LIDAR Detector Pre-Blinding Against Internal Reflection Blindness
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Solution Overview
Problem
Avalanche photodetectors in LIDAR systems experience temporary blindness due to internal reflections, leading to inability to detect objects within short range, as the recovery period exceeds the time for light to exit the system and enter the environment, causing missed detection of close-range objects.
Innovation Solution
Pre-blinding the photodetector by forcing it to avalanche with external light from a source like an LED before the emitted light exits the system, ensuring it is in recovery mode before internal reflections occur, thus preventing premature avalanching and extending the recovery period beyond the light's exit time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the photodetector uses avalanche photodetection to achieve high sensitivity, then the signal output for small photonic energy is greatly enhanced, but the photodetector enters a recovery period after receiving light that blinds it to subsequent incipient light returns
Solution Approach 1:
The patent applies preliminary action by pre-blinding the photodetector before the LIDAR pulse is emitted. A pre-blinding pulse is sent to the photodetector at a time such that the photodetector enters its recovery period before the LIDAR pulse exits the system. This ensures that when the LIDAR pulse returns from external objects, the photodetector is already recovering from internal reflections and can detect external returns without being blinded by them.
Solution Approach 2:
The patent applies preliminary anti-action by using the pre-blinding pulse to counteract the harmful effect of internal reflections before they can occur. By forcing the photodetector into recovery mode in advance, the system prevents the photodetector from prematurely avalanching due to internal reflections, thus eliminating the harmful blinding effect before it can interfere with external object detection.
2Reliability
If the recovery period is extended to prevent blinding from internal reflections, then detection of short-range objects is improved, but the time available for detecting subsequent light returns is reduced
Solution Approach 1:
The patent extends the recovery period through preliminary action by timing the pre-blinding pulse to ensure the photodetector remains in recovery mode throughout the entire duration that internal reflections could reach it. This extended recovery period, initiated before pulse emission, ensures reliable short-range detection while the system manages the detection window through precise timing coordination.
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 ensures the photodetector is not blinded during the critical short-range detection period, allowing for accurate detection of objects close to the LIDAR system by synchronizing the recovery period with the light's exit from the system, thereby enhancing the system's ability to detect objects as close as 10 centimeters away.
Implementation Method 1
The photodetectors may be implemented in a LIDAR system that may emit light into an environment and may subsequently detect any light returning to the LIDAR system
Implementation Method 2
The photodetectors may also more specifically be Avalanche Photodiodes (APD), which may function in the same manner as a normal photodiode, but may operate with an internal gain as well. Consequentially, an APD that receives the same number of incoming photons as a normal photodiode may produce a much greater resulting electrical signal through an 'avalanching' of electrons
Implementation Method 3
In some LIDAR systems (for example, coaxial beam path LIDAR systems), the power transmitted from, and received back by, the LIDAR system may follow the same or largely the same optical path
Data Source
AI summary
Systems, methods, and computer-readable media are disclosed for a systems and methods for pre-blinding light detectors. An example method may include sending, by a processor of a LIDAR system and at a first time, a signal to a light source of the LIDAR system, the signal causing the light source to provide a light input to a photodetector of the LIDAR system, wherein the light input to the photodetector causes the photodetector to initiate a recovery period. The example method may also include emitting, by a laser of the LIDAR system, a first light pulse into an environment at a second time. The example method may also include receiving, by the photodetector, return light associated with the first light pulse from an object in the environment, the return light reaching the photodetector at a third time, the third time being after the photodetector has ended the recovery period.