Abstract: A color tunable optical device electrically connects to a driving power source, and includes a first polarizer, a liquid crystal layer, a phase retarder and a second polarizer. The first polarizer converts a first mixed light into a first polarized mixed light. The liquid crystal layer is located behind the first polarizer and electrically connected to the driving power source for changing an arrangement direction of liquid crystal cells of the liquid crystal layer, and receives the first polarized mixed light. The phase retarder is located behind the liquid crystal layer to generate a second polarized mixed light. The second polarizer is located behind the phase retarder, and a second mixed light is generated by changing an incident angle of the second polarized mixed light incident on the second polarize, wherein a color of the second mixed light is different from that of the first mixed light.