Gated Time of Flight Camera Depth Range Extension
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Solution Overview
Problem
Conventional gated time-of-flight (GT-TOF) range cameras have limited depth range capabilities, as they can only determine distances within a specific range due to the timing of light pulses and gate configurations, leading to features outside this range being undetectable.
Innovation Solution
The implementation of a gating configuration with multiple pulse trains and gates, including multi-exposure and single-exposure gates, allows for an extended depth range by adjusting the ON times of the gates relative to the transmitted light pulses, enabling the camera to register light from features at both closer and farther distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a conventional single gate configuration is used, then the device structure is simple, but the depth range is limited
Solution Approach 1:
The depth measurement range is segmented into multiple intervals, with each gate (first gate, second gate, third gate) responsible for detecting reflected light from a specific depth interval. The first gate detects light from the first depth interval, the second gate detects light from the second depth interval, and the third gate detects light from the third depth interval, thereby extending the overall measurable depth range through segmentation.
Solution Approach 2:
The patent extends the measurement capability from a single depth range to multiple depth ranges by introducing temporal dimensionality through multiple gates operating at different time intervals. Each gate is activated at a different time after the light pulse emission, allowing the system to measure distances that would otherwise be超出 the conventional single-gate measurement range.
2Adaptability or versatility
If multiple gates with different ON times are used, then the depth range is extended, but the device complexity increases
Solution Approach 1:
The system employs periodic gating action where multiple gates are activated in a sequential periodic manner after each light pulse emission. The first gate, second gate, and third gate are activated at different periodic time intervals, allowing the system to repeatedly measure distances across extended depth ranges while maintaining a manageable operational complexity through rhythmic, predictable gating sequences.
3Quantity of substance
If the gate exposure period is increased, then more light is registered, but the time resolution for distance measurement decreases
Solution Approach 1:
The measurement process is segmented into multiple discrete gate events, where each gate has a defined exposure period optimized for capturing sufficient light from its specific depth interval. By dividing the overall measurement into segmented gate operations rather than using a single long exposure, the system maintains time resolution while accumulating adequate light signals across multiple measurement opportunities.
Solution Approach 2:
The system maintains continuous measurement capability by sequentially activating multiple gates across different time intervals. Rather than using a single continuous long exposure that would degrade time resolution, the system performs continuous useful action through repeated short-gate measurements, accumulating light data over multiple cycles while preserving the time resolution needed for accurate distance 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 configuration effectively increases the maximum depth range by 4/3 compared to conventional GT-TOF cameras, allowing for accurate distance measurement of features within a broader range, from the previously unmeasurable lower bound to the upper bound distance.
Implementation Method 1
an indirect detection of reflected radiation pulses, when measuring a distance by means of the photoeffect
Implementation Method 2
determines distances to features in a scene that it images by illuminating the scene and gating ON for a short exposure period to register amounts of light from the illumination that features in the scene reflect back to the camera
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A gated time of flight (GT-TOF) range camera (20) that transmits a plurality of light pulses (40) to illuminate features in a scene (20) and gates ON a photosensor (22) in the camera for one multi-exposure gate (G40) having a plurality of exposure periods (G40e) following each of the plurality of light pulses to register amounts of light reflected by features (31, 32) in the scene from the light pulses and uses the registered amounts of light to determine distances to the features.