A video conferencing system , comprising: a waveguide having an input edge and a viewing surface , the waveguide being configured to receive a display image at the input edge and output the display image from the viewing surface; a projector positioned to project the display image into the input edge, through the waveguide, and out of the viewing surface; a camera positioned to view a camera image traveling into the viewing surface and through the waveguide; a screen substantially covering the viewing surface of the waveguide and configured to selectively switch between a substantially transparent state and a light-scattering state, where the screen includes a polymer stabilized cholesteric textured liquid crystal optical shutter; and a sync system configured to cause the screen to alternate between the substantially transparent state and the light-scattering state, configured to cause the camera to view the camera image while the screen is in the substantially transparent state, and configured to cause the projector to project the display image into the input edge while the screen is in the light-scattering state, where the sync system is configured to dynamically adjust a ratio of time the screen is in the transparent state relative to a time the screen is in the light-scattering state responsive to changes in an ambient brightness, further comprising a face detection system configured to locate a face in the display image and align eyes of the face with the camera, wherein the camera's position and orientation is aligned with the eyes of a face displayed on the screen, such that the camera has the same view as the eyes of the face being displayed, wherein the optical axis of the camera is perpendicular to a viewing surface of the screen and wherein the optical axis of the camera intersects the screen in a point positioned between the eyes of the face, where the camera is moved to align eyes of the face with the camera. a waveguide having an input edge and a viewing surface , the waveguide being configured to receive a display image at the input edge and output the display image from the viewing surface; a projector positioned to project the display image into the input edge, through the waveguide, and out of the viewing surface; a camera positioned to view a camera image traveling into the viewing surface and through the waveguide; a screen substantially covering the viewing surface of the waveguide and configured to selectively switch between a substantially transparent state and a light-scattering state, where the screen includes a polymer stabilized cholesteric textured liquid crystal optical shutter; and a sync system configured to cause the screen to alternate between the substantially transparent state and the light-scattering state, configured to cause the camera to view the camera image while the screen is in the substantially transparent state, and configured to cause the projector to project the display image into the input edge while the screen is in the light-scattering state, where the sync system is configured to dynamically adjust a ratio of time the screen is in the transparent state relative to a time the screen is in the light-scattering state responsive to changes in an ambient brightness, further comprising a face detection system configured to locate a face in the display image and align eyes of the face with the camera, wherein the camera's position and orientation is aligned with the eyes of a face displayed on the screen, such that the camera has the same view as the eyes of the face being displayed, wherein the optical axis of the camera is perpendicular to a viewing surface of the screen and wherein the optical axis of the camera intersects the screen in a point positioned between the eyes of the face, where the camera is moved to align eyes of the face with the camera. <EOS>