Diffractive Optical Elements for Structured Light Intensity Accuracy
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Solution Overview
Problem
Existing structured lighting systems using diffractive optical elements face challenges in achieving a desired intensity profile due to manufacturing process variations and design approximations, leading to inaccuracies in the generated illumination patterns.
Innovation Solution
A two-dimensional diffractive optical element with different periods in orthogonal directions is used to generate a plurality of one-dimensional light patterns, which are compressed in a specific direction to form an aggregate pattern with a zeroth diffraction order intensity below a target threshold, thereby mitigating the effects of manufacturing errors and design inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diffractive optical elements with periodic optical structures are used to generate structured light patterns, then the desired illumination pattern can be produced, but manufacturing process variations and design approximations cause relatively large differences between the desired intensity profile and the actual intensity profile
Solution Approach 1:
The patent segments the single diffractive optical element into multiple DOEs arranged in an array. Each DOE generates a portion of the structured light pattern, and the collective output of all DOEs forms the complete pattern. This segmentation distributes the manufacturing precision requirements across multiple elements, reducing the impact of variations in any single DOE on the overall intensity profile accuracy.
Solution Approach 2:
The patent merges the output of multiple diffractive optical elements to form a single structured light pattern. By combining the light from multiple DOEs, the system achieves the desired intensity profile through collective interference and superposition, thereby improving tolerance to manufacturing variations in individual elements.
2Ease of manufacture
If arbitrary phase profiles are fabricated using semiconductor fabrication or molding processes, then the desired illumination pattern can be generated, but process variations and defects lead to deviations from the target intensity profile
Solution Approach 1:
The patent divides the fabrication task into multiple identical or similar DOE structures that can be manufactured using the same process. This segmentation allows for standardized fabrication procedures while distributing the impact of process variations across multiple elements, maintaining ease of manufacture through repeated patterns.
Solution Approach 2:
The patent changes the parameter of periodicity by using different pitch values for different DOEs in the array. This parameter variation allows the system to achieve the desired intensity profile through constructive and destructive interference patterns, compensating for manufacturing variations while maintaining compatibility with standard fabrication processes.
3Device complexity
If a single diffractive optical element is used to generate the structured light pattern, then the device complexity is low, but the tolerance to design and manufacturing inaccuracies is insufficient
Solution Approach 1:
The patent segments the optical system into multiple DOEs arranged in a two-dimensional array. This segmentation increases device complexity by introducing multiple elements, but it simultaneously improves reliability by distributing the functional requirements across multiple components, thereby enhancing tolerance to design and manufacturing inaccuracies.
Solution Approach 2:
The patent transitions from a single-element system to a two-dimensional array of DOEs. This dimensional expansion allows the system to achieve superior performance in terms of accuracy and robustness, as the two-dimensional arrangement provides additional degrees of freedom for controlling the structured light pattern and compensating for variations.
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 enhances the tolerance to design and manufacturing inaccuracies, resulting in a structured light pattern with a desired intensity profile, improving the yield and reducing costs of diffractive optical elements while maintaining the accuracy of the illumination pattern.
Implementation Method 1
A two-dimensional (2D) diffractive optical element including structures with different periods in two orthogonal directions. The 2D diffractive optical element is configured to use light to generate a plurality of one dimensional (1D) light patterns
Data Source
AI summary
Disclosed herein are techniques for structured light pattern generation. A method for generating a one-dimensional structured light pattern in a first direction and with a desired intensity pattern includes generating a plurality of one-dimensional light patterns using a two-dimensional diffractive optical element with different periods in two orthogonal directions, and combining the plurality of one-dimensional light patterns to form the one-dimensional structured light pattern with the desired intensity pattern. Each of the one-dimensional light patterns includes a one-dimensional light pattern in the first direction. The plurality of one-dimensional light patterns is distributed in a second direction different from the first direction. A separation angle between each pair of adjacent one-dimensional light patterns of the plurality of one-dimensional light patterns in the second direction and with respect to the two-dimensional diffractive optical element is less than a threshold value.