Multifrequency Pulsed Laser Emitter for Differential Absorption Lidar
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pulsed lasers for differential absorption lidar lack the necessary characteristics for effective atmospheric monitoring, such as high energy, stable pulse repetition frequency, and spectral/spatial quality, limiting their ability to measure gas concentrations over long distances with precision.
Innovation Solution
A pulsed laser transmitter with a laser cavity and multiple master lasers that inject beams spectrally spaced by Free Spectral Intervals, allowing for single-mode operation and precise wavelength control, enabling high repetition rates and stable energy output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-mode pulsed laser is used for differential absorption lidar, then spectral precision and measurement accuracy are improved, but the laser cannot emit multiple wavelengths needed for detecting different gaseous components
Solution Approach 1:
The laser cavity length is made dynamically adjustable through a feedback-controlled piezoelectric actuator. The control system continuously monitors the spectral alignment between master laser wavelengths and cavity resonant modes, adjusting the cavity length in real-time to maintain single-mode operation across multiple wavelengths. This dynamic adaptation resolves the contradiction by enabling the laser to switch between different single-mode wavelengths as needed for detecting various gaseous components.
Solution Approach 2:
A feedback control system using a piezoelectric actuator continuously adjusts the laser cavity length to maintain precise alignment between master laser wavelengths and cavity resonant modes. The system monitors spectral alignment and automatically corrects deviations, ensuring single-mode operation is preserved when switching between different wavelengths. This feedback mechanism enables versatile multi-wavelength operation while maintaining the spectral precision required for accurate gas detection.
2Manufacturing precision
If the laser cavity length is adjusted to match master laser wavelength with cavity resonant modes, then single-mode operation and spectral fineness are improved, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The mechanical adjustment of cavity length is replaced with a piezoelectric actuator that converts electrical feedback signals into precise mechanical displacement. This substitution enables automated, high-precision control of cavity length without complex manual adjustment mechanisms. The piezoelectric system provides fine control resolution needed for maintaining single-mode operation while reducing overall device complexity through electronic control compared to purely mechanical systems.
3Adaptability or versatility
If multiple master lasers are used to provide different wavelengths, then the laser can detect various gaseous components, but the energy stability and pulse consistency deteriorate
Solution Approach 1:
Multiple master lasers are integrated into a single homogeneous laser cavity system with unified resonant modes. All master lasers share the same cavity environment, gain medium, and control mechanisms, ensuring consistent operational conditions across different wavelengths. This homogenization of the laser system maintains energy stability and pulse consistency while enabling multi-wavelength emission for detecting various gaseous components.
Solution Approach 2:
A single laser cavity is designed to support multiple wavelengths simultaneously through its resonant mode structure. The unified cavity serves multiple functions: providing resonant enhancement for different master laser wavelengths, maintaining consistent beam properties, and ensuring stable energy output. This universal cavity design enables the laser to function as both a multi-wavelength source and a stable energy provider, resolving the contradiction between versatility and stability.
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 solution provides a pulsed laser transmitter with high spectral and spatial quality, variable pulse repetition rates, and stable energy, enabling effective atmospheric gas concentration measurements over several kilometers with improved precision and efficiency.
Implementation Method 1
said laser cavity providing a plurality of resonant eigenmodes, spectrally spaced by Free Spectral Intervals
Implementation Method 2
said first means for controlling the length of said laser cavity comprise a piezoelectric actuator
Implementation Method 3
at least two master lasers, the at least two lasers sequentially injecting master laser beams into said laser cavity, said laser cavity providing a plurality of resonant eigenmodes
Data Source
Figure 1
Figure 2~3B
Figure 4A~5
AI summary
The invention relates to a pulsed laser emitter comprising a laser cavity (1) and at least two master lasers (41, 42, 43) sequentially injecting master laser beams into said laser cavity, said laser cavity (1) having a plurality of resonant eigenmodes that are spaced apart spectrally by free spectral ranges, characterised in that the wavelengths of said master lasers (41, 42, 43) are spaced apart spectrally by an integer number of free spectral ranges of said laser cavity (1), and in that said laser emitter comprises first means for controlling the wavelength of said laser cavity (1), said means being able to modify the wavelength of said laser cavity (1) until the wavelength of a resonant eigenmode of said laser cavity (1) corresponds to the wavelengths of the master laser beam injected into the cavity.