It is shown that a roof Dove prism is a typical circular beam deflector used in a transmitted parallel beam. Apparently, the importance of this prism is for its multifunction. However, it s unfavorable because of its high value of length-aperture ratio, which imposes restrictions on extending its application to many cases. To overcome the difficulty, a new type of roof Dove, i.e., a square- sectional roof Dove prism and its arrays are developed to reduce greatly the length-aperture ratio. In addition, Dove prisms are used in a certain kind of series of two to form a circular beam deflector. Arrays in the same kind of series also greatly reduce the length-aperture ratio. The potential of these new types of reflecting prisms and prism arrays will rely on the development of fabrication techniques as well as on further research.