Penta prisms are five-sided prisms，featuring deviates an input beam or image through 90° without inverting or reversing the image. Slight movement of the prism does not affect the true right angle at which light rays are reflected, making a penta prism the ideal optical tool for defining a right angle in an optical system. The prisms most sold available in three different sizes (10.0 mm, 15.0mm or 20.0mm).
Additionally, the reflected beam will experience a change in its polarization state when propagated through a penta prisms.
These prisms are fabricated from N-BK7, UV fused silica, etc
They can be AR coated on the incidence face and output face and metal coated with black painting on the two reflective faces.