A holographic display element for three-dimensionally displaying a three-dimensional model and a plane image, for example, in a superimposed manner, which is prevented from causing a change in color or a reduction in contrast of the foreground pattern at an overlap between the foreground pattern and...http://www.google.co.uk/patents/US6687031?utm_source=gb-gplus-sharePatent US6687031 - Holographic display element and method of making the same
