Efficient speckle-suppressed white light source by micro-vibrated and color-mixing techniques for lighting applications

In this paper, we have demonstrated an efficient speckle-suppressed white light source generation when a blue laser diode illuminates on a micro-vibrated phosphor paper. Both micro-vibrated and color-mixing techniques are used in this system. With only micro-vibrated technique, the speckle contrast can be reduced from about 50% to 7.4% for the scattering blue image for a 16-ms integration time. Together with color-mixing technique, mixing speckle contrast is defined for laser diode pumped phosphor and almost speckle-free result is achieved. For color temperature lower than 5000 K, almost speckle-free mixed white can be obtained even without vibration technique.