stray light artifacts are introduced
Solution Approach 1:
The beam expander performs a preliminary action by expanding and conditioning the laser beam before it reaches the distortion correction optics. This preliminary beam expansion reduces the angle of incident light on subsequent optical elements, thereby minimizing stray light generation at the source rather than attempting to correct it afterward
Solution Approach 2:
The patent converts the potential harmful effect of beam divergence into a beneficial characteristic. By intentionally expanding the beam before distortion correction, the system transforms what would normally be a source of stray light into a controlled parameter that actually improves the effectiveness of distortion correction while minimizing artifacts through optimized beam geometry
3Volume of moving object
If post scanning platform optics are used, then smaller form factor is achieved, but distortion correction and focus maintenance become more challenging
Solution Approach 1:
The beam expander is designed to perform multiple functions simultaneously: it expands the beam for distortion correction, conditions the beam to reduce stray light, and maintains compatibility with the infinite focus property. This multi-functionality allows compact optics to achieve complex objectives without requiring larger, more specialized components for each function
Solution Approach 2:
The system utilizes parameter changes in the beam characteristics (expansion ratio, divergence angle) to achieve distortion correction in a compact form factor. By dynamically controlling beam parameters rather than relying on fixed optical paths, the system achieves high precision distortion correction with smaller optical elements
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 solution ensures that the projected image remains in focus at various distances while correcting distortions and reducing stray light, thereby maintaining the infinite focus property and achieving efficient light collection and high image quality.
Implementation Method 1
the focal length of collimating optics controls the expansion rate of an output beam
Implementation Method 2
the curvature of post-scan optics corrects distortions
Data Source
AI summary
Briefly, in accordance with one or more embodiments, a scanned beam display may utilize one or more post-scan optics while at least partially maintaining an infinite focus, or nearly infinite focus, property of the display. The display may comprise a light source to generate a light beam, a scanning platform to generate a raster scan from the light beam projected as a projected image, one or more post-scan optics to at least partially adjust the projected image, and one or more collimating optics to focus the light beam from the light source, the one or more collimating optics having a selected focal length to at least partially provide infinite, or nearly infinite focus, of the projected image at or beyond a selected distance.