“modulate” means to vary a property of something. Light can be modulated temporally or spatially. Example properties of light that may be modulated include amplitude (brightness or intensity), phase and polarization state. Spatial modulation of light can be achieved by selectively attenuating light at spatial locations (e.g. pixels) and/or by steering light. Light steering involves steering light that would otherwise illuminate some spatial locations to other spatial locations. Light steering may be achieved, for example, using variable lenses, variable mirrors and/or phase