Directed Light Inc. has signed a nonexclusive marketing and distribution agreement with Precitec Inc., manufacturer of component parts for laser cutting and welding equipment. Directed Light, distributor of replacement components for industrial CO2 and Nd:YAG laser systems, will offer Precitec's line of cables, nozzles, electronic laser products and retrofit upgrade packages in the US, Canada and Mexico.   . . .   YKK Corp. of America, which manufactures zirconia fiber optic ferrules, optical couplers and connectors in Kurobe, Japan, has launched a new North American Optical Components Div., based in Marietta, Ga. Keith W. Torrance has been appointed sales and marketing manager of the division.