Jurgen Pfaff has been named COO of pulsed-laser developer Lambda Physik. Pfaff has worked with Coherent Inc. for 15 years in research and development, engineering, product marketing and operations, most recently as vice president and general manager, diode-pumped solid-state lasers.   . . .   Precision Optics Corp. Inc. has appointed Joseph N. Forkey as chief scientist, focusing on optical instruments, biophysics and biomedical instrumentation and new photonics-based market opportunities. Forkey, the son of Precision Optics CEO and founder Richard E. Forkey, recently developed a new highly accurate single-molecule fluorescence polarization microscope.   . . .    JDS Uniphase Corp. will continue to provide IPG Photonics Corp. with laser diodes under a new supply agreement. Specific terms were not disclosed. IPG also announced that the companies have resolved their disputes over their prior supply agreement.