High-light-efficiency light modulation device and high-light-efficiency (3-dimensional) 3D projection system

The invention provides a high-light-efficiency light modulation device and is applicable to the technical field of 3D (3-dimensional) projection display. The high-light-efficiency light modulation device comprises a polarization light splitting device, wherein the polarization light splitting device is used for splitting incident light into a transmission light beam and a reflection light beam with mutually vertical polarization states, a first liner polarizer and a first quarter wavelength delay membrane are sequentially arranged on a transmission light beam light path, a reflector, a second linear polarizer and a second quarter delay membrane are sequentially arranged on a reflection light beam light path, the reflector is used for changing the spread direction of the reflection light beam, and a polarization direction converting device and a lens/ lens group are also arranged on the transmission light beam light path or the reflection light beam light path. The high-light-efficiency light modulation device has the advantages that the polarization light splitting device with small chromatic dispersion and high polarization converting efficiency is used for splitting the incident light into two beams of light rays with different polarization states, then, a twisted liquid crystal device is used for regulating the polarization state of one beam of light ray, finally, two beams of light rays on a projection screen are coincided, and the light utilization rate and the brightness of the projection display frame are improved.