euso onboard lidar m.teshima discussion by valentin mitev neuschatel observatory...
TRANSCRIPT
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
+
Atmospheric response function
PRN code Lidar detected signal
EUSO:Laser Diode based, PRN- cw lidar (Pseudo-Random Noise continuous wave)
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
Laser Diode based LIDARLow power, compact, and long life
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 single-wavelength pulsed lidar
compact package +developed technology + long life + sufficiently low consumption
1. Opaque cloud top altitude2. Subvisible clouds optical depth@13. Dust layer transmisson profile @1
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 Detector PMT (532nm) – Quantum Efficiency Detector PMT (355nm) – Quantum Efficiency
38%/300 15% 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
EUSO Lidar: 355nm, 30cm aperture, int. time 0.01sec
0.1
1
10
100
1000
5000 7000 9000 11000 13000 15000
meter, asl
scattering ratio
photon numbers
SNR
EUSO Lidar: 355nm, aperture 30cm, integration 5sec
0.1
1
10
100
1000
10000
5000 7000 9000 11000 13000 15000altitude asl, m
scattering ratio
photon numbers
SNR
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
EUSO Lidar: 30cm aperture, integration time 5 sec, SNR at 355nm, 532nm and 1064nm
1
10
100
1000
5000 7000 9000 11000 13000 15000altitude asl, m
scattering ratio
SNR at 355nm
SNR at 532nm
SNR at 1064nm
EUSO Lidar, aperture 30cm, integration time 0.01sec, SNR at 355nm, 532nm and 1064nm
0.01
0.1
1
10
100
1000
5000 7000 9000 11000 13000 15000altitude asl, m
scattering ratio
SNR at 355nm
SNR at 532nm
SNR at 1064nm
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 altitude2. Subvisible clouds optical depth@355nm3. 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
Lidar Probing, line-of-sight
Laser
Telescope Mirror
Detection box
Beam pointing mirror
EUSO Lidar: concept with honeycomb panels (closed)
Mass ~140KgPower ~ 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