What was found
AT CRUISE ALTITUDE, CARGO SMOKE LIGHT ON CWP CAME ON, ACTIVATED NR 1 CARGO EXTINGUISHER, LIGHT WENT OUT. FOLLOWED QRH FOR CARGO SMOKE, AS PER QRH ACTIVATED BOTH CARGO EXTINGUISHERS, NR 1 FOLLOWED BY NR 2 BOTTLE, AFTER 5 MINUTES FIRED BECAUSE CARGO SMOKE ILLUMINATED ON CWP AGAIN. AIRCRAFT DIVERTED IN CMH. MAINTENANCE CLEANED BOTH SMOKE DETECTOR PHOTO OPTICS AND CONNECTOR PER MM 26-13-00-7. ALL CHECKS AND TEST NORMAL.