Abstract: The present disclosure provides a display system. The display system includes a backlight configured to emit substantially collimated polarized light from an emission surface thereof. The emitted polarized light is polarized along a polarization direction. The display system further includes a display panel configured to receive an illumination light and form an image. The display system further includes a grating system substantially coextensive in length and width with the display panel and the emission surface. The grating system includes a plurality of substantially parallel elongated features extending along an in-plane first direction and arranged along an orthogonal in-plane second direction. The grating system is configured to receive and transmit an incident polarized light as a first transmitted light having different first and second polarization states in response to different respective first and second signals applied to the grating system.

Abstract: A security door stop bolt mounted in the floor preventing entrance through the door including a tube housing imbedded in the floor with a door stop sliding in the tube, nestled in the tube when not in use but raised with a manual lifting means to prevent inadvertent triggering of the stop bolt with a carpet cut out attached to the top of the door stop to hide the entire mechanism.