Acousto-Optic Structured Light for 3D Depth Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current depth sensing techniques based on Fresnel equations are not satisfactory in terms of accuracy, and they fail to effectively utilize state of polarization (SOP) information for improving local depth and spatial resolution.
Innovation Solution
A depth camera assembly (DCA) that uses an acousto-optic structured light generator to produce polarized structured light patterns, which are projected onto a local area and captured by a polarization-sensitive camera, allowing the controller to determine depth information by calculating surface normals and other properties using Stokes reflectance parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If basic Fresnel equations are used for depth sensing, then the system is simple to implement, but the accuracy of depth sensing is not satisfactory
Solution Approach 1:
The patent transitions from intensity-only measurement to polarization state measurement, adding a new dimension of information. By measuring the Stokes parameters (S0, S1, S2, S3) which describe the polarization state, the system gains additional degrees of freedom for determining surface properties and depth, thereby improving measurement precision without simply adding more intensity measurements.
Solution Approach 2:
The patent changes the measurement parameters from only light intensity to include polarization state parameters (Stokes parameters). This parameter change enables the system to extract surface normal information and depth information more accurately by analyzing how polarization states change upon reflection, rather than relying solely on intensity variations.
2Loss of information
If intensity of light signals is used for measurement, then the measurement process is simple, but information about SOP, surface normals and other properties cannot be obtained
Solution Approach 1:
The patent introduces a polarization measurement system as an intermediary between the light source and the detection process. By using Stokes parameters as intermediate variables that encode polarization information, the system can extract surface normal and material properties without directly measuring these quantities, thereby preserving information while managing measurement complexity.
Solution Approach 2:
The system adds polarization state as an additional measurement dimension beyond intensity. By measuring four Stokes parameters (S0, S1, S2, S3), the system captures complete polarization information, enabling extraction of surface normal vectors and material properties that are inaccessible through intensity measurement alone.
3Measurement precision
If polarization structured light patterns are used, then local depth and spatial resolution are enhanced, but the device complexity increases
Solution Approach 1:
The patent uses periodic modulation of polarization states through structured light patterns. By projecting sequences of polarized light patterns with different orientations and analyzing the periodic variations in reflected polarization states, the system achieves high local depth resolution through temporal sampling rather than requiring complex spatial measurements.
Solution Approach 2:
The system modulates the polarization parameters of the projected light patterns and measures the corresponding changes in reflected light. By varying polarization angles and analyzing the response, the system extracts surface normal information and depth with high precision, using parameter modulation instead of complex hardware configurations.
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
Enhances local depth and spatial resolution by effectively utilizing SOP information, enabling accurate determination of surface normals, index of refraction, and degree of polarization, thereby improving the accuracy of depth sensing.
Implementation Method 1
The acousto-optic device generates a structured light pattern from the optical beam, wherein the acousto-optic device is configured to function as a dynamic diffraction grating that diffracts the optical beam to form the structured light pattern
Implementation Method 2
The acousto-optic device generates a structured light pattern from the optical beam
Implementation Method 3
The projection assembly comprising a polarizing element that generates the one or more polarized structured light patterns using the structured light pattern
Implementation Method 4
The imaging device is configured to capture portions of the one or more polarized structured light patterns scattered or reflected from one or more objects in the local area
Implementation Method 5
The imaging device is configured to capture portions of the one or more polarized structured light patterns scattered or reflected from one or more objects in the local area
Data Source
AI summary
A depth camera assembly (DCA) includes a polarized structured light generator, an imaging device and a controller. The structured light generator illuminates a local area with one or more polarized structured light patterns in accordance with emission instructions from the controller. The structured light generator comprises an illumination source, an acousto-optic device, and a polarizing element. The acousto-optic device generates a structured light pattern from an optical beam emitted from the illumination source. The polarizing element generates the one or more polarized structured light patterns using the structured light pattern. The imaging device captures portions of the one or more polarized structured light patterns scattered or reflected from the local area. The controller determines depth information, degree of polarization and index of refraction map for the local area based at least in part on the captured portions of the one or more scattered or reflected polarized structured light patterns.