Other

Bundesdruckerei Gmbh

Klaus Gnaedig

Guenther Dausmann

Thorstein Halldorsson

In a holographic screen for laser front projection, of at least one or more laser wavelengths that selectively back-scatter the incident spectrally narrow-band laser radiation in a predetermined solid angle and simultaneously highly absorbs the disturbing spectrally broad-band ambient light, it is proposed that it have at least one holographic volume grating that is optically coupled to a light absorber.

Screen for front laser projection

The invention concerns a holographic screen for the laser back-projection of at least one or a plurality of laser wavelengths, said holographic screen selectively and diffusely front-scattering the incident narrow-band laser radiation in a predetermined solid angle and simultaneously allowing through the disruptive spectrally broad-band ambient light from the observation area. To that end, the holographic screen comprises at least one holographic transmission grid which is coupled to a light absorber.

Screen for laser rear projection

A method for the production of holograms proof against copying and imitation possessing authenticity features, which are copies of a master hologram. In accordance with the invention as a master hologram a hologram of a randomly structured optical element, as for example a diffusion plate, which constitutes the authenticity feature, is recorded and each hologram copy produced from the master hologram is provided with a layer having at least one layer with a color succession and/or the hologram copy produced on a thick light sensitive layer is caused to shrink or to expand.

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Munich, Germany

Klaus Gnaedig