Michael R. Farris has resigned as CEO, president and a director of laser vision technology developer LaserSight Inc., of Winter Park, Fla., to pursue other interests. Danghui Liu, PhD, vice president of product development and technical marketing, was named interim CEO.   . . .   Daniel L. Smith has been appointed president of Raytheon Co.'s Integrated Defense Systems (IDS) business unit, in Tewksbury, Mass., effective Sept. 1. Smith is currently vice president and deputy to Charles E. Franklin.   . . .   A subsidiary of Molecular Imaging Corp. (MI) has entered into definitive agreements with the University of California, San Diego (UCSD), to open and operate a positron emission tomography (PET) patient imaging facility, the University of California, San Diego Center For Molecular Imaging, at 11388 Sorrento Valley Road, San Diego. The company has also acquired a cyclotron facility, located at the same address, which it said will enable it to produce the radioisotope fluorodeoxyglucose (FDG), a glucose-based radiopharmaceutical labeled with Fluorine-18 that is injected before a PET scan. MI and UCSD said they plan to collaborate in future research to develop other radioisotopes.