Lidar Sensor iFOV Adjustment for Parallax and Noise Reduction
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Solution Overview
Problem
Conventional lidar systems face challenges in maintaining signal quality due to parallax effects and ambient noise, particularly when using micropixels, which require complex design and noise management in both digital and analog receiver technologies.
Innovation Solution
The proposed lidar sensor dynamically adjusts the instantaneous field of view (iFOV) based on time of flight, bundling micropixels to optimize signal collection and account for parallax, distortion, and defocusing by precalculating or calibrating the optimal iFOV, which can be implemented in both digital and analog receiver systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate transmission and receiving optics are used in lidar systems, then the system can measure time of flight to determine distance, but parallax effects cause the projection of reflected light to move on the focal plane depending on distance
Solution Approach 1:
The patent combines transmission and receiving optics into a single integrated optical path, eliminating the offset between transmission and receiving optical axes. This merging of separate optical systems resolves the parallax effect while maintaining the ability to measure time of flight for distance determination.
Solution Approach 2:
The patent introduces a beam splitter as an intermediary element that enables both transmission and reception of light through a single optical axis. The beam splitter directs transmitted light toward the target and redirects reflected light to the sensor, serving as a mediator that eliminates parallax while preserving distance measurement capability.
2Reliability
If a staring array is used to observe the complete field of view, then the receiver can detect reflected light, but signal from ambient light sources or noise from pixels degrades the signal quality
Solution Approach 1:
The patent dynamically adjusts the instantaneous field of view (iFOV) for each scan point to match the expected beam profile and parallax characteristics. This local optimization ensures that only relevant pixels are active for each measurement, reducing noise from irrelevant pixels and ambient light sources while maintaining reliable signal detection.
Solution Approach 2:
The patent implements dynamic adjustment of the iFOV based on the current scan point position and expected target location. This dynamic reconfiguration of the active pixel region adapts to changing measurement conditions, minimizing ambient light interference and pixel noise while maintaining reliable signal detection throughout the field of view.
3Measurement precision
If micropixels with very small width are used, then the pixel count increases providing finer resolution, but individual read-out of each micropixel creates a massive burden to the design
Solution Approach 1:
The patent bundles multiple micropixels into groups that correspond to the dynamically adjusted iFOV for each scan point. This bundling reduces the number of individually read-out pixels by combining signals from micropixels that would otherwise be read out separately, significantly reducing read-out circuit complexity while maintaining the spatial resolution benefits of fine-pixel arrays.
Solution Approach 2:
The patent activates only the subset of micropixels that fall within the dynamically adjusted iFOV for each scan point, rather than reading out all micropixels. This partial action approach reduces the read-out burden by activating only the necessary pixels for each measurement, while still achieving the required spatial resolution through selective pixel activation.
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 signal quality by minimizing noise and optimizing signal collection, independent of object type or properties, while allowing for precise adjustment of iFOV to accommodate varying distances and distortions, thereby improving the overall performance of lidar systems.
Implementation Method 1
Lidar systems measure the time of flight (indirect or direct) of light to measure the distance to objects
Implementation Method 2
the projection of reflected light from a target will move on a focal plane of a receive sensor depending on distance. This effect is known as parallax
Data Source
AI summary
A lidar system includes a laser configured to generate a light pulse and transmit optics configured to receive the light pulse and direct toward an external environment. Receive optics, separate from the transmit optics, are configured to receive light from the light pulse reflected off of an object in the external environment. An array of photodetectors is positioned to receive the light from the receive optics and generate an image corresponding to an instantaneous field of view (“iFOV”) of the external environment. Aa controller is configured to adjust the iFOV as a function of a time of flight of the light pulse generated by the laser.