Pulsed-Wave LiDAR Gain Control for Long-Range Detection
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Solution Overview
Problem
Conventional LIDAR systems face challenges in detecting objects at both short and long distances due to insufficient amplifier power and long measurement times, which complicate speckle processing requirements, particularly in autonomous vehicle applications.
Innovation Solution
Implementing a pulsed-wave LIDAR system that utilizes an erbium doped fiber amplifier (EDFA) with varying gain configurations, an optical switch, a Mach-Zehnder modulator, an electro-absorption modulator (EAM), or a semiconductor optical amplifier (SOA) to generate pulsed envelope signals, enabling efficient object detection across a wide range of distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If amplifier power is increased to detect objects at long distances, then detection range is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements pulsed-wave operation where the laser source emits periodic optical pulses instead of continuous waves. The amplifier operates in synchronization with these pulses, providing high gain only during pulse transmission. This periodic operation allows the system to achieve long detection ranges with reduced average amplifier power consumption and simplified device complexity compared to continuous high-power operation.
2Measurement precision
If measurement time is extended to improve detection accuracy, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The pulsed-wave LIDAR system performs multiple rapid measurements by transmitting periodic optical pulses at high repetition rates. Each pulse generates a return signal that is processed to determine object distance and velocity. This periodic pulsed operation enables the system to achieve high measurement precision through multiple samples while maintaining high productivity through rapid pulse repetition, resolving the contradiction between accuracy and speed.
Solution Approach 2:
The system maintains continuous operation by rapidly repeating the pulse transmission and measurement cycle. The amplifier continuously processes return signals from successive pulses, ensuring that useful measurement action continues without interruption. This continuous pulsed operation provides both high precision through multiple measurements and high productivity through uninterrupted rapid cycling.
3Use of energy by stationary object
If pulsed-wave operation is implemented to reduce amplifier power requirements, then power consumption is reduced, but device complexity increases due to pulse generation components
Solution Approach 1:
The patent employs periodic pulsed operation where the amplifier provides high gain only during brief pulse transmission intervals rather than continuous operation. This time-multiplexed approach reduces average power consumption significantly. The pulse generation complexity is offset by the substantial reduction in amplifier power requirements and thermal management simplifications compared to continuous high-power operation.
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 pulsed-wave LIDAR system achieves accurate object recognition at both short and long distances without requiring excessive amplifier power, while reducing speckle processing requirements, thereby enhancing the safety and efficiency of autonomous vehicle operations.
Implementation Method 1
an erbium doped fiber amplifier (EDFA) configured to receive the optical signal and amplify the optical signal based on a gain configuration of a plurality of gain configurations of the EDFA to generate an amplified signal corresponding to a pulse envelope signal
Implementation Method 2
The amplifier includes the SOA, and wherein the SOA modulates the optical signal using index modulation
Implementation Method 3
a laser source configured to provide an optical signal
Implementation Method 4
chirped detection based on a frequency difference between a transmitted chirped optical signal and a returned signal scattered from an object
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
In some implementations, a light detection and ranging (LIDAR) system includes a laser source configured to provide an optical signal at a first signal power, an amplifier having a plurality of gain levels, and one or more processors. The amplifier is configured to receive the optical signal and amplify the optical signal based on a gain configuration of the plurality of gain configurations The one or more processors are configured to adjust the gain configuration of the amplifier across two or more of the plurality of gain configurations to cause the amplifier to generate a pulse envelope signal at a second signal power. The second signal power is greater than the first signal power by at least an amount corresponding to an inverse of a duty cycle of the optical signal.