An optical device includes a light input part and a light output part. The light input part includes a micro display; a first and a second polarizing beam splitters configured to reflect or transmit incident light including an image displayed on the micro display; and a first quarter wavelength plate configured to receive light transmitted by the first polarizing beam splitter or the second polarizing beam splitter and change a polarized state of the received light. The light output part includes a third and a fourth polarizing beam splitters configured to transmit or reflect light including the image received from the light input part; a second quarter wavelength plate configured to receive the light transmitted by the third polarizing beam splitter or the fourth polarizing beam splitter and change the polarized state of the received light, and a light condenser configured to condense the polarized light.