Projecting images

摘要

An "extra-folded" projection display system includes a selectively reflective material (e.g., a linear reflecting polarizer) placed immediately behind the system's imaging screen. The display system includes an image projector that projects an image beam containing light of a predetermined linear polarization toward the imaging screen. The linear reflecting polarizer reflects the light in the image beam away from the screen. The reflected image beam then encounters a 1/4-wavelength achromatic retarder which converts the linear polarization to circular polarization. The image beam next hits a mirror that reflects the light back through the 1/4-wavelength achromatic retarder, which converts the circular polarization back to linear polarization, with the polarization director rotated 90 DEG from the original polarization director. The linear reflecting polarizer then allows the light to pass through to the image screen. <IMAGE>