Multi-Laser Frequency Sweep Control for Wider FMCW LiDAR Range
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Solution Overview
Problem
The limitations of current laser technologies restrict the frequency sweep range and measurement accuracy of FMCW-based lidars, leading to challenges in increasing pulse peak power, reducing pulse width, and managing multi-lidar interference.
Innovation Solution
A frequency sweep control method and apparatus utilizing multiple laser units with different reference light emitting frequencies and frequency variation upper limits, allowing for alternate output of optical signals to expand the frequency sweep range and reduce field of view interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single laser unit is used for frequency sweep, then the device complexity is low, but the frequency sweep range is limited by physical performance of the laser diode
Solution Approach 1:
The patent divides the frequency sweep function into multiple laser units, each responsible for a specific frequency range. The first laser unit handles the first frequency sweep range while the second laser unit handles the second frequency sweep range, allowing the system to achieve a broader overall frequency sweep range without overloading a single laser unit.
Solution Approach 2:
The patent combines multiple laser units with different reference light emitting frequencies and frequency variation upper limits to create a unified frequency sweep system. By merging the capabilities of multiple laser units and using an optical switch to combine their outputs, the system achieves an extended frequency sweep range that exceeds what any single laser unit could provide.
2Measurement precision
If the frequency sweep time is increased to improve signal-to-noise ratio, then the measurement signal-to-noise ratio improves, but the measurement time increases
Solution Approach 1:
The patent changes the frequency sweep parameters by using multiple laser units with different reference light emitting frequencies and frequency variation upper limits. This allows the system to perform multiple frequency sweeps with different parameters, effectively increasing the total frequency sweep range without proportionally increasing the measurement time, thereby improving the measurement signal-to-noise ratio more efficiently.
3Length of stationary object
If the pulse peak power is increased to extend measurement range, then the measurement range increases, but it is difficult to further increase pulse peak due to laser technology limitations
Solution Approach 1:
The patent segments the measurement range requirement across multiple laser units, each operating at manageable power levels. By dividing the overall measurement range into multiple segments handled by different laser units with different frequency sweep ranges, the system achieves extended measurement range without requiring any single laser unit to operate at excessively high power levels.
Data Source
AI summary
A frequency sweep control method and apparatus are provided. The method includes: outputting a first optical signal of a first laser unit, where a first frequency sweep range of the first optical signal is determined based on a first reference light emitting frequency and a first frequency variation upper limit; and switching to output a second optical signal of a second laser unit when a first frequency variation of the first optical signal is greater than or equal to a first threshold, where a second frequency sweep range of the second optical signal is determined based on a second reference light emitting frequency and a second frequency variation upper limit, and the first threshold is less than the first frequency variation upper limit.