Multi-Spectral Depth Camera Diffractive Optical Element
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Solution Overview
Problem
Conventional depth sensing devices in augmented and virtual reality systems face interference from background ambient light and limited resolution due to the use of a single wavelength range, which affects the accuracy of three-dimensional information capture.
Innovation Solution
A depth sensing device with a projector that utilizes a broadband light source, a diffractive optical element, and an interference filter to separate and isolate multiple wavelength ranges, creating a patterned array for improved depth sensing, allowing for enhanced resolution and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single wavelength range is used for depth sensing, then the device complexity is reduced, but the measurement precision and resolution deteriorate due to interference from ambient light and limited spectral information
Solution Approach 1:
The patent segments the broadband light into multiple wavelength ranges using a diffractive optical element that spatially separates different wavelengths into distinct regions of the patterned array. This allows the imaging device to capture depth information across multiple spectral bands simultaneously, improving measurement precision while maintaining a relatively simple optical configuration.
Solution Approach 2:
The patent changes the spectral parameter of the projected light from a single wavelength to multiple wavelength ranges. By projecting light across different wavelength ranges (e.g., blue, green, red, and infrared) and capturing their reflections, the system improves depth sensing accuracy through multi-spectral information while using a broadband light source and diffractive optical element rather than multiple separate light sources.
2Measurement precision
If multiple wavelength ranges are projected simultaneously, then the measurement precision and resolution improve, but the device complexity increases due to additional optical components
Solution Approach 1:
The patent merges the functions of multiple light sources emitting at different wavelengths into a single broadband light source. The diffractive optical element then spatially separates the wavelengths, and the imaging device captures them simultaneously. This merging approach improves measurement precision through multi-wavelength data while reducing device complexity by eliminating the need for multiple separate light sources and their associated control systems.
Solution Approach 2:
The broadband light source serves multiple functions: it provides illumination across the visible spectrum and beyond, enabling depth sensing, color information capture, and potential other imaging functions. The diffractive optical element simultaneously separates wavelengths and creates the structured light pattern, making the optical system multi-functional rather than requiring separate components for each function.
3Measurement precision
If a broadband light source is used with wavelength separation, then the measurement precision improves through multi-spectral information, but the loss of information increases due to the need to separate and process multiple wavelength ranges
Solution Approach 1:
The diffractive optical element performs preliminary spatial separation of wavelengths before the light reaches the imaging device. By pre-separating the wavelength ranges into distinct spatial regions in the patterned array, the system preserves spectral information in the spatial domain, allowing the imaging device to capture multi-spectral data simultaneously without losing information during subsequent processing.
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 more accurate and robust three-dimensional information capture by mitigating the limitations of single-wavelength range systems, improving resolution and reducing interference from ambient light, thereby enhancing the performance of depth sensing in augmented and virtual reality applications.
Implementation Method 1
a diffractive optical element that separates light emitted by the light source into a plurality of light regions including a plurality of separate wavelength ranges
Implementation Method 2
an interference filter. The interference filter and the diffractive optical element may be disposed over an emissive side of the light source
Data Source
AI summary
The disclosed depth camera assembly may include a projector device to project light into an imaging environment. The projector device may include a light source and may also include a diffractive optical element that separates light emitted by the light source into a plurality of light regions including a plurality of separate wavelength ranges, such that each of the plurality of light regions contain light from only one of the plurality of separate wavelength ranges. The projector device may also include an interference filter. A head-mounted display system and related methods are also disclosed.