Lidar Arrangement With Frequency Shifted Pulses
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Solution Overview
Problem
Current LIDAR systems face limitations in achieving high laser repetition rates, which are necessary for improved scanning rates and compact designs, especially in satellite-based applications for meteorological purposes like wind detection.
Innovation Solution
The proposed LIDAR arrangement and method involve a laser transmitter that emits a pulse sequence with successive pulses having specific frequency shifts, and a receiver with a dispersive element and a spatial resolution matrix sensor, along with an interferometer to map interferograms onto the matrix sensor, enabling spatial separation and measurement of pulses at high repetition rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser repetition rate is increased to improve scanning rate and compact design, then productivity and device compactness are improved, but signal ambiguity and measurement reliability deteriorate
Solution Approach 1:
The patent applies parameter changes by systematically varying the optical frequency of successive laser pulses according to a predefined sequence. Each pulse is assigned a unique frequency offset from the center frequency, creating a frequency-coded pulse train. This frequency parameter modulation enables the receiver to distinguish between overlapping pulses from different transmission cycles, resolving the signal ambiguity that would otherwise occur at high repetition rates.
Solution Approach 2:
The patent introduces an interferometer as an intermediary device between the dispersive element and the matrix sensor. The interferometer creates path length differences that translate frequency differences into spatial separations on the detector plane. This intermediary mechanism converts the frequency-coded information into spatially resolved signals, enabling unambiguous identification of each pulse's origin in the high-repetition-rate pulse train.
2Device complexity
If laser repetition rate is increased to enable compact design, then device complexity is reduced, but measurement precision deteriorates due to signal overlap
Solution Approach 1:
The patent uses parameter changes by assigning distinct frequency offsets to successive pulses in the repetition sequence. This frequency encoding allows the receiver to resolve individual pulses even when their backscattered signals overlap in time, maintaining measurement precision despite the high repetition rate enabled by compact design.
Solution Approach 2:
The patent transitions from temporal separation to spatial separation by using the interferometer to map frequency differences onto different spatial positions on the matrix sensor. This dimensional transformation allows simultaneous detection of multiple pulses in the temporal domain while maintaining individual signal identification through spatial encoding, thereby preserving measurement precision in compact high-repetition-rate configurations.
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 configuration allows for the separation and measurement of high-frequency LIDAR signals, overcoming the ambiguity issues at high repetition rates, and enabling the use of fiber lasers for space LIDARs with improved meteorological data collection capabilities.
Implementation Method 1
the laser transmitter is configured to transmit a pulse sequence in which successive pulses respectively comprise a specific frequency shift to each other
Implementation Method 2
a dispersive element for the spatial separation of the pulses depending on the optical frequency by a frequency-dependent deflection
Implementation Method 3
an interferometer configured for mapping at least partially spatially separated interferograms to the individual pulses of the pulse sequence on the matrix sensor
Data Source
Figure 1a~1c
Figure 2~3
Figure 4~5
AI summary
To improve LIDAR measurements in terms of accuracy and usability, the present invention provides a LIDAR arrangement (10) comprising a laser transmitter (12) for transmitting pulses of a laser radiation to a measurement object (40), and a receiver (13) for receiving pulses of the laser radiation backscattered from the measurement object (40), wherein the laser transmitter (12) is designed for transmitting a pulse sequence in which successive pulses respectively comprise a particular optical frequency shift to each other and wherein the receiver (13) 1.1 includes a dispersive element (16) for separating the pulses in time depending on the optical frequency by a frequency-based deflection, and a position resolution optical matrix transmitter (39) on which the pulses separated in time by the dispersive element are mapped, or 1.2 includes a frequency analyzer (60) for the frequency-based separation of the pulses by superimposition with a reference radiation.