US Patent 7259899 Narrow angle hologram device and method of manufacturing same

A method of manufacturing a master for producing a hologram device. A first master is produced with a compensating angle. The second master is produced from the first master with an index matching material to reduce the interference pattern caused by internal reflections within the holographic plate of the master. The hologram device has a relatively narrow angle of reconstruction to provide visibility from a nearly perpendicular light source such as the headlight of an on-coming vehicle.