Tileable Non-Planar Structured Light Patterns for Wide FOV Depth Sensing
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Solution Overview
Problem
Existing structured light (SL) patterns struggle to achieve a wide field-of-view (FOV) depth sensing due to issues with laser safety compliance and algorithm performance when using a single diffractive optical element (DOE), leading to large zero-order values compared to other diffraction orders.
Innovation Solution
The use of augmented diffractive optical elements (ADOEs) that project SL patterns with tileable boundaries, allowing for a wider FOV by preventing the projection of light outside the desired boundaries, and enabling a non-planar surface arrangement to minimize gaps and overlaps between patterns, thereby improving uniformity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single wide FOV diffractive optical element (DOE) is used to project SL pattern, then the field of view coverage is improved, but the zero-order values become large compared to other diffraction orders leading to laser safety compliance issues and algorithm performance degradation
Solution Approach 1:
The patent divides the wide FOV into multiple smaller FOVs by using multiple DOEs. Each DOE projects an SL pattern within a specific tileable boundary, avoiding the zero-order problem associated with single wide-FOV DOEs. The multiple patterns are then combined to achieve comprehensive wide-FOV coverage while maintaining laser safety and algorithm performance.
Solution Approach 2:
The patent introduces the concept of tileable boundaries that can be arranged in non-planar three-dimensional configurations. By stacking multiple SL patterns in 3D space with proper angular offsets, the system achieves wide FOV coverage without requiring a single large-aperture DOE, thereby avoiding zero-order issues while maintaining pattern uniformity.
2Area of stationary object
If multiple SL patterns are projected to achieve wider FOV, then the field of view coverage is improved, but gaps or overlaps between different SL patterns may occur reducing uniformity
Solution Approach 1:
The patent designs each SL pattern with specific tileable boundary characteristics that ensure complementary coverage with adjacent patterns. By optimizing the local properties of each pattern's boundary and using precise angular offsets between patterns, the system eliminates gaps and overlaps, achieving uniform combined coverage across the wide FOV.
Solution Approach 2:
The patent uses non-planar three-dimensional arrangements of multiple SL patterns, where patterns are stacked at different angular orientations. This 3D configuration allows patterns to tile together without gaps or overlaps by utilizing angular offsets, achieving uniform wide-FOV coverage that cannot be accomplished with simple planar arrangements.
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 allows for efficient wide FOV illumination, enhancing depth sensing accuracy and safety by ensuring that SL patterns are confined within tileable boundaries, reducing distortions and improving the coverage of objects in the local area.
Implementation Method 1
The projector assembly projects the first and second SL patterns by emitting light that is diffracted by first and second respective augmented diffractive optical elements (ADOEs). An ADOE is a diffractive optical element that is designed to diffract light into a SL pattern projection that has a field of view (FOV) corresponding to a respective tileable boundary
Data Source
AI summary
A head-mounted display (HMD) system includes a projector assembly configured to emit a structured light (SL) pattern onto one or more objects in a local area, the projected SL pattern comprises at least a first SL pattern having a first field of view (FOV) corresponding to a first tileable boundary, and a second SL pattern having a second FOV corresponding to a second tileable boundary. The first and second SL patterns are projected such that the first and second tileable boundaries share at least one edge and collectively define a non-planar surface. A detector assembly is configured to capture one or more images of the one or more objects in the local area illuminated by the tiled SL pattern, such that a location of the HMD may be determined using the one or more captured images.