What was found
DFW - FLT 1707 - EN ROUTE DFW-SMF, SHORTLY AFTER TAKEOFF, UPON RAISING NOSE GEAR DETECTED A STRONG VIBRATION. LOWERED GEAR, DECLARED EMERGENCY AND RETURNED DFW WITHOUT FURTHER INCIDENT. RESET NOSE LANDING DOOR SEQUENCE. PERFORMED VISUAL INSPECTION. NO DEFECTS NOTED. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)