There is provided a thin optical system for real-world occlusion in an augmented reality display. The optical system according to an embodiment includes: a first DCRA configured to reflect light beams focused on holes; a mask positioned on a light emitting surface of the first DCRA to pass or block the light beams emitted from the first DCRA; and a second DCRA configured to reflect the light beams which are focused on holes after passing through the mask. Accordingly, the optical system can implement real-world occlusion in the unit of pixel while having a thin form factor.