Abstract: An optical apparatus includes an optical semiconductor device and a lens assembly mounted on opposite surfaces of a substrate. The height of a surrounding wall and the thickness of a cover member of a semiconductor package of the optical semiconductor device are selected so that, when the cover member and the lens assembly abut directly against the opposite surfaces of the substrate, an optimum optical distance will be formed between a lens set of the lens assembly and a light-sensing portion of an optical semiconductor chip in the semiconductor package. A method for making the optical apparatus is also disclosed.