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EUSO Onboard LIDAR
M.Teshima
Discussion by Valentin Mitev
Neuschatel Observatory
[email protected]
Options for EUSO Lidar
1. Stand-alone laser diode based (near-IR)
2. Stand-alone one-wavelengths Nd:YAG based
3. Stand-alone three-wavelengths Nd:YAG based
EUSO:
Laser Diode based, PRN- cw lidar
(Pseudo-Random Noise continuous wave)

+
PRN code
Lidar detected signal
Atmospheric response function
Laser Diode based LIDAR
Low power, compact, and long life
Assumed performances of the PRN lidar subsystems:
Sensor Sub-systems parameters
Parameter
Value
Laser diode, wavelength
800nm
Laser diode, power
20W
Transmitter diameter/divergence
100mm/1mrad
Receiver primary/secondary diameter
500mm/120mm
Receiver divergence
2mrad
Detector APD – Quantum Efficiency/gain
50%/300
Filter FWHM/transmission
2nm/60%
Optical efficiency (no filter transmission included)
45%
Platform and measurement parameters
Parameter
Value
Platform Altitude
480km
Altitude resolution
150m
Candidate:
Upgrade of ‘Beacon laser’: Based on several laser diodes at 808nm, combined in a single
multimode fiber/Total of 8W without redundancy
PRN-cw lidar:
Detection conditions:
1. Desert dust: SR=5@532nm
OD =0.89@800nm
2. Subvisible cloud:
SR=100@532nm
OD=0.62@800nm
3. Optical background: Full
Moon/45°
4. Integration time: 1s
PRN-cw lidar:
Detection conditions:
1. Opaque cloud:
SR=1000@532nm
OD =3.81@800nm
2. Subvisible cloud:
SR=20@532nm
OD=0.12
3. Optical background:
Full Moon/45°
4. Integration time:
0.01s
Conclusion
Laser Diode based, PRN- cw lidar
compact package + long life + low power
But:
Only opaque cloud top altitude
EUSO:
One- (single-) wavelength
pulsed lidar
Assumed performances of the single wavelength, pulsed lidar subsystems:
Sensor Sub-systems parameters
Parameter
Value
Laser, wavelength
1064nm
Laser, pulse energy/pulse rep. rate/ mean power
50mJ/100Hz (2x50) /5W (2x2.5W)
Transmitter diameter/divergence
50mm/0.1mrad
Receiver primary/secondary diameter
400mm/60mm
Receiver divergence
0.3mrad
Detector APD – Quantum Efficiency/gain
38%/300
Filter FWHM/transmission
0.4nm/50%
Optical efficiency (no filter transmission included)
33%
Platform and measurement parameters
Parameter
Value
Platform Altitude
480km
Altitude resolution
150m
Range resolution: 150m; Int. time: 0.01s
Opaque cloud SR = 7993 at1064 at 4km;
OD=2.28
Subvis. cloud SR = 1585 at 1064nm at 10km;
OD=0.12
Range resolution: 150m; Int. time: 5s
Opaque cloud SR = 7993 at 1064 at 4km;
OD=2.28
Subvis. cloud SR = 1585 at 1064 at
10km; OD=0.12
Range resolution: 150m; Int. time: 1s
Dust layer SR = 33.5 at 1064 at 0-4km;
OD=0.67
Range resolution: 150m; Int. time: 1s
Dust layer SR = 33.5 at 1064 at 0-4km;
OD= 0.67
Subvis. cloud SR = 1585 at 1064 at
10km; OD=0.12
Conclusion about the singlewavelength pulsed lidar
compact package +developed technology +
long life + sufficiently low consumption
1. Opaque cloud top altitude
2. Subvisible clouds optical depth@1m
3. Dust layer transmisson profile @1m
EUSO:
Three- wavelength pulsed
lidar
Nd-YAG Pulsed Laser
> simplified ‘clone’ of the laser for ALADIN
1064nm, 532nm, 355nm
Pulse rep rate: 100pps (operational mode)/ 50pps (stan-by
mode)
Power we need: ~ 50-70mJ per wavelength
> NOT 120 mJ per harmonic AS FOR ALADIN
> NO WAVELENGTH LOCKING AND
STABILISATION, AS FOR ALADIN
Assumed performances of the single wavelength, pulsed lidar subsystems:
Sensor Sub-systems parameters
Parameter
Value
Laser, pulse rep rate /total pulse ehergy&optical power 100/ ~180mJ/18W
Laser wavelength/ pulse energy / mean power
1064nm/50mJ//5W
Laser wavelength/ pulse energy / mean power
532nm/50mJ//5W
Laser wavelength/ pulse energy / mean power
355nm/50mJ//5W
Transmitter diameter/divergence
50mm/0.1mrad
Receiver primary/secondary diameter
300mm/60mm
Receiver divergence
0.3mrad
Detector APD – Quantum Efficiency/gain
38%/300
Detector PMT (532nm) – Quantum Efficiency
15%
Detector PMT (355nm) – Quantum Efficiency
25%
Filter FWHM/transmission – all wavelength
0.4nm/50%
Optical efficiency (no filter transmission included)
33%
Platform and measurement parameters
Parameter
Value
Platform Altitude
480km
Altitude resolution
150m
Range resolution: 150m; Int.
time: 0.01s
Opaque cloud SR = 297 at 355nm
at 6km; OD=6.38
Subvis. cloud SR = 4.6 at 355 nm
at 10km; OD=0.11
Range resolution: 150m; Int.
time: 5s
Range resolution: 150m; Int. time: 0.01s
Opaque cloud SR = 1000 at 532nm at
6km;
Subvis. cloud SR = 20 at 532 nm at
10km; OD=0.1
Range resolution: 150m; Int. time: 5s
Conclusion: the three-wavelength
pulsed lidar
More complicated and less compact, less
redundancy, higher consumption
1. Opaque cloud top altitude
2. Subvisible clouds optical depth@355nm
3. Dust layer transmisson profile @355nm
4. Redndancy in information output, due to more
power/wavelength
5. Calibration for EUSO detector
in Chapter 5 – EUSO Red Book
Fig. 5.2.4-11.1 in Chapter 5 – EUSO Red Book
Laser
Detection box
Beam pointing mirror
Telescope
Mirror
Lidar Probing, line-of-sight
EUSO Lidar: concept with honeycomb panels (closed)
Mass ~140Kg
Power ~ 300W
EUSO LIDAR Conclusion
• Laser Diode PRN-cw Lidar is very interesting
technology, however the current performance is
not enough for EUSO
• Three wave lengths Lidar is very powerful,
but Mass and Power are problem
• One wave length Lidar is perhaps optimum in
performance and hardware resources.
– Cloud top information
– Thin cloud transmission
– Dust layer transmission