John Stack, former president and COO of New Jersey-based Edmund Optics Inc. (EO), was recently name president of the optical systems unit at Zygo Corp., a Middlefield, Conn., supplier of optical metrology instruments, precision optics and electro-optics design and manufacturing services to the semiconductor capital equipment and industrial markets. Stack has a bachelor's degree in physics from the University of Pittsburgh and is a graduate of the Wharton Executive Development Program, Wharton School of Business At EO, he was responsible for worldwide sales, manufacturing and engineering.