[Laser] Lunar downlink

[F1AVYopto at aol.com]

Hello all 
Some  elements about a laser EME circuit from the  CERGA.
http://www.obs-azur.fr/cerga/laser/laslune/instrum.htm#télescope
It  is a fantastic challenge:
The losses are enormous.
Test conditions: RX TX  telescope 154 cm in diameter.
Laser YAG 300 pS pulse duration, 200 mJ energy  one pulse, 1064 nm, 10 shoots 
each second
RX with avalanche photodiode TE  cooled at -40° used in Geiger mode (120V 
over-voltage above breakdown voltage at  the probable echo arrival time)
The best reflector is the Apollo 15 one near  Archimedes.
On the Apollo 15 reflector: 
1 returned back photon for 10^20  sent! 
1 successful echo for 3 shoots in the best conditions!!!
A laser  responder will give more power but as Andy K0SM write, the moon 
librations will  need very complex target tracking and automatic optical aiming.
However the  project is not infeasible.
Yves  F1AVY
http://pageperso.aol.fr/yvesf1avy/