1. EUSO Onboard LIDAR M.Teshima Discussion by Valentin Mitev Neuschatel Observatory Valentin.Mitev@ne.ch

2. 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

3. + Atmospheric response functionPRN codeLidar detected signal EUSO: Laser Diode based, PRN- cw lidar (Pseudo-Random Noise continuous wave)

4. 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 LIDAR Low power, compact, and long life

5. 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

6. 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

7. Conclusion Laser Diode based, PRN- cw lidar compact package + long life + low power But: Only opaque cloud top altitude

8. EUSO: One- (single-) wavelength pulsed lidar

10. 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

11. 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

12. Conclusion about the single- wavelength pulsed lidar compact package +developed technology + long life + sufficiently low consumption 1. Opaque cloud top altitude 2. Subvisible clouds optical depth@1  3. Dust layer transmisson profile @1 

13. EUSO: Three- wavelength pulsed lidar

14. 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

16. 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

17. 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

18. 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

19. in Chapter 5 – EUSO Red Book

20. 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

21. EUSO Lidar: concept with honeycomb panels (closed) Mass ~140Kg Power ~ 300W

22. 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