The pilot of the experimental amateur-built Nelsen Lightning was departing from a turf runway. He reported that as he passed his normal rotation point on the runway, he rotated the airplane without verifying his airspeed, which resulted in the airplane becoming airborne prematurely. The airplane rotated, rolled to the left, impacted a light pole, and came to rest inverted, which resulted in substantial damage to both wings and the fuselage. The pilot reported that there were no mechanical failures or malfunctions of the airplane prior to the accident.