Download Development of Atmospheric Polarization

Remote Observations of the Electric Field within Thundercloud:
New LIDAR - Based Techniques
The real time measurement of spatial and temporal distribution of the
electric field in and around thunderclouds is important for understanding the
formation mechanisms of thunderclouds, for predicting the appearance of
lightning strokes and for understanding the processes of the cosmic ray
electrons acceleration and the bremsstrahlung photons generation caused
by the electric field of clouds.
Now the electric field meters, used for this purpose, are set on Earth
surfaces or installed on balloons. These techniques are limited as they
typically provide a single sample at discrete altitudes at one time.
LIDAR systems are the main instrument which allows to realize real
time remote measurement of the electric field strength and direction with
high spatial and temporal resolution.
LIDAR systems are based on the absorption and/or scattering of light
by the gas, liquid or solid state. Atomic and molecular spectra can be
measured very accurately and sensitively using spectroscopy techniques.
Scattering of Electromagnetic Waves
Geometric
Mie Elastic
Reyleigh
Back Raman
Non Elastic
Fluorescence
EM wave induced dipole moment
P ~ χ (1)E + χ (2)E1E2 + χ (3)E1E2E3 + …
Linear
Nonlinear
Four Wave Mixing
P ~ χ (3)E1E2E3exp{ i [ΔKr – Δωt ]}
ω = ω1 – ω2 + ω3
K = K 1 – K2 + K3
I ~ │χ(3)│2 I1I2I3
Four Wave Mixing & Electric Field
1. Difference Frequency Generation
P ~ χ (3)E1E2E
ωE = ω3 = 0
=>
ω = ω1 – ω2
K = K1 – K2
I ~ │χ(3)│2 I1I2E2
Experimentally realized (laboratory)!!!
V. N. Ochkin et all. 1995
1atm, 532nm, 683nm
H2 – 2.4 μm => 20V/cm
2. Sum Frequency Generation
P ~ χ (3)E1E3E
ωE = ω2 = 0
=>
ω = ω1 + ω3
K = K1 + K3
I ~ │χ(3)│2 I1I3E2
Experimentally realized (laboratory)!!!
Second and Third Harmonic Generation & Electric Field
 Electric Field Induced Second harmonic generation (EFISH)
P ~ χ (3)(2ω) E12E
ωE = ω2 = 0
ω1 = ω3
I2ω ~ │χ(3)(2ω)│2 I12E2
 Third harmonic generation
P ~ χ (3)(3ω) E13
I3ω ~ │χ(3)(3ω)│2 I13
 Electric Field
E2 ~ │χ(3)(2ω)/χ(3)(3ω)│2 I1 I2ω ̸ I3ω
Proposed!!!
N2 – ω1 = 4.2 μm
O2 – ω1 = 6.3 μm
CO2 – ω1 = 7.5 μm
H2O – ω1 = 2.7 μm
CARS & Electric Field
 Infrared Wave Generation
ω3 = ωE = 0
ω1 – ω2 = Ω = ωir
Iir ~ │χir(3)│2 I1 I2 E2
 Coherent Antistokes Raman Scattering (CARS)
ω3 = ω1
2ω1 – ω2 = ωas
Ias ~ │χCARS(3)│2 I12 I2
 Electric Field
E2 ~ │χCARS (3) / χir (3) │2 I1 Iir / Ias
Experimentally realized (laboratory)!!!
P. Bohm et all. 2013
1000 mbar
H2 – 2.4 μm => 20V/cm
N2 – 4.29μm => 300V/cm
Comparison of Linear and Nonlinear techniques
Nonlinear spectroscopy
Advantages:
Direct measurement of the electric field.
High spectral resolution (Limited by laser line-widths).
Disadvantages:
Required two laser sources.
Registration of IR signal (required fast IR detector for spatial and temporal resolution).
Strong absorption of the IR radiation by water (required additional investigations).
Development for other molecules, atoms, charged molecules, ions, isotopes etc.
