HEAD-MOUNTED IMAGING DEVICE

An optical system is provided, for use in an electronic device, for example of the kind utilizing a head up display system. The optical system comprising: a light-transmitting waveguide substrate configured for receiving input light indicative of an image being projected, guiding said input light s by total internal reflection, and coupling the light out of the substrate to propagate along an output path in a predetermined direction; at least one transparent optical element accommodated in said output path and interfacing at least a portion of a surface of said waveguide substrate; an interface region between at least a portion of the surface of said waveguide substrate and a surface of the optical element being a patterned interface configured to provide optical coupling between the waveguide substrate and said optical element while maintaining the total internal reflection condition R of light propagation within said light-transmitting waveguide.