An IR and/or UV machine-readable optical security device (e.g., micro-optic security thread) that is made up of at least one IR-absorbing component with a characteristic IR signature detectable at two or more IR-wavelengths, at least one UV-absorbing component with a characteristic UV signature detectable at two or more UV-wavelengths, at least one IR-absorbing component that absorbs IR light and emits light at a different invisible wavelength, at least one UV-absorbing component that absorbs UV light and emits light at a different invisible wavelength, or a combination thereof, is provided. The IR and UV machine-readable features do not interfere with the optical effects projected by the optical material.

An IR and/or UV machine-readable optical security device (e.g., micro-optic security thread) that is made up of at least one IR-absorbing component with a characteristic IR signature detectable at two or more IR-wavelengths, at least one UV-absorbing component with a characteristic UV signature detectable at two or more UV-wavelengths, at least one IR-absorbing component that absorbs IR light and emits light at a different invisible wavelength, at least one UV-absorbing component that absorbs UV light and emits light at a different invisible wavelength, or a combination thereof, is provided. The IR and UV machine-readable features do not interfere with the optical effects projected by the optical material.

A multispectral watermark and method for generating the multispectral watermark. A color pattern can be provided, which appears a single color/pattern under a first lighting condition. A watermark can be created based on the color pattern and under a second lighting condition comprising ultraviolet light, while the watermark is viewable with an infrared camera in an infrared spectrum. The watermark can be configured as a multispectral watermark with a metameric pair of inks with one ink of the metameric pair of inks using more CMYK toners that reflect in the infrared spectrum as compared to the other ink among the metameric pair of inks while simultaneously allowing more of the ultraviolet light or less of the ultraviolet light to reach a fluorescing media upon which the multispectral watermark is rendered.

A multispectral watermark and method for generating the multispectral watermark. A color pattern can be provided, which appears a single color/pattern under a first lighting condition. A watermark can be created based on the color pattern and under a second lighting condition comprising ultraviolet light, while the watermark is viewable with an infrared camera in an infrared spectrum. The watermark can be configured as a multispectral watermark with a metameric pair of inks with one ink of the metameric pair of inks using more CMYK toners that reflect in the infrared spectrum as compared to the other ink among the metameric pair of inks while simultaneously allowing more of the ultraviolet light or less of the ultraviolet light to reach a fluorescing media upon which the multispectral watermark is rendered.

Device for detecting reactive luminescent particles embedded in a substrate or surface having an infrared or ultraviolet illuminator; a near-infrared photodiode sensor; a dark chamber, inside which the illuminator and photodiode sensor are mounted; a logarithm amplifier; an electronic data processor configured to detect the reactive luminescent particles by carrying out the steps of: illuminating the substrate or surface with the illuminator; acquiring the amplified linearized signal captured by the photodiode sensor; detecting the presence of luminescent particles in the substrate or surface from the linearized decay of the acquired signal. A further near-infrared photodiode sensor, a further logarithm amplifier, and a differentiator for obtaining a difference between amplified signals received by each photodiode sensor can be utilized.

Device for detecting reactive luminescent particles embedded in a substrate or surface having an infrared or ultraviolet illuminator; a near-infrared photodiode sensor; a dark chamber, inside which the illuminator and photodiode sensor are mounted; a logarithm amplifier; an electronic data processor configured to detect the reactive luminescent particles by carrying out the steps of: illuminating the substrate or surface with the illuminator; acquiring the amplified linearized signal captured by the photodiode sensor; detecting the presence of luminescent particles in the substrate or surface from the linearized decay of the acquired signal. A further near-infrared photodiode sensor, a further logarithm amplifier, and a differentiator for obtaining a difference between amplified signals received by each photodiode sensor can be utilized.

An optical marking device including at least a first layer and a second layer disposed at least partially opposite each other, at least one of the first and second layers having an optically variable element being able to change colour between a first colour and a second colour, the first and second colours contrasting from a colour of the other layer in such a way that when the optically variable element displays the first colour, the first layer is visible and when the optically variable element displays the second colour, the second colour is visible, or when the optically variable element displays the first colour, the second layer is visible and when the optically variable element displays the second colour, the first layer is visible.

An optical marking device including at least a first layer and a second layer disposed at least partially opposite each other, at least one of the first and second layers having an optically variable element being able to change colour between a first colour and a second colour, the first and second colours contrasting from a colour of the other layer in such a way that when the optically variable element displays the first colour, the first layer is visible and when the optically variable element displays the second colour, the second colour is visible, or when the optically variable element displays the first colour, the second layer is visible and when the optically variable element displays the second colour, the first layer is visible.

A security document includes a security feature with a hologram and a color image arranged on top of each other. Holographic features of the hologram are visible when the security document is viewed under white light, and a plurality of image features of the color image are visible when the document is viewed under UV light. The image features are perfectly aligned with the holographic features. This can be achieved, for example, by providing one or more registration marks when forming the holographic features, and using said registration marks to later print the color image. Another possibility is to use the structure of the hologram to selectively apply two or more UV-sensitive ink materials onto the hologram to automatically align the same with the holographic features.

A security document includes a security feature with a hologram and a color image arranged on top of each other. Holographic features of the hologram are visible when the security document is viewed under white light, and a plurality of image features of the color image are visible when the document is viewed under UV light. The image features are perfectly aligned with the holographic features. This can be achieved, for example, by providing one or more registration marks when forming the holographic features, and using said registration marks to later print the color image. Another possibility is to use the structure of the hologram to selectively apply two or more UV-sensitive ink materials onto the hologram to automatically align the same with the holographic features.