We have designed optical structure to be used as tiles on the outsides of buildings for indoor illumination. To cover an
entire building, we have designed optical units to be used together that can compress light. The important factor in our
design is producing parallel exit beam from our single units. We have used saw-toothed surface with two different principles, the Co-focus and Parallel-plate, to design optical units. Finally, we analyze the efficiency and the beam divergence angle to compare these optical structures.