Swedish inventor who improved lighthouse optics. In 1757 Norberg designed the first flashing light used in a lighthouse. At the Korso lighthouse, he arranged clockworks to rotate two curved mirrors in order to reflect light intermittently. He carefully calculated the most effective parabolic curve to achieve this success. Norberg also developed the first revolving light in 1781. He hung his rotating reflectors inside the Marstrand lighthouse to create the effect of light beams horizontally sweeping the surrounding sea.