Security device

-85. (canceled)

A device comprising a luminescent material, which, when stimulated, emits luminescent radiation, and an optically variable structure, which controls the intensity of emission of said luminescent radiation from said device with angle of emission of said luminescent radiation from said device, based on the wavelength of said luminescent radiation.

-102. (canceled)

A security device including an optically variable structure comprising first and second opposed electromagnetic radiation transmissive interfaces,

• an electromagnetic radiation transmissive medium between said first and second interfaces, and control means for controlling the intensity of radiation emitted from one of said first and second interfaces that is passed through the other of said first and second interfaces and said medium and the emission angle of said electromagnetic radiation from said security device, based on the wavelength of said electromagnetic radiation.

-112. (canceled)

A device comprising:

• luminescent means, which, when stimulated, produces luminescent radiation of first and second wavelengths, the second wavelength being different to the first wavelength, said luminescent means including a luminescent material;
• and
• an optically variable structure for controlling emission of luminescent radiation of at least one of the first and second wavelengths from the device, the device being arranged to permit, from within an area of the optically variable structure, emission of luminescent radiation of the first and second wavelength from the device, wherein the optically variable structure is arranged to cause, from said area, the relative emissivity of the device for luminescent radiation of the first and second wavelengths to change with at least one or both of (1) a change in emission angle of luminescent radiation from said device and (2) a change in the direction or angle of incidence of stimulating radiation on said device for stimulating said luminescent means.

A method of authenticating a security device which includes a luminescent material, which, when stimulated, produces luminescent radiation of first and second wavelengths, the second wavelength being different to the first wavelength, the method comprising the steps of:

• exposing the security device to stimulating radiation for stimulating the luminescent material to produce luminescent radiation of the first and second wavelengths, and observing or detecting in the luminescent radiation from the security device a change in intensity of luminescent radiation of the first or second wavelengths relative to the intensity of the luminescent radiation of the other of the first or second wavelengths with at least one or both of (1) a change in emission angle from the security device and (2) a change in direction or angle of incidence of stimulating radiation on the security device for stimulating said luminescent material.

A method of authenticating a security device which includes a luminescent material, the method comprising the steps of exposing said security device to stimulating radiation for stimulating said luminescent material to produce luminescent radiation and observing a colour shift in the luminescent radiation from said security device with at least one of (1) a change in emission angle from said security device and (2) a change in the direction or angle of incident stimulating radiation on said security device.

(canceled)

(canceled)

A method of authenticating a security device, the security device having first and second opposed electromagnetic radiation transmissive interfaces and an electromagnetic radiation transmissive medium between said first and second interfaces, the method comprising the steps of exposing said first interface to electromagnetic radiation and observing or detecting from the second interface a change in relative intensities of first and second wavelengths of radiation emitted from the security device with a change in emission angle from said security device.

-123. (canceled)