Gating Camera Calibration Using Shared Image Sensor Timing
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Solution Overview
Problem
Existing calibration techniques for gating cameras, such as those described in Patent Literatures 1 to 3, are not applicable to vehicle sensors and result in hardware wastage and reduced imaging capability due to dedicated hardware allocation for calibration.
Innovation Solution
A gating camera system that includes a controller to generate emission and exposure control signals, an illumination apparatus for normal imaging, and a calibration light source for calibration, allowing for the calibration of time differences without additional hardware for flight time measurement, enabling all-pixel imaging during normal operations and reducing hardware waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated hardware is allocated for calibration (reflection unit or light guide portion), then calibration can be performed, but hardware is wasted and cannot be used during normal imaging
Solution Approach 1:
The image sensor performs dual functions: it captures reflected light from objects during normal imaging and detects calibration light during calibration. By making the image sensor universal, the patent eliminates the need for dedicated calibration hardware, thereby preventing hardware waste while maintaining both imaging and calibration capabilities
Solution Approach 2:
The patent merges the calibration detection function into the existing image sensor that is already used for normal imaging. The controller coordinates both operations by selectively activating the calibration light source and adjusting the exposure timing, combining what were previously separate hardware functions into a single integrated system
2Reliability
If a reflection unit is built into the optical distance measuring device, then calibration can be performed, but a part of hardware is allocated for calibration and cannot be used during normal imaging
Solution Approach 1:
The image sensor serves multiple purposes: it images reflected light from objects during normal operation and detects calibration light when activated by the controller. This multi-functionality ensures that hardware productivity is maximized as the same sensor contributes to both calibration and normal imaging without being dedicated to either exclusively
Solution Approach 2:
The controller implements periodic calibration by selectively activating the calibration light source at specific times and coordinating the exposure timing accordingly. This periodic action allows the image sensor to alternate between calibration mode and normal imaging mode, ensuring both functions are performed without permanent hardware allocation
3Reliability
If part of light emitted from light source is incident on image sensor through light guide portion, then calibration can be performed, but part of hardware is allocated for calibration and cannot be used during normal imaging
Solution Approach 1:
The image sensor is designed to detect both reflected light from objects during normal imaging and calibration light during calibration operations. This universal detection capability eliminates the need for separate light guide portions dedicated to calibration, preventing hardware waste while maintaining reliable calibration functionality
4Measurement precision
If TOF camera is used to acquire depth information, then depth information can be obtained, but hardware for measuring time of flight is required which increases device complexity
Solution Approach 1:
The gating camera uses the existing image sensor to detect both reflected light for depth measurement and calibration light for timing calibration. By making the image sensor universal, the system achieves depth information capability without requiring separate dedicated hardware for time of flight measurement, thereby reducing device complexity
Solution Approach 2:
The system performs self-calibration using the same image sensor that captures depth information. The controller coordinates the calibration light emission and exposure timing, allowing the system to calibrate itself without external equipment or additional specialized hardware, thereby simplifying the overall device architecture
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
The solution allows for accurate calibration of the gating camera, preventing timing errors and ensuring all pixels can be used for imaging, while minimizing hardware wastage and maintaining imaging performance.
Implementation Method 1
a calibration light source configured to emit calibration light to the image sensor in accordance with the emission control signal during calibration
Implementation Method 2
an image sensor configured to perform exposure in accordance with the first exposure control signal
Implementation Method 3
an illumination apparatus configured to emit probe light in accordance with the emission control signal during the normal imaging
Data Source
AI summary
A gating camera divides a field of view in a depth direction into multiple ranges, and generates multiple slice images that correspond to the multiple ranges. A controller is configured to generate an emission control signal and an exposure control signal. An illumination apparatus emits probe light according to the emission control signal during normal imaging. An image sensor performs exposure according to the exposure control signal. A calibration light source emits calibration light to the image sensor according to the emission control signal during calibration. The controller sweeps a time difference between the emission control signal and the exposure control signal, and monitors a change in a pixel value of the image sensor during the calibration.