Passive Single-Viewpoint 3D Imaging with Phase Mask
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Solution Overview
Problem
Current 3D imaging technologies for applications like autonomous driving and robotics are power and cost-intensive, with active illumination methods being inefficient for mobile platforms, and multi-camera systems being complex and costly for passive 3D imaging.
Innovation Solution
A passive single-viewpoint 3D imaging system using a camera with an optimized phase mask and a differentiable forward model combined with a reconstruction network for depth estimation, where the phase mask is optimized through end-to-end training and fabricated using photolithography for improved depth map recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-camera systems are used for passive 3D imaging, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The aperture is segmented into multiple sub-apertures with different phase masks, allowing each sub-aperture to capture depth information at different scales. This segmentation enables a single camera to achieve multi-viewpoint depth estimation capability without requiring multiple physical cameras, thus reducing system complexity while maintaining measurement precision.
Solution Approach 2:
The patent introduces a phase dimension by placing phase masks in the aperture plane, transforming the traditional 2D aperture into a 3D phase-modulated aperture. This dimensional transformation encodes depth information in the phase variations, allowing a single camera to extract multi-viewpoint depth estimates from the captured images without needing multiple camera views.
2Measurement precision
If active illumination techniques are used for 3D imaging, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system uses the ambient light in the scene to illuminate the object, allowing the object to reflect and modulate the ambient light through the phase masks. This self-illumination approach eliminates the need for active illumination sources, enabling passive 3D imaging that consumes significantly less energy while maintaining depth estimation accuracy.
Solution Approach 2:
The patent changes the parameter of light modulation by introducing phase masks that modulate the amplitude and phase of transmitted light. This parameter change allows depth information to be encoded in the modulated light patterns captured by the camera, enabling accurate depth estimation using passive ambient light without requiring active illumination.
3Device complexity
If amplitude masks are used for depth estimation, then device complexity is reduced, but light throughput decreases
Solution Approach 1:
The patent changes the mask type from amplitude masks to phase masks, which modulate the phase rather than the amplitude of light. This parameter change allows light to pass through the mask without being blocked, maintaining high light throughput while still encoding depth information through phase variations. Phase masks are transparent and do not absorb light, unlike amplitude masks that block light.
Solution Approach 2:
The patent uses phase masks that combine phase modulation capability with high light transmission properties. These masks are designed to modulate the phase of light while maintaining transparency, effectively combining the benefits of both amplitude modulation for depth encoding and phase modulation for light throughput preservation.
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
The system achieves robust and efficient depth estimation with lower energy consumption and cost, handling challenging scenes and providing better depth variability and light throughput compared to amplitude masks, while maintaining accurate reconstruction of depth maps.
Implementation Method 1
an optimized phase mask placed in an aperture plane of the camera
Implementation Method 2
fabricating an optimal phase mask using photolithography method
Data Source
AI summary
A method for a passive single-viewpoint 3D imaging system comprises capturing an image from a camera having one or more phase masks. The method further includes using a reconstruction algorithm, for estimation of a 3D or depth image.