Depth Sensor Calibration via Window Stray Radiation
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Solution Overview
Problem
Existing depth mapping systems face challenges in accurately recalibrating the locations of laser spots on single-photon detector arrays due to temperature changes and mechanical shocks, which can lead to inefficient operation and the need for time-consuming recalibration processes.
Innovation Solution
The system employs a dual calibration approach using stray radiation reflected from a transparent window to detect changes in the alignment of the depth sensing device, allowing for immediate correction of the calibration of laser spots and updating the coordinate transformation to maintain accurate depth mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional recalibration methods are used after temperature changes or mechanical shocks, then alignment accuracy can be restored, but the process is time-consuming and causes operational downtime
Solution Approach 1:
The patent performs recalibration actions in advance by continuously monitoring the positions of laser spots on the detector array and detecting deviations caused by temperature changes or mechanical shocks. The system maintains readiness to correct alignment issues before they significantly impact operational efficiency, thus reducing actual downtime while preserving measurement precision.
Solution Approach 2:
The system implements a feedback mechanism where the positions of laser spots are continuously monitored and compared against reference positions. When deviations are detected, the system automatically triggers recalibration procedures, ensuring alignment accuracy is restored without requiring manual intervention or causing operational downtime. This closed-loop feedback system resolves the contradiction by making recalibration responsive rather than periodic.
2Area of stationary object
If all sensing elements are activated for depth mapping, then complete scene coverage is achieved, but the signal-to-background ratio decreases due to stray radiation affecting multiple pixels
Solution Approach 1:
The patent applies local quality by selectively activating only those sensing elements that are actually illuminated by laser spots, rather than activating the entire detector array. By determining which specific pixels receive light and activating only those elements, the system maintains complete scene coverage while significantly improving the signal-to-background ratio by excluding pixels affected by stray radiation from inactive regions.
Solution Approach 2:
The system performs partial action by activating only the necessary subset of sensing elements required for current depth mapping needs, rather than using the full array. This selective activation approach achieves sufficient scene coverage with fewer elements, thereby reducing background noise from stray radiation and improving measurement precision without sacrificing essential scene coverage.
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 method enables rapid and accurate recalibration of the depth sensing apparatus, reducing downtime and improving the signal-to-background ratio by actively managing the activation of sensing elements and adjusting the super-pixel configuration based on detected changes, thus enhancing the overall efficiency of depth mapping operations.
Implementation Method 1
a second calibration indicating second locations on which stray radiation is incident on the second array due to reflection of the beams from the window
Data Source
AI summary
Depth sensing apparatus includes a radiation source, which emits a first array of beams of light pulses through a window toward a target scene. Objective optics image the target scene onto a second array of sensing elements, which output signals indicative of respective times of incidence of photons. A first calibration, which associates the beams in the first array with respective first locations on the second array onto which the beams reflected from the target scene are imaged, is used in processing the signals in order to measure respective times of flight of the light pulses. A second calibration indicates second locations on which stray radiation is incident on the second array due to reflection of the beams from the window. Upon detecting a change in the second locations relative to the second calibration, the first calibration is corrected so as to compensate for the detected change.