Development of Nonlinear spectroscopy techniques for remote sensing in situ.
Linear Spectroscopy
Advantages:
One laser source
Disadvantages:
Electric field measurement via its influence on the spectrum of gases (not direct).
Required high resolution spectrometer, including IR.
Required large aperture receiving optics.
Required (in some cases) high power IR laser.
The electric field remote sensing methodology in thunderclouds need additional
investigations and development !!!
Development of Atmospheric Polarization LIDAR System
Laser Emitter (a+b)
Receiving Telescope (c),
Polarization Separator (d).
Laser Emitter
Laser Emitter output beam parameters
Pulse Energy
1064nm 300-500 mJ
532nm 100-200 mJ
Beam Divergence
<10-4 rad
Polarization linearity
<10-3
Pulse duration
10 ns
Repetition rate
10-20 Hz
Output beam diameter
112 mm
1 - Convex mirror, 2 – Electro optical Q-Switch, 3 – Diaphragm, 4 – Output polarizer, 5 – laser oscillator pump
chamber, 6 – Quarter wave-plate, 7 – Concave mirror, 8 and 16 – Two wavelength mirrors, 9 – Glan prism
polarizer, 10 – Flash- lamp driver cables, 11 – mirror, 12 – Cooling system pipes, 13 – Laser amplifier pump
chamber, 14 – Flash-lamps, 15 – Second harmonic generator, 17 – Hole for the output beam.
Polarization Separator
The green points are the
separated cross-polarized beams.
Laser Emitter and Receiving Optical System Alignment
Alignment Laboratory Stand
By means of the laboratory stand was aligned:
 The Laser, including, laser oscillator and laser amplifier.
 The Laser with Beam Expander (14X).
 Diode Laser beam with its beam expander (200X).
 Diode Laser beam optical axis with RT housing tube axis.
 Receiving Telescope (RT) mirror optical axis with Diode Laser
beam optical axis and RT housing axis.
 Polarization Separator (PS) optical axis with RT Mirror optical axis.
 PS with cross-polarized beams outputs and RT mirror focus.
 Signal transportation fibers with cross-polarized beams.
 Adjustment of PMTs for registration of GLD beam.
The YerPhI LIDAR System
System
Triggering
Photodiode
PMTs
Laser Beam
Expander
The Laser
Aiming Optics
Q-Switch
Driver Cables
Laser Cooling
Pipes
Laser Emitter
Alignment
Receiving
Telescope
Flash-lamp
Supply Cables
Signal and
Supply Cables
LIDAR System
Registration
System
Triggering Fiber
Laser Beam
Expander
Laser Emitter
Output Energy
Control Fibers
The Laser
Laser Emitter
Alignment Mount
Receiving
Telescope
Polarization
Separator
Alignment Mount
Polarization
Separator
Aiming Optics
Registration
System
Triggering
Photodiode
Laser Emitter
Alignment
PMTs
Optical Filter
Boxes
Receiving Mirror
Focus Finder
Optical Signal
Outputs
Stepper Motor
end Switch
Optical Signal
Transportation
Fibers to PMTs
Play-free Gear
Stepper Motor
The LIDAR Registration and Control System
LIDAR Controllable Parameters
 LE beam 1064nm output energy.
 LE beam 532nm output energy.
 LE beam repetition rate.
 LE Q-Switch driver pulse delay.
 LE beam polarization finder.
 PS – LE beam polarization angle.
 Registration delay.
 LE – RT angle.
 PMT supply voltage.
 LIDAR azimuth and elevation.
 LE cooling temperature.
System Triggering PD
and its electronics
PMT Power Supplies
NI USB DAQ
NI DAQ BNC
Inputs and Outputs
Triggering Pulse
(5nsec/div).
PD and PMT Amplifier
Power Supplies
Stepper Motor Driver
Oscilloscope 500MHz
PMT with voltage divider and
Signal Amplifier
The YerPhI LIDAR System
Sorry for quality.
