A comprehensive description of the polarization method of element multiplexing in FINCH is provided in Ref. 19. Here, it is reviewed with the help of Fig. 3, showing a FINCH system with an extra glass lens .21,24 An object point, positioned at a working distance from the objective lens , emits a spherical beam which is introduced into the system. An input polarizer, , oriented at an angle of 45 deg to the SLM active axis, allows the operation of two different imaging systems in the same physical single-channel setup. Only the beam polarization component parallel to the SLM active axis is converged by the diffractive lens. The orthogonal polarization component is not affected by the SLM at all. Hence, each of the two simultaneous imaging systems operates with one of two orthogonal polarization beams. For both imagers, the input beam is collected by the objective lens and is then focused to two different image points, at , for the imager in which the SLM-displayed diffractive lens is effective, and at , for the imager in which the SLM does not affect the beam. A digital camera, located between the two image points, records the interference pattern between a spherical beam converging toward and a spherical beam diverging from . The output polarizer, , usually oriented at an angle of 45 deg, projects the two orthogonal polarization components onto a common orientation in order to enable interference between the beams. The hologram digital reconstruction procedure is identical to the process done with the early FINCH versions mentioned above.