Sicpa Holding Sa

Ecole Polytechnique Federale De Lausanne

Romain Testuz

Yuliy Schwartzburg

Andrea Callegari

Mark Pauly

Pierre Degott

Todor Dinoev

Christophe Garnier

Alain Mayer

The invention relates to an anti-copy optical element comprising a caustic layer and a mask layer configured to simultaneously display a visible image reproducing a reference image and form a projected image containing a visible caustic pattern reproducing a reference pattern, upon illumination of the optical element with a light source, the projected image being distinct from the reference image. The invention also relates to a method for designing a relief pattern of a light-redirecting surface of said caustic layer consistently with the transmission properties of the mask layer.

Optical element and a method of visually authenticating an object

The invention relates to a thin optical security element comprising a reflective or refractive light-redirecting surface having a relief pattern operable to redirect incident light from a light source and form a projected image on a projection surface, the projected image comprising a caustic pattern reproducing a reference pattern that is easily visually recognizable by a person. The invention also relates to a method for designing a relief pattern of a light-redirecting surface of a thin optical security element.

Thin optical security element and method of designing it

The invention relates to a thin optical security element comprising a reflective or refractive light-redirecting surface having a relief pattern operable to redirect incident light from a light source and form a projected image on a projection surface, the optical parameters of this optical security element fulfilling a specific projection criterion such that the projected image comprises a caustic pattern reproducing a reference pattern that is easily visually recognizable by a person. The invention also relates to a method for designing a relief pattern of an optical security element.

Optical security element

Method of designing a refractive surface, comprising providing a refractive object having a refractive surface with an initial geometry, determining a refraction of incident illumination through the refractive surface with the initial geometry to create a source irradiance Edistribution on a receiver; and determining a shape of the refractive surface of the refractive object such that a resulting irradiance distribution on the receiver matches a desired target irradiance Eprovided by a user.

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Lausanne, Switzerland

Romain Testuz