A display comprises a backlight comprising a plurality of
individually-controllable light emitters, a light modulator comprising a
plurality of individually-controllable elements, and, a retro-reflective
optical layer positioned between the backlight and the light modulator.
The retro-reflective optical layer is configured to pass light incident
thereon at an angle with respect to a normal to the retro-reflective
optical layer of less than a threshold angle .phi., and reflect light
incident thereon at an angle with respect to a normal to the
retro-reflective optical layer of greater than .phi. in a direction
opposite and generally parallel to an incoming direction of incident
light.