Optical Sensing Device Parallax Shift Time of Flight
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Solution Overview
Problem
Time-of-flight (ToF) based depth mapping systems face inaccuracies at short ranges due to high intensity of reflected light pulses and parallax shift caused by the transverse offset between transmit and receive axes, leading to distorted measurements.
Innovation Solution
The system employs a light source emitting beams at angles, with single-photon detectors and counters configured to account for parallax shift, setting count periods to cover different time intervals based on distance, allowing for accurate depth mapping by combining ToF measurements for distant objects and triangulation for nearby objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ToF-based depth mapping is used, then measurement is straightforward for distant objects, but measurement precision deteriorates at short ranges due to high intensity reflected light and parallax shift
Solution Approach 1:
The patent applies local quality by making different regions of the detector array perform different functions: detectors in the first region (affected by parallax) perform triangulation-based depth mapping, while detectors in the second region (not affected by parallax) perform traditional ToF depth mapping. This resolves the contradiction by optimizing each region's measurement method according to its specific characteristics, achieving high precision across all ranges.
Solution Approach 2:
The patent segments the detector array into two functional regions based on their response to parallax shift. The first region's detectors are configured for triangulation measurement when parallax is present, while the second region's detectors use traditional ToF measurement. This segmentation allows the system to maintain high measurement precision across both short and distant ranges by applying the appropriate measurement method to each segment.
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 approach enhances short-range accuracy and robustness of depth mapping by effectively utilizing parallax shift to improve detection resources, providing better performance compared to traditional ToF-based systems.
Implementation Method 1
a light source, such as a pulsed laser, directs pulses of optical radiation toward the scene that is to be mapped, and a high-speed detector senses the time of arrival of the radiation reflected from the scene
Implementation Method 2
Light collection optics are configured to form an image of the target scene on the first array along a receive axis, which is offset transversely relative to the transmit axis, thereby giving rise to a parallax shift as a function of distance between the target scene and the device
Data Source
AI summary
An optical sensing device includes a light source, which emits one or more beams of light pulses toward a target scene at respective angles about a transmit axis of the light source. A first array of single-photon detectors output electrical pulses in response to photons that are incident thereon. A second array of counters count the electrical pulses output during respective count periods by respective sets of one or more of the single-photon detectors. Light collection optics form an image of the target scene on the first array along a receive axis, which is offset transversely relative to the transmit axis, thereby giving rise to a parallax shift as a function of distance between the target scene and the device. Control circuitry sets the respective count periods of the counters, responsively to the parallax shift, to cover different, respective time intervals following each of the light pulses.