343
Airborne Water Vapor Differential Absorption Lidar
subsystems, and automated system control, the operation of the DIAL system has
been simplified, the cost has been lowered, and the long-term operation stability
has been improved. Furthermore, better retrieval techniques and methods have been
developed, so the measurement accuracy has been increased.
Water vapor absorption lines are present in many regions of the infrared spectrum. For DIAL work, the most suitable wavelengths are around 730, 820, and
940 nm, where interference with other gases is minimal, suitable laser sources and
sensitive detectors are available, and a wide range of line strengths is covered. The
advanced airborne DIAL system operating around each wavelength range and some
of the most valuable measurement results are particularly presented in this study.
14.3.1 aiRBoRne h 2 o dial aRound 730 nM
The operation on absorption lines around 730 nm is usually obtained by a highpower, single-frequency, tunable alexandrite laser. The most advanced and famous
H 2 O DIAL system operating around the 730-nm range is the Lidar Embarque pour
l’etude des Aerosols et des Nuages, de l’interaction Dynamique-Rayonnement et du
cycle de l’Eau (LEANDRE II) of the Centre National de la Recherche Scientifique.
The design details of the LEANDRE II system and the DIAL signal processing were
given by Bruneau et al. (2001a,b). The main structure and the measurement accuracy
of this system are briefly presented here.
14.3.1.1 General Description
A diagram of the LEANDRE II system is presented in Figure 14.3, and the main
properties are summarized in Table 14.1. The transmitter of LEANDRE II is a flash
lamp–pumped alexandrite laser, which operates in a double-pulse, dual-wavelength
mode in the 730-nm spectral domain. A pair of 50-mJ pulses at online and offline
Emitter electronics
Signal acquisition
Transmitter
Real-time
computer
Aircraft
navigation
acquisition
Data
storage
Amplifiers Digitizers
Pulse
detector
Detection
optics
Telescope
Steering
mirror
Wavemeter
interferometers
CCDs
Alexandrite
laser
Laser
power
control
Laser
spectral
control
Wavemeter
acquisition
computer
Laser control electronics
Signal
detector
Scientific
computer
Terminal
FIGURE 14.3 Setup diagram of LEANDRE II H 2 O DIAL system.
Airborne Water Vapor Differential Absorption Lidar
subsystems, and automated system control, the operation of the DIAL system has
been simplified, the cost has been lowered, and the long-term operation stability
has been improved. Furthermore, better retrieval techniques and methods have been
developed, so the measurement accuracy has been increased.
Water vapor absorption lines are present in many regions of the infrared spectrum. For DIAL work, the most suitable wavelengths are around 730, 820, and
940 nm, where interference with other gases is minimal, suitable laser sources and
sensitive detectors are available, and a wide range of line strengths is covered. The
advanced airborne DIAL system operating around each wavelength range and some
of the most valuable measurement results are particularly presented in this study.
14.3.1 aiRBoRne h 2 o dial aRound 730 nM
The operation on absorption lines around 730 nm is usually obtained by a highpower, single-frequency, tunable alexandrite laser. The most advanced and famous
H 2 O DIAL system operating around the 730-nm range is the Lidar Embarque pour
l’etude des Aerosols et des Nuages, de l’interaction Dynamique-Rayonnement et du
cycle de l’Eau (LEANDRE II) of the Centre National de la Recherche Scientifique.
The design details of the LEANDRE II system and the DIAL signal processing were
given by Bruneau et al. (2001a,b). The main structure and the measurement accuracy
of this system are briefly presented here.
14.3.1.1 General Description
A diagram of the LEANDRE II system is presented in Figure 14.3, and the main
properties are summarized in Table 14.1. The transmitter of LEANDRE II is a flash
lamp–pumped alexandrite laser, which operates in a double-pulse, dual-wavelength
mode in the 730-nm spectral domain. A pair of 50-mJ pulses at online and offline
Emitter electronics
Signal acquisition
Transmitter
Real-time
computer
Aircraft
navigation
acquisition
Data
storage
Amplifiers Digitizers
Pulse
detector
Detection
optics
Telescope
Steering
mirror
Wavemeter
interferometers
CCDs
Alexandrite
laser
Laser
power
control
Laser
spectral
control
Wavemeter
acquisition
computer
Laser control electronics
Signal
detector
Scientific
computer
Terminal
FIGURE 14.3 Setup diagram of LEANDRE II H 2 O DIAL system.