A projection-type display device is connectively coupled to a mobile device (such as a smartphone) where the light generated by a small projection device is directed at a relatively transparent holographic optical element (HOE) to provide a display to an operator of the mobile device or a viewer. The projector and HOE may be configured to produce and magnify a virtual image that is perceived as being displayed at a large distance from the operator who views the image through the HOE. The HOE may comprise a volume grating effective at only the narrow wavelengths of the projection device to maximize transparency while also maximizing the light reflected from the display projector to the eyes of the operator.