Beamsplitter cube is usually composed of two right angled prisms, with one of the right angled prisms coated with a beam splitter film on the inclined surface, so that a part of the incident light is transmitted and the other part is reflected, and the optical paths of the two are equal. The cube shape helps to avoid astigmatism and other aberrations, ensuring that the beam does not deviate when passing through the prism. This offset free characteristic makes the splitting prism very useful in precision optical systems, such as interferometers and collimation systems.