US Patent 8064137 Optical system for forming an image in space

An optical system that projects a real image to a location in free space and includes one or more features located along the optical path that enhance the viewability of the real image. The optical system includes a converging element for converging a portion of source light so as to form the real image. One viewability-enhancing feature is the use of a broadband reflector-polarizer having high transmitting and reflecting efficiencies. Another viewability-enhancing feature is the use of polarizing elements having substantially matched bandwidth responses and/or comprising an achromatic design. An additional viewability-enhancing feature is the use of a wide-view film to increase the viewing angle of the image.