Wavelength blending with reduced speckle and improved color for laser projection

In this paper, a theoretical model was established to study speckle reduction using the wavelength blending technique with multiple lasers for the first time. An optimized power ratio of two lasers was then obtained using the theoretical model. A diode pumped solid state (DPSS) laser at 532nm and a semiconductor laser diode (LD) at 520nm were used to verify the simulated results. A speckle reduction system which utilizes wavelength blending was also proposed and demonstrated. Using wavelength blending, this system has a lower speckle as compared with one in which only one wavelength is used, and an improved green primary color (with respect to the Rec. 2020 standard) as compared with the one that only semiconductor LD is employed.