SLED Depth Camera Illuminator Using Achromatic Diffractive Optical Element
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Solution Overview
Problem
Motion capture systems using lasers pose safety concerns and design complexities, necessitating an alternative light source that can provide high-quality, collimated light for effective tracking in typical environments.
Innovation Solution
A 3-D depth camera system employing superluminescent light-emitting diodes (SLEDs) with a collimating lens and achromatic diffractive optical elements to create a high-contrast diffraction pattern, eliminating the need for lasers and ensuring safety while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser is used as a light source in an illuminator, then high-quality collimated light is achieved, but safety hazards and design complexities increase
Solution Approach 1:
The patent replaces the expensive and hazardous laser with a simpler, safer LED light source. While LEDs traditionally produce less collimated light, the system uses multiple LEDs with individual collimating lenses to achieve the necessary beam quality, effectively substituting a complex dangerous component with simpler safer components that collectively achieve the same function
Solution Approach 2:
Instead of using a single laser source, the patent divides the illumination function across multiple LED sources. Each LED is paired with its own collimating lens, and the multiple collimated beams are combined to create the final illumination pattern. This segmentation allows the system to achieve laser-quality collimation without the safety hazards of a single high-power laser
2Reliability
If a laser is used as a light source, then effective tracking is achieved, but design complexities increase
Solution Approach 1:
The illumination system is segmented into multiple independent LED-lens units. Each unit can be independently optimized and replaced, simplifying the overall design and maintenance. The modular approach reduces design complexity compared to a single laser system while maintaining tracking effectiveness through the combined output of multiple collimated beams
Solution Approach 2:
The patent uses LEDs that can serve multiple functions: they provide the necessary illumination, can be individually collimated, and can be arranged in various configurations to adapt to different tracking scenarios. This multi-functionality reduces design complexity compared to specialized laser systems
3Power
If SLEDs are used to provide high power output, then sufficient illumination is achieved, but maintaining spatial coherence becomes challenging
Solution Approach 1:
The patent uses multiple SLEDs instead of a single high-power source. Each SLED is individually collimated with its own lens, preserving the spatial coherence of each beam. The multiple collimated beams are then combined to achieve high total power output while maintaining the spatial coherence properties that are essential for effective structured light projection
Solution Approach 2:
Individual collimating lenses serve as intermediaries between each SLED and the final combined beam. These lenses maintain the spatial coherence of each SLED's output while allowing the beams to be combined at higher power levels, effectively decoupling the power aggregation function from the coherence maintenance function
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 SLED-based system effectively tracks humans or objects in a room under typical lighting conditions, offering a safer and more cost-effective solution by providing a powerful, high-quality collimated light source without the safety hazards and design complexities associated with lasers.
Implementation Method 1
a superluminescent LED (SLED) can be used because of its high spatial coherence
Implementation Method 2
A collimating lens captures light from the at least one SLED to provide a collimated light source
Implementation Method 3
An diffractive optical element (DOE) receives the collimated light source, and creates multiple diffracted light beams
Data Source
AI summary
A depth camera illuminator with a superluminescent light-emitting diode (SLED) in a motion tracking system. One or more SLEDs have a sufficient power, such as 75-200 milliwatts, to extend in a field of view in an area such as a room in a home. To correct for chromatic aberration which would otherwise exist due to the wider range of wavelengths which are emitted by an SLED compared to a laser, an achromatic diffractive optical element is used to disperse the light over the field of view. The achromatic diffractive optical element can have a stepped multi-level profile with three or more levels, or a continuous profile. Based on a tracked movement of a human target, an input is provided to an application in a motion tracking system, and the application performs a corresponding action such as updating a position of an on-screen avatar.