Next field test - optical?

After my very disappointing results on VLF earth-mode yesterday - I must get to the bottom of why results were quite so bad - I think my next test will be at the other end of the spectrum. We have a windmill very close so I may try bouncing optical signals off this to test my optical gear is working still.   It is a long time since I have done any optical experiments.This will not be too far initially, more a test of the gear before venturing any distance.