3D Imaging System Using Polarizing Grid Array for Time-of-Flight Measurement
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Solution Overview
Problem
Current 3D imaging technologies face limitations in resolution, operating range, cost, size, and performance, particularly in challenging lighting conditions and real-time data extraction, making them unsuitable for various applications.
Innovation Solution
A compact 3D camera system is developed by integrating a modulator and a polarizing grid array in front of a sensor array, eliminating the need for complex circuitry and bulky optics, allowing for absolute position measurement using time-of-flight of light, and enabling a monolithic design with reduced manufacturing and calibration complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stereoscopic cameras with multiple lenses and sensors are used to capture 3D information, then 3D effect is achieved, but the system requires large physical size and complex calibration
Solution Approach 1:
The patent merges multiple functions into a single sensor array by integrating polarizing grids and modulators directly on the sensor surface. This eliminates the need for separate transmit and receive apertures required by traditional structured light systems, reducing physical size while maintaining 3D measurement capability through monolithic integration of optical and sensing functions
Solution Approach 2:
The patent extracts the polarization discrimination function from complex mechanical calibration systems and implements it through polarizing grids integrated on the sensor array. This removes the need for precise mechanical alignment and calibration between multiple lenses and sensors, simplifying the system while preserving 3D measurement accuracy
2Measurement precision
If time-sensitive sensors with circuitry for each pixel are used to measure time of flight, then range measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces complex electronic timing circuitry with optical modulation and polarization discrimination. Instead of timing light arrival at each pixel with complex electronics, the system uses modulated illumination combined with polarizing grids to encode depth information optically, which is then read out through standard sensor operations, dramatically reducing circuitry complexity while maintaining measurement precision
Solution Approach 2:
The patent introduces polarizing grids as an intermediary between the modulated light and the sensor array. These grids encode the modulation phase information into polarization states that can be detected by standard sensor pixels, eliminating the need for specialized timing circuitry at each pixel while preserving time-of-flight measurement capability
3Manufacturing precision
If structured light projectors with multiple patterns are used to improve lateral resolution, then range information accuracy is improved, but the system requires distinct transmit and receive apertures that must be precisely aligned
Solution Approach 1:
The patent combines the transmitter and receiver apertures into a single integrated sensor array system. The modulated illumination and polarization encoding are implemented in such a way that the same sensor array both receives the structured light patterns and measures the time of flight, eliminating the need for separate transmit and receive apertures and their complex alignment requirements
Solution Approach 2:
The sensor array is designed to perform multiple functions: it detects the structured light patterns for lateral resolution measurement and simultaneously measures the time of flight for depth information. The polarizing grids and modulators integrated on the sensor enable this multi-functionality without requiring additional aligned components
4Measurement precision
If polarizing grids with 4 different orientations are used to measure polarization states, then surface normal estimation is improved, but the system requires complex Stokes vector measurement and processing
Solution Approach 1:
The patent extracts only the essential polarization information needed for surface normal estimation rather than measuring the complete Stokes vector. By using modulated illumination with specific polarization orientations, the system obtains sufficient data for depth and surface normal calculation without the complex processing required for full Stokes vector measurement
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
This solution provides a more compact, cost-effective, and high-resolution 3D imaging system capable of real-time data extraction in various lighting conditions, suitable for a broader range of applications with improved accuracy and reduced optical aberrations.
Implementation Method 1
measure the time of flight for light to transit to the scene objects and return to the 3D camera sensors
Implementation Method 2
a light pulse is emitted toward a scene and a returned portion of the light pulse is received
Implementation Method 3
A compact 3D camera system is developed by integrating a modulator and a polarizing grid array in front of a sensor array
Data Source
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Figure 2A~2B
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AI summary
A 3D imaging system includes an optical modulator for modulating a returned portion of a light pulse as a function of time. The returned light pulse portion is reflected or scattered from a scene for which a 3D image or video is desired. The 3D imaging system also includes an element array receiving the modulated light pulse portion and a sensor array of pixels, corresponding to the element array. The pixel array is positioned to receive light output from the element array. The element array may include an array of polarizing elements, each corresponding to one or more pixels. The polarization states of the polarizing elements can be configured so that time-of-flight information of the returned light pulse can be measured from signals produced by the pixel array, in response to the returned modulated portion of the light pulse.