Compact Space-Time Stereo Depth Sensing via Hybrid Optical Element
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Solution Overview
Problem
Existing three-dimensional depth sensing systems are bulky, power-intensive, and unsuitable for mobile applications, particularly when dealing with dynamic scenes or objects lacking texture, as they require expensive and complex pattern projection systems that are not efficiently reconfigurable.
Innovation Solution
A compact, low-power pattern projection system using a single hybrid optical element (HOE) with a repositionable diffractive optical element (DOE) and an actuator, capable of dynamically generating and projecting multiple patterns for space-time stereo depth sensing, which enhances depth estimation and noise reduction in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pattern projection systems are used for space-time stereo depth sensing, then depth sensing accuracy is improved, but device size and power consumption increase significantly
Solution Approach 1:
The patent combines the pattern projection and diffraction functions into a single integrated optical element, eliminating the need for separate projection optics and reducing device volume while maintaining depth sensing accuracy through the diffractive optical element's ability to generate and project structured light patterns
Solution Approach 2:
The diffractive optical element serves multiple functions simultaneously: it acts as both the pattern generator and the projection lens, enabling a single component to perform what traditionally required multiple separate optical elements, thereby reducing device size and complexity
2Measurement precision
If traditional pattern projection systems are used for space-time stereo depth sensing, then depth sensing accuracy is improved, but power consumption increases
Solution Approach 1:
By merging the projection and diffraction functions into one element, the system reduces the total number of optical components that require actuation and control, thereby lowering the overall power consumption while maintaining the ability to project multiple patterns for accurate depth sensing
Solution Approach 2:
The system changes the operational parameters by using a diffractive optical element that can dynamically alter its diffraction pattern through phase modulation, enabling multiple projection patterns without requiring multiple physical optical elements, thus reducing power consumption
3Measurement precision
If multiple patterns are projected for space-time stereo depth sensing, then depth estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The diffractive optical element is designed to generate multiple distinct diffraction patterns through phase modulation, allowing a single universal component to replace what would traditionally require multiple separate projection patterns or optical elements, thereby reducing system complexity while maintaining depth estimation accuracy
4Adaptability or versatility
If reconfigurable pattern projection is implemented, then adaptability to different scenes is improved, but device complexity increases
Solution Approach 1:
The system achieves reconfigurability by changing the phase parameters of the diffractive optical element, allowing dynamic adaptation to different scene requirements (such as varying depths, textures, or lighting conditions) without adding mechanical complexity or multiple physical components
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
Enables rapid and accurate three-dimensional reconstruction of dynamic scenes with improved signal-to-noise ratio, suitable for mobile devices, and effective in recognizing gestures and objects with minimal texture or in varying distances, while maintaining a small form factor and efficient power consumption.
Implementation Method 1
a diffractive optical element (DOE) that receives and collimates light from the light source and generates a pattern for projection onto the scene
Implementation Method 2
a hybrid optical element (HOE) that includes a diffractive optical element (DOE) disposed to receive and to collimate light from the light source
Data Source
AI summary
A pattern projection system includes a coherent light source, a repositionable DOE disposed to receive coherent light from said coherent light source and disposed to output at least one pattern of projectable light onto a scene to be imaged by an (x,y) two-dimensional optical acquisition system. Coherent light speckle artifacts in the projected pattern are reduced by rapidly controllably repositioning the DOE or the entire pattern projection system. Different projectable patterns are selected from a set of M patterns that are related to each other by a translation and/or rotation operation in two-dimensional cosine space. A resultant (x,y,z) depth map has improved quality and robustness due to projection of the selected patterns. Three-dimensional (x,y,z) depth data obtained from two-dimensional imaged data including despeckling is higher quality data than if projected patterns without despeckling were used.