Non-Periodic Volumetric Diffractive Elements for Single-Camera Pose
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Solution Overview
Problem
Existing pose determination methods face challenges in achieving high accuracy and large dynamic range, particularly in determining absolute translational and rotational positions of objects, often requiring multiple cameras or additional measurement techniques, and are limited by interplay between accuracy and spatial or solid angle range.
Innovation Solution
A pose determination system using a diffractive element with a nonperiodic volumetric diffraction structure and coherent radiation, combined with a detector and evaluation device, allows for accurate determination of absolute pose in all degrees of freedom over a large dynamic range by analyzing unique two-dimensional diffraction patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple cameras or interferometric techniques are used to improve measurement accuracy, then the achievable accuracy increases, but the device complexity and cost increase
Solution Approach 1:
The patent segments the diffraction structure into multiple volumetric layers with specific scattering center distributions. Each layer contributes to different aspects of the diffraction pattern, enabling a single camera to capture information that would traditionally require multiple cameras or interferometric equipment. The segmentation of the diffraction structure allows for encoding of multiple pose parameters simultaneously in one measurement.
Solution Approach 2:
The patent changes the physical parameters of the diffraction structure by using volumetric scattering centers with specific spatial distributions and known characteristics. By controlling the position, density, and arrangement of these scattering centers in three-dimensional space, the system encodes pose information in the diffraction pattern, allowing a single camera to determine all six pose parameters (three translational, three rotational) with high accuracy.
2Measurement precision
If coherent illumination is used to achieve interferometric accuracy in depth direction, then the measurement precision improves, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent introduces a diffractive element with volumetric scattering centers as an intermediary between the coherent light source and the camera detector. This intermediary structure transforms the coherent illumination into a diffraction pattern that encodes pose information in a way that is directly measurable by a standard camera. The scattering centers act as a mediator that converts phase information into intensity variations that can be captured and processed digitally.
Solution Approach 2:
The patent replaces complex interferometric measurement systems with a simpler optical diffraction-based system. Instead of using interferometers that require precise mechanical alignment and phase stabilization, the system uses a diffractive element with known scattering center distributions to encode pose information that can be directly captured by a camera and processed through computational algorithms.
3Ease of operation
If single-camera systems are used to reduce device complexity, then the ease of operation improves, but the measurement precision and absolute pose determination capability deteriorate
Solution Approach 1:
The patent transitions from two-dimensional surface diffraction to three-dimensional volumetric diffraction by distributing scattering centers throughout a volumetric region. This dimensional change allows the single camera to capture sufficient information to determine all six pose parameters, including absolute position and orientation, by analyzing the three-dimensional diffraction pattern generated by the volumetric scattering center distribution.
Solution Approach 2:
The patent performs preliminary encoding of pose information during the manufacturing process by precisely positioning and characterizing the scattering centers in the diffractive element. This preliminary action stores the reference information needed for absolute pose determination within the element itself, allowing the system to achieve high measurement precision with a single camera without requiring complex calibration procedures.
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 high accuracy and large dynamic range in pose determination, enabling precise measurement of translational and rotational positions without the need for reference measurements, using materials like glass or quartz with low thermal expansion for stability.
Implementation Method 1
at least one detector (12) configured for detecting at least one two-dimensional diffraction pattern caused by diffraction of coherent radiation (14) at the diffractive element (30) in a far field
Data Source
AI summary
Methods and systems are for determining a pose. The methods and systems capture at least one two-dimensional diffraction pattern caused by diffracting coherent radiation at a diffractive element in the far field. The diffractive element has a non-periodic volumetric diffraction structure. A pose of the diffractive element is determined based on the at least one two-dimensional diffraction pattern and data dependent on the non-periodic volumetric diffraction structure.