3D Depth Camera with FMCW LiDAR for Fast Precise Depth Mapping
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Solution Overview
Problem
Existing 3D imaging technologies face challenges in achieving high-speed and high-precision depth sensing, particularly in applications requiring real-time data acquisition and processing, such as biomedical imaging, robotics, and autonomous vehicles.
Innovation Solution
A 3D sensing depth camera employing a time-frequency multiplexed frequency-modulated continuous wave (FMCW) LiDAR technique with a swept source, diffractive optical element for beam steering, and compressed sampling approach, utilizing a beam splitter system, scanner, and diffractive optical element for spectrally encoded scanning, combined with a processing system for generating depth maps through windowed spectral estimation and peak localization analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 3D imaging technologies are used, then depth sensing can be achieved, but high-speed and high-precision depth sensing cannot be simultaneously realized
Solution Approach 1:
The patent divides the 3D imaging process into multiple independent components: a swept source for frequency modulation, a beam splitter system separating reference and sample beams, a scanner for spatial scanning, and a detector for interference signal collection. Each component is optimized independently to achieve both high precision depth localization and high frame rates, resolving the contradiction between measurement precision and productivity
Solution Approach 2:
The patent introduces time-frequency multiplexing by sweeping the light source frequency across a range while simultaneously performing spatial scanning. This adds a temporal dimension to the traditional spatial imaging, enabling parallel acquisition of multiple depth profiles at different frequencies, thereby achieving both high precision and high frame rates through dimensional expansion
2Productivity
If real-time data acquisition is required, then high frame rate is achieved, but measurement precision deteriorates
Solution Approach 1:
The patent performs preliminary frequency sweeping of the light source before the actual imaging measurement. By pre-establishing the frequency-modulated waveform and calibration data during the sweep phase, the system prepares all necessary reference information in advance, allowing rapid real-time depth measurement without sacrificing precision for speed
Solution Approach 2:
The patent maintains continuous frequency sweeping and continuous interference signal detection throughout the imaging process. The swept source continuously generates frequency-modulated light while the detector continuously records interference signals, enabling uninterrupted data acquisition that supports both high frame rates and high measurement precision through continuous operation
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 high-speed, high-resolution 3D imaging with submillimeter depth localization accuracy, suitable for applications in autonomous vehicles, virtual reality, and biomedical imaging, achieving frame rates of up to 30 Hz and precise depth mapping.
Implementation Method 1
a light source for emitting light that is swept across frequencies from a first frequency to a last frequency
Implementation Method 2
a beam splitter system that splits the light source into at least a reference beam and a sample beam
Implementation Method 3
a detector that collects an interference signal between light returning from the reference beam and the sample beam, the interference signal forming an interferogram
Implementation Method 4
a diffractive optical element for spectrally encoded scanning along a second axis
Implementation Method 5
for each interferogram, apply a windowed spectral estimator (e.g. a short-time Fourier transform (STFT)) at a particular spectral window size
Implementation Method 6
a scanner for beam scanning in a first axis
Data Source
AI summary
A 3D sensing depth camera involves a time-frequency multiplexed frequency-modulated continuous wave (FMCW) LiDAR technique. A sample arm of such a system for 3D depth sensing includes a scanner for beam scanning in a first axis and a diffractive optical element for spectrally encoded scanning along a second axis. The sample arm can further include beam shaping optics such as a collimator and a lens. Processing of an interferogram comprising depth information at a different position along the second axis for each frequency sweep of the light source involves applying a windowed spectral estimator at a particular spectral window size with zero-padding and according to a specified lateral sampling approach.