Eastman Kodak Co. announced that Patricia F. Russo has resigned as president and COO, effective immediately, to become CEO of Lucent Technologies Inc. Kodak chairman and CEO Daniel A. Carp will reassume the responsibilities of president and COO.   . . .   Guy Broadbent has been named president and CEO of Spectra-Physics Inc. This follows the completion of a cash tender offer for the common stock of Spectra-Physics by Thermo Electron Corp., the company's 94% stockholder, on Dec. 21. Patrick L. Edsell, who was Spectra-Physics' chairman, president and CEO since 1997, will continue as chairman of the board until a short-form merger by Thermo Electron is completed.   . . .   LifeSpex Inc., a biophotonics company developing light-based products for cancer detection, has named Dipankar Ganguly executive vice president and CTO.