To develop a 3D display which can show true 3D images is very important and necessary. Holography has great potential to achieve the objective because holography can actually reconstruct the recorded object in space by reconstruction of wavefront. Further, computer generated hologram (CGH) is used to solve the major issue of conventional holography, which means the recoding process is quite complicated and needs the real objects. The reconstructed image, however, will be blurred and with the unexpected light if using only one phase-only spatial light modulator (PSLM). Although to use two PSLMs by dual-phase modulation method (DPMM) can modulate the phase and the amplitude information simultaneously to enhance the quality of the reconstructed image, it is hard to use in practical application because of the extremely high accurate calibration of the two PSLMs. Therefore, double phase hologram (DPH) was proposed to use only one PSLM to modulate the phase and the amplitude information simultaneously to make the reconstructed image be more focused and eliminate the unexpected light.