Lidar crossover function and misalignment effects

Area of Science:

• Atmospheric Science
• Optical Remote Sensing

Background:

• The lidar equation requires a crossover function f(R) to model short-range signal attenuation.
• This function accounts for the geometric mismatch between laser pulse volume and receiver field of view.
• Understanding this function is key for accurate near-surface atmospheric measurements.

Purpose of the Study:

• To develop a simplified formulation for the lidar crossover function f(R).
• To investigate the impact of realistic lidar geometries and optical misalignment on f(R).
• To emphasize the importance of precise optical alignment in narrow-beam lidar systems.

Main Methods:

• Utilized a Gaussian intensity profile for the laser pulse transverse distribution.
• Derived a simplified mathematical formulation for the crossover function f(R).
• Performed numerical simulations for various lidar geometries, including optical axes misalignment.

Main Results:

• Presented a straightforward formulation for the lidar crossover function f(R).
• Provided numerical results demonstrating f(R) under different geometric conditions.
• Quantified the influence of optical axes misalignment on the crossover function.

Conclusions:

• The simplified f(R) formulation is effective for near-surface lidar returns.
• Accurate optical alignment is critical for narrow-beam lidar systems (approx. 1 mrad).
• Misalignment significantly impacts lidar performance, particularly for polarization and other sensitive measurements.