Ronald D. Sugar, CEO and president of Northrop Grumman, has been elected chairman of its board, effective Oct. 1, when Kent Kresa, who has been chairman since 1990, will retire. Kresa stepped down as president and CEO in April. Sugar, who was elected president and COO in 2001 and CEO in April, is also a trustee of the National Defense Industrial Association, a governor of the Aerospace Industries Association and a Fellow of the American Institute of Aeronautics and Astronautics.   . . .   Sunex Inc., a Carlsbad, Calif.-based digital imaging optics company, has launched free optical and imaging design tools on its Web site, at: www.optics-online.com. They include a CCD/CMOS Lens Wizard, which calculates the horizontal, vertical and diagonal field of lenses; an Imaging Solution Wizard, which calculates the required effective focal length of a lens; a Lens Element Design Wizard for specifying custom lenses; a depth-of-field calculator; and a Search Lens by Imager Manufacturer Information Wizard.