First Backscattered Signal Observations
Laser flash-lamp
background and Reflected
from a wall signal (250m).
Horizontal
- 30m/div;
Vertical signals - 0.1V/div;
Vertical trigger - 2V/div;
PMT - 0.5kV.
Backscattering from the
Atmosphere.
Horizontal - 750m/div;
Vertical
- 20mV/div;
Laser
- 100mJ;
PMT - 2kV; PS ~ 90deg.
First Backscattered Signal Observations
Scattering from Atmosphere and Clouds. (Hor.-750m/div; Ver.-20mV/div; PMT-2kV; PS-90deg).
First Backscattered Signal Observations
Scattering from Atmosphere and
Clouds.
Horizontal - 750m/div;
Vertical - 50mV/div;
PMT - 2kV;
PS ~ 45deg).
Planned Investigations in Nearest Future
1. Reyleigh and Mie backscattering:
– Depolarization ratio profile.
2. Raman backscattering N2 (607nm), O2 (580nm), H2O (645nm):
– Depolarization ratio of spectral bands.
3. Electric field under and inside the clouds.
Linear
P ~ χ (1)E1 exp{ i [ K1r – ω1t ]}
1. Power
2. Wavelength
3. Line-width
4. Polarization
- Absorption, etc.
- Raman, Fluorescence, Stark, Doppler, etc.
- Stark, Doppler, etc.
- Kerr, Pockels, Faraday, etc.
Polarization
φ = 2π (no - ne) L / λ = 2π B L E12
Bwater = 5.2 10-12 cm/V2
For 1000 V/cm and 500m =>φ = π /2 --> λ/4 plate
Cloud Type
LWC
(g/m3)
Atmosphere
Cirrus
.03
Fog
.05
Stratus
.25-.30
Cumulus
.25-.30
Stratocumulus
.45
Cumulonimbus 1.0-3.0
0.1-5.0
LIDARs for CTA
Germany
France
Argentina
Spain
France
Max Plank U Montpellier2 Buenos Aires U Barcelona U Montpellier
I (Munich)
LUPM
Elastic 1064
Elastic 532
Elastic 355
Raman 387(N2)
Raman 607(N2)
Raman 408(H2O)
Raman 645(H2O)
Elastic Polar.
Distance
Laser
Rep. Rate
1064nm
Energy 532nm
355nm
Pulse width
for MAGIC for HESS
X
X
X
0.5 - 18
20
Soliton
Quantel
GmbH
Brilliant 30
2000
20
0.005
180
65
0.5
5
Polarization
Beam Dia. (Expander)
Divergence
Receiving Mirror Dia.
HPD
Detector
Readout
Hamamatsu
R9792U-40
IFAE/UAB
X
X
X
X
-
LUPM
X
X
X
X
-
Armenia
U Torino
U Naples
YERPHI
ARCADE
X
X
X
X
X
X
X
0.25 - 10 0.1 - 15
Quantel Custom
Centurion made
100
10 - 20
40
300-500
18
100-200
6
8
10
Continuum
Inlite II-50
50
125
60
20
10
Quantel
Brilliant
20
360
180
100
5
Quantel
CFR400
20
400
230
90
7
Polar.
Polar.
Polar.
Polar.
Depolar.
600
PMT
6
0.75
6x400
PMT/HPD
6
0.5
1800
PMT/HPD
7
3.5
1800
PMT
20 (10x)
(3) 0.3
250
PMT
Photonis
XP2012B
51mm
Hamamatsu
H10721-110
25mm
Hamamatsu
H10721-100
38mm
GAGE 8265
LICEL
LICEL
(10x)
600
CEILAP
X
X
X
X
X
X
-
Italy
Hamamatsu Hamamatsu
R329P
R1332Q
50mm
50mm
LICEL
CAEN
km
Hz
mJ
ns
Polar.
110 (14x) mm
(1) <0.1 mrad
250
mm
PMT
FEU-83
FEU-100
25mm
NI DAQ