Raman-shifted eye-safe aerosol lidar

Area of Science:

• Atmospheric Science
• Optical Engineering
• Remote Sensing

Background:

• Elastic backscatter lidar systems are crucial for atmospheric research.
• Previous systems using Raman scattering in methane faced limitations like optical breakdown.
• Development of new wavelengths and improved system designs is ongoing.

Purpose of the Study:

• To present the design features of a novel elastic backscatter lidar system operating at 1543 nm.
• To report initial observations and performance of the new lidar system.
• To demonstrate a system capable of eye-safe operation and dual-wavelength measurements.

Main Methods:

• Utilized stimulated Raman scattering in high-pressure methane for wavelength conversion (1064 nm to 1543 nm).
• Employed a multipass gas cell without focusing the pump beam to prevent optical breakdown.
• Incorporated diode injection seeding for enhanced conversion efficiency and beam quality.
• Used a 40.6-cm telescope and an InGaAs avalanche photodiode detector.
• Enabled dual-wavelength (1064 nm and 1543 nm) and eye-safe operation modes.

Main Results:

• Successfully designed and operated a new elastic backscatter lidar system at 1543 nm.
• Achieved high energy transmission (>200 mJ/pulse at 10 Hz).
• Demonstrated prevention of optical breakdown through non-focused pump beam.
• Collected aerosol backscatter data using vertical and horizontal pointing.

Conclusions:

• The new lidar system design overcomes previous limitations, enabling robust operation.
• The system's eye-safe capability and dual-wavelength mode offer flexibility for atmospheric studies.
• Initial data show the system's effectiveness in measuring aerosol backscatter.