Acousto-Optic Beam Shaping for Depth Camera Illumination
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Solution Overview
Problem
Current depth sensing technologies face challenges in efficiently illuminating a wide field of view with structured light, as the intensity envelope of optical beams changes from the near field to the far field, resulting in inadequate coverage of large areas in augmented and virtual reality systems.
Innovation Solution
A depth camera assembly incorporating an acousto-optic structured light generator with a beam shaping element, such as a mask or spatial light modulator, dynamically modifies the intensity envelope of the structured light pattern to ensure efficient illumination of a larger section of the local area, using an acousto-optic device to diffract the optical beam and a projection assembly to project the modified pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the optical beam is projected without beam shaping, then the device complexity is reduced, but the illumination coverage area decreases in the far field
Solution Approach 1:
A beam shaping device is introduced as an intermediary optical element between the illumination source and the target area. This device modifies the intensity envelope of the optical beam to maintain uniform illumination across the field of view, thereby increasing the effective illumination coverage area without significantly complicating the overall system architecture.
Solution Approach 2:
The beam shaping device dynamically adjusts parameters of the optical beam, specifically the intensity envelope distribution, to compensate for the natural spreading and intensity variation that occurs as the beam propagates from near field to far field. This parameter modification ensures consistent illumination coverage across different distances.
2Area of stationary object
If the intensity envelope is modified to illuminate larger area, then the illumination coverage improves, but the manufacturing precision requirements increase
Solution Approach 1:
The beam shaping device is designed with dynamic adjustability, allowing the intensity envelope modification to be tuned and optimized. This dynamic capability enables the system to adapt to different operating conditions and distances, reducing the need for extremely precise fixed manufacturing tolerances while still achieving uniform illumination coverage.
3Adaptability or versatility
If a dynamic beam shaping element is used, then the adaptability to different field of view requirements is improved, but the device complexity increases
Solution Approach 1:
The dynamic beam shaping element is designed to perform multiple functions: it can adjust the intensity envelope for different field of view requirements, compensate for varying distances, and maintain uniform illumination across diverse operating conditions. This multi-functionality reduces the need for multiple separate optical systems, thereby limiting the increase in overall device complexity.
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 solution enables effective and efficient illumination of a larger area, improving the accuracy and coverage of depth sensing in augmented and virtual reality systems by maintaining a consistent and optimized structured light pattern across the field of view.
Implementation Method 1
The acousto-optic device functions as a dynamic diffraction grating that diffracts the optical beam to form a structured light pattern
Implementation Method 2
The acousto-optic device functions as a dynamic diffraction grating
Data Source
AI summary
A depth camera assembly (DCA) includes a structured light generator, an imaging device and a controller. The structured light generator illuminates a local area with a structured light pattern in accordance with emission instructions from the controller. The structured light generator comprises an illumination source, an acousto-optic device, and a projection assembly. The acousto-optic device generates a structured light pattern from an optical beam emitted from the illumination source. The projection assembly modifies a general intensity envelope of the structured light pattern in order for the structured light pattern to illuminate a larger section of the local area, and projects the modified structured light pattern into the local area. The imaging device captures of portions of the structured light pattern scattered or reflected from the local area. The controller determines depth information for the local area based at least in part on the captured images.