Multiwavelength Raman lidar MRL-400

Application

Multiwavelength Raman Lidar is intended for profiling of microphysical particle parameters in 0.05 – 10 mm radii range.

Atmospheric aerosol of natural and anthropogenic origin is one of the key factors influencing the planet radiation balance. For the modeling of corresponding forcing the information about vertical distribution of particle parameters is demanded. Multiwavelength Raman lidars are the promising tools to provide height resolved microphysical particle parameters without perturbing the aerosol or its surroundings.

Laser beam is expanded by of-axis parabolic collimator. Laser and collimator are fixed on the receiving telescope, thus allowing to perform the measurements at any angle to horizontal Seven-channels LICEL electronic unit makes possible simultaneous analog and photon counting measurements.

Delivered parameters

  • Backscattering coefficients  (355, 532, 1064 nm)
  • Extinction coefficients (355, 532 нм)
  • Particle depolarization ratio ar 355 нм
  • Angstrom parameter
  • Mean and effective radius
  • Number, surface and volume density
  • Refractive index
  • Water vapor mixing ratio

Technical parameters:

Radiation source

Parameters  Value 
Laser type Nd:YAG Brilliant B
Pulse energy 300 / 250 / 200 mJ @
1064 / 532 / 355 nm
Pulse duration 6 ns
Repetition rate 10 Hz
Beam diameter (after collimation) 40 mm
Beam divergence <0.2 mrad

Receiving module

Channels  Wavelengths 
Elastic scattering 355, 532, 1064 nm
Nitrogen Raman scattering 387, 608 nm
Raman scattering by water vapor 408 nm
Depolarization 355 nm

Newton receiving telescope

Parameters  Values 
Aperture 400 mm
Focal length 1200 mm
Field of view 0.25 – 2 mrad

 

 

Variation of the particle  backscattering coefficient  at 1064 nm. Measurements were performed  in Istanbul area  since 9 :00 pm to 6:00  am in May 2009.