Light beam rotary apparatus and method capable of compensating intensity variation caused by polarization

The invention relates a beam rotating device with intensity changed by compensable polarization and a method, belonging to the field of optical technology. The device consists of a polarizing splitting prism, a 1/4 wave plate, a double refracted wave wafer and a porro prism. The invention adopts the revolving porro prism to realize the rotation of beams and adopts the double refracted wave wafer to compensate the porro prism, so as to eliminate the fluctuation of beam intensity caused by resolving the porro prism and further realize beam rotation without changing beam intensity. The inventionhas an application value in the field of optical information processing.