Interferometric Structured Illumination Depth Camera
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Solution Overview
Problem
Conventional depth cameras for artificial reality systems face challenges in achieving high performance, speed, and accuracy while maintaining a compact form factor and low power consumption, particularly in eye tracking applications, due to limited light sources leading to inaccurate models and high power consumption.
Innovation Solution
A depth camera assembly that incorporates a light source and a mask to generate interference patterns across a target area, using multiple light sources with phase-offset patterns to improve spatial resolution and accuracy, with a controller determining depth information from captured images, and employing VCSELs for high-speed illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small number of light sources are used in conventional eye tracking systems, then the device complexity and power consumption are reduced, but the measurement precision and accuracy of the eye model deteriorate
Solution Approach 1:
The patent divides a single light source into multiple virtual light sources by using a mask with multiple openings (e.g., two pinholes or two slits). This segmentation allows the system to generate multiple interference patterns from one physical light source, improving eye model accuracy without increasing the actual number of light sources in the device.
Solution Approach 2:
The mask acts as an intermediary element between the light source and the target area. It creates interference patterns by allowing light to pass through multiple openings, effectively generating multiple phase-offset patterns that improve measurement precision without requiring multiple physical light sources.
2Measurement precision
If multiple light sources are added to improve eye tracking accuracy, then the measurement precision improves, but the power consumption increases significantly
Solution Approach 1:
Instead of using multiple physical light sources that would each consume power, the patent segments one light source using a mask to create multiple virtual sources. This approach maintains measurement precision while avoiding the cumulative power consumption of multiple independent light sources.
Solution Approach 2:
A single light source performs multiple functions by generating multiple interference patterns through the mask. The same light source creates phase-offset patterns at different positions, effectively replacing what would otherwise require multiple separate light sources and their associated power consumption.
3Volume of moving object
If a compact form factor is pursued, then the device size is reduced, but the ability to accommodate multiple light sources for high accuracy is limited
Solution Approach 1:
The mask segments the light path into multiple beams that create interference patterns. This allows the system to achieve high measurement precision with a single compact light source, maintaining a small device volume while improving depth tracking accuracy through the interference pattern analysis.
Solution Approach 2:
The patent uses interference patterns in the optical domain to encode depth information. By analyzing the phase and position of interference fringes rather than relying on multiple spatially separated light sources, the system achieves high precision depth tracking within a compact form factor.
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 provides accurate and efficient depth tracking with a dense illumination pattern, reducing power consumption and achieving greater spatial resolution, enabling effective eye and facial tracking in compact form factors.
Implementation Method 1
the light emitted from the at least one light source and projected from the two openings creates an interference pattern on the target area. The interference pattern for a given light source has a phase that is based on the position of the light source.
Data Source
AI summary
A depth camera assembly (DCA) has a light source assembly, a mask, a camera assembly, and a controller. The light source assembly includes at least one light source. The mask is configured to generate an interference pattern that is projected into a target area. The mask has two openings configured to pass through light emitted by the at least one light source, and the light passed through the two openings forms an interference pattern across the target area. The interference pattern has a phase based on a position of the light source. The camera assembly is configured to capture images of a portion of the target area that includes the interference pattern. The controller is configured to determine depth information for the portion of the target area based on the captured images.