Abstract: An optical apparatus includes a prism, a plurality of filter elements, a plurality of lenses, a light receiver array, a collimator lens and a base. The prism includes a light entering surface and a light exit surface parallel to each other. The filter elements are disposed on the light exit surface. The lenses correspond to the filter elements. The light receiver array includes a plurality of light receivers which correspond to the lenses. The light signal including a plurality of sub-signals enters the prism through the light entering surface. The sub-signals are separated from the light signal by the filter elements and exit from the light exit surface of the prism, and each of the sub-signals is transmitted through one of the lenses to one of the light receivers. The base is a continuous-unitary piece for positioning other elements.