Projector defocusing technique can eliminate projector nonlinearity in real-time three-dimensional shape measurement. However, the high frequency harmonics brought by defocusing can weaken the sinusoidal feature of the defocused fringe pattern, which can cause obvious measurement error. The Sierra Lite dithering algorithm using a serpentine raster is proposed to generate binary dithered fringe patterns. This method improves the sinusoidality of the defocused fringe pattern. Absolute phase is retrieved by applying fringe patterns generated by this method in traditional phase-shifting algorithm with projector defocusing. Simulations and experiments are carried out to verify the proposed method. Results show that both the sinusoidality of the defocused fringe pattern and phase quality are improved greatly. Compared with the fringes generated by Bayer ordered dithering or Floyd-Steinberg dithering, the proposed method achieves higher performance and can generate fringe patterns more sinusoidally, which is more proper for projector defocusing profilometry.