An interference structure having a nanovoided hologram material is described. The nanovoided hologram material may have an index of refraction difference of approximately 0.4. The interference structure may include about 10% to 90% nanovoids by volume. The interference structure may be formed using a mixture of a monomer, an initiator, and solvent. The mixture may be disposed on a substrate and irradiated with two sources of light spaced apart from each other and shining on the same region of the mixture to generate an interference pattern in the mixture, leading to the selective polymerization of regions of the mixture where there is constructive interference of light. Various other devices, methods, and systems are also disclosed.

A process of forming an identification marking within article formed from an at least partially optically transparent material for identification and validation, said process including the steps of (i) forming an indicia with an at least partially optically transparent material by way of subsurface laser engraving (SSLE); and (ii) forming a plurality of defects within or adjacent indicia within said at least partially optically transparent material resultant of the step of forming the indicia and from localized heating and irregularities in said at least partially optically transparent material, wherein said plurality of defects forms said identification marking

A method and apparatus for in-line manufacture of a security document with a structured security element is provided in which a continuous web of document substrate is fed through a series of processing stations. The processing stations include a station for forming a structured security element in a radiation sensitive coating applied to the document substrate, and at least one station for applying at least one additional layer to the document substrate excluding the security element area. In a security document manufactured with the method or apparatus, the additional layer or layers have a combined thickness which is preferably substantially equal to the height of the structured security element or which differs from the height of the structured security element by a predetermined amount.

Waveguide based displays benefit from gratings which are capable of diffracting both S and P polarized light with high efficiency. While typical surface relief gratings (SRGs) diffract P polarized light efficiently, SRGs do not typically diffract S polarized light efficiently. One class of gratings that diffracts S polarized light with high efficiency is deep SRGs. One approach to producing deep SRGs is holographic polymer dispersed liquid crystal (HPDLC) gratings. In producing HPDLC gratings, a reactive monomer mixture is exposed to light in a polymerization process. Reactive monomer mixtures may include co-initiators and photo-initiator dyes. Co-initiators which include liquid amine synergist have been demonstrated to have advantageous results. Further, photo-initiator dyes with high extinction coefficients have demonstrated advantageous results.

A process of forming an identification marking within article formed from an at least partially optically transparent material for identification and validation, said process including the steps of (i) forming an indicia with an at least partially optically transparent material by way of subsurface laser engraving (SSLE); and (ii) forming a plurality of defects within or adjacent indicia within said at least partially optically transparent material resultant of the step of forming the indicia and from localized heating and irregularities in said at least partially optically transparent material, wherein said plurality of defects forms said identification marking.

A method and apparatus for in-line manufacture of a security document with a structured security element is provided in which a continuous web of document substrate is fed through a series of processing stations. The processing stations include a station for forming a structured security element in a radiation sensitive coating applied to the document substrate, and at least one station for applying at least one additional layer to the document substrate excluding the security element area. In a security document manufactured with the method or apparatus, the additional layer or layers have a combined thickness which is preferably substantially equal to the height of the structured security element or which differs from the height of the structured security element by a predetermined amount.