Astigmatic Optical Element for Depth Mapping
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Solution Overview
Problem
Current optical 3D mapping techniques face challenges in accurately determining the distance of objects based on varying light patterns, as they often rely on complex setups or require relative movement between illumination and image capture assemblies, limiting their efficiency and practicality.
Innovation Solution
The use of an astigmatic optical element with different focal lengths in different meridional planes to project patterns that change shape with distance, allowing for the capture and processing of images to derive a 3D map without the need for complex setups or relative movement, by analyzing the elongation and shape variations of projected spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If structured light patterns are projected onto the object to enable 3D mapping, then depth information can be obtained, but the system complexity increases due to requiring multiple projectors and complex pattern analysis
Solution Approach 1:
The patent extracts and utilizes only the essential depth-encoded information from the projected pattern, rather than requiring complex multi-projector setups. The astigmatic optical element inherently encodes depth in the spot shape, simplifying the system while maintaining measurement precision.
Solution Approach 2:
The patent changes the parameter of the projected light spots from uniform circular shapes to astigmatic elliptical shapes with orientation and aspect ratio variations. These shape parameter changes directly encode depth information, eliminating the need for complex structured light patterns and simplifying the overall system.
2Measurement precision
If relative movement between illumination and image capture assemblies is used to obtain depth information, then 3D mapping can be achieved, but the measurement time increases
Solution Approach 1:
The patent performs preliminary encoding of depth information into the spot shapes using the astigmatic optical element before image capture. This eliminates the need for time-consuming relative movement between assemblies, as all depth information is simultaneously available in the captured image.
Solution Approach 2:
The patent replaces the mechanical relative movement system with an optical field-based solution. Instead of physically moving assemblies to gather depth information over time, the astigmatic optical element directly encodes depth in the light field, enabling instantaneous 3D mapping.
3Device complexity
If simple circular light spots are projected onto the object, then the setup is simple, but depth information cannot be extracted from the spot shapes
Solution Approach 1:
The patent transforms the light spot parameter from simple circular symmetry to astigmatic elliptical symmetry with variable orientation and aspect ratio. These parameter changes enable depth information encoding while maintaining relative optical simplicity through the use of standard astigmatic optical elements.
Solution Approach 2:
The patent applies local quality variation to the light spots by making each spot's shape characteristics (orientation, aspect ratio) dependent on the depth of the corresponding object point. This local shape variation encodes depth information without requiring complex global system changes.
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
Enables accurate and efficient 3D mapping by determining object distances through shape and size analysis of projected patterns, enhancing the precision and simplicity of the 3D mapping process.
Implementation Method 1
an astigmatic optical element having different, respective focal lengths in different meridional planes of the element
Implementation Method 2
capturing an image of the pattern on the object
Data Source
AI summary
A method for mapping includes projecting a pattern onto an object (28) via an astigmatic optical element (38) having different, respective focal lengths in different meridional planes (54, 56) of the element. An image of the pattern on the object is captured and processed so as to derive a three-dimensional (3D) map of the object responsively to the different focal lengths.